Comparison of prediction error in toric IOLs: auto-keratometry versus IOLMaster keratometry

Poster Details

First Author: N.Shroff INDIA

Co Author(s):    R. Dutta   A. Koul           

Abstract Details

Purpose:

To compare the prediction error between auto-keratometry and IOLMaster keratometry after implantation of AcrySof Toric intraocular lens for correction of corneal astigmatism.

Setting:

Cataract & Intraocular Lens Implantation Service, Shroff Eye Centre, New Delhi, India.

Methods:

226 eyes (147 patients) in the age group 30 to 86 years had implantation of an AcrySof Toric IOL with cylindrical powers of 1.50 D (SN60T3) to 6.00 D (SN60T9). All eyes underwent Keratometry using both auto-refracto-keratometer (Auto-K) (Model Topcon KR8900) and IOLMaster (IOLM-K) (Model Carl Zeiss IOL Advance Technology version 7.1). Biometry was done using IOLMaster and Immersion ultrasound (Quantel Axis II PR). Toric IOL power calculation was done by the online toric IOL calculator (www.acrysoftoriciolcalculator.com). Anticipated residual astigmatism and suggested axis of implantation were calculated for both methods. All eyes were examined postoperatively at 4 weeks. The anticipated residual astigmatism as given by the toric calculator was compared with the achieved astigmatic correction. The prediction error using the auto-keratometer and the IOLMaster were compared.

Results:

Mean age of the patients was 64.67 ± 12.18 years. The mean Keratometry was 44.35 ± 2.15 D with Auto-K and 44.34 ± 2.15 D with IOLM-K. The mean corneal cylinder was 2.33 ± 1.59 D with Auto-K and 2.52 ± 1.65 D with IOLM-K. The mean difference in suggested axis of implantation between the two methods was 3.87 ± 4.27 degrees. The mean anticipated residual cylinder was 0.38 ± 1.00 D with Auto-K and 0.47 ± 1.30 D with IOLM-K. The mean achieved post operative cylinder acceptance at 4 weeks for 203 eyes was 0.85 ± 0.89 D. The mean prediction error in these eyes was 0.59 ± 0.49 D with Auto-K and 0.62 ± 0.68 D with IOLM-K, and this was not statistically significant (p=.334). The results for rest of the eyes will be update at the time of presentation.

Conclusions:

Toric IOLs have become an integral part of modern cataract surgery for correcting astigmatism. The prerequisite for implantation is a correct Keratometry and biometry. We found out that auto-K and IOLM-K provide equally reliable results as far as prediction error is concerned. FINANCIAL DISCLOSURE?: No