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. 2016 May;42(5):663-71.
doi: 10.1016/j.jcrs.2016.02.038.

New regression formula for toric intraocular lens calculations

Adi Abulafia  1 , Douglas D Koch  2 , Li Wang  2 , Warren E Hill  2 , Ehud I Assia  2 , Maria Franchina  2 , Graham D Barrett  2
Affiliations

New regression formula for toric intraocular lens calculations

Adi Abulafia et al. J Cataract Refract Surg. 2016 May.

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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Comment in

  • Intraocular lens calculations using the Holladay toric calculator.
    Holladay JT. Holladay JT. J Cataract Refract Surg. 2016 Nov;42(11):1694-1695. doi: 10.1016/j.jcrs.2016.08.032. J Cataract Refract Surg. 2016. PMID: 27956309 No abstract available.
  • Reply.
    Abulafia A, Wang L, Koch DD. Abulafia A, et al. J Cataract Refract Surg. 2016 Nov;42(11):1695-1696. doi: 10.1016/j.jcrs.2016.08.034. J Cataract Refract Surg. 2016. PMID: 27956310 No abstract available.