In PVR Surgery
Learn why this surgeon is doing fewer vitrectomies.
By Brooks W. McCuen II, MD
The indications for relaxing retinectomy haven't changed much over time. Basically, it's indicated whenever intractable traction prevents the retina from apposing effortlessly to the retinal pigment epithelium. This occurs most often with anterior proliferative vitreoretinopathy (PVR), major subretinal proliferation, high myopia with loss of retinal elasticity, some cases of proliferative vasculopathies like diabetic retinopathy, and penetrating trauma, particularly with retinal incarceration.
CHOOSING A LOCATION
Retinal pathology dictates where to position the retinectomy. Most commonly, retinectomies are made circumferentially at the posterior edge of a previously placed scleral buckle. It is critically important that all traction has been relieved posterior to the retinectomy site. In cases of retinal incarceration or in some cases of localized intractable traction, a circular retinectomy is used, excising the entire area of pathology.
To create the retinotomy, you can use either a vitreous cutter or scissors. Then, remove the anterior flap with the vitreous cutter as far anteriorly as possible up to the ora serrata. I like to diathermize the retinectomy site to improve hemostasis and to give me a visible line to follow with my incision.
The biggest mistake surgeons make when performing a relaxing retinectomy is making it too small. A 60° or less relaxing retinectomy is usually problematic, as it does not allow the retina to relax enough to deal with the traction, and the edges subsequently lift with retinal redetachment. I rarely go less than 180°.
As most cases are inferior, I try to bring the superior edge of the retinectomy site to at least the horizontal meridian, which helps achieve a better tamponade of the retinectomy edge with either gas or oil. I usually prefer silicone oil to a gas tamponade.
ACHIEVING BETTER OUTCOMES
In 1990, Larry Morse, M.D., and our group1 reviewed 100 consecutive cases of relaxing retinectomy performed at Duke with 6 months' follow-up. At that time, we reported 58% complete attachment, with 64% attached posterior to the scleral buckle. Roughly 30% had visual acuities better than or equal to 5/200 at final follow-up, but we had hypotony in 43% of these cases. These are certainly pretty sobering results.
Prithvi Mruthyunjaya, M.D., and I recently reviewed some of my more recent unpublished results, looking at 51 consecutive patients. The demographics were about the same as for the 1990 study. Preoperatively, 24% had a phakic retinal detachment with PVR; 24% were aphakic or pseudophakic with PVR. The rest of the cases comprised a smorgasbord of different etiologies.
One significant change from 1990 to now was there are fewer repeat vitrectomies performed before turning to relaxing retinectomy. I proceed with relaxing retinectomy sooner now than I did in 1990. The reason is simple: Outcomes are better when retinectomy is employed sooner rather than as a last ditch effort to salvage a dying retina.
In our recent series, the retina was completely attached in 82% of cases, and the macula was attached in 88% of the patients at final follow-up. In 1990, we could remove the silicone from only 17% of patients, but now we're removing it in 42% of cases. In addition, hypotony decreased from 43% to 10% in the current series. I suspect this is due to better removal of the anterior flap and to use of low molecular weight heparin, which decreases the fibrin that can produce a scaffold for contracting membranes that damage the ciliary processes.
Visual results in our recent series are also better. Visual acuities improved 61% in our current series compared to 44% in our previous series. The percentage of eyes with ambulatory vision climbed from 29% in 1990 to 51% currently.
I've decided to do more relaxing retinectomies in severe cases that require such an aggressive traction-relieving approach. However, with rare exceptions, I don't perform retinectomy as a primary procedure. I do think that this effective approach is frequently underutilized and, with appropriate experience, it can be an extremely valuable technique for achieving better reattachment rates and improved vision in highly complex cases.
Dr. McCuen is a Robert Machemer Professor of Ophthalmology, director of Vitreoretinal Service, and vice chairman of the Department of Ophthalmology at Duke University in Durham, N.C.
1. Morse LS, McCuen BW II, Machemer R. Relaxing retinotomies: Analysis of anatomic and visual results. Ophthalmology. 1990;97:642-647.
Retinal Physician, Issue: October 2004