Will Reversible ( Removable ) Refractive Surgery Reverse the Way We Do Refractive Surgery ?

IS IT REALLY REVERSIBLE? In the January/February 2001 issue of the Journal of Refractive Surgery, Asbell and colleagues reported the reversible effect of the intrastromal corneal ring segments (Intacs). 1 They presented compelling evidence to suggest that Intacs can be removed with full reversibility of refractive effect. This is the first corneal refractive surgical procedure to claim reversibility. That claim opens a whole new issue for refractive surgery regarding the reality and importance of reversibility. Glasses and contact lenses are reversible. But can a surgically created change in the shape of the cornea be made unpermanent because the procedure can be reversed? Asbell and colleagues reported a cohort of 34 eyes in which the ring segments were removed and showed that 18 of 21 eyes (86%) examined at 3 months returned to within ±0.50 D of the original refractive error and regained their original uncor-rected and best spectacle-corrected visual acuity. Despite this high percentage of reversibility, not all eyes were fully reversed; Why? Certainly the refrac-tive results of reversibility are quite impressive, but anatomically when the ring segments are placed, adjacent channel deposits and corneal haze can develop, which remain to a lesser degree after the ring segments are removed. Perhaps some of these anatomical changes contribute to the lack of reversibility. The term " reversibility " may be an overstatement ; removability best describes this procedure's feature. Indeed, a truly reversible refractive surgical procedure is not possible, because once surgery is performed the refractive effect of surgery may be removed, but the surgical event and its anatomical consequences cannot be reversed. Only nonsurgical refractive devices, such as spectacles and contact lenses, can truly be considered reversible. IS REMOVABILITY IMPORTANT? In nearly all of the 34 eyes, the reason for ring removal was dissatisfaction of the patient. The overall percentage of removal was nearly 5% in both phase II and phase III of the US FDA trial and over 2% of these patients elected ring removal because of visual symptoms of glare and halos. Although these symptoms are not unique to refractive surgery, they emphasize that Intacs can produce visual distortions and optical aberrations. The unique feature of Intacs is that these symptoms can be eliminated by removal of the ring implant, as noted in every case. The reversibility of refractive effect in most eyes is complimented by elimination of the adverse visual symptoms and aberrations, which makes the claim …