Evaluation of IOL Intracapsular Fixation due to Differences in IOL Design

Abstract

Purpose : Toric and multifocal intraocular lenses (IOLs) are being implanted with increasing frequency. Hence, there has been an evolution of IOL power calculations also. However, a prerequisite for successful IOL outcomes is proper fixation in the eye. IOL manufacturers have various IOL designs for ensuring fixation in-the-bag. This study examines the relationship between intracapsular fixation and IOL design from some common manufacturers.

Methods : Three 20 D IOLs from each of the following manufacturers were tested: XY1 (Hoya), DIB00V (Johnson and Johnson Vision), CNA0T0 (Alcon), and NS-60YG (Nidek). A laboratory apparatus (jig) was prepared to mimic a human lens with a diameter of 10.5 mm. An IOL was placed in the jig and the jig was then filled with saline solution and sealed and an amplitude of 1 Hz and vertical movement of 5 cm was used to simulate daily walking. Each IOL was tested at 31 °C to simulate the temperature of aqueous humor. After 24 hours of vertical movement, the amount of deviation/tilt/rotation was evaluated with a stereomicroscope (Nikon) and a one-shot 3D shape measuring device VR-3100 (Keyence). Furthermore, the compression force / weight / haptic contact area / contact angle with the jig / angle of the haptic coming out of the optic of each IOL were measured to evaluate the correlation with the magnitude of deviation/tilt/rotation.

Results : The deviation (mm) for each type of IOL was: XY1 (0.90±0.31) > CNA0T0 (0.19±0.17) > NS-60YG (0.17±0.22) > DIB00V (0.15±0.02). IOL tilt (°) values were: XY1 (2.0±3.2) > CNA0T0 (1.2±1.3) > (NS-60YG (0.6±0.3) > DIB00V (0.5±0.4). The magnitude of IOL rotation (°) was: XY1 (2.4±1.9) > NS-60YG (0.5±0.1) > CNA0T0 (0.3±0.2) > DIB00V (0.2±0.2). Tilt was weakly correlated to weight (R² = 0.65), haptic contact area (R² = 0.48), and compression force (R² = 0.44). There were no correlations any variables to deviation or rotation.

Conclusions : The magnitude of IOL deviation, tilt and rotation of XY1 was significantly larger compared to other IOLs. Intracapsular fixation is slightly affected by the IOL weight, haptic contact area, and compression force. However IOL deviation/tilt/rotation is affected by multiple variables with complex interactions that require further study.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.