Abstract
PurposeTo compare the intraocular lens calculation formulas and evaluate postoperative refractive results of patients with previous hyperopic corneal refractive surgery.DesignRetrospective, comparative, observational study.SettingMassachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, USA.MethodsClinical charts and optical biometric data of 39 eyes from 24 consecutive patients diagnosed with previous hyperopic laser vision correction and cataract surgery were reviewed and analyzed. The Intraocular lens (IOL) power calculation using the Holladay 2 formula (Lenstar) and the American Society of Cataract and Refractive Surgery (ASCRS) Post-Refractive IOL Calculator (version 4.9, 2017) were compared to the actual manifest refractive spherical equivalent (MRSE) following cataract surgery. No pre-Lasik / PRK or post-Lasik / PRK information was used in any of the calculations. The IOL prediction error, the mean IOL prediction error, the median absolute refractive prediction error, and the percentages of eyes within ±0.50 diopter (D) and ±1.00 D of the predicted refraction were calculated.ResultsThe Holladay 2 formula produced a mean arithmetic IOL prediction error significantly different from zero (P = 0.003). Surprisingly, the mean arithmetic IOL prediction errors generated by Shammas, Haigis-L and Barret True K No History formulas were not significantly different from zero (P = 0.14, P = 0.49, P = 0.81, respectively).There were no significant differences in the median absolute refractive prediction error or percentage of eyes within ± 0.50 D or ± 1.00 D of the predicted refraction between formulas or methods.ConclusionIn eyes with previous hyperopic LASIK/PRK and no prior data, there were no significant differences in the accuracy of IOL power calculation between the Holladay 2 formula and the ASCRS Post-refractive IOL calculator.
Highlights
In eyes with previous hyperopic Laser assisted in situ Keratomileusis (LASIK)/photorefractive keratectomy (PRK) and no prior data, there were no significant differences in the accuracy of Intraocular lens (IOL) power calculation between the Holladay 2 formula and the ASCRS Post-refractive IOL calculator
Laser vision correction (LVC), Laser assisted in situ Keratomileusis (LASIK) and photorefractive keratectomy (PRK) are popular options for the correction of myopia, astigmatism, and hyperopia. [1,2,3] Hyperopic LASIK and PRK treatment algorithms are utilized in the treatment of both hyperopia and presbyopia, with and without astigmatism
The uncorrected visual acuity outcomes achieved by laser vision correction in this cohort are outstanding, [4,5] and, in due course for their cataract surgery, post refractive patients expect the same quality of vision achieved by LVC
Summary
Laser vision correction (LVC), Laser assisted in situ Keratomileusis (LASIK) and photorefractive keratectomy (PRK) are popular options for the correction of myopia, astigmatism, and hyperopia. [1,2,3] Hyperopic LASIK and PRK treatment algorithms are utilized in the treatment of both hyperopia and presbyopia, with and without astigmatism. [6,7] As described by Haigis and Goes, [8] alterations in the corneal shape are responsible for a radius measurement error, [9] a keratometer index error and an IOL formula error; all of which lead to errors in the measure of the true cornea power, causing a refractive surprise after cataract surgery:hyperopia in post myopic LVC patients and myopia in post hyperopic LVC patients. [8,9] Second, the central corneal ablation in a myopic treatment creates a more oblate cornea and, in doing so, changes the anterior curvature more centrally than peripherally, reducing the axial length (AL)[10] and the anterior chamber depth (ACD). Due to the well-documented accuracy and predictability of the Holladay 2 formula,[16,17,18,19] we have used it to calculate the IOL power in eyes with previous hyperopic Lasik or PRK, without considering prior-LASIK / PRK data
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