Prospective trials needed for venous occlusive disease

October 15, 2005

San Francisco—The search for a cure for venous occlusive disease continues but at a slow pace. The last 20 years have seen the introduction of promising medical and surgical therapy for venous occlusive disease. However, the results of prospective trials of these treatments are lacking.

Everett Ai, MD, medical director, Ophthalmic Diagnostic Center, California Pacific Medical Center, San Francisco, described the status of various treatment approaches. Dr. Ai pointed out that there has been a decided dearth of controlled studies on the subject.

For example, of the recent papers presented last year at the annual meeting of the American Society of Retinal Specialists, no data were presented from randomized, controlled clinical trials.

However, in contrast to this, intravitreally injected steroids are commonly administered to treat branch and central vein occlusion. There have been reports of improved outcomes on clinical evaluation and optical coherence tomography following administration of triamcinolone in doses ranging from 2 to 25 mg, according to Dr. Ai.

A study that Dr. Ai and his colleagues conducted in which they used a 10-mg triamcinolone intravitreal injection to treat central vein occlusion in 34 patients showed that the improvement rate was no better than the natural history of the disease. The results of a study involving "standard care" versus intravitreal steroid therapy will help to elucidate long-term results, he said.

Surgical approach

Surgical therapy for branch vein occlusion may be promising, Dr. Ai recounted. Studies of arterial venous sheathotomy have shown postoperative visual acuity improvements. The common adventitial sheath binding the arteriosclerotic artery to the occluded vein is lysed until the artery can be lifted off the vein. Follow-up periods, however, have been short and prospective studies are needed.

Radial optic neurotomy for central vein occlusion relieves compression of the occluded vein within the scleral ring by surgical relaxation of the scleral ring, cribriform plate, and adjacent sclera. This is accomplished by means of a radial cut on the nasal aspect of the optic disc extending to the lamina cribrosa, Dr. Ai explained.

"While this technique has its proponents, its scientific basis has been questioned. A recent study showed that the amount of venous decompression that could be achieved was less than 5%. It is critical that clinical trials be conducted to assess the benefits and risks of this procedure fully," Dr. Ai emphasized.

"After 20 years of progress and the advent of pharmacologic and surgical techniques not previously possible, we continue to await the results of prospective, randomized, controlled clinical trials to clarify indications for these procedures," he said. "Such studies should make an accurate distinction between ischemic and nonischemic vascular occlusion.

"These studies should also incorporate newer diagnostic modalities such as optical coherence tomography to allow more accurate assessment of anatomic results," Dr. Ai concluded. "After all, we all eagerly await more effective treatments in the management of this most frustrating of retinal conditions."