Retinal Review, Issue 1
CASE OF THE MONTH
Welcome to the inaugural issue of Omni’s “Retinal Case Of The Month”. I welcome the opportunity to share interesting cases with you. We will discuss a different case each month, focusing on an unusual retinal problem, a diagnostic dilemma, a new medication or technique, or an update on new approaches to evaluate or treat basic retinal diseases. Please feel free to comment on the cases and to share your interesting cases with us. Also feel free to share these cases with colleagues. If you know of a colleague that would be interested in receiving these cases please let us know. Our email addresses and cell numbers will be listed at the end of the presentation.
CASE PRESENTATION
A 54 year old man presented with sudden, painless vision loss in his right eye. The vision loss occurred the night before and remained stable. Past ocular history is significant for mild myopia and presbyopia. Past medical history is significant for hypertension, for which he takes a calcium channel blocker.
On examination, visual acuity was 20/20 in both eyes. Applanation tensions were 15 bilaterally. The anterior segments were normal. A mild right afferent papillary defect was present. Confrontation and threshold visual fields were significant for a dense inferior altitudinal defect in the right eye and a full field in the left. Dilated examination of the right eye revealed an area of retinal whitening and edema in the superior fundus extending to the macula. Careful inspection of the optic nerve demonstrates an embolus within the superior branch of the central retinal artery. Fluorescein angiography confirms the absence of blood flow to the superotemporal retina. Examination of the left eye is normal.
DIAGNOSIS
DIAGNOSIS
The patient was diagnosed with an embolic branch retinal artery occlusion. Two issues immediately arise:
1. From a medical standpoint, what tests need to be done to investigate the source of the embolus?
2. From an ocular perspective, is there any available treatment that will restore blood flow and improve vision?
MANAGEMENT
Medical evaluation: When patients present with an embolic event, it is critical to determine the source of the embolus. Attention should be paid to systemic issues that increase clotting and also to structural issues that could allow a clot to travel to the eye. In a patient with known atherosclerotic risk factors, clotting issues do not need to be evaluated. One can assume that hypertension, hyperlipidemia, diabetes, or systemic atherosclerosis, contributed to the formation of the clot. In a patient without known risk factors however, a thorough evaluation must be ordered to look for evidence of an underlying disorder. The general categories to evaluate are systemic inflammation, infection, clotting disorders, and blood dyscrasia. Typical tests ordered are: CBC, platelets, ESR, C-reactive protein, ANA, ACE, Lyme titers, RPR, hemoglobin electrophoreses, anticardiolipin panel, protein S, protein C, Factor V Leiden, homocysteine levels, antithrombin III, fibrinogen, fibrin split products, and serum protein electrophoresis. Additionally, one must order tests to evaluate the route the clot took to get to the eye. Clots typically originate in the carotid artery (cholesterol emboli) or either originate or pass through the heart (cholesterol or calcific emboli). Calcific emboli tend to be white and large; cholesterol emboli tend to be smaller and yellow. A carotid duplex study and transesophageal echocardiogram are typically ordered to evaluate these potential areas of concern.
Ocular treatment: Although there is no specific data on humans, animal studies suggest that even if blood flow is reestablished rapidly, vision loss is permanent after a short amount of time in an embolic event to the retina due to retinal ischemia. For central retinal artery occlusions, treatment typically involves sudden shifting of the pressure in the eye either by paracentesis or digital pressure. If the embolus is dislodged shortly after the artery occlusion, vision can be restored. Because the embolus in a branch retinal artery occlusion is stuck in the vessel, pressure shifts will not dislodge the clot. Many experimental modalities have been suggested for branch retinal artery occlusions ranging from intraocular thrombloysis to systemic thrombolysis to direct clot disruption. Several studies have suggested that YAG embolysis (YAG laser-induced disruption of the embolus) can restore flow and in some cases restore vision.
We had a full discussion with the patient regarding medical and ocular implications of his vision loss. We explained that although his acuity was 20/20, without dislodging the embolus he would have permanent inferior visual field loss. We also discussed that even with successful clot disruption, the vision loss could already be permanent. We discussed various treatment options and agreed to proceed with YAG embolysis. Additionally, he was instructed to undergo medical testing as noted above – all tests were negative.
After instillation of local anesthetic, YAG laser was applied directly to the embolus. Since the laser penetrates the artery, an immediate geyser of blood is usually encountered. Digital pressure on the eye is used to tamponade the hemorrhage.
The patient returned one week later for follow up. Acuity remained at 20/20 OU. The vitreous hemorrhage had cleared. Blood flow was completely restored to the branch retinal artery and all retinal whitening had resolved. The embolus was no longer visible. Unfortunately the inferior altitudinal defect persisted. The patient was satisfied that we tried everything possible to restore his vision. If he had come in several hours sooner the result might have been different. He will continue to see his medical doctor to keep track of his hypertension and to make sure he does not develop any further risk factors for clotting.
We hope you enjoyed and learned from the inaugural “Case of the Month”. Please feel free to utilize our services for urgent and nonurgent ocular diseases. We are available 24 hours a day to discuss your patients with you. Please do not hesitate to call either our center directors or specialists with concerns about your patients.
