Houston— Certain dysphotopsias are unavoidable with diffractive multifocal IOLs since light scatter and image defocus are inherent to the optics. The potential for those problems need to be explained preoperatively so that patients can decide if they are willing to accept them as a trade-off for the benefit of reduced spectacle dependence at near, said Jack T. Holladay, MD, MSEE.
However, IOL position also affects additional light scatter and subsequently the development of dysphotopsias. The latter problems are under the surgeon’s control and can be minimized by paying attention to angle kappa when considering candidates for a multifocal IOL and performing the implantation, explained Dr. Holladay, clinical professor of ophthalmology, Baylor College of Medicine, Houston, TX.
“Image defocus and 18% light scatter are unavoidable with diffractive multifocal optics and those phenomena give rise to nighttime halos and reduced contrast,” he said. “Nevertheless, many patients will tolerate those dysphotopsias in exchange for being able to function at near without glasses.
“However, light scatter will be further increased if the incoming rays are not concentric with the diffractive rings, that is the diffractive rings are not concentric with the pupil,” he continued. “In that situation, patients may be dissatisfied because they perceive the resulting loss of contrast as foggy, hazy, or waxy vision.”