Asymmetry of pupil dilation and change in angle kappa in pseudophakic eyes

Session Details

Session Title: Paediatric Ophthalmology & Other Topics

Session Date/Time: Tuesday 25/09/2018 | 08:00-10:30

Paper Time: 09:54

Venue: Room A3, Podium 2

First Author: : H.Zwickl AUSTRIA

Co Author(s): :    S. Maedel   N. Hirnschall   B. Doeller   P. Nguyen   O. Findl        

Abstract Details

Purpose:

Clinical Purkinje meter systems are used to assess intraocular lens (IOL) tilt and decentration with respect to the line of sight (line from center of the pupil passing through the fixation point) or the pupillary axis (line perpendicular to the cornea passing through the center of the pupil). Both axes are non coincident in normal subjects and the angle between them is usually denoted as kappa. Pupil dilation is assumed not to be completely symmetrical, especially in pseudophakic eyes. As the pupil is used as a reference for these measurements a pharmacological mydriasis might have an influence on angle kappa.

Setting:

Vienna Institute for Research in Ocular Surgery (VIROS), Department of Ophthalmology, Hanusch Hospital, Vienna, Austria

Methods:

Altogether, 30 eyes of 30 pseudophakic patients were included in this prospective study. Exclusion criteria were corneal opacities and ophthalmic diseases compromising proper fixation of the fixation light during measurements. Purkinje meter measurements were taken before and 30 minutes after instillation of tropicamide 1% gtt and phenylephrine 10% gtt. Based on these images angle kappa was calculated. Furthermore, based on images taken with the Purkinje meter, the increase in pupil size after dilation was assessed. The amount and direction of shift of the pupil center due to asymmetrical dilation was calculated from these images.

Results:

Before dilation, mean (SD) absolute horizontal and vertical angle kappa was -2.57° (±1.97) and 0.47° (±2.06), respectively. For dilated pupils, horizontal and vertical kappa was -1.56° (±3.76) and -3.22° (±3.34), respectively. Vertical kappa was significantly higher after dilation (ppaired t-test<0.05). Mean (SD) undilated and dilated pupil diameter was 3.93 mm (±0.59) and 6.58 mm (±0.74), respectively. Mean (SD) absolute shift of the pupil center was 0.29 mm (±0.15).

Conclusions:

A significant larger vertical angle kappa was detected after dilation of pupils in our patients. After dilation, a small, but measurable shift of pupil centers was detected in all patients. Pupil centers shifted inferior and/or nasally. In conclusion, Purkinje meter measurements should be performed prior to pupil dilation.

Financial Disclosure:

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