Towards customised raytracing in IOL calculation

Session Details

Session Title: IOL Power Calculations

Session Date/Time: Sunday 11/09/2016 | 16:00-18:00

Paper Time: 16:06

Venue: Hall C2

First Author: : G.Rallatos GREECE

Co Author(s): :    C. Katsoulos   I. Pentari   H. Ginis              

Abstract Details

Purpose:

Despite the established theoretical and clinical knowledge in the field of Intraocular lens calculations errors seem to influence the accuracy of refractive outcomes in some patients. Total refractive error is the combined result of measurement and calculation error. The present work pertains to the development of a framework for customized IOL calculation based on exact ray-tracing and an empirical nomogram for effective lens position.

Setting:

Athens Eye Hospital, Athens Greece.

Methods:

Anatomical data for the anterior segment (Anterior chamber depth, Keratometry, corneal thickness, white-to white), axial length and refraction were analysed for a series of thirty five (35) eyes of thirty five (35) patients that underwent cataract surgery and IOL (Alcon Acrysof SA60AT) implantation. Postoperative IOL depth, refraction and keratometry were measured one month postoperatively. All measurements were performed with the LenStar LS900 optical biometry (Haag-Streit AG Koeniz, Switzerland). Exact ray-tracing was implemented for these patients using OpticStudio15.5 (Zemax LCC, Kirkland, WA) optical design software.

Results:

As expected, IOL position -expressed as aqueous depth- was correlated to preoperative anterior chamber depth. Exact raytracing revealed that measurement error corresponds to refractive error on the range of 0.25D. IOL position correlated strongly with preoperative white-to-white diameter (Pearson’s r = 0.85). This correlation was stronger than that between IOL position and preoperative Anterior chamber depth (Pearson’s r = 0.43)

Conclusions:

Exact raytracing may provide accurate calculations of IOL power. The most significant error in IOL calculation results from errors in the prediction of the IOL location. Parameters such as the white to white diameter may improve this predictability.

Financial Disclosure:

NONE