Consider hypertension as cause of bilateral disc edema

Los Angeles-Hypertension in a patient should raise a red flag for ophthalmologists because it may be associated with optic neuropathy. Anthony C. Arnold, MD, provided his pearls for the safe management of these patients.

"Optic disc edema in hypertension is a complex topic. Bilateral optic disc edema occurs with severe hypertension and may be caused by elevated intracranial pressure, diffuse leakage from microcirculatory incompetence, ischemia, or components of all of those. Associated retinopathy may help make the diagnosis," said Dr. Arnold, who is chief, neuro-ophthalmology division, Jules Stein Eye Institute, University of California-Los Angeles. "Intracranial mass and inflammation must be ruled out. Importantly, overaggressive blood pressure control must be avoided because it can cause infarction of the optic nerve."

The case of a 28-year-old woman illustrates the importance of a careful examination. The patient had a 2-month history of worsening headache, recent onset of blurred vision in the left eye (20/40), 20/20 vision in the right eye, no afferent pupillary defect, and bilateral disc edema. The patient had a slightly enlarged blind spot in the right eye and an enlarged blind spot in the left eye.

Steps to diagnosis The first order of practice in a patient with these findings is to rule out the presence of an intracranial mass, said Dr. Arnold. In the absence of a mass, bilateral papilledema should prompt consideration of other causes of elevated intracranial pressure, such as pseudotumor cerebri and meningitis. Additionally, other infectious or inflammatory causes of optic neuropathy must be eliminated from the diagnosis, including neuroretinitis and papillitis. Finally, the blood pressure must be checked-a factor that is sometimes overlooked.

Several pathophysiologic factors associated with hypertension may lead to the development of optic nerve involvement and hypertensive retinopathy, including impaired autoregulation, vasospasm, and ischemia, he pointed out.

Impaired autoregulation, among other things, breaks down the blood-brain and retinal barriers. This results in brain edema, elevated intracranial pressure, and multiple retinal findings, including focal intraretinal periarterial transudates, edema, and exudates such as the macular star figure, Dr. Arnold explained. Microcirculatory incompetence and leakage of the optic nerve in the presence of relatively normal optic nerve function may also be involved. Furthermore, impaired autoregulation results in increased risk of infarction of the optic nerve if blood pressure drops too quickly, the vascular system cannot compensate, and perfusion pressure drops.

Vasospasm and ischemia may result in optic nerve problems due to ciliary flow impairment. These can range from mild reversible edema with no optic nerve dysfunction to edema preceding optic neuropathy to overt anterior ischemic optic neuropathy. A few hypotheses have been proposed to explain the presence of disc edema, he said. Disc edema may develop because intracranial pressure is elevated or because there is diffuse retinal leakage in the posterior pole, retina, and optic disc, causing the inner surface of the optic disc to swell. Another possibility is that the optic disc alone is the problem and may swell due to vascular incompetence. Finally, the disc may be ischemic to varying degrees, with varying degrees of corresponding dysfunction.

The key clinical features of optic disc edema in hypertension are usually severe and acute hypertension, headache (usually bilateral), and visual acuity that corresponds to maculopathy and disc edema but not to optic nerve dysfunction, noted Dr. Arnold. "In most cases, the optic nerve is functioning relatively normally; however, in severe accelerated cases, especially with enceph-alopathy, the ischemic component may predominate and optic nerve dysfunction develops."

Retinopathy offers clue A primary clue to diagnosis is that there is usually prominent hypertensive retinopathy (as evidenced by retinal arterial spasm and some chronic sclerotic changes) associated with the optic disc edema. There also may be focal intraretinal periarterial transudates, nerve fiber layer infarctions, cotton-wool patches, and edema, as well as some degree of lipid exudates.

Fluorescein angiography can help differentiate between focal intraretinal periarterial transudates and cotton-wool patches because the former, although deeper in the retina, leak fluorescein, whereas the cotton-wool patches, which are more superficial in the retina, do not leak fluorescein.

The presence of numerous focal intraretinal periarterial transudates in association with disc edema may be a marker of hypertension. The star figure is also a common finding in retinopathy associated with disc edema.