The eye is proverbially the window to the soul, and literally a window into the vascular system. Evaluation of the retinal vasculature gives insight into multiple systemic diseases affecting the patient. Simply by evaluating the retina, one can determine diseases such as severe hypertension, diabetes mellitus, embolic disease, lupus, infection, and extended abdominal trauma.
REVIEW OF OPHTHALMIC BLOOD SUPPLY
The eye is fed by the first branch of the internal carotid artery. This ophthalmic artery then branches off into the central retinal artery, the posterior ciliary arteries, and the muscular branches. The venous system is comprised of the posterior vortex veins, which drain into the superior and inferior orbital veins which then drain into the cavernous sinus; and the central retinal vein, which drains the retina and the optic nerve directly into the cavernous sinus.1
Systemic hypertension is diagnosed when the blood pressure is greater than 140 systolic and 90 diastolic measured on three separate occasions separated by at least 2 weeks. High blood pressure is extremely common to the industrialized countries. The ocular signs in hypertension are directly related to the rate and degree of systemic blood pressure. Atherosclerosis is a common finding in systemic hypertension. It can also occur in the normal aging population. The retinal changes seen in hypertension may overlap with those found in other retinal vascular diseases such as diabetes (Figure 22-1).2
Systemic hypertension is one of the most common diseases affecting patients throughout the world. The most common ocular manifestations include focal constriction and dilation of retinal arteries, narrowing and irregularity of the retinal arteries, AV nicking, blot retinal hemorrhages, microaneurysms, and cotton-wool spots. Several classification schemes have been used to stage hypertensive retinal changes. The most commonly accepted are the Keith-Wagener-Barker classification (Table 22-1) and the Scheie classification (Table 22-2). With these classification systems, one is able to evaluate the degree of hypertension systemically and begin therapy.
TABLE 22-1.Keith-Wagener-Barker Classification ||Download (.pdf) TABLE 22-1. Keith-Wagener-Barker Classification
|Group 1 ||Moderate narrowing or sclerosis of the artery. |
|Group 2 ||Marked narrowing of the artery, exaggeration of the light reflex, and AV nicking. |
|Group 3 ||Arterial narrowing and focal constriction, retinal edema, cotton-wool spots, and hemorrhages. |
|Group 4 ||Same as group 3 plus papilledema. |
TABLE 22-2.Scheie Classification ||Download (.pdf) TABLE 22-2. Scheie Classification
|Grade 0 ||No changes. |
|Grade 1 ||Barely detectable arterial narrowing. |
|Grade 2 ||Obvious arterial narrowing with focal irregularities. |
|Grade 3 ||Retinal hemorrhages exudates. |
|Grade 4 ||Same as group 3 plus papilledema3 (Figure 22-2). |