Previously anyone at high risk of a retinal detachment could do little but wait and hopefully keep on seeing. But two Birmingham ophthalmologists have now completed a pilot study on a laser procedure that may become the first reliable retinal detachment preventative procedure for high-risk eyes.
With rhegmatogenous retinal detachment (RRD) being so effectively repairable, not much attention has been given to preventing it. “But not everyone gets back all their vision after a retinal reattachment, and it’s sometimes a difficult operation,” said Robert Morris, MD, with Retina Specialists of Alabama and a clinical associate professor at UAB. “If someone has already lost vision due to a retinal detachment in one eye, they don’t want the other shoe to fall. Those second eyes are the ones we’ve performed this procedure on in this first study.”
Morris and his partner C. Doug Witherspoon, MD, also with Retina Specialists and UAB, devised their laser prophylaxis as an extension of the current repair process for retinal tears. Retinal tears are a primary cause of RRD as the opening allows vitreous cavity fluid to pass behind the retina, floating it away from the eye wall. If not treated quickly, this leads to vision loss and even blindness.
To repair retinal tears, a laser surrounds the tear with “burns” to create a chorioretinal scar that effectively welds the surrounding retina to the eye wall (figure 1). This treatment is over 95 percent effective in preventing progression of that particular retinal tear to retinal detachment. “Basically, it creates tight adhesion by means of a well-controlled microscopic scar that effectively bonds those tissues together,” Witherspoon said. “But new tears often occur at other clock hours in the peripheral retina.”
When repairing an existent retinal detachment, many physicians encircle the retina in some fashion with a laser treatment to help prevent any future tears or retinal detachment (figures 2 and 3). It was in this technique that the two ophthalmologists saw even more potential. “We took the encircling laser to a purely preventive level by applying it to the second eye where no tears existed, only high risk of tears or detachment,” Morris said.
They realized that if encircling worked in eyes with existent RRD, it might be similarly effective in eyes at high risk from other causes, such as being severely nearsighted with a family history of retinal detachment. “The new thing we’re doing,” Witherspoon said, “is taking the encircling procedure to a second eye as a preventive measure, especially in eyes that have had cataract removal.”
So they used the encircling technique to create a new “boundary” on the retina in eyes that were known to be at risk but not actually damaged. “Most tears occur in the outer regions of the retina, so we take that area out of play,” Morris said.
Using a laser, they burn a ring of minute scars several millimeters wide, just behind the ora serrata, the anterior line of the retina. “We’re creating a second line — a second ora — further back from the ora serrata. We’re calling that the ora secunda,” Morris said.
The ora serrata circumscribes the back two-thirds of the eye orb — in front of the equator of the eye — so the laser “welding” effectively creates a new retinal boundary. “All the lasering is done in front of the equator of the eye where little vision occurs,” Morris said. “The lasering is far out in the peripheral field, but those are the exact same areas that suffer tears that cause detachment.”
The primary candidates for this new procedure are eyes that harbor multiple risk factors, such as cataract surgery, a family history of detachments, eye trauma, and severe myopia. With over 1.35 million cataract surgeries in the U.S. and about 1 percent suffering retinal detachments, that leaves 13,500 eyes at risk of RRD. Morris notes that if a patient has had cataract surgery in both eyes and a retinal detachment in one, there’s a 20 percent chance of a RRD in the second eye.
“All these things can add up, and the key is to determine the actual risk for that particular eye,” Witherspoon said. “Although laser is noninvasive, you don’t want to be lasering eyes that don’t have a high risk of retinal detachment.”
The two ophthamologists researched this innovative surgery in a study of 266 eyes and accumulated five to ten years of follow-up data. They recently released a paper introducing the concept, and plan to present the hard data this year in more formal medical journals.
The Helen Keller Foundation for Research and Education in Birmingham, of which Morris is president, helped sponsor this discovery.
July 2008
