Clinical efficacy of cataracts surgical treatment in patients after ARK using IOL power calculation basic formulas

Abstract

Purpose. To analyze possible refractive errors when calculating IOL power in patients after ARK (anterior radial keratotomy). Material and methods. The data of Intraocular lens (IOL) power calculation in 46 patients (46 eyes) with anterior radial keratotomy (ARK) who also underwent cataract surgery were analyzed. The IOL calculation was performed taking into account the data obtained by the Lenstar LS 900 (HAAG-STREIT AG, Switzerland) and keratotopography (Pentacam HR, Oculus, Germany), with a target refraction corresponding to emmetropia up to ±0.50 D. Results. The analysis of the clinical efficacy of phacoemulsification with IOL implantation in patients after ARK with the refractive error (RE) calculation and refractive prediction error (RPE) calculation according to the basic formulas were performed. It was found that emmetropia (up to ±0.5 D) in the postoperative period was achieved in 52% of cases. The value of the postoperative RPE had no reliable dependence on the values of the eyeball length, it was depended on the corneal optical power in the central zone of the cornea only with some formulas for IOL calculation (Barrett, Barrett Universal II, MIKOFRK/ALF). The obtained results of the analysis provide justification for a deeper study of post keratotomy corneal deformation as a pathological condition with the presence of hidden risk factors. Conclusion. Phacoemulsification with IOL implantation in patients with previously performed ARK is accompanied by the achievement of target refraction in 52% of cases. The high proportion of IOL calculation errors in cataract surgery in patients after ARK largely depends on hidden factors, which determines the need for a detailed study of post keratotomy corneal deformation as a pathological condition. Key words: IOL power calculation, anterior radial keratotomy, emmetropia