Clinical and Theoretical Results of Intraocular Lens Power Calculation for Cataract Surgery After Photorefractive Keratectomy for Myopia

Abstract

Objectives: To describe the refractive results of cataract surgery after photorefractive keratectomy (PRK) for patients with myopia, and to find a more accurate method to predict intraocular lens (IOL) power in these cases.Design: Nonrandomized, retrospective clinical study. Patients and Methods:Nine patients (15 eyes) who underwent cataract surgery after prior PRK to correct myopia were identified. The medical records of both the laser and cataract surgery centers were reviewed. Main Outcome Measures:Eight different keratometric values (K values; measured or calculated) were entered into 3 different IOL calculation formulas: SRK/T, Holladay 1, and Hoffer Q. The actual biometry and IOL parameters were used to predict postoperative refraction, which was compared with the actual refractive outcome. Also, the relative underestimation of the refrac-tive change in corneal dioptric power by keratometry after PRK was calculated.

Determining corneal power using Orbscan II videokeratography for intraocular lens calculation after excimer laser surgery for myopia

“…Formulas used for post-RK and post-LASIK eyes with good efficacy include the Haigis, Binkhorst, Holladay 2, Hoffer Q, and SRK/T, 7,8,10,18,34,35 particularly after adjustment for calculations of ELP. 36 Aramberri 37 points out that if post-refractive surgery K-values are used by thirdgeneration theoretical formulas to calculate ELP, a hyperopic refractive outcome can result.…”

Accurate intraocular lens power calculation after myopic laser in situ keratomileusis, bypassing corneal power

“…The clinical history method is available on the Carl Zeiss IOLMaster and was used to calculate our IOL power. It is important to note that the clinical history method available on the Carl Zeiss IOLMaster corrects for the vertex distance to the corneal plane, which can result in a higher postoperative corneal power, as described by Odenthal et al 7 The double-K method was also used as a comparison.…”

Estimation of true corneal power after keratorefractive surgery in eyes requiring cataract surgery: BESSt formula

“…[2][3][4][5]12,13 These methods aim to improve IOL power calculation accuracy for cataract or refractive lens exchange (clear lens) surgery. They include the clinical history method, [14][15][16] contact lens overrefraction method, 11,16,17 double-K adjustment, 6 vertexed IOL power method, 17 effective refractive power calculated from corneal topography using the Holladay Diagnostic Summary (EyeSys Vision), 18 intraoperative autorefraction, 13 and Gaussian optics formula for paraxial imagery. 3,19,20 The Holladay 2 formula (Holladay IOL Consultant Program, Holladay Consulting, Inc.) seems to provide unprecedented levels of accuracy in eyes after keratorefractive surgery.…”