Reply: Optimized constants for an ultraviolet light-adjustable intraocular lens

We appreciate Dr. Lam's comments about the promise of the light-adjustable IOL. This IOL allows the surgeon to correct residual spherical refractive error and astigmatism after cataract surgery noninvasively by shining a spatially profiled beam of ultraviolet (365 nm) light on the IOL.

In his letter, Dr. Lam expressed concern that only 52% of eyes were within ±0.50 D of emmetropia after implantation but before adjustment, less than the benchmark of 77% proposed by Hahn et al.,¹ which was published with an excellent and also critical editorial by Steinert.² In our study, the comparatively low percentage of eyes with ± 0.50 D of emmetrophia short term after surgery but before the necessary light adjustment/lock-in procedure was intentional. The accuracy of the refractive error adjustment is slightly better for hyperopic errors than for myopic errors, so surgeons using the light-adjustable IOL are trained to target a refractive outcome of ±0.50 D after the cataract surgery. The accuracy of the light-adjustable IOL would be more appropriately judged as the percentage of eyes between plano and ±1.00 D, but that piece of data was not analyzed in the report.

Of course, the important refractive result in assessing any IOL is not the refractive outcome 1 month after surgery but the outcome at the point of stability. At the point of stability, 96% of eyes treated with the light-adjustable IOL achieved a refraction within ±0.50 D of the intended spherical equivalent and an uncorrected distance visual acuity of 0.8,³ an outcome superior to Dr. Lam's proposed benchmark.