Article

New regression formula for toric intraocular lens calculations

Abulafia, Adi MD^*; Koch, Douglas D. MD; Wang, Li MD, PhD; Hill, Warren E. MD; Assia, Ehud I. MD; Franchina, Maria MD; Barrett, Graham D. MD

Author Information

From Ein-Tal Eye Center (Abulafia, Assia), Tel-Aviv, Assaf Harofeh Medical Center (Abulafia), Zerifin, Meir Medical Center (Assia), and Kfar-Saba, affiliated with Tel-Aviv University, Tel-Aviv, Israel; Cullen Eye Institute (Koch, Wang), Baylor College of Medicine, Houston, Texas, and East Valley Ophthalmology (Hill), Mesa, Arizona, USA; Sir Charles Gairdner Hospital (Franchina, Barrett) and Lions Eye Institute (Barrett), Nedlands, Western Australia, Australia

^*Corresponding author: Adi Abulafia, MD, Zerifin 70300, Israel.

E-mail: [email protected]

Submitted November 3, 2015; revised January 29, 2016; accepted February 1, 2016.

Guy Kleinmann, MD, Arie L. Marcovich, MD, PhD, and Adi Michaeli, MD, were physicians and surgeons for some of Ein-Tal’s patients. Shay Ofir, MD, Adi Levy, BSc, and Olga Reitblat, MD, helped with the data acquisition for Ein-Tal’s patients.

First author:

Adi Abulafia, MD

Ein-Tal Eye Center (Abulafia, Assia), Tel-Aviv, Israel

Journal of Cataract & Refractive Surgery 42(5):p 663-671, May 2016. | DOI: 10.1016/j.jcrs.2016.02.038

Abstract

Purpose

To evaluate and compare the accuracy of 2 toric intraocular lens (IOL) calculators with or without a new regression formula.

Setting

Ein-Tal Eye Center, Tel-Aviv, Israel, and the Lions Eye Institute, Nedlands, Western Australia, Australia.

Design

Retrospective case series.

Methods

A new regression formula (Abulafia-Koch) was developed to calculate the estimated total corneal astigmatism based on standard keratometry measurements. The error in the predicted residual astigmatism was calculated by the Alcon and Holladay toric IOL calculators with and without adjustments by the Abulafia-Koch formula. These results were compared with those of the Barrett toric calculator.

Results

Data from 78 eyes were evaluated to validate the Abulafia-Koch formula. The centroid errors in predicted residual astigmatism were against-the-rule with the Alcon (0.55 diopter [D]) and Holladay (0.54 D) toric calculators and decreased to 0.05 D (P < .001 [x-axis], P = .776 [y-axis]) and 0.04 D (P < .001 [x-axis], P = .726 [y-axis]) with adjustments by the Abulafia-Koch formula. The Alcon and the Holladay toric calculators had a higher proportion of eyes within ±0.50 D of the predicted residual astigmatism with the Abulafia-Koch formula (76.9% and 78.2%, respectively) than without it (both 30.8%). There were no significant differences between the results of the Abulafia-Koch-modified Alcon and the Holladay toric calculators and those of the Barrett toric calculator.

Conclusion

Adjustment of commercial toric IOL calculators by the Abulafia-Koch formula significantly improved the prediction of postoperative astigmatic outcome.

Financial Disclosure

Dr. Abulafia received a speaker’s fee from Haag-Streit AG. Dr. Barrett has licensed the Barrett Toric Calculator to Haag-Streit AG. Dr. Koch is a consultant to Alcon Laboratories, Inc., Abbott Medical Optics, Inc., and Revision Optics, Inc. Dr. Hill is a paid consultant to Haag-Streit AG and Alcon Laboratories, Inc. None of the other authors has a financial or proprietary interest in any material or method mentioned.

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New regression formula for toric intraocular lens calculations