LAUSR

Problems With Different Meanings and Types of Refractive Lens Exchange We read the article by Schallhorn et al.1 in the November 2017 issue with interest, but we believe that some issues should be clarified. In this retrospective study, the authors compared the outcomes of monovision LASIK and presbyopia-correcting intraocular lenses (IOLs). Patients between 45 and 60 years of age with preoperative manifest sphere between -10.00 and +3.00 diopters sphere were included in the study. They underwent bilateral LASIK or lens surgery with the Tecnis Symfony IOL (Johnson & Johnson Vision Care, Inc., Santa Ana, CA) in at least one eye, and the term refractive lens exchange (RLE) was used at several points. However, the definition of RLE covers surgery with transparency and softness of the crystalline lens, absence of cataract, and abnormal ocular anatomy associated with high refractive error, which in this particular case is the indication for RLE.2 Presbyopia and spectacle independence may also constitute an important indication for RLE, and presbyopic lens exchange (PRELEX) aims solely to correct the loss of accommodation. Distinguishing between RLE and PRELEX is critical because patients who have PRELEX are more demanding and have excellent corrected distance visual acuity and often good uncorrected distance visual acuity.3 With that, offering RLE to emmetropic patients is a contentious clinical decision, especially when postoperative halo and glare are concerns.4 Another issue is the possibility of vision-threatening complications of RLE, of which retinal detachment is the most common in myopic eyes, presenting an incidence of between 1.5% and 8.1%.2 Even refractive surgery itself may induce some increase in the occurrence of such pathology. During lens surgery, a transient decrease in intraocular pressure (decompression effect) can cause changes in the vitreous body, especially if vitreous degenerations already exist.5 Intraoperatively, minimal disturbance of the intraocular environment is of great importance. Thus, it would be relevant to know whether any retinal pathologies were found in the preoperative examination and how they were managed. What was the incidence of intraoperative capsular tear with vitreous loss during RLE, because it significantly increases the risk for retinal detachment? With that, we believe that a 3-month follow-up period might be insufficient to fully confirm the safety and outcomes of these methods. The authors state that this is the largest study comparing outcomes of monovision LASIK and RLE, presenting results separately among different refractive categories. All myopic patients with RLE experienced more postoperative visual phenomena and had worse near visual acuity than patients with monovision LASIK. It was concluded that monovision LASIK might be a better option in this population. A scrupulous analysis of Table B reveals that patients with RLE in all refractive groups had an increase in glare or halos postoperatively. With that, a pronounced rate of plano presbyopes had an increase in dysphotopsias in both monovision LASIK and RLE, which was not statistically different. It should be underscored that several optical principles might be applied to achieve multifocality in IOLs—diffractive and/or refractive design, bifocality and trifocality, bioanalogic IOLs, and small aperture design. In the presented study, only one type of multifocal IOL was implanted, the Tecnis Symfony IOL. Thus, the results refer to this particular lens, and not RLE in general.