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IOL Power calculation in irregular corneas, employing Scheimpflug derived central 2mm spherical equivalent keratometry values.
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First Author: A.Achiron ISRAEL
Co Author(s): O. Elhaddad D. Leadbetter K. Smith V. Avadhanam K. Darcy D. Tole
Abstract Details
Purpose:
Accurate intraocular lens (IOL) calculation in subjects with irregular corneas is challenging. Here we present our approach of using Scheimpflug derived central 2 mm keratometry values for IOL calculation.
Setting:
Bristol Eye Hospital
Methods:
Retrospective review of all subjects who underwent cataract surgery in the Bristol Eye hospital using the Holladay analsis of Scheimpflug images of the anterior and posterior cornael surfaces, in the central 2 mm. We used these equivalent keratometry readings (EKR) for SRK/T IOL calculation between 2011 and 2020. The accuracy of our central 2 mm EKR method was evaluated through the calculation of the prediction error (PE) and absolute PE (APE). In addition, percentages of eyes within PE of ¬±0.5D to ±3.0, percentage of subjects achieving vision of 6/6, <6/9, and <6/12, were also analyzed.
Results:
This study included 35 eyes of 32 patients. (mean age 60.8±15.6, 54.2% male, Kmax 55.5±7.6 Diopter). Following surgery visual acuity significantly improved (UCVA: from 1.2±0.48 logMar to 0.66±0.45 logMar, p<0.01; BCVA: from 0.59±0.48 logMar to 0.25±0.24 logMar, p<0.01). The PE was -0.27±1.6 and the APE was median 0.70 (interquartile range: 2.01). Percentage of subjects with 6/6, <6/9 and <6/12 was 14.3%, 54.3% and 65.7% respectively. Percentage of subjects with PE of ±0.5D, ±1.0D, ±1.5D, ±2.0D, 2.5D and ±3.0D was 31.4%, 62.9%, 68.6%, 73.3%,85.7% and 88.6% respectively
Conclusions:
Using the Scheimpflug central 2mm EKR for IOL calculation in irregular cornea results in an accurate prediction of actual postoperative refraction. This method may be used in cases where IOLmaster is not able to provide a reliable reading in abnormal corneas.
Financial Disclosure:
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