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Mauricio Galvan, Sara Gonzalez, Roxana Saucedo, Cecilio Velasco; Intraocular lens power calculations in patients with an axial lenght greater than 25mm. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1153.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the accuracy of intraocular lens (IOL) power calculations in eyes with an axial lenght greater than 25 mm.
Retrospective, transversal, descriptive study. Eyes with AL over 25mm, after phacoemulsification with IOL implantation at Hospital Dr. Luis Sánchez Bulnes: Asociación para evitar la ceguera en México I.A.P. Mexico City, Mexico, were evaluated. The accuracy of the third generation formulas (Holladay 1, SRK/T, Hoffer Q, and SRK II) and the fourth generation formulas were analyzed by comparing the mean difference between the actual and predicted postoperative spherical equivalent and the mean absolute error (MAE).
108 eyes were included. In 27 (25%) AL was between 25-28 mm (Group A), 32 eyes (29.6%) AL was between 28-30 mm (Group B) and 48 eyes (44.4%) AL was greater than 30 mm (Group C). In 83 (76.85%) (Subgroup 1) had keratometry <46 D and 25(23.14%) >46 D (Subgroup 2). The smallest MAEs observed were: A1 (Barret U2 -0.21 D), A2 (Barret U2 - 0.71 D), B1 (Barret U2 - 0.40 D), B2 (Barret U2 - 1.19 D), C1 (Barret U2 - 0.69 D) and (SRK 2 -1.51D).
The 3rd and 4th generation formulas in high myopes usually give residual hypermetropic results. At longer axial length and more curved keratometry, greater residual hypermetropia. Therefore, with optimized constants, the Barret U2 will fit the best for AL between 25-30 mm with no influence in keratometry and AL >30 mm with <46 D, while for an AL >30 mm >46 D SRK II will produced small deviation of postoperative refraction from target refraction.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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