O

CD m

CD oo looking down and to the right cover

uncover

The right eye moves outward to fix on the light. (The left eye is not seen but moves inward to the same degree.)

The left eye moves outward to fix on the light. The right eye deviates inward again.

A Left Cranial Nerve IV Paralysis

A Left Cranial Nerve III Paralysis looking straight ahead

The left eye cannot look down when turned inward. Deviation is maximum in this direction.

The eye is pulled outward by action of the 6th nerve. Upward, downward, and inward movements are impaired or lost. Ptosis and pupillary dilation may be associated.

TABLE 5-11 ■ Normal Variations of the Optic Disc

TABLE 5-11 ■ Normal Variations of the Optic Disc

Rings and Crescents

Rings and crescents are often seen around the optic disc. These are developmental variations in CUP which you can glimpse either white sclera, black retinal pigment, or both, especially along the temporal border of the disc. Rings and crescents are not part of the disc itself and should not be included in your estimates of disc diameters.

Medullated Nerve Fibers

Medullated nerve fibers are a much less common but dramatic finding. Appearing as irregular white patches with feathered margins, they obscure the disc edge and retinal vessels. They have no pathologic significance.

Physiologic Cupping

The physiologic cup is a small whitish depression in the optic disc from which the retinal vessels appear to emerge. Although sometimes absent, the cup is usually visible either centrally or toward the temporal side of the disc. Grayish spots are often seen at its base.

Temporal

TABLE 5-12 ■ Abnormalities of the Optic Disc

Normal

Optic Atrophy

Papilledema

Glaucomatous Cupping

Process

Appearance

Tiny disc vessels give normal color to the disc.

Color yellowish orange to creamy pink

Disc vessels tiny

Disc margins sharp (except perhaps nasally)

The physiologic cup is located centrally or somewhat temporally. It may be conspicuous or absent. Its diameter from side to side is usually less than half that of the disc.

Death of optic nerve fibers leads to loss of the tiny disc vessels.

Color white

Disc vessels absent

Venous stasis leads to engorgement and swelling.

Color pink, hyperemic

Disc vessels more visible, more numerous, curve over the borders of the disc

Disc swollen with margins blurred

The physiologic cup is not visible.

Increased pressure within the eye leads to increased cupping (backward depression of the disc) and atrophy.

The base of the enlarged cup is pale.

The physiologic cup is enlarged, occupying more than half of the disc's diameter, at times extending to the edge of the disc. Retinal vessels sink in and under it, and may be displaced nasally.

(Source of photos: Tasman W, Jaeger E (eds): The Wills Eye Hospital Atlas of Clinical Ophthalmology, 2nd ed. Philadelphia, Lippincott Williams & Wilkins, 2001.)

TABLE 5-1 3 ■ Retinal Arteries and Arteriovenous Crossings: Normal and Hypertensive

Normal Retinal Artery and Arteriovenous (A-V) Crossing

The normal arterial wall is transparent. Only the

-Arterial wall (invisible) column of blood within it can usually be seen.

_ , ,, , , The normal lieht reflex is narrow—about one

fourth the diameter of the blood column.

Light reflex

Retinal Arteries in Hypertension

Narrowed column of blood

Focal narrowing | -Narrowed light reflex

Arterial Wall

Artery

Arterial Wall

Because the arterial wall is transparent, a vein crossing beneath the artery can be seen right up to the column of blood on either side.

Artery

In hypertension, the arteries may show areas of focal or generalized narrowing. The light reflex is also narrowed. Over many months or years, the arterial wall thickens and becomes less transparent.

Sometimes the arteries, especially those close to the disc, become full and somewhat tortuous and develop an increased light reflex with a bright coppery luster. Such a vessel is called a copper wire artery.

Occasionally a portion of a narrowed artery develops such an opaque wall that no blood is visible within it. It is then called a silver wire artery. This change typically occurs in the smaller branches.

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