Identification of Design Factors related to Intraocular Lens Fixation in the Lens Capsule

Abstract

Purpose : Proper intraocular lens (IOL) fixation is a prerequisite for the implant to fully achieve the desired correction and visual quality. The relationship between intracapsular fixation and each manufacturer’s IOL design was presented at ARVO 2023. The outcomes indicated that the XY1 (Hoya) IOL had greater variability in deviation, tilt, and rotation than other IOLs. However we were unable to determine the main cause of this variability. Therefore, in this study we investigate the main factors that affect IOL deviation, tilt, and rotation.

Methods : This study evaluated 4 different 20 D power IOLs as follows: XY1 (Hoya), DIB00V (Johnson and Johnson Vision), CNA0T0 (Alcon), and NS-60YG (Nidek). A sealed jig with a 10.5 mm diameter which approximated a human lens, was moved up and down for 24 hours under conditions simulating daily walking (vertical movement with an amplitude of 1 Hz and 5 cm). As deflection in the IOL haptics was observed, deflection values were calculated to confirm the correlation with the magnitude of deviation, tilt, and rotation. For each manufacturer’s IOL, the correlation was also confirmed between the deflection and the haptic base thickness, hardness, compression force, weight, haptic contact area with the jig, contact angle with the jig, and haptic angle. The optimal thickness of the IOL haptics was calculated from the tendency in the deflection values for each IOL.

Results : The highest to lowest deflection values of the IOL haptics were XY1>CNA0T0>NS-60YG>DIB00V.
The correlation between the deflection values and the magnitude of deviation, tilt, and rotation was R²=0.96, R²=0.94, and R²=0.94, respectively. The highest to lowest correlation with factors assumed to affect deflection were: haptic base thickness, R²=0.69; weight, R²=0.41; haptic contact area, R²=0.39; compression force, R²=0.24; contact angle, R²=0.20; haptic angle, R²=0.07; hardness, R²=0.003. Based on the correlation formula between the haptic base thickness and the deflection, the thickness that reduced deflection was calculated to be at least 0.321 mm for XY1, 0.332 mm for DIB00V, 0.290 mm for CNA0T0, and 0.377 mm for NS-60YG.

Conclusions : The magnitude of deviation, tilt, and rotation was highly correlated with IOL deflection. The outcomes of this study also indicated that the deflection originated from the haptic base thickness.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.