Improve Your Vision Without Glasses or Contact Lenses

Easy Clear Vision Ebook

Dr. Benjamin Miller says that the steps given in the Easy Clear Vision guide make it is possible to get perfect 20/20 vision without wearing unattractive & highly breakable glasses or uncomfortable & even painful contact lenses and without undergoing any risky & expensive eye surgery. Further he explains that you dont have to invest anything in vision enhancing products once you follow the steps in his guide. The concept of exercising eye muscles is not new at all. Dr. Bates strategy had some major flaws. You see, it was based upon the incorrect concept that the eyeball altered its shape when focusing on various objects. Given that this theory was disapproved, it has been looked at as inefficient as well as potentially hazardous. It just attended to nearsightedness and not farsightedness. Dr. Benjamin created this program in effective and natural way. You dont need any surgery or medicines to improve your eyesight. We all know that eye muscles can be trained. Doctors also agreed that eye exercises can improve the eyesight. Muscles can increase their functionality if they subjected to exercise and eye muscles are not different.

Easy Clear Vision Overview

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Form Deprivation Myopia

Increased synthesis and accumulation of aggrecan, which increases the volume of extracellular matrix in the posterior sclera, are responsible for the ocular enlargement observed in form-deprived chick myopia (161). Synthesis of scleral proteoglycans including aggrecan is higher during the day than at night, but there are no significant differences between rhythms in scleras from normal and form-deprived eyes (162). The turnover rate of scleral proteoglycans is vision-dependent and is accelerated in the posterior sclera during the development of experimental myopia (163). Treatment with beta-xyloside, a specific inhibitor of proteoglycan synthesis, results in a significant reduction in the axial length, vitreous chamber depth and rate of axial elongation of form-deprived eyes (164).

Dyschromatopsias Associated with Neuro Ophthalmic Disease

Lanthony Desaturated

People with congenital dyschromatopsias are frequently not aware that their color perception differs from those with normal, trichromatic color vision. Others have learned to adapt to their limited perception of certain colors. Thus, a person with faulty red green color discrimination will often describe a dark green color as red. Some of these people know that they cannot properly identify colors accurately in certain ranges of hue and luminance. Patients with acquired dyschromatopsias are often unaware of the changes in their color perception, due to the subtle onset and gradual progression of the damage. Not infrequently, this allows major color vision disturbances to go unnoticed. Unilateral dyschromatopsias - if not associated with cataract - should be examined with tests of color saturation in the affected eye, since this is frequently the clinical presentation for an optic neuropathy. Other neuro-ophthalmic disorders (see Table 6.1) should initiate a targeted search for an...

Micronutrients Cataracts

For prevention of cataract cataractdevelop- Fig. 5.2 Vitamin Eand cataracts. Among 300 individuals taking supplemental vitamin E (> 400 mg day), the prevalence of cataract was 56 lower than in those not consuming supplements. Another study found the prevalence of nuclear cataract in 671 adults to be 48 less among individuals with higher plasma concentrations of vitamin E.

Vision and Eye Disorders

The two most important aspects of vision in relation to driving are visual acuity and visual fields. Visual acuity may simply be defined as the best obtainable vision with or without spectacles or contact lenses. Most countries require a binocular visual acuity greater than 6 12 for licensing purposes. In the United Kingdom, the eyesight requirements are to read a car number registration plate at 20.5 m, which corresponds to between 6 9 and 6 12 on the Snellen chart. The minimum field of vision for safe driving is generally regarded as at least 120 on the horizontal when measured with a Goldman IV4e target or its equivalent (14).

Ophthalmologic Applications

Light that penetrates into the eye is partially refracted in the cornea, passes through the aqueous humor and the pupil (the opening in the center of the iris), is further refracted in the crystalline lens, passes through the vitreous humor, and converges on the retina (Fig. 1), Diverse polymeric devices, such as spectacles, contact lenses, and intraocular implants, are used to correct the optical function of the eye. The materials used in spectacle lenses are outside the scope of this chapter. Contact lenses, however, being in intimate contact with the tissues of the eye, are subject to the same regulations that govern the use of implant materials, and they are included in this chapter with other biomaterials used to preserve and to restore vision, such as intraocular implants.

Implants for glaucoma

Polymeric devices are used to control abnormally high intraocular pressure in otherwise intractable glaucoma (Krupin et al., 1988). These devices consist essentially of tiny tubes that transport the aqueous humor which normally maintains the physiological intraocular pressure and flows in and out of the eye in a well-regulated manner from the anterior chamber to some artificially created space between the sclera and the other tissues that surround the eyeball then the aqueous humor is absorbed into the blood circulation. The main problem with glaucoma implants is tissue proliferation around the outlet of the plastic device. Tissue proliferation, or capsule formation, takes place in and around all implanted biomatenals and may retard or even stop the outflow of aqueous humor from the eye.

Sulfonamides In The Treatment Of Glaucoma

Glaucoma is a chronic, degenerative eye disease, characterized by high IOP, which causes irreversible damage to the optic nerve head, and, as a result, the progressive loss of visual function and eventually blindness (Bartlett and Jaanus 1989 Maren 1992, 1995). Elevated IOP (ocular hypertension) is generally indicative of an early stage of the disease (Bartlett and Jaanus 1989 Soltau and Zimmerman 2002 Hoyng and Kitazawa 2002). CAIs represent the most physiological treatment of glaucoma, because by inhibiting the ciliary process enzyme (the sulfonamide susceptible isozymes CA II and CA IV), a reduced rate of bicarbonate and aqueous humor secretion is achieved, which leads to a 25 to 30 decrease in IOP (Maren 1967, 1992, 1995). Acetazolamide 8.1, methazolamide 8.2, ethoxzolamide 8.3 or dichlo-rophenamide 8.4 were and are still extensively used as systemic drugs in the therapy of this disease (Maren 1967 Supuran and Scozzafava 2000, 2001, 2002 Supuran et al. 2003), as they all act as...

Soft Hydrogcl Contact Lenses

The soft hydrogcl contact lenses (SCL) are supple and fit snugly on the corneal surface. Because there is little tear exchange under these lenses, most of the oxygen that reaches the cornea must permeate through the lens. The oxygen permeability coefficient of hydrogel materials increases exponentially with the water content. The hydrogel lenses are made of slightly cross-linked hy-drophilic polymers and copolymers. The original hydrogel contact lens material was poly(2-hydroxyethyl methacrylate) (PHEMA) (Wichterle and Lim, I960) at equilibrium swelling in physiological saline solution, it contains about 40 water of hydration. (Hydration of hydrogel contact lenses is customarily given as a percentage of water by weight, on a wet basis.) The oxygen transmissibil ity of the original rather thick PHEMA hydrogel contact lenses was found to be insufficient for normal corneal metabolism. New hydrogel contact lenses were soon developed with higher water content or with a water content...

Applications of Physicochemical Properties of Hyaluronan A Cataract Surgery

The use of viscoelastic materials in surgery is based on a general concept of solving problems that occur during cataract surgery (6). In this case, viscoelastic materials protect the endothelial layer of the cornea from damage during phacoemulsification and aspiration and maintain operative space. Two types of HA are used in cataract surgery higher molecular weight HA (1900-3900 kDa) and lower molecular weight HA (600-1200 kDa). The former has high viscoelasticity and is mainly used to maintain operative space. The latter has higher dispersity and is mainly used to protect the endothelial layer. HA has now become indispensable in cataract surgery (7).

Glaucoma

Cannabis smoking and the oral ingestion of several of its derivatives have been shown to cause an appreciable drop in intraocular pressure (Hepler and Frank, 1971 Cooler and Gregg, 1976 West and Lockhart, 1978) and it is known that patients with open angle closure glaucoma smoke cannabis for this purpose. When smoked, cannabis containing the equivalent of 20-30 mg of THC has been shown to lower intraocular pressure in an heterogeneous group of glaucoma patients (Crawford and Merritt, 1979) and more specifically, patients with open angle glaucoma (Merritt et al., 1979, 1981a). However, the treatment was not without side effects six of 32 patients developed severe systemic hypotension this was significantly greater in hypertensive glaucoma patients (Crawford and Merritt, 1979). Cannabis caused a dose-related, clinically significant, reduction in intraocular pressure of 2530 , occurring at 1 hour and lasting 5-6 hours, which was discrete from the sedative effects of the drug. Orthostatic...

Eye Problems

IFN has been associated with multiple neurovisual complications. The most common ocular complication associated with IFN use has been the development of a mild-to-moderate ischemic retinopathy (22-27). On fundoscopy, this manifests as cotton-wool spots or hemorrhage, which is similar to diabetic retinopathy. The reported incidence of this retinopathy has varied greatly in different series (2-86 ), but most cases are not associated with significant visual loss. Several cases of glaucoma have also been reported in association with IFN therapy, but a causative association remains unproven. Several case reports have also described a toxic effect of IFN on the optic nerve, in which patients presented with blurred vision similar to that seen with optic neuritis. Measurement of visually evoked response, in the subgroup of patients treated with chronic IFN therapy for hepatitis C, disclosed some patients with an increased latency in the visually evoked response (23). These patients had no...

Diet Healthy Eyes

To maintain good eyesight foods rich in vitamins A, C, E, riboflavin, selenium, and zinc should be consumed. All these nutrients are important for vision and are supplied by a balanced diet with generous amounts of fruits and vegetables, such as carrots, cantaloupe, oranges, and broccoli. Generous intake of antioxidant nutrients (see pp. 115) over a lifetime may help prevent cataract, the most common cause of impaired vision in older adults.1 Age-related macular degeneration (AMD) is a common cause of vision impairment in older people, and the risk of AMD can be reduced by a diet high in antioxidants, ca-rotenoids, and zinc.2 3 Nutrient supplementation may help correct minor eye troubles such as dry, burning, itchy eyes and eyestrain.

Diet Cataracts

Most cataracts are caused by oxidative damage from lifetime exposure of the lens to light and radiation entering the eye. The antioxidant vitamins A, C, and E are a major defense against oxidative damage, and eating foods rich in these nutrients each day can reduce the risk of cataract (see Fig. 5.2).1 Regular consumption of galactose, found in the milk sugar lactose, may cause cataracts in people with inherited defects in galactose metabolism. In cases of an inability to metabolize galactose, milk and dairy product consumption should be sharply restricted. Hyperlipidemia, diabetes, and obesity also increase the risk of cataract. All these conditions are modifiable by dietary changes and nutritional supplementation.

Rigid Contact Lenses

The rigid contact lenses, as well as the FFP lenses, fit loosely on the cornea and move with the blink more or less freely over the tear film that separates the lens from the corneal surface. The mechanical properties of rigid and FFP contact lenses must be such that any flex on the lens provoked by the blink must recover instantaneously at the end of the blink. The first widely available contact lenses were made of poly-(methyl methacrylate), which is an excellent optical biomaterial in almost all respects except for its virtual impermeability to oxygen. Several materials that were specially developed for the manufacture of rigid gas-permeable (RGP) contact lenses are copolymers of methyl methacrylate with siloxanylalkyl meth-acrylates (Refojo and Dabezies, 1984). To compensate for the hydrophobic character imparted to the polymer by the high siloxane content of these copolymers (required for oxygen permeability), the copolymer also contains some hydrophilic com-onomers. The most...

Visual Loss of Uncertain Origin Diagnostic Strategies

The practicing ophthalmologist faces a common challenge on a daily basis A patient's vision is worse than was expected, based on the appearances of the initial examination. Usually, a renewed and more careful examination explains the discrepancy. Often, however, additional examination finds nothing to explain the conflicting findings. Time is limited, and one is tempted to refer the patient to a neurologist or another ophthalmic service. The diagnostic modalities available at the next site often lead to an unguided attempt at diagnosis when it is felt that some sort of explanation for the visual loss must be found. This scenario can be both expensive and dangerous, subjecting the patient to a random wandering through neurodiagnostic procedures. At the end of this process, the patient is unsatisfied and anxiety ridden and returns to the ophthalmologist or seeks the counsel of other physicians or even alternative medicine practitioners. If the ophthalmologist wishes to find the correct...

The Comprehensive Physical Examination

Head, Eyes, Ears, Nose, Throat (HEENT). Head Examine the hair, scalp, skull, and face. Eyes Check visual acuity and screen the visual fields. Note the position and alignment of the eyes. Observe the eyelids and inspect the sclera and conjunctiva of each eye. With oblique lighting, inspect each cornea, iris, and lens. Compare the pupils, and test their reactions to light. Assess the extraocular movements. With an ophthalmoscope, inspect the ocular fundi. Ears Inspect the auricles, canals, and drums. Check auditory acuity. If acuity is diminished, check lateralization (Weber test) and compare air and bone conduction (Rinne test). Nose and sinuses Examine the external nose using a light and a nasal speculum, inspect the nasal mucosa, septum, and turbinates. Palpate for tenderness of the frontal and maxillary sinuses. Throat (or mouth and pharynx) Inspect the lips, oral mucosa, gums, teeth, tongue, palate, tonsils, and pharynx. (You may wish to assess the cranial nerves during this...

Recommended Daily Intakes

The usual therapeutic dose range is 15-45 mg day.10 Carotene supplements derived from natural sources are preferable. They contain, along with beta-carotene, a mixture of carotenoids, including lutein, alpha-carotene, and lycopene, and may have additional health benefits. For example, ly-copene is a potent antioxidant11 and may decrease the risk of prostate cancer and cataract.

Biochemical Parameters of Nutrition in the Elderly

And metabolism should be studied more closely. Vitamins that act as antioxidants appear to have a role in preventing coronary artery disease and cancer 53 . Current work is focusing on the actions of vitamins as related to immune function, the formation of cataracts, and the development of osteoporosis, all associated with ageing 53 . The Food and Nutrition Board, the Institute of Medicine, and the National Academy of Science and Health of Canada have recently developed a standard set of nutrient recommendations, known as dietary reference intakes (DRIs), which has added, with regard to vitamin intakes, the groups for ages 51-70 years and for 70 years and older 54 . These recommendations are listed in Table 3 54 .

Overview of Carotenoid Function in the

It has long been recognized that carotenoids may have an important role in ocular physiology. As far back as the 18th century anatomists noted that the primate fovea, the region of the retina responsible for high-resolution visual acuity, displayed a deep yellow coloration that they termed the macula lutea or yellow spot (2). In 1945, George Wald studied organic extracts of primate macular tissue and determined that the macular yellow pigment had spectro-scopic and chemical features characteristic of xanthophyll carotenoids, ubiquitous plant derived carotenoids containing at least one oxygen atom along the core C40H56 isoprenoid carotene structure (3). Several decades later, Bone and Landrum preliminarily identified the macular carotenoids as lutein and zeaxanthin (4), and in a follow-up investigation, they were able to demonstrate the stereochemical nature of the macular pigment as a mixture of dietary (3R,3'R,6'R)-lutein, dietary (3R,3'R)-zeaxanthin, and nondietary (3R,30...

Pilocarpine and Analogs and Congeners

(167) to rationalize pilocarpine's pharmacologic properties. The potential utility of pilocarpine in treatment of glaucoma is limited by its low ocular bioavailability. A double prodrug strategy (168, 169) involves hydrolytic cleavage of the lactone ring of pilocarpine and esterification of the freed carboxyl and alcohol groups (129) to produce derivatives with a greatly enhanced lipophilic character. In the presence of human plasma or rabbit eye ho-mogenates, pilocarpine was reformed from these derivatives in quantitative amounts because of the action of tissue esterases.

Use in Prevention and Therapy

Riboflavin functions as an antioxidant throughout the body and may be especially important in the lens of the eye. Ample intake of riboflavin can reduce the risk of developing cataract. As a cofactor of glutathione reductase, riboflavin helps maintain the body's supply of reduced glutathione, an important antioxidant.1

Bruckner Test Strabismus

Ckner Test

High hyperopia Hyperopia of less than 3 D High astigmatism Astigmatism of less than 2 D the patient with an injury or an episode of inflammatory activity plausibly associates the cause of the poor vision. In all likelihood, the event was only a cause for drawing attention to the eye and discovery of its poor acuity. Not uncommonly, the history given by the patient and the patient's family can be useless. Some patients even forget that they have had strabismus surgery. Patient questioning and verification of the information (when possible) is needed. If the Lang stereotest finds evidence of good stereopsis, one can rule out strabismic amblyopia and or microstrabismus (even though occasional exceptions are found). Bilateral amblyopia must have a convincing cause very high hyperopia, high corneal astigmatism, ocular malformations. A myopic eye (or the more myopic of a pair) only rarely develops a refractive amblyo-pia if the refractive error is not extreme. A dominant eye cannot be...

Les Enantiomeres Du Carteolol

Albuterol Sulfate Reaction

Imidazolines apraclonidine (33) and bri-monidine (34) are selective a,-agonists employed topically in the treatment of glaucoma. Stimulation of a,-receptors in the eye reduces production of aqueous humor and enhances outflow of aqueous humor, thus reducing intraocular pressure. Brimonidine is substantially more selective for a,-receptors over ax- 2.1.8 Applications of -Antagonists. p-An-tagonists are among the most widely employed antihypertensives and are also considered the first-line treatment for glaucoma. There are 16 j3-blockers listed in Table 1.1 and 15 of them are in the chemical class of aryloxypro-panolamines. Only sotalol (25) is a phenylethylamine. Acebutolol (45), atenolol (46), biso-prolol (48), metoprolol (53), nadolol (54), penbutolol (55), pindolol (56), and proprano-are used to treat hypertension but not glaucoma. Betaxolol (47), carteolol (49), and timolol (58) are used both systemically to treat hypertension and topically to treat glaucoma. Levobetaxolol...

Lebers Hereditary Optic Neuropathy Definition

The visual acuity in LHON is reduced to 20 200 or worse. The visual field shows a large, central or cecocentral sco-toma, and color perception is badly damaged. The acute phase is marked by a peripapillary microangiopathy with irregular areas of microvascular dilation, tortuosity, and variations in caliber sometimes described as telangiecta-sias. The next stage (within a few weeks) is marked by increasing optic disc pallor and a disappearance of the initial microangiopathy. It is notable that the microangiopathy can be found in asymptomatic carriers of the maternally inherited deficit.

Diagnosis of Graves Disease

The diagnosis of Graves' disease, aside from a history of thyroid problems, uses measures of visual acuity, pupillary light responses, and ocular motility. The configuration and movement of the lid margins should be carefully studied. The slit-lamp examination should include the measure of intraocular pressure by applanation tonometry both in downgaze and in the primary position. Because of the foreshortened rectus muscle's traction on the globe, attempts to force the eye into the primary position often result in a marked, though transient, elevation of the intraocular pressure. Visual field testing and a sonographic determination of rectus muscle thickness by A-scan complete the workup. Echographic confirmation of rectus muscle thickening in the midportions of muscle belly, but with no thickening at the tendinous insertions, is characteristic of Graves' disease and differentiates it from orbital myositis, in which the inflammatory swelling extends all the way to the point of...

Multiple System Atrophy

Adult-onset hereditary spastic spinocerebellar ataxia. A 43-year-old man developed rapidly progressing visual impairment, cerebellar ataxia, and weakness in all extremities. By age 44, he was blind and had pale, sharply outlined discs. Deep tendon reflexes were brisk, and Hoffmann and Babinski signs were present on both sides. All extremities were weak and spastic. Cerebel-lar ataxia and intention tremor were present in the upper extremities. Sensation was normal. His condition steadily deteriorated and, at age 49, he died. His mother and two sisters, aged 51 and 37 years, respectively, suffered from a similar illness. A and B. The optic nerves are partially demyelinated (Weil stain). C. The cerebellar cortex and white matter are diffusely atrophic. D. The corticospinal tracts and the spinocerebellar tracts are degenerated in the spinal cord (Weil stain). Adult-onset hereditary spastic spinocerebellar ataxia. A 43-year-old man developed rapidly progressing visual impairment,...

Determination of the Angle of Strabismus

Subjectively, the angle of deviation can usually be determined more quickly and reliably by having the patient report the locations and separations between the doubled images. Prerequisites for this method are normal retinal correspondence, adequate visual acuity, and patient cooperation. For patients with spontaneous diplopia the motil-ity deficit can be estimated without additional equipment during fixation on an object that has sufficient contrast with its background. For example, consider uncrossed di-plopia at the primary position (the image from the right eye is seen to the right, while the image from the left eye is seen to the left) that increases in right gaze and decreases in left gaze. This means that gaze to the right produces an increasing esodeviation. To judge cyclodeviations the examiner must provide a straight line (a yardstick, for example) that the patient can use to describe the angle of tilt. The perceived image rotation is the opposite of the eye's rotation....

Measurements And Events

Some endpoints assess events, while others provide a measurement of an outcome. Events occur at a specific point in time and their assessment is binary, i.e., either the event has occurred or it has not. Examples of events are death, stroke, cure of infection, progression to AIDS, myocardial infarction, or a flare of asthma. In contrast, measurements have several or many potential values that may change over time. Examples of measurements include blood pressure, strength, weight, CD4+ cell count, tumor size, quality of life scored on a standard scale, and visual acuity. Several factors may affect the decision to use a measurement-based or an event-based endpoint. Measurements can detect a broad range of change in the outcome measure in each patient therefore, measurement-based endpoints will often be more sensitive and yield greater power than event-based endpoints. Measurements, however, may detect very small changes, and therefore may raise more questions about clinical...

Q Optic Nerve Chiasm and Tract

Hyaluronan in the retrolaminar optic nerve appears to decrease with age and is further reduced in primary open-angle glaucoma (POAG) (115). Glial hyaluronate-binding protein (GHAP) is a naturally occurring versican degradation product (116), and forms a delicate mesh surrounding myelinated optic nerve axons although no or only faint staining of GHAP is observed in the optic nerve head (117). Hyaluronan and GHAP disappear from hyaluronidase-injected optic nerves, optic chiasm and contralateral optic nerves (118). In hyaluroni-dase-injected crushed optic nerves, regenerated axons are able to grow for short distances into the distal stump undergoing Wallerian degeneration (118). Versican V2 is identified as a major inhibitor of axonal growth in the extracellular matrix of the mature central nervous system including optic nerves (119). Versican and aggrecan have been shown to be present in the embryonic rat optic tract (120).

Oculomotor Pareses in Children

Acquired oculomotor pareses in childhood are mostly traumatic, the consequence of frequent migraine episodes, associated with tumors, or in the context of acute meningitis. Aneurysms as a cause of oculomotor paresis are a rarity in children. An acquired, nontraumatic paresis in a child requires an MRI study with contrast enhancement. If meningitis is suspected, a lumbar puncture is indicated. Depending on the child's age, evaluation to rule out or treat amblyopia in the affected eye is necessary

Infranuclear Disorders of Ocular Motility

Infranuclear disorders of ocular motility are marked by abnormal eye movements caused by lesions below the level of the cranial nerve nuclei. These lesions include damage to the cranial nerves, the extraocular muscles, or the connective tissue of the orbit. Their origins range from relatively harmless disorders to severe diseases that are life threatening. Infranuclear disorders produce paretic and or mechanical strabismus with severe deficits of visual perception by means of diplopia (image duplication), visual confusion (image overlap), and acutely by oscillopsia (illusory movement of the environment). The principle responsibility of the ophthalmologist is to provide some symptomatic relief, determine the most likely source of the problem, and to arrange for appropriate consultation with other clinical disciplines. The search for these goals requires a thorough exploration of the history, precise measurements of ocular motility, and attention to potential accessory signs and...

Clinical Features

The multiplicity of MS plaques and their locations at various anatomic sites account for the great variability of clinical symptoms and signs (Table 8.2). Visual impairment, varying from diminished visual acuity to total blindness in one or both eyes, orbital pain, and frontal headaches are often the presenting symptoms. However, any cerebral or spinal cord dysfunction may introduce the disease.

Variants of Multiple Sclerosis

Neuromyelitis optica or Devic's disease. A 30-year-old woman presented with a history of headaches and rapidly progressing loss of vision in the left eye that began about 5 weeks following a difficult labor and a short febrile episode. Shortly after the onset of visual impairment, she developed paresthesias and weakness in all four extremities and urinary retention. After a short period of improvement, her condition deteriorated she became quadriplegic and experienced respiratory difficulties. Six months after the onset of symptoms, she died. A. Extensive demyelination in left optic nerve. B. Extensive demyelination in the swollen cervical and thoracic cord (Weil stain). C. Massive perivascular lymphocytic infiltration (HE). Neuromyelitis optica or Devic's disease. A 30-year-old woman presented with a history of headaches and rapidly progressing loss of vision in the left eye that began about 5 weeks following a difficult labor and a short febrile episode. Shortly after the onset of...

Spasm of the Near Reflex

Spasms of accommodation and convergence are usually functional in nature, but are occasionally the result of a severe head injury or part of a dorsal midbrain syndrome. A highly variable (moment-to-moment) esotropia is accompanied by pupillary miosis and accommodative myopia. When binocular horizontal pursuit movements are tested, the adducting eye takes up fixation in either direction. This pseudo-abducens palsy is usually enhanced during cover uncover testing ( Fig. 10.8). The spasms can last for a few seconds or for several hours. In addition to the blurring and diplopia, headache is associated with the longer lasting spasms.

Approach to Interpreting Acid Base Disturbance

Carbonic anhydrase inhibitors - compounds that reduce the secretion of H+ ions through alkalinization of the urine drugs that are commonly used to treat glaucoma Classification of metabolic acidosis can be based on a normal anion gap versus an elevated anion gap. For example, metabolic acidosis with a normal anion gap is associated with renal diseases such as proximal or distal renal tubular acidosis, renal insufficiency with HCO3- loss, and hypoaldosteronism with potassium-sparing diuretics. Other causes include loss of alkali due to diarrhea or ureterosigmoi-dostomy or ingestion of carbonic anhydrase inhibitors, such as the medications used to treat glaucoma.5 Metabolic acidosis with a high anion gap is generally due to addition of acid from ketoacidosis lactic acidosis from hypoperfusion or decreased circulation toxic ingestions of aspirin, ethylene glycol, or methanol or renal insufficiency.

Topical Synthetic Antibacterials

Table 13.1 summarizes the topical synthetic antibacterial agents in common use today. These agents possess a wide variety of chemical structures and properties, and they act by many different mechanisms to produce their antibacterial effects. Some of them are extremely toxic, which restricts their use to sterilizing surgical instruments and fumigating structures. Others are powerful agents that are irritating to skin. They are used to disinfect dairy barns, hospital areas, and the like. Less irritating agents are used as surgical scrubs. Still milder agents that possess potent antibacterial activity are used as antiseptics for treating wounds, or as mouthwashes. Very mild and nonirritating compounds may be used to kill bacteria on contact lenses. Thus there is a broad spectrum of needs for topical antibacterial agents, and a large number of chemical agents have been developed to meet these needs.

Acetazolamide Complexes

Among the sulfonamide CAIs, acetazolamide (H2acm) see Scheme 6.1) has been extensively used clinically (under the trademark Diamox) as a diuretic drug, and is still used at present to treat glaucoma, epilepsy and other neuromuscular diseases and as a diagnostic tool (Maren 1967 Supuran and Scozzafava 2000 Supuran et al. 2003).

Concluding Discussion

Receptors and their endogenous agonists in disease states. Given the known pharmacological properties of cannabis and cannabinoid receptor agonists and the distribution pattern of cannabinoid receptors, initial experiments should perhaps focus on the role of the endogenous cannabinoid system in disorders of cognition, memory, affect, motor control and immune function. The therapeutic potential of cannabinoid receptor ligands as anti-inflammatory agents and analgesics and in the control of glaucoma, bronchial asthma, epilepsy and or gastrointestinal motility disorders also merits attention (Hollister, 1986). Another important goal is to establish more fully the part played by cannabinoid receptors in tolerance. A summary of current information about the pathophysiology of cannabinoid receptors and about their role in the production of cannabinoid tolerance can be found elsewhere (Pertwee, 1997).

Alkaloids With Cholinergic Effects

Pilocarpine, from a South American plant (Pilocarpus spp.), acts directly on end-organs innervated by postganglionic nerves (parasympathetic system plus sweat glands) it also stimulates and then depresses the central nervous system. The chief clinical use of pilocarpine is to lower intraocular pressure in chronic simple glaucoma, as an adjunct to a topical beta-blocker it produces miosis, opens drainage channels in the trabecular network and improves the outflow of aqueous humour. Oral pilocarpine is available for the treatment of xerostomia (dry mouth) in Sjogren's syndrome, or following irradiation of head and neck tumours. The commonest adverse effect is sweating adverse cardiac effects have not been reported.

The Visual System

Parietal Lobe Lesion Quadrantanopia

Fig. 34 The visual pathways as seen from above the brain. Letters A-F refer to visual field defects following lesions in the corresponding brain areas. Circles indicate what the left and right eyes see (the left and right visual fields). Black areas represent visual field defects. A. Constricted field left eye (e.g end-stage glaucoma). When constricted fields are bilateral, it sometimes signifies hysteria. B. Central scotoma (e.g., optic neuritis in multiple sclerosis), C. Total blindness of the left eye. D. Bitemporal hemianopia (e.g., pituitary gland tumor). H. Right homonymous hemianopia (e.g stroke). F. Right superior quadrantanopia.

Magnetic Resonance Imaging MRI and spectroscopy

Computed Tomography Fatty Liver

From a safety point of view, magnetic resonance techniques represent no radiation risk, but as discussed in Chapter 11, the presence of a strong magnetic field and the switching of magnetic field gradients make metallic objects (splinters, tattoos, coloured contact lenses, piercings, uterus coils), other medical devices (pace makers, cardiac valves, clips, electrodes, neuro-stimulators), implants, prosthetics, shunts and stents contraindication for the MR examination. Another practical consideration is the restricted space in the clear bore of the magnet. The usual clear diameter of 60-70 cm can exclude morbidly obese patients from the examination. Nevertheless, the advantages and the versatility of the method as well as the wider spread of clinical MR systems predetermine broad application in future clinical praxis.

Signs and Symptoms of Optic Nerve Gliomas

A common presentation includes exophthalmos with strabismus of the affected eye, associated with a loss of visual acuity, visual field defects, optic atrophy, and a relative afferent pupillary defect. Not infrequently, an acquired nystagmus is the first clinical sign. The most common sign is optic atrophy on the affected side, and bilateral involvement is not uncommon. The mass grows slowly and advanced stages of enlargement are commonly associated with diencephalic disorders, including diabetes insipidus, adiposity, delayed sexual maturation, and somnolence.

Adrenergic Neuron Blocking Drugs

Guanethidine has been used to reduce intraocular pressure in open angle glaucoma and to reduce thyrotoxic eyelid retraction for cosmetic effect. Other members of the group are debrisoquine and bethanidine. Metaiodobenzylguanidine (MIBG) is used diagnostically as a radioiodinated tracer, to locate chromaffin tumours (mainly phaeochromo-cytoma) which accumulate drugs in this class (p. 495).

Swinging Flashlight Test

Swinging Flashlight Test

A repetition of the subjective and objective refractions with pupillary dilation and cycloplegia is necessary. This will occasionally uncover an undetected or an irregular corneal astigmatism. Corneal epithelial disease can cause profound losses of visual acuity. The most common cause of this problem is a defective tear film. Not uncommonly, patients with follicu-lar conjunctivitis are referred to the ophthalmologist. Their symptoms, blurring and ocular pain that is sometimes aggravated by ocular movement, can falsely suggest the possibility of optic neuritis. This mistake can be corrected by everting the upper lid, exposing the (sometimes giant) follicles. In addition, the visual problems caused by marginal blepharitis and or chalazions are frequently underestimated, though they can produce significant changes in corneal astigmatism with associated reductions in acuity. Since the corneal surface is the strongest refracting interface of the eye, seemingly insignificant disturbances,...

Polyglucosan Diseases

A newborn boy was severely jaundiced, and his feeding was difficult because of frequent vomiting. In early childhood, his development was very slow and, after a few years, became arrested. At 7 years of age, he was physically underdeveloped and severely mentally retarded. Bilateral cataracts were diagnosed a few years later. He suffered from hypoglycemic episodes, frequent convulsions, and status epilepticus. Galactosemia. A newborn boy was severely jaundiced, and his feeding was difficult because of frequent vomiting. In early childhood, his development was very slow and, after a few years, became arrested. At 7 years of age, he was physically underdeveloped and severely mentally retarded. Bilateral cataracts were diagnosed a few years later. He suffered from hypoglycemic episodes, frequent convulsions, and status epilepticus.

Lysosomal Carbohydrate Diseases

Purkinje Cell Degeneration

Juvenile neuronal ceroid lipofuscinosis. The disease of a 6-year-old girl began with failing eyesight. Over the years, her mental functions, motor skills, and speech progressively deteriorated. After an 8-year clinical course, she died. A. The brain shows a moderately severe cortical atrophy. B. The cerebellum shows Purkinje cell losses and storage of PAS-positive material in remaining Purkinje cell and dendrites (PAS stain). Juvenile neuronal ceroid lipofuscinosis. The disease of a 6-year-old girl began with failing eyesight. Over the years, her mental functions, motor skills, and speech progressively deteriorated. After an 8-year clinical course, she died. A. The brain shows a moderately severe cortical atrophy. B. The cerebellum shows Purkinje cell losses and storage of PAS-positive material in remaining Purkinje cell and dendrites (PAS stain).

Classification Of Drugs

The antimuscarinic activity is a significant problem and may lead to dry mouth, blurred vision, glaucoma and micturition hesitancy and retention. Gastrointestinal symptoms, rash and agranulocytosis occur. Effects on the cardiovascular system include hypotension and cardiac failure (negative inotropic effect)

Gcap Mutations And Retina Disease

Patients with autosomal dominant cone dystrophy have reduced visual acuity and experience a complete loss of color vision. In a four-generation British family (27 members, 7 affected), dominant cone dystrophy was mapped to chromosome 6p21.1, the locus of the GCAP1 GCAP2 gene array (Payne et al., 1998). A missense mutation (A G) at codon 99 in exon 2 of the gene encoding GCAP1 (GUCA1A) was identified. The mutation replaced Tyr at position 99 with Cys (Y99C), a change that was absent in over 200 unrelated controls. The same mutation was later identified independently in two ancestrally related families (Downes et al., 2001a). The Y99C mutation in GCAP1 has been reported to cause both cone-rod dystrophy and isolated macular dysfunction (Michaelides et al., 2005). The authors suggested that the phenotypic variation indicated an intrafamilial heterogeneity of retinal dysfunction that can be observed in persons harboring the same mutation. The residue Tyr99 immediately precedes the EF3-hand...

Physiological Functions Of Cas

In higher organisms, including vertebrates, the physiological functions of CAs have been widely investigated over the last 70 years (Maren 1967 Chegwidden and Carter 2000 Supuran et al. 2003). Thus, isozymes I, II and IV are involved in respiration and regulation of the acid base homeostasis (Maren 1967 Chegwidden and Carter 2000 Supuran et al. 2003). These complex processes involve both the transport of CO2 bicarbonate between metabolizing tissues and excretion sites (lungs, kidneys), facilitated CO2 elimination in capillaries and pulmonary microvas-culature, elimination of H+ ions in the renal tubules and collecting ducts, as well as reabsorption of bicarbonate in the brush border and thick ascending Henle loop in kidneys (Maren 1967 Chegwidden and Carter 2000 Supuran et al. 2003). Usually, isozymes I, II and IV are involved in these processes. By producing the bicarbonate-rich aqueous humor secretion (mediated by ciliary processes isozymes CA II and CA IV) within the eye, CAs are...

Central Disturbances of Vision

A central disturbance of vision should be suspected when an ophthalmic examination finds normal visual acuity and normal appearing anterior and posterior segments in both eyes, in the setting of a plausible complaint of difficulty with recognition of visual images. The human visual system does not terminate at the primary visual cortex. On the contrary, central processing of images begins at the striate cortex. Given the well-vascularized tissue of the poststriate visual cortex, damage to vision in these regions is compar

Subnormal Photoreceptor Functions

Electroretinogram

Contact lenses, foil, or fiber electrodes are used for detecting the electrical potentials of the flash ERG. The fiber electrodes are most readily tolerated by children. As in EOG testing, recording is done with fully dilated pupils. A uniform illumination of the retina is obtained by having the patient positioned at a Ganzfeld sphere (a nearly spherical device with a neutral white interior finish much like that of a perimeter, and with a small port left open for access to the patient's eye) into which the light is flashed.

Carbonic anhydrase inhibitors

This action is due not to diuresis (thiazides actually raise intraocular pressure slightly). The formation of aqueous humour is an active process requiring a supply of bicarbonate ions, which depends on carbonic anhydrase. Inhibition of carbonic anhydrase reduces the formation of aqueous humour and lowers intraocular pressure. This is a local action and is not affected by the development of acid-base changes elsewhere in the body, i.e. tolerance does not develop. In patients with acute glaucoma, acetazolamide can be taken either orally, or intravenously. Acetazolamide is not recommended for long-term use because of the risk of hypokalaemia and acidosis, but brinzolamide or dorzolamide are effective as eye drops, well tolerated, and thus suitable for chronic use in glaucoma.

Fetal Alcohol Syndrome

A 46-year-old chemical operator was exposed to organic mercury compounds for approximately 3 years. At age 50 years, he was evaluated for unsteadiness of gait, clumsiness of hands, and deteriorating eyesight. His neurologic deficits slowly progressed, along with mental decline. At age 74, he died. CT scan of the head at age 72 years shows (A) prominent cal-carine and Sylvian fissures and marked atrophy of the medial aspects of the occipital lobes and insular regions. B. Horizontal slice of the brain shows cortical and white matter atrophy of the medial occipital lobes. C. The cerebellar cortex is severely atrophic. D. The striate cortex shows significant neuronal losses and abundance of corpora amylacea (PAS). E. The cerebellum shows diffuse losses of granule cells and only moderate Purkinje cell losses (HE).

Hyperbetalipoproteinemia

LDL uptake by the steroid-generating tissues because of poor receptor specificity. This leads to deposition of cholesterol esters in tissues, hepatomegaly, and even loss of eyesight due to clouding of the cornea.26,27,31 Heterozygote variants have some normal apoB-100 and therefore exhibit less severe problems. A pattern for a patient with hyperbetalipoproteinemia would be as follows

Osteonectin In Embryonic Development And Differentiation

Interference with this temporally controlled activation of osteonectin results in developmental abnormalities. Thus, when osteonectin antibodies are introduced into the blastocoel of Xenopus embryos, defective neurulation and organogenesis occur (Purcell et al. 1993). Microinjection of specific peptides derived from osteonectin induces abnormalities in the establishment of the embryonic axis in morphogenesis. The injection of osteonectin peptides containing FC domains and copper-binding sequences did not affect this process, but peptides containing the disulphide-bonded Ca2+-binding domain profoundly inhibited axial formation, leading to ventralisation of the embryos. The disulphide bonding seemed to be essential for axial inhibition, because peptides lacking cysteine residues were unable to induce axial abnormalities (Damjanovski et al. 1997). However, the recent work of Gilmour et al. (1998) suggests that osteonectin deficiency may not damage developmental...

Successful Identification of Novel Leads through Virtual Screening

Recently, Grueneberget al. discovered sub-nanomolar inhibitors of carbonic anhydrase II by virtual screening (15). The study was performed following a protocol of several consecutive steps of hierarchical filtering (Fig. 7.3). Carbonic anhydrase II is a metalloenzyme used as prominent target for the treatment of glaucoma. Its binding site is a rather rigid, funnel-shaped pocket. Known inhibitors such as dorzolamide bind to the catalytic zinc ion by a sulfonamide group. In a recent crystallo-graphic study it could be demonstrated that only the sulfonamide group represents an ideal anchor for zinc coordination (377). An initial data set of 90,000 entries from the May-bridge (378) and LeadQuest (379) libraries was converted to 3D structures with Corina (380). In a first filtering step, compounds were requested to possess a known zinc-binding group. These compounds were then processed through UNITY (355) using a protein-derived pharmacophore query. The pharmacophore hypothesis had been...

Pathologic Calcification of Biomaterials

Calcification of biomaterials can affect a variety of prostheses implanted into the circulatory system, within connective tissues, or at other sites (Table 1). For example, dystrophic calcification has been encountered as degeneration of biopros-thetic or homograft cardiac valve replacements, calcification in blood pumps used as cardiac assist devices, mineralization of intrauterine contraceptive devices, encrustation of urinary prostheses, and mineral deposition within soft contact lenses.

Hyperviscosity Syndrome

The circulatory disturbances resulting from hyper-viscosity lead to various clinical manifestations. Headache, blurred vision, reduced visual acuity, and drowsiness are common. Occasionally, patients may present with dementia or psychosis.104 Progressive, severe CNS dysfunction results in obtundation, vertigo, seizure, gait ataxia, and coma. Dyspnea may precede overt congestive heart failure. Bleeding occurs most commonly as epistaxis, ecchymosis, and sometimes GI

Functional Visual Loss and Malingering

Ophthalmic Differential Diagnosis Tables

Malingering is an intentionally deceptive mimicry of a nonexistent disorder, and augmentation is an intentionally exaggerated account of an existing disorder. Functional visual loss is a subjectively described visual disorder without an objectively observed abnormality. It is an unconscious, often subconscious, simulation of a nonexistent disease. (Synonyms include psychogenic visual loss, conversion, and hysterical visual loss). The related group of psychogenic ocular disorders includes functional disease, psychosomatic disease, and artificial eye diseases. Psychosomatic eye disease is initiated by a psychically triggered (or heavily influenced) organic disease with demonstrable pathological findings, as for example, in some reported cases of glaucoma, uveitis, or central serous retinopathy. Artificial eye diseases arise by self-inflicted trauma (autoaggression) and have demonstrable pathological findings during the eye examination. This type is usually associated with psychoses or...

Traumatic Optic Neuropathy Definition

Traumatic optic neuropathy results primarily from indirect injury, rather than by direct crushing or tearing mechanisms. A direct blow to the eye can cause an avulsion of the optic nerve (more properly called an expulsion). The mechanism appears to be one of a sudden, explosive increase in intraocular pressure with rupture of the scleral coat in a circumpapillary ring where the sclera is very thin. Most often, this occurs in patients that have moderate to high degrees of axial myopia and or a posterior staphyloma. The eye has no light perception, the pupil is fixed in mid-dilation, and ophthalmoscopy reveals disappearance of the optic disc, with folds of retina that have been dragged through the posterior rupture. Another mechanism appears to be a small-vessel infarction of the intracanalicular portion of the nerve, presumably caused by shearing of the perineural blood vessels. This commonly happens without a fracture, and there is initially no ophthalmoscopic abnormality. The eye has...

Optic Atrophy after Papilledema Definition

The pathogenic mechanism is not well understood, but ischemia is thought to play an important role. The time needed to develop this complication is variable and is not predictable in individual cases. The transient obscurations of vision often associated with papilledema seem to be unrelated to the risk of atrophy. The visual impairment can begin acutely or subacutely, often with arcuate visual field defects that are very similar to those in patients with chronic open-angle glaucoma, and as is the case with glaucoma, the central-most portions of the visual field are initially spared. The process, once begun, can seem impossible to stop, resulting in total optic atrophy and blindness. Patients with chronic papilledema need to be monitored by an experienced ophthalmologist. Papillede-ma that threatens in this manner (i.e., moderate to marked levels of papilledema that last longer than a few weeks) must be brought under control, either by shunting procedures or...

Hereditary Disorders of Neuro Ophthalmic Relevance

Alport Syndrome Sign And Symptoms

Hereditary disorders of importance for neuro-ophthalmology include genetically inherited disorders of the posterior segment and afferent visual pathway that characteristically present as visual field defects, visual acuity loss, strabismus, or even complete blindness. These disorders have significant social and economic importance with lifelong consequences for the afflicted patient. The prevalence of inherited retinal disorders is approximately 20 cases per 100,000 people. Lens filters, for protection from higher levels of light and improvement of contrast sensitivity, are a rational option that can be of help in the management of some hereditary retinal diseases. Additionally, cataract extraction at an appropriate time and the use of magnifying reading lenses might improve visual acuity in some cases.

Quality of Life Reports

Scores for those who received combined chemotherapy and CrSp RT as compared to those treated with CrSp RT alone 135 . The most common long-term complications after diagnosis and treatment of GCTs were endocrine disturbances, especially in patients with suprasellar tumors. Interestingly, most of these endo-crinopathies were present at the time of diagnosis or following surgery, although radiation could be implicated in a subset of patients 120, 124, 125, 136 . Other common long-term sequelae include neurocognitive defects, which in most cases were mild 120, 122, 124, 125, 137 , and ophthalmologic abnormalities, with Parinaud syndrome seen in pineal region tumors and visual impairment seen in suprasellar tumors. Future trials for GCTs should aim at improving survival while minimizing long-term sequelae of therapy.

Tumors of the Neurohypophysis

Its cellular origin is controversial, as reflected by the various names given to it choristoma, referring to the nests of large, granulated, dusty cells in the infundibular region granular cell myoblas-toma, implying a mesenchymal origin and pituicytoma, suggesting an origin from the neurohypophysis. The tumor occurs most frequently in middle-aged women and presents with visual impairment, enlarged sella, and endocrine disturbances.

Effects of prolonged administration chronic organ toxicity

Toxic cataract can be due to chloroquine and related drugs, adrenal steroids (topical and systemic), phenothiazines and alkylating agents. Corneal opacities occur with phenothiazines and chloroquine. Retinal injury occurs with thioridazine (particularly, of the antipsychotics), chloroquine and indomethacin.

Oxidative Stress Hypothesis And Aging In Ds

Individuals with DS show increased levels of SOD1 and a general imbalance of the antioxidant enzymes, which is thought to lead to accumulation of reactive oxygen species and oxidative stress to the cells (68). In addition, individuals with DS and cell lines from individuals with DS have been shown to be impaired in their ability to repair oxidative damage to mitochondrial DNA compared with age-matched control cells. Oxidative damage is thought to contribute to some other parts of the phenotype of aging in DS for example, the increased rates of adult-onset cataract formation is hypothesized by some to occur in response to increased oxidative stress.

Neuroradiologic Imaging

It is the intended purpose of this chapter to provide the practicing ophthalmologist with an understanding of the indications for neuroradiologic procedures, and to illustrate the various imaging methods with typical examples and descriptions of their findings. The use of conventional radiologic imaging in ophthalmology has been reduced to its role in the detection of metallic foreign bodies for a more detailed study of soft tissues, tomographic images have completely replaced them.

Retinal Degeneration and ABCA4 ABCR

Rod Photoreceptors

In addition to ABCA1, the ABCA4 (ABCR) gene located on chromosome 1p21 (Tabs 3.1 and 3.2) is another example how several mutations in one ABC transporter gene can cause pleiotropic effects. Thus, many different clinical phenotypes, associated with various forms of eye degeneration, and the age of onset as well as disease severity are associated with distinct mutations in ABCA4 9 . As summarized in Tab. 3.2, ABCA4 has been found to be a causal gene for a series of retinal diseases. As an effort of several laboratories in 1997 149-151 , mutations in ABCA4 have been identified in Stargadt disease (STGD), a juvenile-onset macular dystrophy characterized by rapid central visual impairment and progressive bilateral atrophy of the retinal pigment epithelium, as well as in the late-onset form termed fundus fla-vimaculatus. Although only 60 of the mutations in the ABCA4 gene of STGD have been determined, all segregated chromosomal regions in these patients have been mapped to a locus between...

Applications Of Metal Complexes Of Sulfonamides In Therapy

As a consequence of these very powerful enzyme inhibitory properties, several interesting applications have been reported for some metal complexes of heterocyclic sulfonamides possessing strong CA inhibitory properties. Thus, some Zn(II) and Cu(II) complexes of heterocyclic sulfonamides of type 6.20 to 6.25 and 6.28, 6.29 were very efficient intraocular pressure (IOP) lowering agents when administered topically in normotensive or glaucomatous rabbits, although most of the parent sulfonamides from which they were obtained do not show topical antiglaucoma activity (Supuran et al. 1998a, 1999 Briganti et al. 2000 Scozzafava et al. 2001, 2002). The observed topical activity has been explained by a modulation by the metal ion on the physicochemical properties of the complex, which in some cases becomes more polar and thus penetrates better though the cornea to inhibit ciliary processes CAs, thereby reducing elevated IOP in animal models of glaucoma (Supuran et al. 1998a, 1999 Briganti et...

Historical Context

For long outside the body and enters through mucous membranes or skin, typically sexually transmitted (venereal) passed from mother to child (congenital) or spread through blood transfusions. Its four recognizable stages are primary, secondary, latent, and tertiary. Treatment should begin at first indication, usually when, in the sexually transmitted kind, a chancre or lesion appears on the genitals within four to six weeks of infection. If untreated, the secondary stage from six to 12 weeks after infection includes headache, fever, nausea, swollen lymph nodes, rashes, sore throat, and fatigue. Lesions may persist, and grayish patches with red areolae may occur on the mucous membranes of the mouth and genital region. Hair patches often fall out (alopecia areata). After three months symptoms may come and go but the whole body is now infected as bacteria invade vital organs, bone marrow, and the central nervous system. During a period of latency, from a few years to the end of life, the...

Functional Assessment

Dementia Functional Assessment

Vision Screening Visual impairment is an independent risk factor for falls, which has a significant impact on quality of life. Direct visual testing with a Snellen chart or Jaeger card is the most sensitive and specific approach to visual screening. Referring all older people for a complete eye examination has the advantages of improving the quality of the examination and allowing for cataract and glaucoma screen-in . The majority of conditions leading to vision loss in the elderly are presbyopia, macular degeneration, glaucoma, cataract, and diabetic retinopathy. The incidence of presbyopia increases with age. Patients have difficulty focusing on near objects while their distant vision remains intact. Age-related macular degeneration (AMD) is the leading cause of severe vision loss in the elders. AMD is characterized by atrophy of cells in the central macular region of the retinal pigment epithelium, resulting in the loss of central vision. Glaucoma is characterized by a group of...

Other Uses of Hyaluronan in Ocular Surface Disorders A Hyaluronan as a Mask in Refractive Surgery

HA was used with success in assisting excimer laser surgery for the correction of irregular astigmatism resulting from previous corneal refractive surgery. During corneal healing after excimer laser surgery, a variable degree of irregular astigmatism can occur. Most of the time, its effect on visual acuity and refraction is minimal but sometimes the corneal surface irregularity can cause light dispersion, which is responsible for the occurrence of decreased visual acuity and visual discomfort.

Activity Efficacy and Safety of Corticosteroids in Palliative Treatment of Cancer Cachexia

Trial of Moertel et al. dates back to 1974 85 , and other important trials were published in the 1980s 86-89 , some considerations can be made approaching the results from an outcome point of view. All trials showed that corticosteroids (dex-amethasone or prednisolone, or methylpred-nisolone) induce a temporary benefit against different cachexia-related symptoms, improving the appetite, food intake, sensation of well-being, and performance status. Conversely, no trial demonstrated an improvement in body weight. Moreover, the trials of Robustelli della Cuna and Popiela 88, 89 approached the dimension of quality-of-life assessment during the treatment, and tried to go beyond symptom assessment in the outcome assessment in palliative care. Besides these interesting results detailed in Table 2, there is much evidence that corticosteroids can act against some other symptoms, that are related to, but not constitutive of, cancer cachexia, such as asthenia, or nausea and vomiting 90-93 . It...

Role Of Cas In The Skin

Models that receive particular attention in providing further evidence and helping explain the evolving concepts of CAs physiology are those that report the clinical effects and systemic adverse events from the use of CAIs. Such interesting pharmacological agents, sulfonamide CAIs, have a firm place in medicine and are mainly useful as diuretics or to treat and prevent a variety of diseases such as glaucoma, epilepsy, congestive heart failure, mountain sickness, gastric and duodenal ulcers, neurological disorders and osteoporosis (Supuran and Scozzafava 2000a Supuran et al. 2003). Cases of olygohydrosis, a potentially serious adverse event characterized by deficient production and secretion of sweat, were reported in six children treated with zonisamide, an antiepileptic drug chemically classified as a sulfonamide and first marketed in Japan in 1989 (Knudsen et al. 2003). The apparent increased risk of oligohydrosis in the pediatric age group might be related to the dose and resulting...

Optical coherence tomography OCT

The limitations of OCT include the inability to obtain high-quality images through media opacities such as dense cataract or vitreous haemorrhage. The use of OCT is also limited to cooperative patients who are able to maintain fixation for the full acquisition time of 2.5 sec per section. with visual acuity. OCT can be used to follow the clinical response to focal laser treatment for clinically significant macular oedema.

Radiotherapy for Tumors of the Anterior Visual Pathway

Radiation therapy of the anterior visual pathway has long been used with a certain degree of reluctance, since the side effects are potentially disastrous. For many years, it was believed that radiation therapy of optic nerve tumors was of little use, since the healthy portions of the nerve had practically the same radiosensitivity as the tumor. The risk of bilateral radiation optic neuropathy and total blindness prevented even consideration of radiotherapy as a valid choice for treatment. In addition, if the globe lay within the field of treatment, the risk of a radiation retinopathy and or cataract were additional possibilities. If the tumor was located close the pituitary gland, endocrinopathies were also possible. Table 23.1 lists the critical radiation doses for the various structures in and around the anterior visual pathway.

Volatile Organic Toxicity Screening

The patient also exhibited CNS disturbances with decreased responsiveness to pain and dilated pupils. Nystagmus or lazy eye and vision disturbances indicate toxicity of the optic nerve. These signs are characteristic of methanol and or ethylene glycol toxicity.13 Elevated lactic acid and calcium oxalate crystals also point toward ethylene glycol poisoning. Treatment was begun on the assumption of the presence of these toxins. The gas chromatography report later confirmed methanol and ethylene glycol poisoning.

Artificial Endothelium

Ophthalmic surgeons may use diverse polymeric devices to correct the optical function of the eye. Thus, intracorneal implants can be used instead of spectacles or contact lenses to correct nearsightedness and farsightedness (Fig, 4). The intracorneal implants most likely to succeed are made of hydrogel materials tailored to have high permeability to metabolites and able to correct severe myopia (McCarey el at., 1989), The stromal cells (keratocytcs) and the epithelium receive their nutrients from the aqueous humor and also release waste products in the same direction. Therefore, some previously used intrastromal implants, such as poly (methyl methacrylate) and poly-sulfone, which are impermeable to metabolites, will result in the ulceration and vascularization of the overlying stroma. A more recent development is the intrastromal ring made of poly (methyl methacrylate) or silicone rubber, which may change the corneal curvature and, hence, the eye's optical power. These rings can make...

Other sources of bias and error

Many patients with diabetes have complications leading to reduced visual acuity, and this requires that the print size of self-administered questionnaires is larger than that used in other populations, to ensure that misreading biases are not introduced. Likewise, other sources of bias should be considered and eliminated, such as with tools designed to assess quality of life, where a relative or friend of the patient may fill in the form for them.

Intraocular lens implants

Intraocular lenses (lOLs) are used after cataract extraction to replace the opaque crystalline lens of the eye (Apple et al., 1984). I01.S consist of an optical portion and haptics that support the optical portion in its proper place in the eye (Fig. 5). lOLs may be placed in the anterior chamber, in the pupil, and in the posterior chamber. The last type are most commonly used at this rime they are usually placed within the posterior capsule of the crystalline lens, which remains in the eye after the lens contents have been removed surgically (Fig. 5). A large variety of 101. designs and shapes are available the choice does not necessarily depend on need but rather on the preferences of surgeons and manufacturers. Corneal astigmatism may result from tissue distortions occurring as a consequence of the uneven healing of the wound made when the 101, was implanted. There ss currently a strong interest in developing soft 101-s, which can be inserted in the eye through smaller surgical...

Alphaglucosidase inhibitor blocks hydrolysis of an

Buffer - a mixture of chemicals that resist changes in pH by combining with free H+ (proton acceptor) and OH-, generally a strong salt and weak acid or base human buffer systems include anionic proteins, deoxyhemoglobin, phosphate buffers, and bicarbonate carbonic acid buffers calculi - any abnormal concretion of precipitated inorganic materials, commonly called a stone, within the body (singular calculus) canalicular - within canals or small ducts carbonic anhydrase inhibitors - compounds that reduce the secretion of H+ ions through alkaliniza-tion of the urine drugs that are commonly used to treat glaucoma carboxypeptidase - a pancreatic enzyme that hydro-

On The Applied Side The Pigeon As A Quality Control Inspector

In industrial settings, workers often are hired as quality control inspectors. Quality control usually is a monotonous job of checking samples of a product to identify any defects. The most important skills or attributes needed for such jobs are good visual acuity and color vision. Based on these visual requirements, Thom Verhave (1966) suggested to the

The Treatment of Diabetes Mellitus

In T1DM plasma insulin levels are low or absent and treatment with insulin is always necessary. Since it is not yet possible to mimic the normal function of a beta-cell, which precisely adjusts the rate of insulin secretion in response to biological needs, the treatment ofT1DM is complicated by episodes of hypoglycemia and hyperglycemia. Hypoglycemia can cause coma, and hyperglycemia increases the risk for diabetic complications in the form of eye disease, kidney disease, nervous system damage, and coronary artery disease and stroke 69 .

TABLE 1615 Pupils in Comatose Patients

Pupillary size, equality, and light reactions help in assessing the cause of coma and in determining the region of the brain that is impaired. Remember that unrelated pupillary abnormalities, including miotic drops for glaucoma or mydriatic drops for a better view of the ocular fundi, may have preceded the coma.

Intracapsular Extraction

Intracapsular cataract extraction is the method of removing the entire lens, including the capsular bag. This method separates the lens from its zonular attachments and from attachments to the anterior portion of the vitreous. This latter attachment, called Weigert's ligament, generally wanes as we age, but is quite strong in childhood and young adulthood. When the intracapsular technique was performed on younger age groups, disruption of the vitreous, termed vitreous loss, frequently occurred. This is a complication of cataract surgery that has long-term effects, even when it is adequately managed intraoperatively. The instruments used to perform intracapsular surgery were initially forceps, which were used to grasp the anterior capsule and remove the lens by either tumbling it from behind the pupil or sliding it from the eye. In each instance, the mechanical action of removing the lens caused traction on and release of the zonules that held the lens in position. In some cases, a...

Extracapsular Extraction

Extracapsular cataract surgery obviated many of the concerns posed by the intracapsular techniques. This method has several variants but, in principle, maintains a portion of the surrounding capsular bag. In this procedure, the anterior capsule (i.e., the portion of the lens capsule facing the pupil) is opened. This anterior capsulotomy then permits the contents of the lens capsule (i.e., the nucleus and cortex) to be removed. When the nucleus is totally removed as a single structure, it is called nucleus expression, and the technique is termed planned extracapsular cataract extraction. Another method called pha- coemulsification removes the nucleus by fragmenting it with an ultrasonic needle. In recent years, phacoemulsification has become the favored method for cataract removal. Advantages of the extracapsular technique are related to maintenance of an intact posterior capsule. An eye with an intact capsule has greater internal stability and lower incidence of retinal detachment and...

Development And Types Of Iols

Figure 1 illustrates some of the more common types of IOLs and identifies their components. The first IOL was implanted in 1949 and was termed the Ridley posterior chamber lens. It was made of poly(methyl methacrylate) (PMMA) and designed to resemble the characteristics of the human lens. It had two dissimilar radii of curvature, was biconvex in its shape, and weighed about 112 mg in air, making it an extremely heavy lens. To benefit from the support of an intact posterior capsule, the IOL was implanted after an extracapsular cataract extraction (Ridley, 1951). Although this original Ridley posterior chamber lens restored visual function, problems related to the weight and size of the implant, as well as its displacement into the vitreous body, limited its usefulness. The fact that the IOL produced reasonable results when complications did not ensue stimulated ophthalmologists to design other types of IOLs.

Complications Of Posterior Chamber Iols

In recent years, more than one million posterior chamber IOLs were implanted annually in the United States. These IOLs have been significantly modified from the style of the original Shearing lens. The haptics of these lenses are no longer the conventional J-shape but have evolved to a C-shaped, softer configuration. Optic sizes have also been modified to accomodate newer techniques for cataract removal, and drilled positioning holes in the optic have all but disappeared. The finish of these one-piece PMMA lenses is excellent. Yet, despite the technological advances in IOL manufacture, clinical complica

Capsular Opacification

Extracapsular cataract extraction retains an intact posterior capsule, a portion of the anterior capsule, and the lens equator. As previously described, there is a region of epithelial cells that proliferate and migrate along the posterior capsule. When this occurs to a significant extent, the visual axis is obscured and results in reduced visual acuity (Obstbaum, 1988). Since some degree of capsular opacity frequently develops, this event is considered to be a consequence rather than a complication of extracapsular surgery.

Small Incision Surgery

Extracapsular cataract surgery, either by planned extracapsular techniques or by phacoemulsification, achieves satisfactory visual results. Over the past 7 years there has been a progressive trend toward using phacoemulsification for cataract removal, although planned extracapsular procedures are still performed by many ophthalmologists. Phacoemulsification permits cataract removal through an incision that is approximately 2 3 smaller than with conventional extracapsular surgery. The benefits of small incision surgery include mechanical stability of the incision, rapid return to normal activities, and rapid visual functional rehabilitation. With advances in the techniques of phacoemulsification and the technological developments of phacoemulsification equipment, the results of the surgery have favored this method of cataract surgery. Phacoemulsification has also hastened the development of IOLs that enhance the benefits of the smaller incision. These include narrow profile PMMA IOLs...

Linking the Visual Module with the Language Module

Figure 3.12 illustrates a simple concept for such a text annotation system. Video input from the eyeglasses-mounted camera is operated upon by the gaze controller and objects that it selects are segmented and represented by the already-developed visual module, as described in the previous subsection. The objects that were used in the visual module development process were those that a blind person would want to be informed of (curbs, roads, cars, people, etc.). Thus, by virtue of its development, the visual module will search each new frame of video for an object of operational interest (because these were the objects sought out by the human educator who's examples were used to train the gaze controller perceptron) and then that object will be segmented, and after consensus building, represented by the module on all of its three layers.

Botulinum Toxin and Brow Lift with Suspension Threads

It is amazing to point out that the vast majority of patients still believe that the treatment of crow's feet is undertaken with blepharoplasty. The purpose of this cosmetic eye surgery is basically the removal of eye bags and skin excess. It is likely that with the resection of skin excess there will be a mild to moderate improvement in crow's feet wrinkling. However, we must make it clear to our patients that crow's feet result from muscle action and the proper treatment for this is BNT-A.

Subarachnoid Damage to the Oculomotor Nerve

From the ventral midbrain, through the interpeduncular fossa and to its entry into the cavernous sinus, the third nerve lies in the subarachnoid space, where it is exposed to hemorrhages from aneurysms arising from the supracli-noid carotid artery, mostly at the exit of the posterior communicating artery. Rupture of such an aneurysm produces paralysis of the third nerve, but also the dramatic symptoms of acute subarachnoid bleeds, including abrupt headache of the worst sort, reduced levels of consciousness up to complete coma, and pronounced meningismus. The ophthalmologist will not be confronted by this syndrome in his her own office. In about one third of cases the course is more gradual, beginning with an incomplete internal and external oculomotor nerve paralysis, which precedes onset of extreme levels of head pain referred to the orbital apex. The ocular presentation may lead the patient to consult the ophthalmologist, who should then immediately arrange for emergent...

Signs and Symptoms of Pituitary Tumors

The most common ophthalmological sign of a pituitary adenoma is the bitemporal loss of visual field (see Chaps. 3 and 4). Fundus findings are at most (and often subtly) optic disc pallor. A loss of visual acuity is not always present (see above). Disturbances of motility involving dysfunction of the trochlear or abducens nerves are found in only about 10 of patients. With very large, eccentrically growing tumors, there is occasionally damage to the first two branches of the trigeminal nerve.

Dural Carotid Cavernous Fistula

Dural carotid-cavernous fistulas arise spontaneously and primarily in elderly women. Dural branches of the internal or external carotid are equally involved, and fistulas often arise spontaneously from both sources. The resulting venous congestion causes an ectasia of the orbital and conjunctival veins that are clearly differentiable from inflammatory hyperemia (large, rope-like conjunctival vessels that contrast with white scleral tissue), as well as chemosis with lid swelling, exophthalmos, retinal vascular dilatation with intraretinal hemorrhages, and elevated intraocular pressure. The latter feature is caused by the marked elevation in episcleral venous pressure that is transmitted directly to the anterior chamber. The elevated pressure in the cavernous sinus causes damage to the third, fourth, and sixth cranial nerves, resulting in diplopia. Frequently, patients hear a pulse-synchronous bruit when background noise is diminished, usually when retiring for the evening, and often...

Magnification Systems

Prism Telescopic Dental Loupes

Although dental loupes are widely used, they have a considerable disadvantage. Ihe clinician's eyes must converge to view the operative field. Ibis may result in eyestrain, fatigue, and even pathologic vision changes, especially alter prolonged use of poorly fitted loupes. Dental loupes provide a limited range ot magnification (1.5> to l()x). Those delivering magnification ol less than 2.5x are usually inadecpiate for the visual acuity necessary tor periodontal microsurgery. Those providing magnification of more than 4.5x are awkward to use because ol their small field of view, shallow depth of focus, and excessive weight. I he latter makes it quite difficult for i surgeon to maintain a stable visual field. employ Galilean optical principles1 and have binocular eyepieces joined by offsetting prisms with parallel optical axes. Galilean optics allows stereoscopic viewing of the operative field without eye convergence. I bis positions the eyes as il they were focused on infinity to...

Periodontal Microsurgery

Rhe use ol magnification in periodontics is not an isolated development. It is pari ol .1 broader trend in medicine and dentistry toward the application of minimally invasive techniques lor procedures that previously required extensive surgical incisions 10 11 Microsurgery is defined .is a refinement in operative technique by which visual acuity is enhanced through the use of the surgical operating microscope. It is a methodology, through which surgical techniques are modified to accommodate the improved motor coordination made possible through magnification.1*' In addition to clinical microsurgery, magnification in periodontics may he applied to diagnostic and nonsurgical procedures as a result of the improved visual acuity and motor coordination.

Toxic Optic Neuropathies Definition

Ethambutol and other antitubercular drugs, cytostatic agents, heavy metals, hexachlorophene, and methanol can all cause a toxic optic neuropathy (also see Chap. 17). The first priority is to identify the offending agent and then to block further exposure. Specific measures that follow are determined by the nature of the toxin. The most common syndrome of toxic damage to the optic nerve chiasm is that of tobacco-alcohol amblyopia. It is thought that the toxin in question is cyanide, which is present in trace quantities in tobacco smoke. Interventional therapy with oral multivitamins (e.g., vitamin B complex) and intramuscular injections of hydroxycobalamine (the decyanated form of vitamin B12) can reverse the visual loss in the early stages of the disease. These vitamins are thought to chelate trace levels of cyanide and detoxify the affected tissues. Some individuals may be more at risk than others are, based on the composition of their mitochondrial DNA and variations in the...

Neurosurgery of the Visual Pathway

The visual pathways take an extraordinary and extensive intraorbital and intracranial course from the globe to the visual cortex within the occipital lobes. Hence, a large number of orbital and intracranial pathologies interfere with the optic pathways. The diagnosis and treatment of these pathologies demands an interdisciplinary team with ophthalmologists, neuroradiologists, neurosurgeons, and radiation therapists. The management algorithm takes into consideration presenting signs and symptoms, as well as ophthalmologic and imaging findings. It requires a multimodal treatment protocol depending on the biological nature and location of the pathology.

CAIs In Macular Edema Macular Degeneration And Related Ocular Pathologies

Optic nerve blood flow is diminished in the eyes of primary open-angle glaucoma suspects and patients (Pilts-Seymour et al. 2001). Because sulfonamides with CAI properties act as vasodilators (Supuran and Scozzafava 2000), this might explain the use of such drugs for treating retinal edema and age-related macular degeneration. In consequence, these pharmacological agents represent a new approach for improving visual function. Retinal edema (also referred to as cystoid macular edema) consists of a swelling process within the critically important central visual zone, and might develop in association with a variety of ocular conditions, such as diabetic retinopathy, ischemic retinopathies, intraocular surgery (such as cataract procedures) or laser photocoagulation (Cox et al. 1988 Grover et al. 1997 Sponsel et al. 1997 Barnes et al. 2000). It is also common in patients affected by retinitis pigmentosa, a hereditary disorder leading to total blindness (Orzalesi et al. 1993). The precise...