Position-dependent accommodative shift of retropupillary fixated iris-claw lenses

Abstract

Purpose: After implantation of retropupillary fixated iris-claw lenses, changes of the objective refraction can occur depending on the patients' position. The purpose of this study was to evaluate and quantify these changes as well as the influencing factors.

Methods: Within a retrospective study, postoperative refraction visual, acuity and anterior chamber depth after implantation of a retropupillary fixated iris-claw lens (Artisan® / Verisyse®) were measured in 51 eyes (49 patients) depending on their head position. These parameters were determined with the assistance of a mobile auto-refractometer, acoustic biometry, IOL-Master, chart projector and accommodometer in primary position, as well as in forward- and backward-tilted head position.

Results: The data analysis indicated a position-dependent change of the anterior chamber depth, which was largest in the backward-tilted head position (median: 4.25 mm/min.: 3.39 mm/max.: 5.37 mm). In comparison to the primary position (4.15 mm), it decreased in a forward-tilted position of the head (4.08 mm). A significant difference in anterior chamber depth was verified for backward- and forward-tilted heads (median: 0.155 mm). Refraction showed a significant difference (0.37 D) between forward- and backward-tilted head position. In comparison to the back-tilted head position (mean: -0.065 D), a smaller spherical equivalent could be demonstrated by bending the head forward (mean: -0.438 D). In addition, no correlation was found between lens movement and other continuous attributes.

Conclusions: Significant changes in anterior chamber depth and refraction due to the iris-claw lens shift were found, depending on head position. The phenomenon of pseudophakic accommodation is explained by pseudo-myopia and pseudo-hyperopia. A considerable influence on visual acuity depending on patients´ head position could not be verified.