Fig. 16.2 Diagram to attempt to describe a plausible pathoanatomy for the clinical situation depicted in case 16.1. The central retinal vein (CRV) has two trunks entering the optic disc. The thrombus involves both hemicentral retinal veins, but extends closer to the lamina cribrosa (LC) in the case of the superior hemicentral retinal vein. For this reason, there are fewer collateral branches (the white arrows indicating collaterals) to decompress the

obstructed vein leading to dilation of the few collaterals that exist, producing the clinical picture of disc collaterals. There are more collaterals for the more posteriorly obstructed inferior hemicentral retinal vein. They decompress the obstructed inferior hemicentral vein more successfully, thus there are no disc collaterals and there are fewer inferior intraretinal hemorrhages (redrawn and adapted from Hayreh9)

This case exhibits one of the clinical pearls that retina specialists learn. When a patient has blurred vision, a small relative central scotoma, and no obvious fundus abnormalities, it is worthwhile to look closely for signs of an old macular BRVO. The OCT and FA can be helpful by showing more evidence than the clinical examination.

16.3Case 16.3: Old Hemicentral Retinal Vein Occlusion with Late Vitreous Hemorrhage and Hyphema

An 85-year-old man with type 2 diabetes mellitus, hypercholesterolemia, and a cigarette smoking habit was seen in 2003 with blurred vision OD due to an inferior hemicentral retinal vein

occlusion (HCRVO) with ME. Best corrected VA (BCVA) was 20/400 in the right eye and 20/50 in the left eye. The ME was treated with an intravitreal triamcinolone injection (IVTI) of the right eye with improvement in VA to 20/80 and reduction in central subfield mean thickness (CSMT) from 568 to 202 m. Because he was not able to appreciate this objective improvement in BCVA and CSMT as improved visual quality of life, he declined further injections. The cataract of the right eye progressed after the IVTI, and he underwent uneventful cataract surgery with posterior chamber intraocular lens implantation in 2005. Six periodic examinations between 2005 and 2010 revealed no changes of the right eye until he presented on 11/10/2010 with a history of overnight VA loss in the right eye. The VA of the right eye was reduced to light perception, the intraocular pressure was 35, and both hyphema and vitreous

Fig. 16.3 Images from a patient with a chronic macular branch retinal vein occlusion and ME. (a) Color fundus photograph showing a single microaneurysm superonasal to the center of the macula (the black arrow). (b) Frame from the mid-phase FA of the left eye. More abnormalities are apparent than could be seen clinically or on the color fundus photograph. The microaneurysm is indicated by the yellow arrow. (c) A magnified portion of the frame in (b) shows two microaneurysms (the yellow arrows) and

an intraretinal collateral vessel (the green arrow). (d) A spectral domain OCT line scan showing a cyst (the yellow arrow) involving the center of the macula. (e) Frame from the late-phase FA showing minimal late hyperfluorescence involving the superior hemimacula (surrounded by yellow oval). This is not a retinal pigment epithelial window defect as can be seen by the absence of hyperfluorescence in the superior hemimacula in the earlier phase of the FA (compare to b)