Peripheral Monochromatic Aberrations in Young Adult Caucasian and East Asian Eyes.

SIGNIFICANCE: Myopia prevalence rates differ between racial groups. If the growth of the eye is sensitive to differences in optical input, the difference in spherical aberration between East Asian and Caucasian eyes found in this study may be important in understanding myopia development. PURPOSE: The aim of this study was to determine differences in peripheral wavefront aberrations between two racial groups. METHODS: Wavefront aberrations were measured using a COAS-HD aberrometer across the 42 × 32° central visual field on 37 right eyes of young adults (18 Caucasians, 19 East Asians; mean age 21.5 ± 2.4 years). The mean spherical equivalent refraction was -1.94 ± 1.63 diopters (D) with a range of -5.87 to +0.16 D. Effect of race and visual field position on refractions, individual Zernike aberration coefficients up to the fourth order, higher-order root-mean-square aberration, and total root-mean-square aberration were assessed by repeated-measures analysis of covariance. RESULTS: Caucasians and East Asians had similar relative peripheral myopia across the visual field. All higher-order aberration coefficients were affected by visual field position. Race had no significant effect on any higher-order Zernike coefficient, but the difference in mean vertical coma coefficient (Equation is included in full-text article.)across the visual field (i.e., average of 38 field locations) approached significance, being less positive in Caucasians than in East Asians (P = .08). When correction was made for the Caucasian group being slightly less myopic than the East Asian group, spherical aberration coefficient (Equation is included in full-text article.)was less positive in Caucasians than in East Asians by 0.04 µm (P = .001). The rates of change of coma coefficients across the field were not affected by race. CONCLUSIONS: Caucasians and East Asians had similar relative peripheral myopia, but with less positive spherical aberration coefficient in Caucasians than in East Asians. It remains to be determined whether aberrations have a role in the difference of myopia prevalence rates in different countries.

Comparison of Ocular Monochromatic Higher-order Aberrations in Normal Refractive Surgery Candidates of Arab and South Asian Origin.

PURPOSE: To compare the ocular monochromatic higher-order aberration. (HOA) profile in normal refractive surgery candidates of Arab and South Asian origin. METHODS: This cross-sectional, observational, comparative study was performed in the cornea department of a specialty hospital. Normal refractive surgery candidates with no ocular morbidity except refractive error were recruited. Refractive surgery candidates underwent a preoperative evaluation, including wavefront aberrometry with the iDesign aberrometer (AMO, Inc., Santa Ana, California, United States). The HOA from right eyes were analyzed for HOA signed, absolute, and polar Zernike coefficients. RESULTS: Two hundred Arab participants (group 1) and 200 participants of South-Asian origin (group 2) comprised the study sample. The age and refractive status were comparable between groups. The mean of the HOA root mean square (RMS) was 0.36 ± 17 µ and 0.38 ± 18 µ for Arab and South-Asian eyes, respectively (P < 0.05, rank sum test [RST]). Of the 22 higher order signed Zernike modes, only Z3 (-3), Z3 (-1),3 (1), Z4 (-4), Z4 (-2), Z4 (0), Z4 (4), and Z5 (-5) were significantly different from zero (one sample t-test, P < 0.002, with a Bonferroni correction of 0.05/22). All the signed and absolute Zernike terms were comparable between groups (RST, P > 0.002 [0.05/22]). The polar coefficients for coma, trefoil, spherical aberration, and tetrafoil were comparable between groups (P > 0.05, RST). Combined RMS values of third, fourth, fifth, and sixth order also were comparable between groups (P > 0.05, RST). CONCLUSIONS: Preoperative whole eye HOA were similar for refractive surgery candidates of Arab and South-Asian origin. The values were comparable to historical data for Caucasian eyes and were lower than Asian (Chinese) eyes. These findings may aid in refining refractive nomograms for wavefront ablations.

Biometric and refractive changes after orbital decompression in Korean patients with thyroid-associated orbitopathy.

PURPOSE: To determine the biometric and refractive changes after orbital decompression in Korean patients with thyroid-associated orbitopathy (TAO). METHODS: Retrospective, observational study (between October 2012 and September 2014) was performed. Patients with TAO undergoing orbital decompression for stable proptosis received ophthalmic examinations, including Hertel exophthalmometry, A-scan biometry, autorefraction measures, corneal topography, and wavefront aberration measures, before orbital decompression and again 2 months after surgery. RESULTS: Included in the study were 43 eyes from 23 patients. The mean exophthalmometric value decreased by 4.1 mm 2 months after orbital decompression (P<0.001). On average, axial length (AL) increased significantly by 0.08 mm (P<0.001); specifically, 37 (86%) of the 43 eyes had increased AL. Whereas anterior chamber depth and lens thickness showed no significant changes (P=0.086 and P=0.905, respectively), the mean spherical refraction and spherical equivalent (SE) decreased by 0.35 and 0.48 D, respectively (P=0.008 and P<0.001, respectively). However, cylindrical refraction and axis showed no significant changes (P=0.057 and P=0.218, respectively). The changes in AL and SE were significantly correlated (R=-0.411, P=0.009). Notably, there were no changes in corneal topography or wavefront aberration after orbital decompression. CONCLUSIONS: TAO patients who underwent orbital decompression showed myopic refractive change via increase in AL. Possible refractive changes should be considered in cases of TAO complaining of decreased visual acuity after orbital decompression.

Higher-order aberrations and best-corrected visual acuity in Native American children with a high prevalence of astigmatism.

PURPOSE: To determine whether higher-order aberrations (HOAs) in children from a highly astigmatic population differ from population norms and whether HOAs are associated with astigmatism and reduced best-corrected visual acuity. METHODS: Subjects were 218 Tohono O'odham Native American children 5-9 years of age. Noncycloplegic HOA measurements were obtained with a handheld Shack-Hartmann sensor (SHS). Signed (z06s to z14s) and unsigned (z06u to z14u) wavefront aberration Zernike coefficients Z(3,-3) to Z(4,4) were rescaled for a 4 mm diameter pupil and compared to adult population norms. Cycloplegic refraction and best-corrected logMAR letter visual acuity (BCVA) were also measured. Regression analyses assessed the contribution of astigmatism (J0) and HOAs to BCVA. RESULTS: The mean root-mean-square (RMS) HOA of 0.191 ± 0.072 µm was significantly greater than population norms (0.100 ± 0.044 µm). All unsigned HOA coefficients (z06u to z14u) and all signed coefficients except z09s, z10s, and z11s were significantly larger than population norms. Decreased BCVA was associated with astigmatism (J0) and spherical aberration (z12u) but not RMS coma, with the effect of J0 about 4 times as great as z12u. CONCLUSIONS: Tohono O'odham children show elevated HOAs compared to population norms. Astigmatism and unsigned spherical aberration are associated with decreased acuity, but the effects of spherical aberration are minimal and not clinically significant.

Ocular Aberrations and Corneal Shape in Adults with and without Astigmatism.

PURPOSE: To characterize and compare the corneal shapes and monochromatic aberrations in Chinese myopic adults with and without astigmatism. METHODS: Forty-six Hong Kong Chinese aged 50 to 70 years with compound against-the-rule myopic astigmatism (n = 18) or simple myopia (n = 28) were recruited. Corneal shapes were measured by a Scheimpflug-based corneal topographer: the semimeridian corneal shape factors at the nasal, temporal, inferior, and superior corneal quadrants measured from the corneal apex to 3 mm midperiphery were analyzed. The ocular aberrations were measured by the COAS (Complete Ophthalmic Analysis System) Shack-Hartmann wavefront aberrometer; the corneal aberrations were computed using the corneal topographic map data measured by the Medmont E300 corneal topographer; and the internal aberrations were calculated from the ocular and corneal aberrations. RESULTS: Compared with simple myopia, myopic astigmatism had more oblate nasal and temporal corneal shapes and showed significantly more negative Y trefoil and more positive vertical coma. The asymmetry in corneal shape along the vertical principal meridian (inferior - superior) was significantly associated with the Y trefoil and vertical coma of the cornea, suggesting that this regional asymmetry in corneal shape may contribute to the ocular aberrations. CONCLUSIONS: The significant relationships found between astigmatism, corneal shapes, and monochromatic aberrations underscore the importance of taking corneal shape into account when correcting the optical defects in myopic Chinese adults with astigmatism.

Utility of an open field Shack-Hartmann aberrometer for measurement of refractive error in infants and young children.

PURPOSE: To assess the utility of an open-field Shack-Hartmann aberrometer for measurement of refractive error without cycloplegia in infants and young children. METHOD: Data included 2698 subject encounters with Native American infants and children aged 6 months to <8 years. We attempted right eye measurements without cycloplegia using the pediatric wavefront evaluator (PeWE) on all participants while they viewed near (50 cm) and distant (2 m) fixation targets. Cycloplegic autorefraction (Rmax [Nikon Retinomax K-plus2]) measurements were obtained for children aged ≥ 3 years. RESULTS: The success rates of noncycloplegic PeWE measurement for near (70%) and distant targets (56%) significantly improved with age. Significant differences in mean spherical equivalent (M) across near versus distant fixation target conditions were consistent with the difference in accommodative demand. Differences in astigmatism measurements for near versus distant target conditions were not clinically significant. Noncycloplegic PeWE and cycloplegic Rmax measurements of M and astigmatism were strongly correlated. Mean noncycloplegic PeWE M was significantly more myopic or less hyperopic and astigmatism measurements tended to be greater in magnitude compared with cycloplegic Rmax. CONCLUSIONS: The PeWE tended to overestimate myopia and underestimate hyperopia when cycloplegia was not used. The PeWE is useful for measuring accommodation and astigmatism.

Corneal spherical aberration of eyes with cataract in a Japanese population.

PURPOSE: To investigate the distribution of corneal spherical aberration in Japanese eyes with cataract for implantation of aspheric intraocular lenses (IOLs). METHODS: Corneal spherical aberration (Zernike coefficient Z04) in the central 6-mm zone was measured with a wavefront analyzer (KR9000PW, Topcon) in 257 eyes of 168 Japanese patients with cataract. Axial length was also measured for each eye. RESULTS: Mean corneal spherical aberration was 0.203+/-0.100 microm (range: -0.103 to 0.497 microm). A significant negative correlation was found between axial length and corneal spherical aberration (r =/-0.135, P=.036). CONCLUSIONS: Corneal spherical aberration varied among cataract patients and correlated with axial length. Japanese patients showed a relatively smaller corneal spherical aberration than previous studies of Caucasians. Preoperative measurement of wavefront aberrations is thus important in using aspheric IOLs.

Ethnic differences in higher-order aberrations: Spherical aberration in the South East Asian Chinese eye.

PURPOSE: To determine the distribution of higher-order corneal and ocular aberrations in a healthy refractive surgery population. SETTING: Island Hospital, Penang, Malaysia. METHODS: In this prospective observational study, 1 eye of ethnic Chinese refractive surgery patients was evaluated with an Orbscan II corneal topographer and a Zywave Hartmann-Shack aberrometer with a 6.0 mm pupil. Height data were analyzed to derive the higher-order aberrations (HOAs) from the 3rd to 5th Zernike order. RESULTS: The mean spherical equivalent in the 70 eyes evaluated was -6.46 diopters +/- 3.10 (SD). The mean total corneal HOA was 0.574 +/- 0.218 microm (range 0.269 to 1.249 microm) and the mean total ocular HOA, 0.525 +/- 0.354 microm (range 0.138 to 2.145 microm). There was no statistically significant correlation with age. The mean 3rd-order ocular aberration was 0.399 +/- 0.287 microm; the mean 4th-order, 0.297 +/- 0.223 microm; and the mean 5th-order, 0.108 +/- 0.101 microm. Corneal spherical aberration was greater than ocular spherical aberration (mean 0.312 +/- 0.114 microm versus 0.200 +/- 0.170 microm). Multilinear regression showed that the only dependent that predicted ocular spherical aberration was anterior corneal asphericity (r(2) = 0.227, F = 17.95, P<.001). CONCLUSION: Corneal and ocular aberrations in South East Asian Chinese eyes were significantly greater than that reported in other populations. Population differences in wavefront errors were significant, and this should be noted in patient management.