Normal distribution of iTrace estimated angle alpha in a cataract surgery patient population

Session Details

Session Title: Presented Poster Session: Training & Quality of Vision

Venue: Poster Village: Pod 3

First Author: : M.Mahr USA

Co Author(s): :    J. Erie                       

Abstract Details

Purpose:

To determine the normal distribution of angle alpha - the difference between the visual axis and the estimated center of the capsular bag and intraocular lens implant.

Setting:

Mayo Clinic Department of Ophthalmology - Rochester, MN USA

Methods:

Complete iTrace (Tracey Technologies; Houston, Texas USA) measurements were recorded for 8,773 eyes in a cataract surgery patient population from 2014-7. Data were deidentified, exported, and analyzed using R and RStudio.

Results:

Estimated angle alpha orientation as reported by iTrace was asymmetrically distributed. The axis was horizontal in 94%, vertical in 2%, and oblique in 4% of eyes (p<0.01). Angle alpha distance had a mean and median of 0.41mm. The angle alpha distance was <0.35mm in 35%, between 0.35 and 0.45mm in 26%, and 0.45mm or greater in 39% of eyes.

Conclusions:

Estimated angle alpha is almost exclusively horizontally oriented (p<0.01). For surgeons who use an angle alpha magnitude cutoff for multifocal IOL eligibility, these normative results can quantify the impact of screening criteria on potential patient eligibility.

Financial Disclosure:

None