16.5 Case 16.5: Conversion of a Nonischemic Hemicentral Retinal Vein Occlusion to an Ischemic One

Fig. 16.5 Fundus photographs of the right eye of a 65-year-old man with a nonischemic central retinal vein occlusion (CRVO) and ME (ME). (a) Fundus photograph of the right eye after following the patient for 1 month with no improvement. The VA was 20/100. (b) Fundus

photograph of the left eye 6 months later after two unsuccessful attempts at creating a laser chorioretinal venous anastomosis (the black arrows). The CRVO with ME spontaneously resolved

for treatment. Neither site produced a successful anastomosis (Fig. 16.5). Nevertheless, 6 months later all of the intraretinal hemorrhages had resolved, the ME had regressed, and the VA had returned to 20/25 (Fig. 16.5).

16.4.1 Discussion

This case emphasizes the variable natural history of CRVO (see Chap. 7). In this case, a treatment was performed that failed to achieve its intended effect – the production of a chorioretinal venous anastomosis.3,16 Nevertheless, the CRVO resolved – clearly in a spontaneous manner. Had the anastomosis procedure worked, it is probable that the credit for improvement would have been attributed to the procedure, when, in fact, the eye was destined to spontaneously improve anyway. It is for this reason that any proposed therapy of CRVO with ME must be tested in a randomized, controlled trial with standard therapy (at the time of this case – observation; now, IVI of anti-VEGF drugs) as a control arm. Without this rigorous approach, one cannot be sure that a good outcome is not just the natural history of the particular case.

16.5Case 16.5: Conversion

of a Nonischemic Hemicentral Retinal Vein Occlusion

to an Ischemic One

A 66-year-old woman with diabetes and hypertension developed acute, painless blurring of the right eye with some associated photopsias. She was seen on the day her symptoms arose at which time her VA was 20/25. Her fundus appearance was as shown in Fig. 16.6. She was diagnosed with a nonischemic HCRVO and advised to return in 1 month. At follow-up, she reported that her vision had decreased further 2 weeks before. At the second examination, her VA was 20/160. If this were your patient, how would you analyze what has occurred and how would you manage the situation?

16.5.1 Discussion

At baseline, the right eye had ischemic retinal whitening, few hemorrhages, good VA, and minimal ME. The capillary perfusion was good.

Fig. 16.6 Fundus images of a 66-year-old patient with a hemicentral retinal vein occlusion of the right eye. (a) At presentation, there is ischemic retinal whitening in the superior hemimacula. The OCT (inset) shows a parafoveal cyst in the outer nuclear layer. (b) Color fundus image and OCT 1 month after presentation. The ischemic whitening persists, but the borders have changed. There is more intraretinal hemorrhage, a sign of an increasingly ischemic HCRVO. The OCT (inset) shows more outer retinal edema, some subretinal fluid, and increased

reflectivity and loss of laminar definition of the inner retinal layers suggesting cytotoxic edema secondary to the ischemia. (c) Frame from the mid-phase FA at presentation shows delayed venous filling superiorly. Capillary detail is preserved in most of the involved retina. (d) Frame from the mid-phase FA at the 1-month follow-up visit shows loss of capillary detail in most of the involved retina. The previously nonischemic HCRVO has converted to an ischemic form

Over the course of 1 month, capillary perfusion in the involved area worsened, ME worsened, and the VA dropped. These changes are typical of conversion from a nonischemic to an ischemic HCRVO. For CRVOs, conversion of nonischemic to ischemic cases occurs in approximately onethird of cases over 3 years.14,25,26 There are no reliable statistics on conversion rates in HCRVOs, but presumably the rates would be similar given the similar pathophysiology and demographics of CRVO and HCRVO.

No treatment was necessary at the first visit given the VA of 20/25, but close follow-up was recommended. At the second visit 1 month later, when the ME was severe, IVBI was recommended. Two IVBIs given at monthly intervals led to improvement in ME but return of VA to only 20/100, mainly because of macular ischemia. The patient did not recognize enough benefit from the IVBIs to continue with them. Four months after the second IVBI, the VA was 20/100.