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Reassessment of refractive lens exchange risks needed
The evidence available at present suggests a cautious approach is warranted, one surgeon says.
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Despite technical and technological advances in lens removal, refractive lens exchange remains a controversial procedure. A leading surgeon suggests that before the procedure is widely adopted, its benefits and risks should be re-examined.
Although refractive lens exchange (RLE) is a very effective procedure for high refractive errors, the risks involved should not be underestimated, and a careful preoperative evaluation and patient selection is mandatory, said Joseph Colin, MD, Ocular Surgery News Europe/Asia-Pacific Edition editorial board member.
“Complications are rare but may be severe,” Prof. Colin said. He added that “of all objections raised against RLE, the risk of retinal detachment still poses the greatest obstacle to the procedure’s acceptance, particularly in myopic patients.”
In other words, conclusions are much the same as before. Prof. Colin cited a publication from 1987 in which M.F. Goldberg said: “Based on the available evidence, I conclude that the risk/benefit ratio for RLE is currently too high for it to be recommended.”
RLE with IOL implantation, however, is gaining adherents in the United States. David Leaming’s 2002 survey of members of the American Society of Cataract and Refractive Surgery showed that 25% of respondents performed one to two RLEs per month, compared with 19% of respondents in the previous year. In patients over 45 years with hyperopia of more than +5 D, the number of RLE procedures surpassed all the other treatments, including LASIK. In younger patients and highly myopic eyes, the number was considerably lower.
“Undoubtedly, the latest innovations and the increasing popularity of the procedure require a reassessment of its risks and benefits,” Prof. Colin said.
A review of literature
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Reviewing the literature on the subject, Prof. Colin said that studies on myopic RLE and cataract extraction reach different conclusions, depending on the patient population and length of follow-up.
In a meta-analysis of 13 papers (1996-2003) on myopic RLE and cataract extraction, Richard Packard showed that in 1,790 eyes, the rate of retinal detachment at 37 months was 1.53%.
A survey published by J.C. Javitt in 1994 concluded that patients who have had RLE for myopia could expect a 4.6% chance of moderate visual impairment and a 3.3% chance of severe visual impairment strictly as a result of retinal complications. There was also evidence that the risk of visual loss is enhanced by bilateral surgery, the study found.
“The results published back in 1999 by myself and other authors showed how the rate of retinal detachment increased with time,” Prof. Colin said. “In our series, we had no case of RD at 1 year, 2% at 4 years, 8% at 7 years and 10% at 10 years. All our patients were high myopes (>12 D) and were treated with phacoemulsification, PMMA IOL implantation and preoperative retinal argon laser prophylaxis when necessary. We also concluded that the need for Nd:YAG capsulotomy after RLE, which was performed in 60% of our cases, increased the risk of retinal complications.”
Further risk factors included peripheral retinal lesions, the status of the posterior vitreous and a personal or family history of retinal detachments, he said.
Open questions
On the whole, these results demonstrate an increased rate of retinal detachment after RLE compared with the natural rate of retinal detachment in highly myopic eyes, Prof. Colin said. The lifetime risk of retinal detachment is 40 times higher in unoperated highly myopic eyes than in emmetropic eyes, he said. E.S. Perkins estimated the incidence of retinal detachment in the unoperated patient population with myopia greater than –10 D to be 0.68% annually, or 6.8% over 10 years, Prof. Colin said.
However, some questions remain, according to Prof. Colin. The first concerns the role of retinal prophylaxis before RLE.
“Whether retinal prophylaxis might be effective and increase the safety of the procedure or might on the contrary be dangerous, it had not yet been established,” he said.
The second question is how much the use of foldable IOLs might weigh on the future outcomes of RLE.
“Previous results have been based on data collected over a long period of time and therefore with the prevalent use of IOLs of the past generation,” he said. “The new materials, which notoriously cause less PCO, will cut down on the incidence of YAG capsulotomy. Will this factor contribute to decreased RD rates?”
The last question concerns a possible correlation between myopic macular degeneration and RLE.
“Whether RLE could be a risk factor in the progression of the disease is still unknown and needs investigation,” Prof. Colin said.
Cautious approach
RLE for hyperopia is known to have a lower risk for retinal complications, Prof. Colin said. However, eyes with extreme hyperopia present a series of anatomical contraindications, such as small axial length, shallow anterior chamber, small corneal diameter and nanophthalmos, he said.
“Hyperopic eyes with a shallow anterior chamber are more prone to angle closure, and nanophthalmic eyes are at risk of intraoperative and postoperative complications such as uveal effusion, retinal detachment, intraocular hemorrhage and malignant glaucoma,” Prof. Colin pointed out.
Although none of these complications have so far been reported in hyperopic or presbyopic eyes that underwent RLE procedures, a cautious attitude is advisable in such cases, he said.
“Great care should be taken pre-, intra- and postoperatively, and patients should be made aware of the possible long-term effects of the procedure. New prospective studies are necessary to establish whether the latest advances of cataract surgery might enhance the long-term safety of the treatment,” he said.
For Your Information:
- Joseph Colin, MD, can be reached at Hôpital Pellegrin, Place Amélie Raba-Lèon, 33076 Bordeaux, France; +33-5-56795608; fax: +33-5-56795909; e-mail: joseph.colin@chu-bordeaux.fr.
Reference:
- Goldberg MF. Clear lens extraction for axial myopia. Ophthalmology. 1987;94:571-582
- Leaming DV. Practice styles and preferences of ASCRS members — 2002 Survey. J Cataract Refract Surg. 2002;28(9):1681-1688
- Colin J, Robinet A, Cochener B. Retinal detachment after clear lens extraction for high myopia: Seven-year follow-up. Ophthalmology. 1999;106(12): 2281-2284.