Sudden Loss of Vision
April 1, 2020
San Diego County Optometric Society Newsletter: Retina Corner
By Nikolas J.S. London, MD FACS
President and Director of Clinical Research, Retina Consultants San Diego
Chief of Ophthalmology, Scripps Memorial Hospital La Jolla
Dear SDCOS membership,
April is upon us and most of us are laying low in our homes due to the COVID-19 pandemic. What strange times – it is surreal to me how quickly and dramatically things have changed over the past several weeks. As you read this, we are likely at or near the peak of the crisis, hopefully with light at the end of the tunnel. As a retina practice, our group is still seeing our more urgent patients including those receiving ongoing anti-VEGF treatment, as well as emergency new patients. In that vein, I wanted to spend this month reviewing one of those urgent conditions, the patient who presents with sudden, often profound, loss of vision, and requires quick thinking. Before I give you the diagnosis I am referring to, let me present two similar cases to get the wheels turning.
Case #1: A 62-year-old man complains of a defined dark shadow in the lower part of his central vision of the right eye. Examination reveals a prominent whitening in the superotemporal macula with a Hollenhorst plaque at the proximal aspect of the whitening. What is the most appropriate initial management?
• Obtain erythrocyte sedimentation rate and C-reactive protein
• Refer to an internist for a carotid Doppler
• Refer urgently to a stroke center
• Send to a cardiologist for echocardiogram
Case #2: An 86-year-old man with acute visual loss in the left eye and a history of transient ischemic attacks involving right-sided motor function has macular whitening with preserved foveal pigmentation. Which of the following tests is most appropriate to diagnose his condition?
• Anti-nuclear antibody test
• Carotid ultrasound
• Fasting plasma homocysteine
• MRI of the brain
Both of these cases are classic presentations of retinal artery occlusion, the first consistent with a branch retinal artery occlusion (BRAO), and the second consistent with a central retinal artery occlusion (CRAO). Both require urgent attention. Case #1 reviews the management options. While all of the choices are reasonable to consider, the most appropriate first step in the vast majority of cases is to refer the patient to the closest emergency department (ED) for a stroke workup. This is never a popular option for patients, but is important to possibly prevent a significant cerebrovascular accident. The ED may initiate a “stroke code” with a workup including carotid and cardiac imaging, blood work, and brain MRI. Erythrocyte sedimentation rate and C-reactive protein are often obtained, but are not generally indicated as giant cell arteritis is typically associated with CRAO, but not BRAO.
Case #2 presents a classic CRAO. One of the key points in this case is that all of the findings suggest left-sided vascular dysfunction. Ipsilateral CRAO and hemispheric transient ischemic attacks in an elderly patient suggest the possibility of ipsilateral carotid atherosclerotic disease and secondary embolization. As with the first case, the best initial management is to send the patient directly to the ED for a stroke workup. In this case the most useful ancillary test is likely to be carotid ultrasound, which may reveal stenosis. In addition to carotid ultrasound, an echocardiogram to evaluate for valvular disease should also be considered, and, unlike BRAO, any CRAO patient over the age of 55 should also have urgent bloodwork to rule out giant cell arteritis – erythrocyte sedimentation rate, C-reactive protein, and a platelet count.
As for the other answer options for Case #2, although several systemic conditions including as auto-immune disease, sarcoidosis, hyperhomocysteinemia, and hyperlipidemia may coexist with central retinal artery occlusion, these are less common than atherosclerotic causes. MRI of the brain would be reasonable given the history of TIAs and left-sided motor function deficit, but this would be non-localizing as to the cause of the CRAO. Susac syndrome could be suggested by a brain MRI but would be unlikely to present as a new vascular occlusion at this age.
Thanks again for reading. Please don’t ever hesitate to contact me.
Best wishes, and until next time,