Enhanced vergence-based toric algorithm and its impact on reducing residual refractive error: a retrospective analysis

Session Details

Session Title: Presented Poster Session: Toric IOLs

Venue: Poster Village: Pod 1

First Author: : M.Packer USA

Co Author(s): :    K. Venkateswaran   N. Tiwari   G. Lau   A. Pilon   V. Kolesnitchenko           

Abstract Details

Purpose:

To determine the efficacy of a platform-specific (enVista IOL, Bausch & Lomb), vergence-based toric algorithm incorporating optical geometry of the eye with estimates of surgically induced astigmatism (SIA) and posterior corneal astigmatism (PCA), and to compare estimates obtained using the enhanced vergence-based toric calculator with a retrospective analysis of estimated total astigmatism of non-toric subjects and refractive outcomes of subjects implanted with toric IOLs selected with the aid of a first-generation, fixed-ratio algorithm.

Setting:

Tatvum Research Optics Laboratory, Orange County, California, USA

Methods:

Clinical data from subjects implanted with variants of the enVista platform (MX60T, MX60) IOLs selected with the aid of a fixed-ratio algorithm were used to determine the platform-specific SIA and PCA from published literature to predict post-operative refractive outcomes.  An enhanced vergence-based algorithm employing anterior chamber depth (ACD) and effective lens position (ELP) based on optical modeling averaged over the dioptric range was developed to limit the influence of biometric errors. Regression analysis was used to uncover the scaling factor needed to predict the power relationship between corneal and IOL planes across a range of spherical powers.

Results:

Study data revealed a mean SIA of 0.50D @ 85⁰ from toric and non-toric eyes (n=310) and PCA of 0.3D with-the-rule (WTR).  Incorporation of the platform-specific inputs (SIA, PCA) in combination with an enhanced vergence based analysis yielded a reduction in predicted residual refractive error to a level below 0.25D residual cylinder in 87% of subjects as compared with 48% of subjects with the fixed-ratio algorithm.  Statistical analysis comparing results of modeling and clinical data will be presented.

Conclusions:

The development of platform-specific, vergence-formula based toric algorithms has the capacity to further reduce residual refractive error and yield improved subject outcomes with toric IOLs. This next-generation calculator incorporating optical variables with unique diagnostic data in conjunction with customized SIA and PCA results derived from previous studies has the capacity to improve post-operative refractive outcomes for subjects implanted with a toric lens.

Financial Disclosure:

... is employed by a for-profit company with an interest in the subject of the presentation, ... receives consulting fees, retainer, or contract payments from a competing company, ... receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented