To assess low- contrast visual acuity (LCVA) after photorefractive keratectomy in relation to ocular higher- order wavefront aberration and corneal subepithelial haze. Prospective, crosssectional analysis. Photorefrac...To assess low- contrast visual acuity (LCVA) after photorefractive keratectomy in relation to ocular higher- order wavefront aberration and corneal subepithelial haze. Prospective, crosssectional analysis. Photorefractive keratectomy was performed in 51 eyes of 27 subjects with myopic refractive error of- 2.0 to - 10.5 diopters. Ocular higher- order wavefront aberrations for a 4- mm pupil were measured using Topcon Hartmann- Shack wavefront aberrometer, and the extent of corneal subepithelial haze was quantified with Nidek TSPC- 3 hazemeter before and 1 month after photorefractive keratectomy. Low- contrast visual acuity was recorded with Vector Vision CSV- 1000- LanC10% chart. Total higher- order, third- order (coma- like), and fourthorder (spherical- like) aberrations of the eye were determined. The influence of wavefront aberration and corneal subepithelial haze on LCVA was analyzed. Total higher- order, third- order, and fourth- order aberrations significantly increased by surgery (P < .001, Wilcoxon signed rank test). Photorefractive keratectomy induced a significant increase in corneal haze(P < . 01), but no case presented severe corneal haze (grade 3 or greater by Fantes grading). By surgery, LCVA was reduced significantly (P < .001). The logarithm of the minimal angle of resolution LCVA showed a significant correlation with total higher- order aberration (Spearman rank correlation coefficient, r s=0.642, P < .000 1). Both third- order (r s=0.618, P < .000 1) and fourth- order aberrations (r s=0.552, P < .000 1) also significantly correlated with logarithm of the minimal angle of resolution LCVA. There was no correlation between the degree of corneal haze and logarithm of the minimal angle of resolution LCVA (r s=0.094, P=. 523). In eyes with mild to moderate corneal haze after photorefractive keratectomy, deterioration of LCVA is mainly attributable to increases in wavefront aberration, and not to corneal haze.展开更多
PURPOSE. To investigate prospectively the relation between induced changes in higher- order aberrations of the eye and changes in contrast sensitivity by conventional laser in situ keratomileusis (LASIK) for myopia. M...PURPOSE. To investigate prospectively the relation between induced changes in higher- order aberrations of the eye and changes in contrast sensitivity by conventional laser in situ keratomileusis (LASIK) for myopia. METHODS. In 200 eyes of 110 consecutive patients (mean age, 32.7 ± .8.4 years) undergoing LASIK, ocular aberrations and contrast sensitivity function were determined before and 1 month after surgery. The amount of myopic correction was 5.2 ± .2.8 D (range, 1.0- 13.0). Ocular higher- order aberrations were measured for a 4- mm pupil using the Hartmann- Shack wavefront analyzer (KR- 9000PW; Topcon, Tokyo, Japan). The root mean square (RMS) of the third- and fourth- order Zernike coefficients was used to represent coma- and spherical- like aberrations, respectively. Total higher- order aberrations were calculated as the RMS of the third- and fourth- order coefficients. Contrast sensitivity and low- cont- rast visual acuity were measured. From the contrast sensitivity data, the area under the log contrast sensitivity function (AULCSF) was calculated. RESULTS. LASIK significantly improved logMAR best corrected visual acuity (Wilcoxon signed- rank test, P < .0.001), but significantly reduced AULCSF (P < 0.001) and low- contrast visual acuity (P=0.007). Total higher- order (P < 0.001), coma- like (P < 0.001), and spherical- like (P < .0.001) aberrations were significantly increased after LASIK. The greater the amount of achieved myopia correction was, the more the changes in contrast sensitivity function and ocular higher- order aberrations were. The induced changes in AULCSF by LASIK showed significant correlations with changes in total higher- order (Pearson r=- 0.221, P=0.003), coma- like (r=- 0.205, P=0.006), and spherical- like (r=- 0.171, P=0.022) aberrations. The changes in logMAR low- contrast visual acuity by surgery significantly correlated with changes in total higher- order (r=0.222 , P=0.003), comalike (r=0.201 , P=0.007), and spherical- like (r=0.207, P=0.005) aberrations. CONCLUSIONS. Conventional LASIK significantly increases ocular higher- order aberrations, which compromise the postoperative contrast sensitivity function.展开更多
文摘To assess low- contrast visual acuity (LCVA) after photorefractive keratectomy in relation to ocular higher- order wavefront aberration and corneal subepithelial haze. Prospective, crosssectional analysis. Photorefractive keratectomy was performed in 51 eyes of 27 subjects with myopic refractive error of- 2.0 to - 10.5 diopters. Ocular higher- order wavefront aberrations for a 4- mm pupil were measured using Topcon Hartmann- Shack wavefront aberrometer, and the extent of corneal subepithelial haze was quantified with Nidek TSPC- 3 hazemeter before and 1 month after photorefractive keratectomy. Low- contrast visual acuity was recorded with Vector Vision CSV- 1000- LanC10% chart. Total higher- order, third- order (coma- like), and fourthorder (spherical- like) aberrations of the eye were determined. The influence of wavefront aberration and corneal subepithelial haze on LCVA was analyzed. Total higher- order, third- order, and fourth- order aberrations significantly increased by surgery (P < .001, Wilcoxon signed rank test). Photorefractive keratectomy induced a significant increase in corneal haze(P < . 01), but no case presented severe corneal haze (grade 3 or greater by Fantes grading). By surgery, LCVA was reduced significantly (P < .001). The logarithm of the minimal angle of resolution LCVA showed a significant correlation with total higher- order aberration (Spearman rank correlation coefficient, r s=0.642, P < .000 1). Both third- order (r s=0.618, P < .000 1) and fourth- order aberrations (r s=0.552, P < .000 1) also significantly correlated with logarithm of the minimal angle of resolution LCVA. There was no correlation between the degree of corneal haze and logarithm of the minimal angle of resolution LCVA (r s=0.094, P=. 523). In eyes with mild to moderate corneal haze after photorefractive keratectomy, deterioration of LCVA is mainly attributable to increases in wavefront aberration, and not to corneal haze.
文摘PURPOSE. To investigate prospectively the relation between induced changes in higher- order aberrations of the eye and changes in contrast sensitivity by conventional laser in situ keratomileusis (LASIK) for myopia. METHODS. In 200 eyes of 110 consecutive patients (mean age, 32.7 ± .8.4 years) undergoing LASIK, ocular aberrations and contrast sensitivity function were determined before and 1 month after surgery. The amount of myopic correction was 5.2 ± .2.8 D (range, 1.0- 13.0). Ocular higher- order aberrations were measured for a 4- mm pupil using the Hartmann- Shack wavefront analyzer (KR- 9000PW; Topcon, Tokyo, Japan). The root mean square (RMS) of the third- and fourth- order Zernike coefficients was used to represent coma- and spherical- like aberrations, respectively. Total higher- order aberrations were calculated as the RMS of the third- and fourth- order coefficients. Contrast sensitivity and low- cont- rast visual acuity were measured. From the contrast sensitivity data, the area under the log contrast sensitivity function (AULCSF) was calculated. RESULTS. LASIK significantly improved logMAR best corrected visual acuity (Wilcoxon signed- rank test, P < .0.001), but significantly reduced AULCSF (P < 0.001) and low- contrast visual acuity (P=0.007). Total higher- order (P < 0.001), coma- like (P < 0.001), and spherical- like (P < .0.001) aberrations were significantly increased after LASIK. The greater the amount of achieved myopia correction was, the more the changes in contrast sensitivity function and ocular higher- order aberrations were. The induced changes in AULCSF by LASIK showed significant correlations with changes in total higher- order (Pearson r=- 0.221, P=0.003), coma- like (r=- 0.205, P=0.006), and spherical- like (r=- 0.171, P=0.022) aberrations. The changes in logMAR low- contrast visual acuity by surgery significantly correlated with changes in total higher- order (r=0.222 , P=0.003), comalike (r=0.201 , P=0.007), and spherical- like (r=0.207, P=0.005) aberrations. CONCLUSIONS. Conventional LASIK significantly increases ocular higher- order aberrations, which compromise the postoperative contrast sensitivity function.
