RESUMEN
PURPOSE: To evaluate the effect of refractive surgery on intraocular lens (IOL) power calculation, compare methods of IOL power calculation after refractive surgery, evaluate the effect of pre-refractive surgery refractive error on IOL deviation, review the literature on determining IOL power after refractive surgery, and introduce a formula for IOL calculation for use after refractive surgery for myopia. SETTING: Laser & Corneal Surgery Associates and Center for Ocular Tear Film Disorders, New York, New York, USA. METHODS: This retrospective noncomparative case series comprised 21 patients who had uneventful cataract extraction and IOL implantation after previous uneventful myopic refractive surgery. Six methods of IOL calculation were used: clinical history (IOL(HisK)), clinical history at the spectacle plane (IOL(HisKs)), vertex (IOL(vertex)), back-calculated (IOL(BC)), calculation based on average keratometry (IOL(avgK)), and calculation based on flattest keratometry (IOL(flatK)). Each method result was compared to an "exact" IOL (IOL(exact)) that would have resulted in emmetropia and then compared to the pre-refractive surgery manifest refraction using linear regression. The paired t test was used to determine statistical significance. RESULTS: The IOL(HisKs) was the most accurate method for IOL calculations, with a mean deviation from emmetropia of -0.56 diopter +/-1.59 (D), followed by the IOL(BC) (+1.06 +/- 1.51 D), IOL(vertex) (+1.51 +/- 1.95 D), IOL(flatK) (-1.72 +/- 2.19 D), IOL(HisK) (-1.76 +/- 1.76 D), and IOL(avgK) (-2.32 +/- 2.36 D). There was no statistical difference between IOL(HisKs) and IOL(exact) in myopic eyes. The power of IOL(flatK) would be inaccurate by -(0.47x+0.85), where x is the pre-refractive surgery myopic SE (SEQ(m)). Thus, without adjusting IOL(flatK), most patients would be left hyperopic. However, when IOL(flatK) is adjusted with this formula, it would not be statistically different from IOL(exact). CONCLUSIONS: For IOL power selection in previously myopic patients, a predictive formula to calculate IOL power based only on the pre-refractive surgery SEQ(m) and current flattest keratometry readings was not statistically different from IOL(exact). The IOL(HisKs), which was also not statistically different from IOL(exact), requires pre-refractive surgery keratometry readings that are often not available to the cataract surgeon.
Asunto(s)
Queratomileusis por Láser In Situ , Lentes Intraoculares , Miopía/cirugía , Óptica y Fotónica , Refracción Ocular/fisiología , Adulto , Anciano , Córnea/cirugía , Técnicas de Diagnóstico Oftalmológico , Femenino , Humanos , Implantación de Lentes Intraoculares , Masculino , Cómputos Matemáticos , Persona de Mediana Edad , Facoemulsificación , Periodo Posoperatorio , Estudios RetrospectivosRESUMEN
We report the results of laser in situ keratomileusis (LASIK) to correct myopia in a 47-year-old woman with congenital motor nystagmus and myopia. The patient had simultaneous bilateral LASIK using the Alcon-Summit-Autonomous LADARVision excimer laser. Her uncorrected visual acuity (UCVA) preoperatively was 20/600 in the right eye and 20/800 in the left eye; best corrected visual acuity was 20/40 in both eyes. Twelve months after bilateral LASIK, with an enhancement procedure in both eyes at 4 months, UCVA was 20/40 in both eyes. Corneal topography showed well-centered ablation zones.