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Chapter 10: THE HISTORY, PHYSICAL EXAMINATION, AND CARDIAC AUSCULTATION

EXAMINATION OF THE RETINA*

Inspection of the smaller vessels of the body is possible in only three areas: the retina, the conjunctiva, and the nail beds. The ophthalmoscope has made the retina by far the easiest and most rewarding site.201 Viewing this two-dimensional vascular display is generally much easier if the pupils are dilated. Pulse and blood pressure determinations should be made prior to the instillation of rapidly acting mydriatics, since both may increase after absorption of the drops. The pupils are left undilated in patients in whom the iris seems closely apposed to the cornea and in those with a history of closed-angle glaucoma. Examination of the retina should proceed methodically. Best pupillary dilatation is maintained if the optic disk is observed first. Assess for evidence of edema and blurred margins and for cupping with sharp contours. Rule out neovascularization or the pallor of optic atrophy. Next, scan along the superior temporal arcade, inspecting the arteries carefully for embolic plaques at each bifurcation. Observe the arteriovenous crossing for obscuration of the vein and for pronounced nicking and banking of the vessels. The lower arcade and the nasal vessels may be inspected next. Avoid the macular area until all else has been viewed because the pupil constricts most intensely when this area is illuminated. To discover diabetic microaneurysms early, look just temporal to the fovea, along the horizontal raphe. To find cotton-wool infarcts, look circularly around the disk two disk diameters out. Using this method, the retina can be efficiently searched for evidence of cardiovascular disease201 (Table 10-5).

Table 10-5: Retinal Topography

Finding Most Common Location

Table 10-5: Retinal Topography

Finding Most Common Location

Arteriovenous crossings Upper temporal quadrant

Cotton-wool spots

Around optic disk

Hard exudates

Between disk and fovea

Microaneurysms

Temporal to fovea

Emboli

Arterial bifurcations

Diabetic new vessels Nerve head and arcades

Diabetic new vessels Nerve head and arcades

Alterations in retinal caliber along the course of a single artery or vein are more important than estimates of arteriovenous ratios or absolute vascular diameter. Determining the degree of tortuosity of straightening are of little value where the veins are large, dark, and tortuous.

Variations in the caliber of a single vessel are more important than determinations of arteriovenous ratios. These changes may take the form of focal narrowing, sometimes called beading or spasm.

Thickening of the Vascular Wall

Normally, only the blood column is visible when the retinal vessels are viewed. When changes in the walls do occur, they are most visible along the sides of the vessels, since the location of the tangential line of sight presents a greater thickness to the viewer. Fatty exudate (hard exudate) may collect along venous walls (never arteries), particularly in diabetic exudative retinopathy.

Arteriosclerosis

In arteriosclerosis, medial smooth muscle (which may hypertrophy in chronic hypertension) becomes hyalinized with the deposition of collagen. As the wall thickens, the vessel takes on a burnished coppery luster; with further thickening, this may transmute to silver.

Arteriovenous Compressions

Arteriovenous compressions or "nicking" results from the sharing by the artery and vein of a common adventitial sheath at their crossings. Arteriosclerotic thickening impedes venous outflow at these locations, with venous tortuosity, engorgement, and darkening of the flood column distal to the compression.20!

Atherosclerosis

Retinal atheromata have a predilection for the bifurcation and bends within the first two branches of the central retinal artery, appearing as segments of irregular yellowish sheathing and having the crystalline knobbiness of a salted pretzel stick.210

Cotton-Wool Spots

Cotton-wool spots are generally a sign of serious systemic disease. They may be seen in patients with severe hypertension, blood dyscrasias, collagen diseases, or hemorrhagic shock. Cotton-wool spots also are seen frequently in patients with acquired immunodeficiency syndrome (AIDS) (Fig. 10-47, Plate 43). Cotton-wool "exudates" are not exudates but consist of a cluster of cell-like swollen ends of fragmented axons (cytoid bodies) in an area of edematous retina.201

Figure 10-47: (Plate 43) Retinal cotton-wool spot. Cotton-wool spots are most frequently found close to the optic disk. Although they occur in acute uncontrolled systemic hypertension, the more common cause now, in younger patients, is infection with the human immunodeficiency virus (HIV). This normotensive 37-year-old man had no visual symptoms and no other retinopathy. There is a myopic crescent at the temporal disk edge, which is not abnormal. He died of complications related to the acquired immunodeficiency syndrome (AIDS) 2 years later.

Hard Exudates

Hard exudates are most likely residues of edema. They occur in situations where the vessels become leaky, and as the more watery component of the extravasation is resorbed, the lipid residue forms a hard, yellow, waxy deposit. These deposits may surround the leaking vessel in a circinate ring or may accumulate in the macula, radiating from the fovea in the spokes of a macular "star" (Fig. 10-48, Plate 44).

Periarteritis Nodosa

Figure 10-48: (Plate 44) Disk swelling and hard exudate in a macular "star" pattern. In this hypertensive patient with periarteritis nodosa, vascular leakage has led to the deposit of hard exudates around the fovea. Radial perifoveal connective tissue results in the star pattern of the exudate. Note also that the optic disk is edematous, with blurred margins, secondary to hypertension.

Figure 10-48: (Plate 44) Disk swelling and hard exudate in a macular "star" pattern. In this hypertensive patient with periarteritis nodosa, vascular leakage has led to the deposit of hard exudates around the fovea. Radial perifoveal connective tissue results in the star pattern of the exudate. Note also that the optic disk is edematous, with blurred margins, secondary to hypertension.

Microaneurysms

Microaneurysms are not unique to diabetes but occur in many disease states, including retinal venous obstructive disease, sickle cell disease, the dysproteinemias, Behget's disease, sarcoidosis, and other forms of uveitis. They may represent abortive attempts at revascularization of compromised capillary bed (Fig. 10-49, Plate 45).

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