PURPOSE: To compare forward shift of posterior corneal surface and higher-order aberration (HOA) changes after LASIK, LASEK, and wavefront-guided LASEK surgery in moderate myopia METHODS: One hundred eighty four eyes undergoing LASIK, LASEK and wavefront-guided LASEK with VISX STAR S4 were included in this study. The posterior corneal elevation was measured with Orbscan before, 2 and 4 months after surgery. Changes of the elevation were assessed using the difference map generated from preoperative and postoperative elevation maps. The values of higher-order aberrations were evaluated preoperatively and 2 months postoperatively with Wavefront aberrometer. RESULTS: The posterior corneal surface displayed forward shift of 27.2+/-11.45 micrometer, 24.3+/-9.76 micrometer in LASIK group, 23.4+/-10.5 micrometer, 23.6+/-10.55 micrometer in LASEK group, 24.0+/-14.95 micrometer, 28.4+/-14.72 micrometer in wavefront-guided LASEK group at 2 months and 4 months, respectively. There were no statistically significant differences among those three groups, and between 2 and 4 months. The root mean score (RMS) of HOA was increased after LASIK and LASEK (p=0.000, p=0.000, respectively). The mean change of HOA-RMS was significantly smaller in wavefront-guided LASEK than LASIK or LASEK (p=0.000, p=0.000, respectively, Bonferroni-corrected). CONCLUSIONS: The changes of posterior corneal surface forward shift showed no difference among LASIK, LASEK and wavefront-guided LASEK in moderate myopia. HOAs were significantly increased after LASIK and LASEK. The changes of HOAs were significant smaller in wavefront-guided LASEK than LASIK or LASEK.
Adult ; *Corneal Topography ; Humans ; Myopia/diagnosis/*physiopathology/*surgery ; Postoperative Period ; *Refractive Surgical Procedures ; Severity of Illness Index

PURPOSE: To evaluate choroidal blood flow changes in eyes with high myopia according to the pulsatile components of ocular blood flow analysis. METHODS: A total of 104 subjects (52 males and 52 females) were included in this study. One eye of each participant was randomly selected and assigned to one of four refractive groups, designated as, hyperopes (n = 20; refractive error, > or =+1.00 diopter [D]), emmetropes (n = 28; refractive error, +/-0.75 D), lower myopes (n = 33; refractive error, -1.00 to -4.75 D), and high myopes (n = 23; refractive error, < or =-5.00 D). Components of pulse amplitude (OBFa), pulse volume (OBFv), pulse rate (OBFr), and pulsatile ocular blood flow (POBF) were analyzed using a blood flow analyzer. Intraocular pressure and axial length were measured. RESULTS: Pulsatile components of OBFa, OBFv, and POBF showed positive correlations with refractive error and showed negative correlations with axial length (r = 0.729, r = 0.772, r = 0.781, respectively, all p < 0.001; r = -0.727, r = -0.762, r = -0.771, respectively, all p < 0.001). The correlations of refractive error and axial length with OBFr were irrelevant (r = -0.157, p = 0.113; r = 0.123, p = 0.213). High myopes showed significantly lower OBFa, OBFv, and POBF than the other groups (all p < 0.001). CONCLUSIONS: Axial length changes in high myopes potentially influence choroidal blood flow, assuming the changes are caused by narrowing of the choroidal vessel diameter and increasing rigidity of the choroidal vessel wall. These finding explains the influence of axial length on OBFa, OBFv, and POBF, but not on OBFr. Thus, changes in axial length and the possible influence of these changes on the physical properties of choroidal vessels is the mechanism believed to be responsible for putting high myopes at risk for ocular vascular diseases.
Adult ; *Axial Length, Eye ; Choroid/*blood supply ; Female ; Humans ; Male ; Myopia/diagnosis/*physiopathology ; Regional Blood Flow/*physiology ; Young Adult

PURPOSE: To describe the characteristics and investigate the differences of higher-order aberrations (HOAs) between the eyes with a natural, uncorrected visual acuity (UCVA) of 20/12 and eyes with highly myopic eyes in Korean adults. METHODS: Thirty-one eyes of 20 subjects with UCVA of 20/12 (Group 1) and 54 eyes of 36 myopic patients with greater than -6 diopters (Group 2) were analyzed for type and magnitude of HOAs across a 6.0 mm pupil. HOAs were measured by Wavescan (VISX, Santa Clara, CA, USA) in natural scotopic conditions and were presented as root-mean-square (RMS: micrometer) in Belle aberration maps. RESULTS: The mean spherical equivalent (SE) of manifest refraction was -0.15+/-0.25 D (range: +0.37 to -0.50 D) in Group 1 and -7.25+/-0.78 D (range: -6.00 to -9.25 D) in Group 2. The total root-mean-square (RMS) values of HOAs for Group 1 and Group 2 were 0.28+/-0.09 micrometer and 0.27+/-0.087 micrometer, respectively (P>0.05). The mean values of coma, trefoil, and spherical aberration were 0.14+/-0.091 micrometer, 0.14+/-0.089 micrometer, 0.091+/-0.059 micrometer in Group 1 and 0.16+/-0.077 micrometer, 0.14+/-0.073 micrometer, 0.082+/-0.059 micrometer in Group 2, respectively. CONCLUSIONS: This study helped establish ocular aberration standards for those with natural supervision and those with highly myopic eyes among Koreans. Individuals with natural supervision had significant amounts of HOAs, and there was no significant difference in the amount of HOAs between the two groups. The index of higher-order aberrations may not be a perfect predictor of the amount of refractive error.
Adult ; Cornea/*physiopathology ; Diagnostic Techniques, Ophthalmological ; Female ; Humans ; Korea/epidemiology ; Male ; *Myopia/diagnosis/epidemiology/physiopathology ; Prevalence ; *Refraction, Ocular ; Severity of Illness Index ; Surface Properties ; Visual Acuity

PURPOSE: To describe the characteristics and investigate the differences of higher-order aberrations (HOAs) between the eyes with a natural, uncorrected visual acuity (UCVA) of 20/12 and eyes with highly myopic eyes in Korean adults. METHODS: Thirty-one eyes of 20 subjects with UCVA of 20/12 (Group 1) and 54 eyes of 36 myopic patients with greater than -6 diopters (Group 2) were analyzed for type and magnitude of HOAs across a 6.0 mm pupil. HOAs were measured by Wavescan (VISX, Santa Clara, CA, USA) in natural scotopic conditions and were presented as root-mean-square (RMS: micrometer) in Belle aberration maps. RESULTS: The mean spherical equivalent (SE) of manifest refraction was -0.15+/-0.25 D (range: +0.37 to -0.50 D) in Group 1 and -7.25+/-0.78 D (range: -6.00 to -9.25 D) in Group 2. The total root-mean-square (RMS) values of HOAs for Group 1 and Group 2 were 0.28+/-0.09 micrometer and 0.27+/-0.087 micrometer, respectively (P>0.05). The mean values of coma, trefoil, and spherical aberration were 0.14+/-0.091 micrometer, 0.14+/-0.089 micrometer, 0.091+/-0.059 micrometer in Group 1 and 0.16+/-0.077 micrometer, 0.14+/-0.073 micrometer, 0.082+/-0.059 micrometer in Group 2, respectively. CONCLUSIONS: This study helped establish ocular aberration standards for those with natural supervision and those with highly myopic eyes among Koreans. Individuals with natural supervision had significant amounts of HOAs, and there was no significant difference in the amount of HOAs between the two groups. The index of higher-order aberrations may not be a perfect predictor of the amount of refractive error.
Adult ; Cornea/*physiopathology ; Diagnostic Techniques, Ophthalmological ; Female ; Humans ; Korea/epidemiology ; Male ; *Myopia/diagnosis/epidemiology/physiopathology ; Prevalence ; *Refraction, Ocular ; Severity of Illness Index ; Surface Properties ; Visual Acuity