Intraocular Lens Power Adjustment After Myopic Excimer Laser Surgery: Validation Studies for Geggel Ratio and Consensus Group


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Abstract

Purpose:To validate the Geggel ratio (GR) and consensus group in myopic excimer laser patients undergoing cataract surgery.Methods:Two separate consecutively collected case series (group 1, 32 eyes; group 2, 34 eyes) were retrospectively analyzed. Data from group 1 was used to generate a new linear regression formula for the GR based on the Haigis formula. Predicted implant powers based on the Shammas, Latkany, Savini, Seitz, Haigis-L, and GR based on either SRK/T or Haigis formulas and combined consensus methods were computed. Mean error, range, percent within ±0.5 D, ±1.0 D and −1.0/+0.5 D were calculated.Results:In group 1, the original GR (SRK/T) formula produced higher mean values (−0.44 D) and lower percentage within ±0.5 D (41%) compared with the other 5 formulas (−0.03 to −0.33 D; 65%–82%). A linear regression formula (−0.142*ΔSE +0.2) for the GR was derived as a correction factor added to the Haigis formula. Group 2 validated the 5 formulas again plus the GR (Haigis). All group 2 formulas gave excellent results with means ranging from −0.18 to −0.37 D, percentages with ±0.5 D ranging from 55% to 78%, and percentages within −1.0/+0.5 D ranging from 85% to 100%. Consensus formulas produced mean error −0.30 D, 70% ±0.5 D, 93% −1.0/+0.5 D with only 2 outliers at 0.6 D and −1.1 D.Conclusions:These six methods achieve high levels of IOL accuracy. The GR method works better based on the Haigis formula. Consensus calculations minimize both under- and overcorrections.

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