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A. Berthout, S. Milazzo, S. Bijaoui, P. Turut; Accuracy of Predictive IOL Power Formulas, SRK-T and SRK-II, for Patients With Cataract and High Myopia. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5430.
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to compare the accuracy of two IOL power formulas (SRK-T and SRK-II) in order to improve the accuracy of predictive IOL powers for patients with cataract and high myopia.
This retrospective and comparative study reviewed 103 eyes of 75 patients with high myopia (axial lengths higher than 26 mm) and cataract who had cataract surgery during 2005. Eyes with pathology or operative complications affecting the refractive status were excluded. All the patients had a phakoemulsification with implantation in the capsular bag. In each case, an interferometry (Zeiss, IOL master) or an echometry was performed before surgery and a slightly myopic IOL whose A constant was considered, was selected. The postoperative refraction was evaluated about three months. The patients were divided in five groups: axial lenghts (AL) > 26 mm and < 28 mm (41 eyes), AL > 28 mm and < 30 mm (36 eyes), AL > 30 mm (26 eyes), and IOL selected with echometry (31 eyes), IOL selected with interferometry (72 eyes). The postoperative refraction was then compared with the predictive refraction of each formula.
The mean postoperative refraction was -1,2 D. The mean refractive error with SRK-II was -0,32 D and with SRK-T -0,75 D, and this difference was significative (p<0,001). SRK-II seemed more accurate than SRK-T (p<0,001). Whatever the axial length, the refractive error was less important with SRK-II than SRK-T (p< 0,05) When the AL was more than 30 mm, the refractive error improved whatever the used formula but SRK-II remained more predictive (p<0,05). With echometry, the refractive error was not significative if SRK-II was used contrary to SRK-T and interferometry (p<0,05).
SRK-II seems to be more accurate than SRK-T for patients with cataract and high myopia. It seems to be all the more accurate when it is used with echometry.
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