ABSTRACT
PURPOSE: The corneal change induced by refractive procedures influence both the postoperative refractive status and the ocular spherical aberration (SA). We evaluated changes in corneal SA after three types of surface ablation: phototherapeutic keratectomy (PTK), myopic photorefractive keratectomy (PRK), and myopic wavefront-guided laser epithelial keratomileusis (LASEK). METHODS: Twenty-six eyes (25 patients) were subjected to PTK 26 eyes (14 patients) to PRK, and 34 eyes (17 patients) to wavefront-guided LASEK. Corneal SA was measured with the iTrace in all patients both preoperatively and 6 months postoperatively. RESULTS: Six months after surgery, mean corneal SA was -0.173 +/- 0.171 micrometer in the PTK group, 0.672 +/- 0.200 micrometer in the PRK group, and 0.143 +/- 0.136 micrometer in the wavefront-guided LASEK group. The mean difference between the preoperative and postoperative corneal SA (DeltaSA) was -0.475 micrometer in the PTK group, 0.402 micrometer in the PRK group, and -0.143 micrometer in the wavefront-guided LASEK group. CONCLUSIONS: Surgically induced changes in corneal SA vary with procedure. The prediction of the pattern of SA change induced by various surface ablation procedures may be helpful for developing future surgical procedures.
Subject(s)
Adult , Aged , Female , Humans , Male , Middle Aged , Corneal Dystrophies, Hereditary/surgery , Corneal Wavefront Aberration/surgery , Follow-Up Studies , Keratomileusis, Laser In Situ/methods , Myopia/surgery , Photorefractive Keratectomy/methods , Prospective Studies , Treatment OutcomeABSTRACT
PURPOSE: The corneal change induced by refractive procedures influence both the postoperative refractive status and the ocular spherical aberration (SA). We evaluated changes in corneal SA after three types of surface ablation: phototherapeutic keratectomy (PTK), myopic photorefractive keratectomy (PRK), and myopic wavefront-guided laser epithelial keratomileusis (LASEK). METHODS: Twenty-six eyes (25 patients) were subjected to PTK 26 eyes (14 patients) to PRK, and 34 eyes (17 patients) to wavefront-guided LASEK. Corneal SA was measured with the iTrace in all patients both preoperatively and 6 months postoperatively. RESULTS: Six months after surgery, mean corneal SA was -0.173 +/- 0.171 micrometer in the PTK group, 0.672 +/- 0.200 micrometer in the PRK group, and 0.143 +/- 0.136 micrometer in the wavefront-guided LASEK group. The mean difference between the preoperative and postoperative corneal SA (DeltaSA) was -0.475 micrometer in the PTK group, 0.402 micrometer in the PRK group, and -0.143 micrometer in the wavefront-guided LASEK group. CONCLUSIONS: Surgically induced changes in corneal SA vary with procedure. The prediction of the pattern of SA change induced by various surface ablation procedures may be helpful for developing future surgical procedures.
Subject(s)
Adult , Aged , Female , Humans , Male , Middle Aged , Corneal Dystrophies, Hereditary/surgery , Corneal Wavefront Aberration/surgery , Follow-Up Studies , Keratomileusis, Laser In Situ/methods , Myopia/surgery , Photorefractive Keratectomy/methods , Prospective Studies , Treatment OutcomeABSTRACT
As an object approaches the eye, the eye has to increase its power to keep the image focused on the retina. If the eye is short or the lens not round enough as in hypermetropia, the image is defocused. The aim of the study: was to report the visual outcome and keratometric values of the higher order aberrations after hypermetropic correction with LASIK. A retrospective patient chart review study of 60 eyes of 30 patients. Prospective and postoperative analysis of the wavefront scans of the patients, utilizing zernike's polynomials was done and calculations of the RMS of the anterior higher order aberrations recorded. There were 60 eyes of 30 patients. 28 females [46.7%] and 32 males [53.3%]. 32 [53.3%] right eyes and 28 [46.7%] left eyes. Mean patient age was 36.46+13.99 years [range 16 to 54 years]. Mean sphere was+3.30+1.55D range+1.0 to+5.50D]. Mean cylinder was-1 .31+1.45 D [range-4.75 to+0.5D]. Spherical aberration preoperatively was 0.29 [+0.05] and postoperatively-0.02 [+0.24] and a mean difference of 0.23 and p value of 0.01. Coma aberration preoperatively was 0.29 [+0.10] and postoperatively 0.44 [+0.32] and a mean difference of-0.15 and p value of 0.86. RMS of higher order aberrations preoperatively was 0.43 [+0.10] and postoperatively 0.66 [+0.29] and a mean difference of-0.22 and p value of 0.05. LASIK for correction of hypermetropia and hypermetropic astigmatism causes increasing in all corneal higher order aberrations which is directly proportional to the refractive error