Hypertensive Retinopathy

Hypertensive Retinopathy

Signs and Symptoms

The patient with hypertensive retinopathy, as expected, suffers from hypertension. However, the hypertension may be unknown to the patient and the eye exam may yield the first clue to this relative asymptomatic systemic disease. Most commonly, the patient is middle age or older. In addition, hypertension is more common in African-Americans than Caucasians. Patients with only hypertensive retinopathy are nearly always visually asymptomatic.

Findings in hypertensive retinopathy include cotton wool spots and flame shaped hemorrhages. Only rarely will there be retinal or macular edema. In advanced cases, there will be a macular star (ring of exudates from the disc to the macula) and disc edema. Arteriolosclerosis (arteriolar narrowing, arterio-venous crossing changes with venous constriction and banking, arteriolar color changes, vessel sclerosis) is often found concurrently.

Pathophysiology

The findings in hypertensive retinopathy all stem from hypertension-induced changes to the retinal microvasculature. Hypertension leads to a laying down of cholesterol into the tunica intima of medium and large arteries. This leads to an overall reduction in the lumen size of these vessels. In arteriolosclerosis, hypertension leads to focal closure of the retinal microvasculature. This gives rise to microinfarcts (cotton wool spots) and superficial hemorrhages. In extreme cases, disc edema develops. The mechanism behind this phenomenon is poorly understood, but it may be related to a hypertension-related increase in intracranial pressure, and hence is considered true papilledema.

Arteriolosclerotic changes in the retinal microvasculature persist even with the reduction of systemic blood pressure. However, hypertensive retinopathy changes resolve over time with the reduction of systemic blood pressure (BP). Cotton wool spots develop in 24 to 48 hours with the elevation of BP, and resolve in two to 10 weeks with the lowering of BP. A macular star develops within several weeks of the development of elevated BP and resolves within months to years after the BP is reduced. Papilledema develops within days to weeks of increased BP and resolves within weeks to months following BP lowering.

Management

Management of hypertensive retinopathy involves appropriate treatment of the underlying hypertension. Medical co-management with the primary physician is of paramount importance. However, if a patient presents with papilledema from hypertension, then the patient has malignant hypertension and should be considered to be in medical crisis. This patient needs immediate consult with a primary care physician and, most likely, immediate transport to a hospital emergency room.

It must be reiterated, however, that there are many causes of papilledema. Other causes of papilledema, such as an intracranial mass lesion, must also be considered in the patient with hypertension. However, in a case where blood pressure is extremely elevated (e.g. 250/150mmHg) and there is disc edema with a macular star, malignant hypertension is the likely cause.

Clinical Pearls

• In order for cotton wool spots to develop from hypertension, autoregulatory mechanisms must first be overcome. For this to happen, the patient must have at least 110mmHg diastolic readings.

• Patients who develop papilledema from hypertension have malignant hypertension and typically have BP in the range of 250/150mmHg

• Fluorescein angiography is not indicated in cases of hypertensive retinopathy as it yields no diagnostic information.

• Hypertensive retinopathy presents with a ‘dry’ retina (few hemorrhages, rare edema, rare exudate, and multiple cotton wool spots) whereas diabetic retinopathy, in comparison, presents with a ‘wet’ retina (multiple hemorrhage, multiple exudate, extensive edema, and few cotton wool spots).

CHOROIDAL MELANOMA

Malignant Choroidal Melanoma

SIGNS AND SYMPTOMS

The benign choroidal melanoma, referred to clinically as a choroidal nevus, appears as a flat or slightly elevated slate gray lesion of the posterior fundus. The margins are typically indistinct, and often there are overlying areas of drusen noted within the nevus. In most instances, choroidal nevi remain under two disc diameters (DD) in size, although they may attain sizes of up to 5 DD in some cases.

The malignant choroidal melanoma, in contrast, appears as a mottled, often significantly elevated lesion, ranging in coloration from white to greenish-gray. As it grows, it may break through Bruch's membrane, taking on a mushroom-like appearance. Serous retinal detachments are commonly associated with this presentation. You may also observe overlying orange pigmentation known as lipofuscin. Most malignant melanomas are over 10 DD in size at the time of diagnosis. Most patients with choroidal melanomas are asymptomatic. However, should a significantly large lesion occur in proximity to the macula, the patient may present with metamorphopsia, acuity loss, visual field deficit and/or a hyperopic refractive shift.

PATHOPHYSIOLOGY

A choroidal melanoma represents a focal accumulation of melanocytes at the level of the uvea. In a choroidal nevus, these melanocytes are normal in both form and function. In malignant melanoma, the cells undergo neoplasia, reproducing at a faster rate than usual and resulting in a dysfunctional tumor mass. This tumor is capable of not only local extension but also of distant metastasis. While choroidal nevi do not typically lead to this type of damage, it is believed that they can convert to malignancy; the rate of malignant transformation over a 10-year period is estimated at 21 in 100,000.

Choroidal Nevus

MANAGEMENT

Nevi of 2 DD or less are harmless. Document the presentation with photography and, when possible, perform a B-scan and follow-up annually. Nevi between 2 and 5 DD are more suspicious. Either perform or refer for angiography to help differentiate the mass, and follow-up regularly at six-month intervals.

When the lesion is greater than 5 DD, consider it a malignant melanoma until proven otherwise. It may not require immediate treatment if relatively small and demonstrates no growth. But if the presentation suddenly changes dramatically or if sight is threatened, refer to a retinal specialist for treatment.

CLINICAL PEARLS

• While a nevus is of little concern, malignant melanoma presents a potentially life-threatening situation because of its propensity toward metastasis. These tumors have been known to spread to the liver, lungs, skin and gastrointestinal tract.

• Refer patients with newly detected malignant melanomas to a primary care physician for testing, which may include liver enzymes, carcinoembryonic antigen (CEA), neuroimaging, and chest CT.