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Three-step program beneficial for PVR after retinal detachment
Partially reattaching the retina and delaying retinectomy minimize the release of cytokines and growth hormones that lead to PVR.
Proliferative vitreoretinopathy after retinal detachment is better managed by a three-step program of operations in the most severe cases, according to a surgeon.
Proliferative vitreoretinopathy (PVR) can be a frequent complication of retinal detachment if access to health care is delayed. The rate varies from 5% when retinal detachment is detected immediately to as much as 53% when health care is delayed 2 or more months, Tom H. Williamson, MD, said at the Euretina Congress in Vienna, Austria.
The retinal pigment epithelium cells appear to be the main source of the proliferation. These cells are dispersed into the vitreous cavity through the retinal break and change into myofibroblasts by the action of growth hormones released as a result of the retinal detachment, he said.
However, the response is variable and subjective: Some eyes produce a PVR shortly after retinal detachment and other eyes with chronic detachment remain free of proliferation. The reason of this variability is unknown, Dr. Williamson said.
Key to success
Dr. Williamson said the key to successful PVR surgery is timing.
“The temptation is to achieve a completely flat retina as soon as possible, for example by early relaxing retinectomy,” he said. “However, operating on an eye with active PVR can result in a proliferation of membrane formation because the surgical procedure increases the stimuli for PVR.
“PVR must be in a quiescent state before retinectomy is performed, but this requires at least partial reattachment of most of the retina to minimize the release of cytokines and growth hormones from the breaking down of the blood- retinal barrier,” Dr. Williamson said.
For this reason, a three-step program of operation was designed to allow reattachment of the majority of the retina with consequent reduction of PVR stimuli, delaying retinectomy to 3 to 6 months later and finally proceeding to silicone oil removal.
“At the first operation, vitrectomy is performed and the eye is filled with silicone oil, which in most circumstances flattens two-thirds of the retina. The goal is to reattach as much of the retina as possible, obtaining a flat macula and leaving it in place for 3 to 6 months until the PVR process becomes quiescent,” Dr. Williamson said.
At a second operation, the inferior retina is cut as far peripherally as possible to perform a relaxing retinectomy. Diathermy to the visible peripheral retinal blood vessels is applied to avoid bleeding. The retina is cut with vertical cutting scissors to fashion the retinectomy, cutting through the diathermy points, he said. The vitreous cutter is used to remove the redundant anterior retina, and radial cuts are performed in case of retinal folds. Three rows of laser are applied to the posterior edge of the retinectomy and around any radial cut.
At a third stage, after 3 to 6 months, silicone oil is removed, and the retina is inspected for any retinal problems or re-detachment.
A high success rate
Dr. Williamson said a high rate of PVR was seen at patient presentation in central London. Between 2003 and 2005, of the 544 patients presenting with retinal detachment, 86 (16%) had PVR.
Twenty-seven of them were included in a study in which the three-step operation program was used. A flat retina was achieved in 93% of the cases and in 81% of the cases with removal of the silicone oil.
“In other studies, the overall success rate is lower or might be higher with primary retinectomy, but the silicone oil is in the eye for as long as 2 years,” he said.
Keeping the silicone oil in the eye for such a long time causes a high rate of severe complications, such as glaucoma and corneal problems, Dr. Williamson said.
For all cases of PVR, the overall success rate was 85% without silicone oil. Complication rate was relatively low, with only four cases of glaucoma in the long term.
“Patients are stable, and this is not easily achieved with [retinal detachment] and PVR combination.” he said.
Success rate is usually low, at about 62% to 65%, in patients with PVR, in spite of the variety of methods used.
“This program appears to provide a high chance of reattached retina and silicone oil removal,” Dr. Williamson said. “Visual acuity remains low, but this reflects the damage to the macula from the PVR process and the retinal detachment.”– by Michela Cimberle
- Tom H. Williamson, MD, is a consultant ophthalmologist at St. Thomas’ Hospital. He can be reached at 114a Harley St., London W1G 7EL U.K.; +44-20-73234432; fax +44-20-75806855; e-mail: tom@retinasurgery.co.uk.