Differences in anterior chamber configuration in negative dysphotopsia

Session Details

Session Title: Cataract Surgery Complications

Session Date/Time: Monday 16/09/2019 | 16:30-18:00

Paper Time: 17:12

Venue: Free Paper Forum: Podium 2

First Author: : J.Beenakker THE NETHERLANDS

Co Author(s): :    L. van Vught   G. Luyten                          

Abstract Details

Purpose:

Negative Dysphotopsia (ND), commonly described as a dark shadow or missing part of the peripheral visual field, is a currently unexplained complaint that can occur directly after cataract surgery. Holliday and Osher (JCRS,2017) indicated that ND might originate from light passing through a nasal gap between the iris and intraocular lens (IOL). Hence, a larger angle kappa might be associated with ND, which would indicate that the iris is tilted with respect to the visual axis. In this study we assessed the anterior chamber configuration in patients with and without ND, to obtain more insight in the origin of ND.

Setting:

Department of Ophthalmology, Leiden University Medical Center (LUMC), Leiden, the Netherlands.

Methods:

Fifty-five pseudophakic eyes of twenty-seven ND-patients and twenty-eight pseudophakic controls were evaluated prospectively. Corneal topography (Pentacam, Oculus) and Biometry (Lenstar, Haag-Streit) measurements were performed in all patients. The tilt of the iris was defined as the horizontal angle between the optical axis and the iris plane. This plane was obtained by fitting a plane through the iris, as segmented by the corneal topographer. Additionally, the horizontal decentration of the pupil center with respect to the corneal vertex (Pentacam) and with respect to the visual axis (Lenstar) were assessed. These measures were compared between both groups using t-tests.

Results:

ND-patients showed a significant higher temporal tilt of the iris compared to pseudophakic controls (p <0.001), with mean tilts of respectively 6.3 (SD:1.4) and 4.5 (SD:1.5) degrees. Temporal tilt was defined as a more posterior iris on the temporal side compared to the nasal side. Additionally, significant differences were found in the decentration of the pupil center with respect to the corneal vertex (0.17 and 0.01 mm respectively, p <0.01) and with respect to the visual axis (0.19 and 0.03 mm respectively, p = 0.02). A positive decentration was defined as a shift towards the temporal side.

Conclusions:

We find significant differences in the anterior chamber configuration of eyes with and without ND. The significant difference in iris tilt is in line with some of the hypothesised origins of ND that suggest that a tilted iris, which relates to the angle kappa, allows for light rays passing through the nasal gap between the iris and IOL. The significant difference in pupil center is likely caused by the temporal rotation of the iris, since these measurements are highly correlated geometrically. As such, this study provides important new objective clinical data and evidence on the origin of ND.

Financial Disclosure:

None