Quantitative Assessment Of Straylight From Laser Pits In Explanted Intraocular Lenses

Nd:YAG laser capsulotomy is widely used for the treatment of posterior capsule opacification (PCO). However, misfocused laser pulses may produce pits on intraocular lenses (IOLs). The optical consequences of these defects, particularly their contribution to straylight, and thus glare phenomena, has been debatable. This study aimed to quantify straylight generated by laser pits and to evaluate structural factors associated with its increase.

David J. Apple Center for Vision Research, Department of Ophthalmology, University of Heidelberg, Germany.

9 explanted monofocal IOLs (n=9) with laser pits were analyzed using a goniometer-based optical setup. For each lens, two representative pits were selected for quantitative and morphological evaluation (n=18). To assess factors contributing to straylight generation, edge-related scattering from individual pits was qualitatively evaluated, and quantitative analyses were performed to determine the association between pit scatter depth, pit area, and measured straylight. Linear regression analysis was used to evaluate correlations between structural parameters and straylight.

Our investigation revealed that scattering predominantly originated from pit edges and exhibited angular asymmetry, with straylight from pit regions consistently exceeded that from adjacent control areas. Mean straylight ranged from 0.14 to 0.78 logs across samples. Correlation analysis revealed a statistically significant negative association between depth ratio and straylight (r=−0.497, R²=0.247, p=0.036, n=18) and a significant positive association between pit area and straylight (r =0.510, R²=0.260, p=0.031, n=18). The combined weighted parameter showed no statistically significant relationship with straylight (r=0.299, R²=0.089, p=0.23, n=18).

Laser-induced pits increase straylight, primarily in association with edge-related structures, pit depth and defect area. However, the moderate explanatory power and inter-sample variability indicate that straylight generation is multifactorial and not solely determined by pit geometry. These findings provide quantitative insight into the optical impact of laser pits.