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New approaches increase visual recovery in CRVO, BRVO patients
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The diagnosis of central retinal vein occlusion or branch retinal vein occlusion is usually made initially by the comprehensive ophthalmologist.
The typical presenting complaint in central retinal vein occlusion (CRVO) is usually a severe, acute, painless loss of vision. The classic “blood and thunder” appearance of the retina easily confirms the diagnosis when acute. In branch retinal vein occlusion (BRVO), the symptoms can be more subtle, and depending on the area of occlusion, patients may not be aware they have a problem unless macular edema ensues. BRVO is frequently diagnosed during ophthalmoscopy in asymptomatic patients. The most common associated systemic diagnoses include diabetes mellitus and hypertension. These are easy to screen for, but other rarer causes include anything that increases blood viscosity or coagulation. In most cases, a referral back to the individual’s primary care physician is appropriate.
An important associated ocular diagnosis is undiagnosed or inadequately treated glaucoma. In addition, emboli to the central or branch retinal arteries can indirectly reduce venous flow at areas of arteriovenous crossing and result in secondary vein occlusion. The most common causes of early vision loss are macular and/or subretinal edema and vitreous hemorrhage. Late, in neglected cases, rubeosis iridis can cause secondary glaucoma and, if inadequately treated, lead to a blind, painful eye.
The treatment of macular and/or subretinal edema and vitreous hemorrhage in the U.S. is usually performed by a retina specialist. The classic watchful waiting or grid photocoagulation is now being replaced by the injection of steroids and anti-VEGFs into the vitreous. There is no consensus as to the ideal protocol for using these drugs, and they often achieve the best outcomes when used in combination. Each retina specialist has his or her own preference, and the regimens must, as always, be customized for each individual patient’s disease.
For the comprehensive ophthalmologist who sees these patients after intravitreal injection, a few thoughts.
While one must be alert for sterile or infectious endophthalmitis, these complications occur rarely, as they do in cataract surgery. The presenting signs and symptoms are similar. For those patients treated with intravitreal steroids, the major concerns are steroid-induced glaucoma and cataract in the phakic eye. A careful look at the iris and gonioscopy when indicated to rule out rubeosis are appropriate.
Unlike a decade ago, patients can achieve remarkable visual recovery with intravitreal injection and resolution of macular and subretinal edema. However, the recurrence rate for macular and/or subretinal edema is high. While one can monitor these patients with serial visual acuity, IOP and ophthalmoscopy, macular optical coherence tomography is more sensitive in diagnosing early recurrence, prompting a referral back to the treating retina surgeon for further therapy. These patients require frequent and long-term follow-up, and this task is usually delegated to the comprehensive ophthalmologist, generating another reason to own an OCT. Prospective randomized clinical trials can be expected to better delineate the ideal therapeutic approach for the CRVO or BRVO patient.
Still, for an ophthalmologist of 40 years, it is nothing short of amazing to see patients with severe CRVO, like their once permanently blinded fellow humans suffering from exudative macular degeneration or diabetic macular edema, recover good vision after appropriate intravitreal injections. This is another great example of the amazing power of the innovation cycle and the joint effort of research scientists and those who work to translate their research into reality.