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F. M. Alfardan, M. S. Alkharashi, M. Khuthaila, M. Discepola; The Variability in Residual Astigmatism After Toric Intra Ocular Lenses Implantation With Different Keratometric Measuring Methods. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4579.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the effectiveness of different keratometric measuring methods in predicting the least post-operative astigmatism with TORIC Intra Ocular Lenses
A retrospective study (n=46 patients). Preoperative keratometery measurements using 3 different methods namely the IOL Master (Zeiss 5.0version), Automated K Topcon (KR 8800) and Topographic K (Zeiss Atlas) were collected, the former was the keratometry of choice and the one substituted in the online TORIC IOL calculator (acrysof) to find out the proposed IOL type, power and axes. Preoperative slit lamp Axis demarcation was and all patients had SN60T3 IOL’s implanted with a predetermined surgical Induced Astigmatism (SIA) at 0.5 D, a standard Incision location (OD 220° , OS 40°). The follow up was 6 months. Post operative UCVA, auto-refraction and complications rate was studied. Then for each patient Automated Ks and Topographic Ks were substituted in the same online TORIC IOL calculator to find out the new proposed parameters and then by back calculations and vector addition analysis were compared to the data given by the IOL Master K’s trying to find which k reading among those three methods would have resulted in the least post operative residual astigmatism.
Preoperative Data: Mean Age (67 years), BCVA (20/70), Astigmatic Cylinder: Range (0.75-5.25D), mean= 1.98D, Preoperative SE (-7.13 to +7.38D).Preoperative Keratometry:IOL Master K’s: Range: 0.42-2.9D, mean= 1.66D, Automated K’s: (0.5-2.6D), mean: 1.52D, Topographic K’s: (0.49-2.73D), mean=1.58D.Postoperative data: UCVA mean (20/25). Postoperative SE (-1 to +1.25D) mean= 0.5D, Cylinder eliminated: (0.3-1.54D), mean=0.66 D. Residual Cylinder: (0-1.25D), mean 0.43D.Substitution with Automated and Topographic K’s:7 (15.2%) patients and 5 (10.9%) patients in the Topographic and Automated K’s subgroups; respectively were suggested to have non-TORIC lenses. By doing back calculations for each individual patient the average residual cylinder was found to be (0-1.50D), mean=0.54D and (0-1.75D), mean=0.76D in the Automated K’s and Topographic K’s subgroups; respectively. No post-operative complications were documented.
TORIC IOL’s resulted in excellent level of postoperative uncorrected visual acuity (UCVA) and eliminated about 66% of corneal astigmatism when IOL Master K’s were. IOL Master K’s resulted in the least amount of residual astigmatism when used in the TORIC IOL calculations in comparison to the automated and topographic K’s.
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