Optimized constants for an ultraviolet light-adjustable intraocular lens

In their paper on the refractive outcome with the light-adjustable intraocular lens (IOL) (Calhoun Vision, Inc), Conrad-Hengerer et al.¹ reported that in their series of 125 eyes, 52% were within 0.50 diopters (D) of the target refraction prior to the first adjustment, using the SRK/T formula with an optimized A constant.

Recently, Hahn et al.² proposed that, as a benchmark for refractive outcome, 77% of eyes should be within 0.50 D of the target refraction after 1 month postoperatively and 80% should be within 0.50 D after 3 months. Hahn et al. used the SN60AT IOL (Alcon Laboratories, Inc.) and the SRK/T formula in their series. In both series, the IOLMaster (Carl Zeiss Meditec AG) was used for preoperative biometry.

It is interesting to note the significant disparity in the refractive outcome between the 2 series prior to adjusting the power of the light-adjustable IOL, which is performed 3 weeks postoperatively or later.

It is doubtful that such disparity is due to differences in surgical techniques, since both series use small-incision phacoemulsification, or difference in the timing of postoperative refraction between the 2 series. It is possible that the difference in the design of the IOLs could contribute to such disparity in the postoperative refractive outcome.

The light-adjustable IOL is a promising technology. However, it appears that there is still significant improvement to be made in attaining better refractive accuracy with this IOL, prior to adjusting the IOL power. With more accurate refractive outcome, less adjustment would be necessary.