9.3 Central Retinal Vein Occlusion

Fig. 9.1 Fundus images of a 72-year-old hypertensive woman who noticed blurred vision of the left eye for several weeks. She had a nonischemic macular branch retinal vein occlusion. (a) Monochromatic fundus photograph of the left eye shows telangiectatic venules but no hemorrhage suggesting that this BRVO has been present for much longer than the patient suspected. (b) Frame from the mid-phase fluorescein angiogram showing the arteriovenous crossing at which the occlusion occurred (the yel-

low arrow). The absence of hemorrhage makes capillary perfusion unambiguous. The capillaries and venules to the involved region of the retina are dilated but perfused (the yellow oval). (c) Late frame from the fluorescein angiogram shows profuse late leakage of fluorescein dye. (d) Time domain OCT shows thickening of the superior macula. The vertically oriented line scan shows edema primarily in the mid and outer retina

14 months at a mean of 5.2 months after the baseline visit. The only predictive factor was male gender.6

9.3 Central Retinal Vein Occlusion

9.3.1 Clinical Characteristics

Assessment of ischemia in CRVO is important because of the consequences of ischemia. An immediate consequence is poorer visual acuity

(VA) if the ischemia involves the macula. The most feared later consequence of retinal ischemia in CRVO is ocular neovascularization, which has multiple forms. At all follow-up times, the order of frequency of the various forms of ocular neovascularization after ischemic CRVO is NVE < NVD < neovascular glaucoma (NVG) < NVA < NVI (Table 9.2). Approximately 85% of cases of the various forms of ocular neovascularization will develop by 1 year following ischemic CRVO, but the last 15% may continue to develop over an additional 2 years.23

Fig. 9.2 Fundus images of a 56-year-old hypertensive woman with an old ischemic inferotemporal branch retinal vein occlusion. The best corrected visual acuity was 20/63. (a) Color fundus photograph shows the sheathed first-order branch retinal vein (the arrow). The arterioles have increased light reflexes consistent with chronic hypertension. Small venular remodeling can be seen in the inferior macula. (b) Frame from the early-phase fluorescein angiogram of the right eye. The arrow denotes the disruption of the perifoveal capillary arcade. Other areas of capillary nonperfusion are evident in the inferotemporal quadrant. Despite the ischemia, no neovascu-

larization is present. (c) Frame from the late phase of the fluorescein angiogram of the right eye. Although there is some staining of venular walls, there is little leakage of fluorescein into the interstitium. (d) Spectral domain OCT (SD-OCT) line image through the right macula shows atrophy of the inner retina temporally (the arrow). The demarcation between cell layers is effaced and the nerve fiber and ganglion cell layers are thin compared to the normal fellow eye (see e). (e) SD-OCT line image through the left macula. The arrow denotes the normal temporal macular thickness and profile (compare to d)

Fig. 9.3 Fundus images from a 63-year-old man with hypertension, diabetes mellitus, and hypercholesterolemia who reported a several year history of visual acuity loss of the right eye and was found to have an old superotemporal branch retinal vein occlusion. (a) Color fundus photograph shows white, “ghost” venules (the black arrows). The green arrow denotes the arteriovenous crossing at which the occlusion occurred. Hypertensive arteriolar changes are present. The yellow arrow denotes the narrowed, underperfused proximal segment of the draining branch vein. (b) Frame from the laminar venous phase angiogram showing delayed circulation superotemporally and nonperfused superotemporal retina. (c) Frame from the mid-phase fluorescein angiogram shows venous col-

laterals (the yellow arrow) that traverse the nonperfused zone of retina. The tortuous segments of the collaterals occur above the horizontal raphe (the yellow line) in the nonperfused zone. (d) Frame from the late-phase fluorescein angiogram showing late leakage in the relatively better perfused parafoveal zone (the yellow oval) compared to the ischemic zone (the orange oval). (e) SD-OCT line scan showing some derangement of the retinal outer layers (the yellow oval) of the ischemic zone. The hyperreflective intraretinal foci suggest areas of resolved edema. Residual cysts are present where the fluorescein leakage was most prominent (the green arrow). (f) SD-OCT of the normal fellow eye shows normal outer retina in a symmetric locus (the orange arrow)

Fig. 9.4 Fundus images of a 50-year-old man with hypertension who developed a macular branch retinal vein occlusion (BRVO). Macular BRVOs do not lead to subsequent ocular neovascularization, but focal signs of ischemia can be seen. The visual acuity was 20/70. (a) Color fundus photograph of the left eye at baseline. A cotton wool spot that occupies most of the area of the BRVO is present (the black arrow). By definition, a cotton wool spot is an area of focal ischemia, yet all macular BRVOs are nonischemic, because the levels of intraocular VEGF

Table 9.2 Percentages of eyes with ischemic central retinal vein occlusion developing subsequent forms of intraocular neovascularization

are low corresponding to the small area of nonperfusion. (b) Frame from the early-phase fluorescein angiogram. Capillary perfusion is difficult to judge because the opaque nerve fiber layer and intraretinal blood block the view (yellow oval), but the area is so small that even assuming capillary nonperfusion, the BRVO would be classified as nonischemic (less than five disc areas of nonperfusion) (c) Frame from the late-phase fluorescein angiogram. Leakage of fluorescein from hyperpermeable retinal small vessels is shown (yellow oval)

The clinical distinction of ischemic from nonischemic CRVO is multidimensional and involves an integration of initial visual acuity (VA); extent of intraretinal hemorrhage; severity of macular edema (ME); presence and severity of a relative afferent papillary defect (RAPD); degree of retinal capillary nonperfusion on FA; electroretinographic changes; visual field changes; patient age; presence of diabetes,