Short and long term outcomes after small-incision lenticule extraction: A tertiary referral centre experience.

PURPOSE: The objective of this study is to evaluate the preoperative and short- and long-term postoperative results in terms of visual acuity, refractive error, and corneal wavefront aberrations in patients with myopia and myopic astigmatism undergoing small incision lenticule extraction (SMILE). METHODS: Seventy-nine eyes of 52 myopes with or without astigmatism (41 right and 38 left) were enrolled in this retrospective study. The measurements included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent (SE) and wavefront aberrations. All the measurements before and after SMILE surgery were systematically recorded. RESULTS: Mean preoperative UDVA was 1.19±0.24 logMAR and improved to 0.06±0.17 logMAR at the 3-year postoperative follow-up. At the conclusion of the 3-year follow-up, UDVA was better than or equal to 20/20 and 20/25 in 73% and 84% of eyes, respectively. At 1 month postoperatively, CDVA was 0.05±0.23 logMAR and significantly lower than the preoperative CDVA, 0.02±0.04 log MAR (P>0.05). However, at 1 year and 3 years after surgery, CDVA showed a significant increase compared to preoperative CDVA. At the conclusion of the 3-year follow-up, SE was -0.47 D, and 69.6% and 83.5% of the eyes were within±0.50 D and±1.00 D, respectively, of the intended correction. HOA's, coma, and spherical aberration increased significantly. No significant change in trefoil was detected. CONCLUSION: This study showed that SMILE produces a stable, safe outcome for surgical treatment of myopia and myopic astigmatism.

Distribution of corneal spherical aberration in a Tanzanian population.

PURPOSE: To investigate the distribution of corneal spherical aberration (SA) in Tanzanian people of African descent, and to examine the correlation between corneal SA and ocular parameters. DESIGN: Cross-sectional population-based study. METHODS: Residents aged 40 years and older in three villages in the Mkuranga district in Tanzania were enlisted as study participants. Corneal higher-order aberrations (HOAs) for the right eye were measured with a wavefront analyzer (KR-1W, Topcon) and calculated for the central 6.0-mm zone. Corneal curvature radius (CR), corneal astigmatism, and axial length (AL) were also measured and their correlation with corneal SA was assessed. RESULTS: The right eyes of 657 participants (336 male, 321 female) were analyzed. The mean age of the subjects was 57.2 ± 10.3 years (mean ± SD). The mean corneal SA (Zernike spherical aberration coefficient C40) was 0.188 ± 0.095 µm (-0.242 to 0.613). The SAs in about three-quarters of all subjects were between 0.10 and 0.30 µm. The root mean squares of total corneal HOAs and the third- and fourth-order aberrations were 0.629 ± 0.250 µm, 0.539 ± 0.236 µm, and 0.269 ± 0.110 µm, respectively. Corneal SA showed weak significant correlations with CR (Spearman's rank correlation coefficient, r = -0.177, p < 0.001), corneal astigmatism (r = -0.142, p < 0.001), AL (r = -0.168, p < 0.001), and age (r = -0.085, p < 0.05). CONCLUSIONS: This finding may be beneficial for selecting aspheric intraocular lens in this population.

Analysis of Corneal Spherical Aberrations in Cataract Patients with High Myopia.

To evaluate the corneal spherical aberrations in cataract patients with and without high myopia, we conducted a retrospective case series of 502 cataract eyes with high myopia and 1500 age-related cataract eyes and measure their corneal biometric data and axial length using Pentacam and IOLMaster. Both the anterior and total corneal primary spherical aberrations were lower in the high myopia group than that in the control group (0.317 ± 0.215 vs 0.338 ± 0.148 µm, P = 0.043; and 0.281 ± 0.207 vs 0.314 ± 0.153 µm, P < 0.001). The incidence of eyes with negative total corneal primary spherical aberration increased as axial length increased in the high myopia group, and the overall incidence was higher in the high myopia group than that in the control group (2.59% vs 1.47%). These were mainly contributed to the younger age of cataract patients with high myopia (55.76 ± 13.10 vs 60.18 ± 15.72 years, P < 0.001), along with the positive correlations between age and anterior and total corneal primary spherical aberrations. In clinical practice, an aspheric IOL with a low negative or zero primary spherical aberration is recommended for cataract patients with high myopia. Negative total ocular primary spherical aberrations resulting from aspheric IOL implantation should be avoided in extremely high myopic eyes.

Distribution of posterior corneal astigmatism and aberration before cataract surgery in Chinese patients.

PURPOSE: To study the prevalence of posterior corneal astigmatism (PCA) and aberration in Chinese eyes before cataract surgery. METHODS: A cross-sectional study was conducted in Eye and ENT Hospital of Fudan University, Shanghai. In all, we enrolled 1976 eligible eyes of 1976 cataract patients. The astigmatism and aberrations of anterior and posterior cornea were measured by the rotating Scheimpflug System (Pentacam HR, Oculus). Cataract was diagnosed using slit-lamp examination. RESULTS: The mean age of patients was 61.82 ± 13.67 years old. Mean PCA was 0.28 ± 0.16 (range 0-1.0) D and 87.04% eyes had PCA values <0.5 D. WTR astigmatism predominated the anterior cornea astigmatism (43.1%), while ATR astigmatism predominated posterior (85.4%) and total corneal astigmatism (47.2%). We found a shift tendency of WTR to ATR with aging in anterior corneal astigmatism, while PCA remains ATR. A positive correlation between the magnitude of anterior and posterior corneal astigmatism (r2 = 0.089, P < 0.001) was found, especially in WTR anterior cornea astigmatism eyes (r2 = 0.298, P < 0.001). Compared with total corneal astigmatism, anterior corneal measurements overestimated WTR astigmatism by a mean of 0.24 ± 0.13 (D), and underestimated ATR astigmatism and oblique astigmatism in most eyes. Furthermore, anterior corneal aberrations measurements overestimated the total corneal aberration in most eyes. CONCLUSIONS: About 12.96% of eyes had PCA ≥0.5 D. The posterior surface remained ATR astigmatism in most cases with aging. Neglecting the posterior cornea would result in overestimation in WTR anterior corneal eyes and underestimation in ATR and oblique anterior corneal eyes. Also, the posterior corneal aberration was also essential in clinics.

Higher-Order Aberrations in Children and Adolescents of Southwest China.

SIGNIFICANCE: This study provides a descriptive characterization of higher-order optical aberrations for the eyes of a larger number of Chinese children and adolescents. PURPOSE: To determine the distribution of higher-order aberrations (HOAs) of Han Chinese young subjects with normal vision and their relationship to age. METHODS: Children and adolescents, aged from 3 to 17 years, with normal visual acuity were enrolled, and their wavefront aberrations for a 6-mm pupil were evaluated by the Zywave II aberrometer. Their correlations with age were analyzed, and the 95% statistical reference ranges were computed for each Zernike term. RESULTS: A total of 1634 eyes (287 for preschool-age children, 897 for school-age children, and 450 for adolescents) were analyzed. There was a significant correlation with age and the root mean square (RMS) of total HOAs (r = 0.256, P < .0001), third-order aberrations (r = 0.062, P = .029), fourth-order aberrations (r = 0.197, P < .0001), fifth-order aberrations (r = 0.067, P = .017), and trefoil-like aberrations (r = 0.100, P < .0001) in the myopic group. There were significant differences in RMS values (except coma-like aberrations, χ = 4.179, P = .124) as well as the Zernike coefficients among three different age groups. Therefore, the 95% statistical normal reference values were calculated separately for three age groups. CONCLUSIONS: The RMS value of total HOAs, coma-like, trefoil-like, third-order, fourth-order, and fifth-order aberrations are correlated with age, and the RMS values and Zernike coefficients of aberrations were different in different age stages of the subjects. This study described the distribution of HOAs in children and adolescents and established 95% statistical normal values of HOAs for different ages of children and adolescents by analyzing the HOAs in a large number of the Han Chinese clinical population.

Visual acuity and corneal higher-order aberrations after EX-PRESS or trabeculectomy, and the determination of associated factors that influence visual function.

PURPOSE: This study investigated postoperative visual acuity and corneal higher-order aberrations following EX-PRESS or trabeculectomy. METHODS: Out of 56 eyes of 56 patients analyzed, 30 eyes were treated using trabeculectomy, while 26 eyes were treated with EX-PRESS. Visual acuity and corneal higher-order aberrations were analyzed in both groups before and at 2 weeks, 1, 2, and 3 months after the surgeries. Risk factors that could potentially influence corneal higher-order aberrations were evaluated. RESULTS: Significant reductions in the IOP were observed at 3 months after the surgery in both groups. Although a significant decrease in the visual acuity (logMAR) was observed at 2 weeks after the surgery in both groups, at 1 month after the surgeries, there were no significant differences found for the vision as compared to the baseline. At each study visit in the trabeculectomy group, significantly higher corneal higher-order aberrations compared to baseline were noted. In the EX-PRESS group, however, these aberrations were no longer significantly different from the baseline at month 2 (P = 0.36). Analysis of the risk factors indicated that hypotony could influence corneal higher-order aberrations after surgery. CONCLUSIONS: Corneal higher-order aberrations were significantly increased at 1 month after EX-PRESS treatment, with levels returning to baseline by 2 months. After trabeculectomy, however, corneal higher-order aberrations remained significantly increased at 3 months after the procedure.

Ocular higher-order aberrations in a school children population / Aberraciones oculares de alto orden en una población de escolares

Purpose: The primary objective of the study was to explore the statistics of ocular higher-order aberrations in a population of primary and secondary school children. Methods: A sample of 557 children aged 10---15 years were selected from two primary and two secondary schools in Heraklion, Greece. Children were classified by age in three subgroups: group I (10.7 ± 0.5 years), group II (12.4 ± 0.5 years) and group III (14.5 ± 0.5 years). Ocular aberrations were measured using a wavefront aberrometer (COAS, AMO Wavefront Sciences, USA) at mesopic light levels (illuminance at cornea was 4 lux). Wavefront analysis was achieved for a 5 mm pupil. Statistical analysis was carried out for the right eye only. Results: The average coefficient of most high-order aberrations did not differ from zero with the exception of vertical (0.076 m) and horizontal (0.018 m) coma, oblique trefoil (−0.055 m) and spherical aberration (0.018 m). The most prominent change between the three groups was observed for the spherical aberration, which increased from 0.007 m (SE 0.005) in group I to 0.011 m (SE 0.004) in group II and 0.030 m (SE 0.004) in group III. Significant differences were also found for the oblique astigmatism and the third-order coma aberrations. Conclusions: Differences in the low levels of ocular spherical aberration in young children possibly reflect differences in lenticular spherical aberration and relate to the gradient refractive index of the lens. The evaluation of spherical aberration at certain stages of eye growth may help to better understand the underlying mechanisms of myopia development (AU)

Objetivo: El objetivo primario del estudio fue la investigación de la distribución de las aberraciones oculares de alto orden en una población de niños de enseñanza primaria y secundaria. Métodos: Se seleccionó una muestra de 557 niños, de edades comprendidas entre 10 y 15 años, de dos escuelas de enseñanza primaria y secundaria en Heraklion, Grecia. Se clasificó a los niños por edades en tres subgrupos: el grupo I (10,7 ± 0,5 años), el grupo II (12,4 ± 0,5 años) y el grupo III (14,5 ± 0,5 años). Se midieron las aberraciones oculares utilizando un aberrómetro de frente de onda (COAS, AMO Wavefront Sciences, USA) en condiciones de de visión mesópica (la iluminancia en la córnea fue de 4 lux). El análisis con frente de onda se logró para una pupila de 5 mm. El análisis estadístico se llevó a cabo únicamente con los datos del ojo derecho. Resultados: El coeficiente medio para la mayoría de aberraciones de alto orden no difirió de cero, a excepción del coma vertical (0,076 m) y horizontal (0,018 m), el astigmatismo oblicuo (-0,055m) y la aberración esférica (0,018 m). El cambio más sobresaliente entre los tres grupos se observó en la aberración esférica, que pasó de ser de 0,007 m (SE 0,005) en el grupo I a 0,011 m (SE 0,004) en el grupo II y 0,030 m (SE 0,004) en el grupo III. También se hallaron diferencias significativas para el astigmatismo oblicuo y la aberración comática de tercer orden. Conclusiones: Las diferencias en los bajos niveles de aberración esférica ocular en niños reflejan posiblemente las diferencias en cuanto a aberración esférica lenticular y se refieren al gradiente de índice de refracción del cristalino. La evaluación de la aberración esférica en ciertas edades del crecimiento ocular puede ayudar a comprender mejor los mecanismos subyacentes al desarrollo de la miopía (AU)

Ocular higher-order wavefront aberrations in the Japanese adult population: the Yamagata Study (Funagata).

PURPOSE: To investigate the relationship between age and ocular higher-order wavefront aberrations (HOAs) in an adult Japanese population, in addition to factors associated with HOA variations. METHODS: In the Yamagata Study (Funagata) cohort, 227 adult Japanese participants (aged 37-86 years) underwent systemic and ophthalmologic examinations in 2012. Ocular, corneal, and internal HOAs were measured in micrometers. From the Zernike coefficients, we calculated the root mean square of the total HOA, coma, and spherical aberration for a pupil diameter of 4 mm. Linear regression analyses were used to determine whether HOAs were associated with age or other factors. RESULTS: Multiple adjusted linear regression analyses demonstrated that all components of logarithmic HOAs increase with age. Ocular, corneal, and internal HOAs increased by 0.012/y (P < 0.001), 0.007/y (P = 0.010), and 0.014/y (P < 0.001), respectively. Ocular coma also significantly increased with age (0.010/y, P = 0.007), but corneal (P = 0.963) and internal (P = 0.476) coma did not. Age-related spherical aberration increased only in the internal component (0.019/y, P = 0.001). In addition to age, ocular and corneal HOAs were mainly affected by corneal indexes. CONCLUSIONS: Aging is associated with increases in ocular HOAs, independent of other possible confounding factors. The association of ocular HOAs with corneal parameters indicates that ocular HOAs are mainly generated by the cornea. Internal HOAs, supposedly generated from cataract progression, may be associated with systemic factors, including serum creatinine levels and blood pressure.

Ocular monochromatic aberrations in a rural Chinese adult population.

PURPOSE: To investigate the distribution of monochromatic aberrations in a rural Chinese adult population and the possible effect of aberrations on the development of refractive error. METHODS: A total of 404 Chinese adults who grew up in rural Yongnian County, Handan City, Northern China, were included. Monochromatic aberrations of left eyes were measured using iTrace Dynamic Laser Refraction at 5.0-mm pupil size without cycloplegia. RESULTS: Mean age of all participants was 49.9 ± 10.5 years (range, 31 to 86 years). Mean spherical equivalent was 0.22 ± 1.14 diopters (D) (range, -7.06 to +3.62 D). With age, the refraction demonstrated a significant hyperopic shift (r = 0.25, p < 0.01). Oblique trefoil (C3), vertical coma (C3), horizontal coma (C3), and spherical aberration (SA) (C4) significantly differed from zero (-0.065 ± 0.133 µm, -0.043 ± 0.161 µm, +0.070 ± 0.115 µm, and +0.058 ± 0.082 µm, respectively). Total root mean square values of higher-order aberrations (HOAs) were 0.296 ± 0.147 µm, with predominant ones of coma (0.180 ± 0.115 µm), trefoil (0.151 ± 0.116 µm), and SA (0.081 ± 0.060 µm). Root mean square values of total HOAs, coma, trefoil, SA, and third- to seventh-order aberrations significantly increased with age (p < 0.01). Total HOAs, SA, coma, and trefoil were not significantly different between hyperopic, emmetropic, and myopic eyes after adjusting for age (p = 0.26, 0.15, 0.24, and 0.28, respectively). Zernike coefficient of SA showed a significant difference between hyperopic (0.076 ± 0.086), emmetropic (0.056 ± 0.079), and myopic (0.028 ± 0.088) eyes (p = 0.00). CONCLUSIONS: Ocular refraction in rural Chinese adults showed significantly hyperopic shift with age. Magnitudes of HOAs in rural Chinese adults were similar to that of other populations and significantly increased with age but showed no differences in myopic, emmetropic, and hyperopic adults. The existence of HOAs is not, in itself, sufficient to account for the myopia epidemic in China.

Higher order aberrations after keratoplasty for keratoconus.

PURPOSE: To compare higher order aberrations (HOAs) caused by the anterior and posterior corneal surfaces after conventional penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK), and automated lamellar therapeutic keratoplasty (ALTK) in patients undergoing corneal transplantation for keratoconus (KC). METHODS: This retrospective, observational, cross-sectional study included one eye of the following subjects: 40 patients with KC, 23 KC patients after PK, 17 KC patients after DALK, 18 KC patients after ALTK, and 38 healthy controls. All underwent imaging with a rotating Scheimpflug camera (at least 6 months after complete suture removal in grafted subjects) to assess the HOAs from the anterior and posterior corneal surfaces within the central 4-mm and 6-mm zones. The conversion of the corneal elevation profile into corneal wavefront data was performed using Zernike polynomials. Total and third- and fourth-order HOAs were considered. The root mean square of the Zernike vector magnitude, expressed in micrometers, was used. Differences among groups were assessed using the Kruskal-Wallis and Duncan multiple range tests. Statistical significance was defined as p < 0.05. RESULTS: In both 4-mm and 6-mm central zones, the total HOAs from the anterior corneal surfaces were significantly lower in DALK than in ALTK and PK groups (p < 0.05). The total HOAs from the posterior corneal surface were comparable amongst postoperative groups (p > 0.05). The aberration components that were significantly greater included coma in the KC and ALTK eyes, trefoil and coma in the DALK eyes, and trefoil in the PK eyes. CONCLUSIONS: The corneal anterior surface optical quality appeared significantly better after DALK than after ALTK and PK.

Keratometry measurements, corneal astigmatism and irregularity in a normal population: the Tehran Eye Study.

PURPOSE: To determine the mean corneal power, astigmatism, and irregularity in a sample from the population of Tehran. MATERIALS AND METHODS: Four hundred and forty-two people residing in the first four municipality districts of Tehran were selected through a random stratified cluster sampling approach, 410 of which met the inclusion criteria and were enrolled in the study to have Orbscan II acquisitions between 9:00 am and 7:00 pm. The values obtained for keratometry, corneal astigmatism, and corneal irregularity were studied. RESULTS: The mean keratometry reading was 44.39 diopter (D) [95% confidence interval (CI): 44.22-44.57]. Age, spherical equivalent and corneal diameter were significantly correlated with mean keratometry reading in the multivariate model. Mean corneal astigmatism was 0.98 D (95% CI: 0.89-1.06), also significantly correlated with spherical equivalent in the multivariate model. Mean corneal irregularity in the central 3 mm zone was 1.25 D (95% CI: 1.20-1.29); this was significantly correlated with age. CONCLUSIONS: In a sample of the Tehran population, we found higher values of mean corneal power, astigmatism, and irregularity compared to other reports. Considering the high prevalence of cases of suspect keratoconus in the studied population, it is important to pay more attention to corneal indices in keratorefractive surgery.

Gender and wavefront higher order aberrations: do the genders see the world differently?

INTRODUCTION: wavefront sensing technology has emerged as a means to advance our understanding of high-order aberrations of the human eye. PURPOSE: to evaluate the differences in ocular high-order aberrations between males and females and the distribution of high-order aberrations in males and females. SUBJECTS AND METHODS: 3,597 eyes (1,029 female and 2,568 male) of 1,874 patients who obtained wavefront measurements performed using the VISX Wavescan device were included in this study. Mean RMS (root mean square) values of high-order aberrations (HOAs) and the mean of each Zernike polynomial from the second to the sixth order were calculated from multiple scans of each eye. Analysis was performed to assess the association between HOAs and gender, and symmetry of HOAs between eyes in both males and females. RESULTS: overall HOA did not differ significantly between males and females (p= 0.93). Overall HOA did not differ between left eyes (p=0.852) or right eyes (p=0.76). Individual Zernike polynomials did reveal a significant difference between male and female eyes: Z14 (Tetrafoil x, p=.036); Z16 (Secondary Trefoil y, p=0.015); Z24 (Secondary Spherical, p-=0.003); Z25 (Tertiary Astigmatism x, p=0.010); and Z26 (Secondary Tetrafoil x, p=0.004). CONCLUSION: overall HOA does not differ between the genders; however, individual HOA Zernike terms do demonstrate statistically significant differences between males and females. This is the first such study to describe these differences. The clinical significance of these differences has yet to be determined.