This case brings up an interesting conundrum inherentintheStandardCareVersusCorticosteroid for Retinal Vein Occlusion (SCORE) studies.28,29 The SCORE BRVO study concluded that IVTI is not indicated for BRVO with ME (GL is better), but the SCORE CRVO study concluded that IVTI is associated with improved outcomes for CRVO with ME (compared to observation). HCRVOs were pooled with BRVOs in the SCORE studies, but many would argue that HCRVOs should be pooled with CRVOs.9 Because the results of the SCORE BRVO and CRVO studies differ with respect to IVTI, the choice of classification matters in this treatment decision (see Chap. 4). Currently, most retina specialists consider antiVEGF injections more effective for RVO with ME, which renders considerations regarding IVTI in RVO moot (see Chap. 13).

16.6Case 16.6: Nonarteritic Ischemic Optic Neuropathy Following Branch Retinal Vein Occlusion

An 85-year-old man with hypertension and hypercholesterolemia developed a superotemporal BRVO of the right eye in 1992. The BRVO led to retinal neovascularization that was treated with sector PRP. Subsequently in 2010 he developed nonarteritic ischemic optic neuropathy (NAION) of the right eye and 1 month later NAION of the left eye (Fig. 16.7).

The pathophysiology of the two conditions is distinct. BRVO arises from turbulence at the site of a retinal artery crossing over a retinal vein that in turn leads to a local thrombus (see Chap. 2). NAION is a result of nocturnal hypoperfusion of the optic nerve leading to disc edema, further compression of capillaries, resulting worsened optic disc perfusion, and a continued vicious cycle of worsening perfusion and resulting disc edema. There is no known effective therapy for nonarteritic ischemic optic neuropathy. There is a hypothesis that NAION represents a variant of CRVO, but this proposal is controversial and not widely accepted.

16.7Case 16.7: Differentiating Central Retinal Vein Occlusion from the Ischemic Ocular Syndrome

A 68-year-old female with diabetes mellitus and a 40-year smoking history was seen with a complaint of blurred vision in the left eye. She was known to have a complete occlusion of the left carotid artery as determined from a previous neurological workup for transient ischemic attacks. The VA was 20/30 in the both eyes. She had an embolus of the right central retinal artery, but otherwise the right fundus was normal. The left fundus had many dark, outer retinal blot hemorrhages and dilated, dark retinal veins (Fig. 16.8).

16.6.1 Discussion

It is well known that patients with BRVO can subsequently develop a subsequent RVO in the same or fellow eye.27 However, BRVO is not considered to be a risk factor for NAION. Because both BRVO and NAION have overlapping sets of risk factors, such as hypertension and diabetes, it is not uncommon that both conditions will occur in the same patient.

16.7.1 Discussion

The clinical pictures of the ischemic ocular syndrome (IOS) secondary to severe carotid artery atherosclerosis and CRVO have certain features in common, but can be distinguished clinically. The key distinguishing points are that optic disc edema never occurs in carotid occlusive disease, but is common in CRVO; and the retinal artery perfusion pressure is always low in carotid occlusive disease, but is normal in CRVO. The latter

Fig. 16.7 Fundus images of an 85-year-old man with an old BRVO of the right eye who developed NAION of both eyes in short succession 19 years later. (a) Color fundus photograph of the right eye on 1/7/2011 showing the superotemporal laser scars and the inferior optic disc edema and hemorrhage from the NAION (the black arrow). (b) Color fundus photograph of the right optic nerve 6 weeks later (2/25/2011) shows resolution of the optic disc hemorrhage and edema (black arrow). At this

time, the optic disc is atrophic and pale. (c) Optic disc photograph of the left eye on 1/7/2011 shows no abnormality. The cup is small, a risk factor for NAION. The black arrow shows a normal inferonasal neural rim (compare d). (d) Optic disc photograph of the left eye on 2/25/2011. The inferonasal optic disc is edematous with splinter hemorrhages (black arrow). The patient was asymptomatic, but on visual field testing had a superior altitudinal scotoma

sign is elucidated by indirect ophthalmoscopy while applying digital pressure to the involved globe through the eyelid. In carotid occlusive disease, gentle pressure will extinguish the central retinal artery perfusion. In CRVO, firm compression is required to elicit pulsation and even

greater pressure to stop perfusion momentarily. Other finer discriminating points are listed in Table 16.2.

The two conditions have different workups and management, signifying the importance of making the correct diagnosis. The patient with

Fig. 16.8 Fundus images of the left eye of a 68-year-old woman with a total occlusion of the left internal carotid artery causing the ischemic ocular syndrome, visual acuity of 20/30 in the left eye, and subjective blurring. (a) The veins are dilated and dark. Round, deep retinal hemorrhages are present. The optic disc has sharp margins. (b) Peripheral, round, deep retinal hemorrhages are pres-

ent in the inferonasal quadrant. Similar findings were present in the other quadrants (not shown). (c) A frame from the mid-phase fluorescein angiogram shows good capillary perfusion. (d–a) Frame from the late-phase fluorescein angiogram shows no macular leakage of fluorescein nor any disc leakage. (e) Spectral domain OCT images show no macular edema

IOS needs a carotid artery evaluation, and may need carotid endarterectomy or medical management to reduce the risk of stroke.13 In contrast, the management of CRVO involves

considerations of risk factor modification, treatment of edema, and ocular neovascular consequences as have been covered in this textbook (see Chaps. 6 and 13).