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The Medical Post June 3, 1997 Ophthalmology Update FORT LAUDERDALE, FLA. - Patients with high myopia should not be subjected to excimer laser treatment because they could end up with detached retinas and serious loss of vision, according to a British surgeon. After operating on 10 patients who suffered retinal detachment from one to 20 months after undergoing photorefrative keratectomy (PRK) by excimer laser, doctors at Moorfield's Eye Hospital in London ended up doing retinal repair in 11 eyes. Nine patients had undergone PRK, five bilateral and four unilateral, to correct myopia. One had subsequently suffered retinal detachment. They ranged in age from 24 to 56 years and eight of them were male. From what they observed, said Dr. David Chartersis of Moorfeild's, the series of retinal detachments (in this group of patients) forms a heterogeneous group that appears to affect the predisposition of myopes to rhegmatogenous retinal detachment. "Myopic patients undergoing excimer laser PRK are likely to be at greater risk of retinal detachment than the general population," Dr. Charteris said, adding, "It is possible that the acoustic shock waves generated within the globe at the time of excimer laser keratectomy precipitate a detachment or extension of detachment in an eye with a predisposing vitreoretinal pathology." Based on the results, he recommended to the annual ophthalmology meeting here "that patients undergoing PRK have a detailed fundal examination to detect any presiposing vitreoretinal pathology." He didn't advocate prophylactic treatment of any retina before PRK. The conclusion of the report by Dr. Charteris, a consultant surgeon at Moorfield's, came as no surprise to Harvard medical school clinical ophthalmology instructor Dr. Alex Gaudil. "If you take 100 cases of retinal detachment, 70% of these people will be high myopes, so this makes the whole business of dealing with corneal curvature more difficult," he said adding that he also didn't believe prophylactic treatment was ever warranted. "I don't believe you can identify all patients likely to develop retinal detachment. I also don't think, at least in the Boston area where retinal detachment surgery was born, there is a great tendency to do prophylactic treatment. Besides that, I am not certain that it would even work," he said during an interview at the meeting where Dr. Charteris' paper was presented. While Dr. Gaudil said it is possible to identify those patients who will develop retinal detachment who have lattice degeneration of holes in the periphery, "Many times when you do that (prophylactic repair), they go on to detachment anyway but not in the area where you did the prophylactic treatment. "When you already have an eye at risk, I don't think you should increase that risk," Dr. Gaudil said, "so the excimer laser should not be used with this type of patient." The main point, said Dr. Charteris, is that PRK and PTK patients should have a posterior examination before they have excimer laser. "Consideration should be given whether they need prophylactic treatment of treatment of any pre-existing detachments." The second point is that if a patient suffers visual loss after excimer laser, it should not be automatically attributed to segment problems. "The posterior segment should be examined and retinal detachment should be excluded as a possible cause of the problem," he said. Because excimer laser treatment for ending near-sightedness is being popularized by some member of the ophthalmology profession, Dr. Charteris fears that many high myopes will suffer needless retinal detachments with attendant loss of vision. "These patients are at risk with the increased use of laser, and I believe they should be closely evaluated before they receive this treatment," he cautioned, adding some of the patients be treated were left with the ability to see only light movement after repair of their retinas. "A couple of the patients had macular involvement, so they are permanently affected. There is no way we can restore their central vision," he said adding this was found in five of the 11 eyes he and his team repaired. Dr. Charteris said it was impossible to state whether these patients would have escaped retinal detachment had they not had excimer laser treatment. "That is a question we can't definitely answer at this stage. Some of these patients would have had a detachment anyway. "But if you go to a patient like number nine, who had excimer laser for high myopia and then one month later developed multiple retinal tears and then had a vitreous hemorrhage, it is very suggestive that events at the time of the laser had a casual relationship." Dr. Charteris is now looking at the records of all patients who received excimer laser surgery at Moorsfield Hospital. |