PMID: 9432235Feb 12, 1998Paper

Assessment of refractive difference after photorefractive keratectomy. A comparison between keratometry and computer-assisted video keratography

Der Ophthalmologe : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft
P HuggerD D Koch

Abstract

The purpose of this study was to determine which corneal curvature values most closely correlated to change in subjective manifest refraction following excimer laser photorefractive keratectomy (PRK). Excimer laser PRK was performed on ten eyes of ten patients (mean age: 37.3 years). Preoperative refractive errors ranged from -2.25 to -8.75 diopters. Preoperatively and 1 month postoperatively, we determined the spherical equivalent of the manifest refraction (corrected for a 12 mm vertex distance) and measured corneal power using standard keratometry (Bausch and Lomb keratometer) and computerized videokeratography (EyeSys Corneal Analysis System). We collected five corneal values: standard keratometry, videokeratography-derived simulated keratometric readings calculated using the axial, instantaneous and refractive formulas, and corneal refractive power over the central 3-mm zone (effective refractive power); apart from the traditional refractive index of the cornea (n = 1.3375), we used the refractive value of the anterior corneal stroma (n = 1.376). For each of the five corneal values, we subtracted the change in corneal power from the change in manifest refraction and calculated the means and standard deviations. The mean di...Continue Reading

Citations

Mar 21, 2000·Current Opinion in Ophthalmology·B Seitz, A Langenbucher
Feb 1, 2000·American Journal of Ophthalmology·P HuggerD D Koch

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