Ischemic macular edema. Recognition and favorable natural history in branch vein occlusion
D. Finkelstein
Department of Ophthalmology, Wilmer Institute, Johns Hopkins University School of Medicine, Baltimore, Md 21205.
Eyes with macular edema caused by retinal branch vein occlusion underwent
masked evaluation of fluorescein angiography to determine complete macular
perfusion vs incomplete macular perfusion (capillary dropout, ischemia).
Cases evaluated as incomplete macular perfusion showed a greater frequency
of improvement (91%) in visual acuity than did perfused cases (29%) (P =
.003) after a mean follow-up of 39 months. Ischemic edema is often
transient, and is associated with a good outcome in visual acuity (median
final visual acuity was 20/30). Perfused macular edema has a poorer
prognosis for visual acuity (median final visual acuity was 20/80). Macular
ischemia is usually associated with a broken foveal capillary ring.
Previous animal research on ischemic brain edema has shown that following
brain ischemia, an intracellular and an extracellular hypertonic
environment lead to intracellular and extracellular edema (cytotoxic
edema), which is often followed by vascular protein leakage (vasogenic
edema). A similar occurrence in ischemic retina could explain the transient
edema reported herein, with good outcome in visual acuity following the
spontaneous resolution of edema.
