Difference In Refractive Error Research Articles

Retinal nerve fiber layer thickness after laser-assisted subepithelial keratomileusis and femtosecond LASIK: a prospective observational cohort study.

PurposeBased on the assumption that high levels of intraocular pressure (IOP) during femtosecond laser-assisted in situ keratomileusis (FS-LASIK) may compromise the retinal nerve fiber layer (RNFL), newer femtosecond platforms that operate without causing significant IOP elevation have been developed in recent years. However, this assumption has not been adequately tested. The aim of the current study was to evaluate possible changes in RFNL thickness in nonglaucomatous myopic patients undergoing FS-LASIK using the 60 KHz IntraLase® device that significantly elevates the IOP for an appreciable period of time vs an advanced surface ablation technique (laser-assisted subepithelial keratomileusis, LASEK) that does not induce any IOP elevation.MethodsThis was a prospective, observational, controlled cohort study. One randomly selected eye of 114 consecutive eligible patients was analyzed. Inclusion criteria were myopia up to -6.00 diopters and astigmatism up to -2.00 diopters. As clinically indicated, 50 patients underwent LASEK and 64 underwent FS-LASIK. The RNFL thickness was determined with a spectral-domain optical coherence tomography device preoperatively and 3 months postoperatively by the same masked observer.ResultsThere was no significant difference in preoperative refractive error, age, or sex between the groups. Preoperatively, central corneal thickness was significantly lower in the LASEK group (529.1±36.1 vs 562.4±31.6 µm, P=0.001). For the LASEK group, there was no significant difference between preoperative and postoperative RNFL thickness in the studied sectors (superior-temporal, temporal, inferior-temporal, average). For the FS-LASIK group, compared to preoperative RNFL measures, statistically significant thicker postoperative values were found for the average RNFL (mean difference: 0.67 µm, 0.7% increase, P=0.008) and the inferior-temporal sector (mean difference: 0.92 µm, 0.6% increase, P=0.02).ConclusionLASIK with a femtosecond platform that induces high intraoperative IOP did not cause RNFL thinning. The observed differences between preoperative and postoperative values are below the axial resolution limit of optical coherence tomography devices.

Macular choroidal thickness in highly myopic women during pregnancy and postpartum: a longitudinal study

BackgroundHigh myopia, a cause of serious visual impairment, is a significant global public health concern. We investigate longitudinal changes in macular choroidal thickness (CT) during pregnancy and 6-months postpartum in women with high myopia (HM).MethodsA prospective longitudinal study was conducted in HM-pregnant women during the course of pregnancy (n = 42 eyes, 42 patients) and 6 months postpartum (n = 40 eyes, 40 patients, two cases lost).Macular CT was measured via enhanced-depth imaging (EDI)-optical coherence tomography (OCT) (EDI-OCT). Intraocular pressure (IOP), axial length (AL), refractive error, mean arterial pressure (MAP), mean ocular perfusion pressure (MOPP), and body mass index (BMI) were also measured.ResultsMacular CTs of HM pregnant women (214.3 ± 52.3 μm) had increased significantly during the third trimester of pregnancy compared with postpartum women (192.7 ± 51.9 μm, p = 0.014). No significant differences in AL, refractive error, or MAP were found between pregnant and postpartum groups (p > 0.05 for all parameters).During pregnancy, macular CT was negatively correlated with AL (first trimester: p = 0.010; second trimester: p = 0.013; and third trimester: p = 0.008) and positively correlated with refractive error (first trimester: p = 0.038; second trimester: p = 0.024; and third trimester: p = 0.010). No correlations between macular CT and age, IOP, MOPP, MAP, or BMI were found.ConclusionsOur study revealed the presence of a significantly thicker choroid during the third trimester of pregnancy compared with 6-mo postpartum in HM women. Macular CT positively correlated with refractive error and negatively correlated with AL during pregnancy, but did not correlate with gestational age, MOPP, IOP, MAP, or BMI.

Optic Disc Drusen in Children: The Copenhagen Child Cohort 2000 Eye Study.

Optic disc drusen (ODD) are seen in up to 2.4% of the general population, but the etiology and pathophysiology of the condition is still unknown. The purpose of this study was to determine the prevalence of ODD in a population-based child cohort and to determine if scleral canal diameter and fetal birth and pubertal parameters are associated with the presence of ODD. This observational, longitudinal population-based birth cohort study, with a nested case-control, included 1,406 children. Eye examinations were performed when the children were between 11 and 12 years of age. Assessment was performed of optical coherence tomography (OCT) scans from 1,304 children with gradable enhanced depth imaging scans of the optic disc. ODD in one or both eyes were found in 13 (1.0%) of all children. All but one of the cases were found in children with scleral canal diameter in the lowest quartile (1,182-1,399 μm) in the nested case-control study. Children with ODD had a mean disc diameter of 1,339 μm (interquartile range, 30 μm), whereas it was 1,508 μm (interquartile range, 196 μm) in the 130 controls without ODD (P < 0.001). No differences in sex, birth weight, refractive error, and Tanner stages (of puberty) were found between children with and without ODD. The prevalence of ODD was 1% in a large child cohort examined by OCT. ODD was found only in eyes with a narrow scleral canal, which is consistent with the hypothesis that ODD might arise as a consequence of retinal nerve fiber congestion in the scleral canal.

Accommodative Function in Individuals with Autism Spectrum Disorder.

Accommodative responses were significantly poorer in individuals with autism spectrum disorder (ASD) compared with age-matched typically developing control subjects, and hypoaccommodation was associated with reduced near visual acuity (NVA) and convergence. Autism spectrum disorder is a neurodevelopmental disorder with a reported prevalence of 1.1 to 1.5%. Accommodative dysfunction has been noted in other developmental conditions including cerebral palsy and Down syndrome. The aim of this study was to investigate how accommodative accuracy and near visual function in ASD compared with typically developing control subjects. This study investigated accommodative function in children with ASD, in conjunction with other vision measures with habitual refractive corrections. Accommodative accuracy was assessed using modified Nott dynamic retinoscopy. Individual accommodative demand and response were calculated incorporating residual refractive error (difference between cycloplegic and habitual refractive state). Near visual measures included NVA, near point of convergence, fusional reserves, and stereoacuity. Cycloplegic autorefraction confirmed refractive error. Accommodative responses were measured from 124 participants with ASD (6 to 17 years old) and 204 age-matched control subjects. There was no significant difference in the magnitude of residual refractive error between groups (P = .10). The prevalence of a clinically significant lag of accommodation was greater in the ASD group compared with control subjects (ASD = 17.4%, control subjects = 4.9%, χ = 13.04, P < .0001). Near visual acuity was significantly reduced in the ASD group with a clinically significant lag of accommodation (P < .01). A few participants (n = 24 control subjects, n = 14 ASD) had uncorrected or undercorrected refractive errors (spherical equivalent refractive error ≥+2.00 D, >1.00 DC), and when these were removed from analysis, there was still an increased prevalence of hypoaccommodation in ASD (14.7%). Children with ASD were significantly more likely to have accommodative deficits (and associated near visual deficits) in their presenting refractive state than typically developing children. Appraisal of refractive error, accommodation, and NVA should be considered in visual assessment of children with ASD.

Aberrometry Repeatability and Agreement with Autorefraction.

Commercially available aberrometers are essential to clinical studies evaluating refractive error and image quality. The Discovery System (Innovative Visual Systems, Elmhurst, IL) is a promising clinical instrument that allows investigators to export aberration data for research and analysis purposes. An assessment of the Discovery System's performance is essential to the interpretation of the data obtained. The aims of this study were to determine the between-visit repeatability of refractive error and higher-order aberration measurements with the Discovery System and to examine between-instrument agreement of refractive error measurements with the Discovery System and Grand Seiko WAM-5500 open-field autorefractor (Grand Seiko Co., Hiroshima, Japan). Cycloplegic refractive error values from the Discovery System (over a 3-mm pupil) and the Grand Seiko autorefractor were converted to power vectors (M, J0, and J45), and averaged. Zernike coefficients were also calculated by the Discovery System over a 6-mm pupil through the sixth radial order. Between-visit repeatability and agreement were evaluated using Bland-Altman difference-versus-mean plots. A t-test compared each mean difference (bias) to zero, and the 95% limits of agreement were calculated. Twenty-five young adults with a mean (±SD) cycloplegic spherical-equivalent refractive error of -2.91 ± 1.85 diopters (D) (range, -6.96 to +0.74 D) were enrolled. There were no significant between-visit differences with the Discovery System for M, J0, J45, third- through sixth-order root mean square (RMS), higher-order RMS, or spherical aberration (all P > .30), and the repeatability for defocus and higher-order RMS were ±0.31 D and ±0.095 μm, respectively, for a 6-mm pupil. At a 3-mm pupil, the Discovery System, on average, measured slightly more positive values than the Grand Seiko for M (0.28 D), J0 (0.11 D), and J45 (0.12 D; all P < .005). The Discovery System was very repeatable and would be an appropriate instrument to measure cycloplegic refractive error and higher-order aberration changes in adults. Small differences in refractive error were found between the Discovery System and Grand Seiko.

Myopia progression control lens reverses induced myopia in chicks.

To determine whether lens induced myopia in chicks can be reversed or reduced by wearing myopia progression control lenses of the same nominal (central) power but different peripheral designs. Newly hatched chicks wore -10D Conventional lenses unilaterally for 7 days. The myopic chicks were then randomly divided into three groups: one fitted with Type 1 myopia progression control lenses, the second with Type 2 myopia progression control lenses and the third continued to wear Conventional lenses for seven more days. All lenses had -10D central power, but Type 1 and Type 2 lenses had differing peripheral designs; +2.75D and +1.32D power rise at pupil edge, respectively. Axial length and refractive error were measured on Days 0, 7 and 14. Analyses were performed on the mean differences between treated and untreated eyes. Refractive error and axial length differences between treated and untreated eyes were insignificant on Day 0. On Day 7 treated eyes were longer (T1; 0.44 ± 0.07 mm, T2; 0.27 ± 0.06 mm, C; 0.40 ± 0.06 mm) and more myopic (T1; -9.61 ± 0.52D, T2; -9.57 ± 0.61D, C; -9.50 ± 0.58D) than untreated eyes with no significant differences between treatment groups. On Day 14 myopia was reversed (+2.91 ± 1.08D), reduced (-3.83 ± 0.94D) or insignificantly increased (-11.89 ± 0.79D) in treated eyes of Type 1, Type 2 and Conventional treated chicks respectively. Relative changes in axial lengths (T1; -0.13 ± 0.09 mm, T2; 0.36 ± 0.09 mm, C; 0.56 ± 0.05 mm) were consistent with changes in refraction. Refractive error differences were significant for all group comparisons (p < 0.001). Type 1 length differences were significantly different from Conventional and Type 2 groups (p < 0.001). Myopia progression control lens designs can reverse lens-induced myopia in chicks. The effect is primarily due to axial length changes. Different lens designs produce different effects indicating that lens design is important in modifying refractive error.

Paravascular inner retinal abnormalities in healthy eyes.

To investigate the prevalence and characteristics of paravascular inner retinal abnormalities in healthy eyes. In this prospective observational case series, we included 178 healthy eyes (178 patients) with no ocular diseases. Eyes with co-existing ocular diseases, e.g., epiretinal membrane, glaucoma, or high myopia, were excluded from the current study. The posterior pole and paravascular areas of the temporal arcade vessels were comprehensively examined by dense radial scanning of optical coherence tomography (OCT) with the extended field imaging technique. On fundus photography, no inner retinal abnormalities were detected along the temporal arcade vessels. On OCT sections, paravascular inner retinal abnormalities were seen in 77 (43.3%) eyes. In 71 (39.9%) eyes, inner retinal cystoid or fissure-like spaces that had no connection to the vitreous cavity were seen adjacent to the temporal arcade vessels. Most of these lesions were detected only on several consecutive OCT sections. In four (2.2%) eyes, inner retinal cleavages with openings to the vitreous cavity were seen adjacent to the temporal arcade vessels. These lesions were more frequently detected in the inferior hemisphere and along the major retinal veins. No eyes showed typical broad defects of the inner retinal tissue. There were no significant differences in age, gender, visual acuity, refractive error, or axial length between eyes with or without paravascular inner retinal abnormalities. Paravascular cystoid or fissure-like spaces were frequently seen in the inner retina of healthy eyes. However, we detected no typical paravascular inner retinal defects in healthy eyes.

Visual Field Defects in Young Patients With Open-angle Glaucoma: Comparison Between High-tension and Normal-tension Glaucoma.

To investigate the clinical features of young Korean patients with open-angle glaucoma (OAG), and to compare visual field (VF) defects between patients with normal-tension glaucoma (NTG) and those with high-tension glaucoma (HTG). Patients with OAG younger than 40 years of age were divided into NTG and HTG groups based on untreated intraocular pressure (IOP) level. The patients were matched according to the mean deviation of standard automated perimetry. VFs were divided into 2 pairs of corresponding areas across the horizontal meridian, and the depths of VF defects were compared. Tilt ratio and torsion degree of their optic discs were also compared between the 2 groups. Thirty-four pairs of NTG and HTG eyes were matched. Although untreated IOP showed intergroup differences, there was no difference in age, refractive error, tilt ratio, torsion degree, and depth of VF defects between the 2 groups. However, NTG eyes showed deeper VF defects in the superior paracentral area than in the inferior paracentral area (-8.29±9.33 vs. -4.45±6.03 dB, P=0.038), whereas the HTG eyes showed symmetric VF defects. Moreover, the superior paracentral area showed deeper VF defects compared with the superior arcuate area in the NTG group (P=0.002). Young patients with NTG showed asymmetric VF defects in the paracentral area, whereas those with HTG did not show such asymmetric defects. This suggests that the level of IOP may affect the pattern of VF defects in young patients with OAG. However, these findings may not be generalizable to other populations.

RISK FACTORS FOR DEVELOPMENT OF MACULAR HOLE RETINAL DETACHMENT AFTER PARS PLANA VITRECTOMY FOR PATHOLOGIC MYOPIC FOVEOSCHISIS

To identify the risk factors for the development of macular hole retinal detachment (MHRD) after vitrectomy without internal limiting membrane peeling for pathologic MF. We retrospectively reviewed the records of 131 eyes (115 patients) treated with vitrectomy for pathologic MF from 2009 to 2014. The best-corrected visual acuity (BCVA), refractive error, axial length, and spectral-domain optical coherence tomography findings were analyzed. Postoperative MHRD developed in 7 eyes (5.3%). Between patients with or without secondary MHRD after vitrectomy, there were no significant differences in age, sex, axial length, preoperative BCVA, refractive error, lens status, and presence of posterior staphyloma. Spectral-domain optical coherence tomography showed all 7 eyes (100%) had foveal detachment, while only 47 patients (37.9%) of 124 eyes had foveal detachment (P = 0.004). There was no significant difference between preoperative and postoperative BCVA in the 7 eyes with MHRD. The postoperative BCVA in the 124 eyes without MHRD was significantly improved (P < 0.001). Among the 124 eyes, both preoperative and postoperative BCVA of eyes with foveal detachment was worse than the eyes without foveal detachment (P < 0.001, respectively). Preoperative foveal detachment is a risk factor for the development of MHRD after vitrectomy for pathologic MF.

The Refractive Error of Professional Baseball Players.

High levels of visual acuity are required to hit a baseball effectively. Research has shown that any decrease in vision is likely caused by low-order optical aberrations. This study is designed to validate the SVOne autorefractor, and describe the amount and type, of low-order optical aberrations present in a large cohort of professional baseball players. A retrospective chart review on the 608 Major League Baseball players evaluated during the 2016 Spring Training Season was performed. Results for a subset of players who had both manifest refraction as well as autorefraction were calculated. Subsequently, after determining the accuracy of the autorefraction system in this population, refractive results for the entire population were determined. There was a borderline statistically significant difference in mean spherical refractive error (M) between the manifest refraction and the SVOne auto refraction (-0.273D in the manifest refraction method vs. -0.503D in the SVOne method, P = .06) in the subset of athletes who underwent both tests. Additionally, there was no difference in the J0 or J45 cylindrical component vectors for each method. For the entire eligible population, the SVOne autorefraction system found a mean spherical refractive error (M) of -0.228D, a J0 value of -0.013D, and a J45 value of -0.040D. These data suggest that the SVOne autorefraction system is generally able to measure the refractive error in the baseball population. The system was slightly biased, often reporting more myopia in myopic subjects. Thus, careful evaluation of the refractive status of these athletes coupled with careful subjective refractive correction for those with less than average vision for baseball is strongly suggested.

Intraocular lens power calculations in eyes with previous hyperopic laser in situ keratomileusis or photorefractive keratectomy

To evaluate the accuracy of 7 intraocular lens (IOL) calculation formulas in patients with previous hyperopic laser in situ keratomileusis (LASIK) or excimer laser photorefractive keratectomy (PRK). Retrospective case series. Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, and private practice, Mesa, Arizona, USA. The 7 formulas evaluated were the adjusted Atlas 0-3, Masket, Modified Masket, Haigis-L, Shammas-PL, Barrett True-K, and Barrett True-K No-History. The Masket and Modified Masket were calculated using the single-K version of Holladay 1 and Hoffer Q formulas; the adjusted Atlas 0-3 was calculated using the double-K version of Holladay 1 and Hoffer Q. The IOL power predicted by each formula was calculated by targeting the postoperative manifest refraction. The IOL prediction error was obtained by subtracting the predicted IOL power from the implanted IOL power. The mean IOL prediction error, median absolute refractive prediction error, and percentages of eyes within ±0.50 diopter (D) and ±1.00 D of the predicted refraction were calculated. Twenty-one eyes of 21 patients were evaluated. There were no significant differences in the median absolute refractive prediction error or percentages of eyes within ±0.50 D or ±1.00 D of the predicted refraction between formulas or methods. The IOL mean prediction errors were comparable between the Holladay 1 and Hoffer Q calculations for all formulas except for a greater error for the double-K version of the Hoffer Q of the adjusted Atlas 0-3. In eyes that had hyperopic LASIK or PRK, there were no significant differences in the accuracy between the 7 IOL calculation formulas.

Factors Associated with Visual Fatigue from Curved Monitor Use: A Prospective Study of Healthy Subjects.

PurposeTo investigate the factors associated with visual fatigue using monitors with various radii of curvature.MethodsTwenty normal healthy adults (8 men, 12 women; mean age, 26.2 ± 2.5 years) prospectively watched five types of monitors including flat, 4000R, 3000R, 2000R, and 1000R curved monitors for 30 min. An experienced examiner measured the ophthalmological factors including near point of accommodation (NPA), near point of convergence (NPC), refraction, parameters during pupil response at light and saccadic movement just before and after the visual tasks. The questionnaires about subjective ocular symptoms were also investigated just before and after the visual tasks.ResultsThe NPA increased after the visual tasks with a flat monitor compared with the curved monitors, with the 1000R curved monitor showing the smallest change (p = 0.020). The NPC increased for every monitor after the visual tasks; the largest increase occurred with the flat monitor (p = 0.001). There was no difference in refractive error, pupil response, or saccadic movement in the comparison of before and after the visual tasks. Among the nine factors in the questionnaire, the score of “eye pain” was significantly higher for the flat monitor versus the 1000R curved monitor after the visual tasks (p = 0.034).ConclusionsWe identified NPA, NPC, and eye pain as factors associated with visual fatigue. Also, the curvature of the monitor was related to the visual fatigue.

성인병 여부에 따른 백내장 수술 효과의 차이 연구

목적: 본 연구는 성인 한국인에게 많이 발생하는 성인병인 녹내장, 고혈압, 당뇨가 백내장에 어느 정도 영향을 미치는 위험 요인을 분석하여 수술 효과에 따른 차이를 밝히는데 목적을 갖는다. 방법: 분석방법은 전남 지역 소재 병원에서 백내장 수술을 받은 환자를 대상으로 수술 전 후 진료 결과에 영향을 미칠 수 있는 변수로 진료의 투입적 변수인 환자 특성과 의료 특성을 진료의 과정적 변수로 기능적 상태, 일반적 상태, 임상적 결과를 분석방법에 반영하였다. 결과: 성인병 중 녹내장, 고혈압, 당뇨가 있는 환자들은 기본적으로 백내장 수술 전부터 성인병이 없는 환자보다 시력이 약 10%정도 낮은 것으로 나타났으며 수술효과 또한 상대적으로 수술 후 시력과 굴절력에서 약 16%정도의 차이가 나는 것으로 나타났다. 결론: 이상의 연구 결과를 통해 성인병 환자의 녹내장, 당뇨, 고혈압이 백내장과 밀접한 상관성을 가짐을 확인하였으며 이들 성인병의 유병 정도에 따라 백내장 또한 수술 전 후 시력 및 안구 굴절력이 기존 일반 성인 대조군과 비교할 때 낮고 큰 차이를 나타내는 것을 확인할 수 있었다. Purpose: This study is intended to look into the difference in surgery effects through the analysis of risk factors on how the common adult diseases among Korean adults diseases (glaucoma, hypertension and diabetes) are affecting cataract. Methods: Cataract surgery patients' daily records at hospitals in Jeonnam were used as analysis data. Factors - which can affect the results of medical treatment before and after an operation - were classified into the input, process and outcome of medical treatment. The medical treatment and patient characteristics were reflected as the input of medical treatment, and clinical results, functional status and general status as the process of medical treatment. Results: There was a close relationship between adult diseases of glaucoma, diabetes and hypertension, and cataract. Visual acuity of adult diseases patients was 10% lower than of non-adult diseases patients. And for post-surgery it was around 16% difference in refractive error and visual acuity between two groups. Conclusions: According to a study result, the cataract has been confirmed that there is a close relationship of Adult disease patients's glaucoma, diabetes and hypertension. Depending on the type about these adult diseases, before and after cataract surgery, vision and refractive power was found to indicate a significant difference when compared with conventional low normal adult control.

Stereoacuity and Related Factors: The Shandong Children Eye Study.

ObjectiveTo assess stereoacuity in a population-based sample of children and to examine ocular and systemic parameters related to stereoacuity.MethodsUsing a random cluster sampling method, four- to 18-year-old children from kindergartens, elementary schools, junior high schools and senior high schools from a rural area and an urban area in the East Chinese province of Shandong were included in the school-based cross-sectional study. All participants underwent a comprehensive eye examination including assessment of cycloplegic refraction and measurement of stereoacuity using the Titmus Stereo test.ResultsOut of 6364 eligible children, 5780 (90.8%) children with a mean age of 10.1 ± 3.2 years (range: 4 to 18 years) participated. Mean (± standard deviation) stereoacuity was 50.2 ± 50.6 arc seconds. Stereoacuity improved significantly (P<0.01) from the age group of 4 years to the age group of 6 to 7 years, then showed a plateau, deteriorated (P = 0.001) for both sexes from the age group of 9 years to the age group of 12 years (P<0.001), after which it improved (P = 0.001) again in the age group of 16 years or older to the pre-puberty values. In multivariate analysis, larger angle of binocular disparity (i.e., lower stereoacuity) was significantly associated with lower best corrected visual acuity (logMAR; P<0.001), higher intereye difference in refractive error (spherical equivalent) (P<0.001), higher cylindrical refractive error (P<0.001), higher refractive error (spherical value; P<0.001), higher intereye difference in best corrected visual acuity (logMAR) (P = 0.001), higher intereye difference in axial length (P = 0.001), and rural region of habitation (P = 0.006).ConclusionsStereoacuity as tested with the Titmus Stereo test improved significantly from an age of 4 years to an age of 6 and 7 years, then remained constant, temporarily deteriorated for both sexes in pre-puberty and puberty, after which it improved again to pre-puberty or better values at the age of 16 years or older. Lower stereoacuity was associated with lower best corrected visual acuity and higher intereye difference in best corrected visual acuity, higher cylindrical and spherical refractive errors, higher inter-eye difference in refractive error, higher intereye difference in axial length, and rural region of habitation.

Posterior scleral reinforcement for the treatment of pathological myopia.

To investigate the effects of posterior scleral reinforcement (PSR) in the treatment of pathological myopia. The study included 52 eyes in 43 patients with pathological myopia who underwent PSR (PSR group), and 52 eyes in 36 age- and myopia-matched patients who did not undergo such treatment as control group. Axial length, refraction error, best corrected visual acuity (BCVA), and macular scans by optical coherence tomography (OCT) were recorded at baseline, 6mo, 1, 3 and 5y after the surgery, and the complications were noted. There were no statistical differences in axial length, refractive error, or BCVA between the PSR group and the control group at baseline. At the end of the follow-up, the mean axial length was 29.79±1.26 mm in the PSR group, which was significantly shorter than that in the control group (30.78±1.30 mm) (P<0.01), and the mean refractive error was -16.86±2.53 D in the PSR group, which was significantly lower than that in the control group (-19.18±2.12 D) (P<0.01). A statistically significant difference in BCVA was found between the PSR group (0.51±0.25 logMAR) and the control group (0.62±0.26 logMAR) at the postoperative 5-year follow-up (P<0.01). There were no serious complications during the 5-year follow-up period. PSR can prevent axial elongation and myopia progression in eyes with pathological myopia.

Profile of refractive errors in European Caucasian children with Autistic Spectrum Disorder; increased prevalence and magnitude of astigmatism.

Autistic Spectrum Disorder (ASD) is a common neurodevelopmental disorder characterised by impairment of communication, social interaction and repetitive behaviours. Only a small number of studies have investigated fundamental clinical measures of vision including refractive error. The aim of this study was to describe the refractive profile of a population of children with ASD compared to typically developing (TD) children. Refractive error was assessed using the Shin-Nippon NVision-K 5001 open-field autorefractor following the instillation of cyclopentolate hydrochloride 1% eye drops. A total of 128 participants with ASD (mean age 10.9 ± 3.3 years) and 206 typically developing participants (11.5 ± 3.1 years) were recruited. There was no significant difference in median refractive error, either by spherical equivalent or most ametropic meridian between the ASD and TD groups (Spherical equivalent, Mann-Whitney U307 = 1.15, p = 0.25; Most Ametropic Meridian, U305 = 0.52, p = 0.60). Median refractive astigmatism was -0.50DC (range 0.00 to -3.50DC) for the ASD group and -0.50DC (Range 0.00 to -2.25DC) for the TD group. Magnitude and prevalence of refractive astigmatism (defined as astigmatism ≥1.00DC) was significantly greater in the ASD group compared to the typically developing group (ASD 26%, TD 8%, magnitude U305 = 3.86, p = 0.0001; prevalence (χ12=17.71 , p < 0.0001). This is the first study to describe the refractive profile of a population of European Caucasian children with ASD compared to a TD population of children. Unlike other neurodevelopmental conditions, there was no increased prevalence of spherical refractive errors in ASD but astigmatic errors were significantly greater in magnitude and prevalence. This highlights the need to examine refractive errors in this population.

Comparison of accuracy of Partial Coherence Interferometry based Zeiss IOL Master 500 and Immersion Ultrasound [Ocuscan RXP] for intraocular lens power calculation

Aim: To compare accuracy of intraocular lens power (IOL) calculation using Partial coherence Interferometry based Carl Zeiss IOL master 500 and Immersion ultrasound (Alcon Ocuscan RXP). Methods: A prospective randomized study of patients who underwent clear corneal phacoemulsification with foldable (IOL) by a single surgeon, during the period September 2010 to 2012. Group A included those patients in whom IOL power calculation using Immersion ultrasound (Ocuscan RXP) was used. Group B included those patients in whom IOL power calculation using Partial coherence Interferometry based Zeiss IOL master was used. SRK T formula was used to calculate the IOL power in both the groups. Postoperative final refraction was done at 6 weeks. Unaided visual acuity and best corrected visual acuity was assessed. Postoperative refractive error was compared with predicted refractive error with each biometry method. Statistical analysis was done using SPSS 16.5. Continuous variables expressed as mean (standard deviation). P &lt; 0.05 was considered significant.Results: There were 50 patients in Group A, 44 patients in Group B. Axial length of the patients varied from 22-26mm in both the groups. The postoperative refraction using Ocuscan, 88% had refractive error ≤± 0.5 D, 94% had ≤±1.00D, and 100% had ≤±2.0D of emmetropia. Using Zeiss IOL Master 72.7% had ≤± 0.5 D, 100% had ≤±1.00D of refractive error. Difference in absolute postoperative refractive error using Ocuscan vs. IOL Master was not statistically significant. Conclusion: In our study both ultrasound Ocuscan and IOL master were accurate in calculating intraocular lens power and achieving postoperative refraction closer to emmetropia.

A cross sectional study on refractive error among school children aged 6 to 17 years in Chennai, India

Background: Blindness due to refractive error is a substantial public health problem in many parts of the world. Refractive error would become the second largest cause of treatable blindness after cataract. Refractive error is the most common and avoidable causes of visual impairment. Screening programs need to be implemented to detect individuals suffering from refractive error. Early diagnosis and treatment is the simple and most effective measure to prevent refractive error blindness. The current study was designed to estimate the Prevalence of refractive error among school children. Methods: This cross sectional study was conducted among 1720 school children of 6- 17 years age group in Chennai. The sample size was estimated by the prevalence of refractive error as 20%, alpha error 5% and relative precision 10% of refractive error. School children were screened for defective vision with the help of Snellen’s chart. Results: Total of 1720 children was examined; 49.7% were boys and 50.3% were girls. The overall Prevalence of refractive error was 20.9% and the 95% Confidence interval was found to be 19.9% to 20.9%. The Prevalence of refractive error among boys was 10.8% and in girls was 10.1%. The difference in refractive error among male and female children was small and the difference was found to be statistically insignificant (p>0.05). Conclusions: Refractive error is the most common and avoidable causes of visual impairment. Uncorrected refractive error can affect their learning. So, early detection and intervention can improve child’s potential tremendously during the formative years.

The Effect of Age, Accommodation, and Refractive Error on the Adult Human Eye.

To quantify changes in ocular dimensions associated with age, refractive error, and accommodative response, in vivo, in 30- to 50-year-old human subjects. The right eyes of 91 adults were examined using ultrasonography, phakometry, keratometry, pachymetry, interferometry, anterior segment optical coherence tomography, and high-resolution magnetic resonance imaging. Accommodation was measured subjectively with a push-up test and objectively using open-field autorefraction. Regression analyses were used to assess differences in ocular parameters with age, refractive error, and accommodation. With age, crystalline lens thickness increased (0.03 mm/yr), anterior lens curvature steepened (0.11 mm/yr), anterior chamber depth decreased (0.02 mm/yr), and lens equivalent refractive index decreased (0.001/yr) (all p < 0.01). With increasing myopia, there were significant increases in axial length (0.37 mm/D), vitreous chamber depth (0.34 mm/D), vitreous chamber height (0.09 mm/D), and ciliary muscle ring diameter (0.10 mm/D) (all p < 0.05). Increasing myopia was also associated with steepening of both the cornea (0.16 mm/D) and anterior lens surface (0.011 mm/D) (both p < 0.04). With accommodation, the ciliary muscle ring diameter decreased (0.08 mm/D) and the muscle thinned posteriorly (0.008 mm/D), allowing the lens to shorten equatorially (0.07 mm/D) and thicken axially (0.06 mm/D) (all p < 0.03). Refractive error is significantly correlated with not only the axial dimensions but also the anterior equatorial dimension of the adult eye. Further testing and development of accommodating intraocular lenses should account for differences in patients' preoperative refractive error.

Anterior Chamber Depth, Lens Thickness, and Related Measures in African American Females With Long Anterior Zonules: A Matched Study With Control for Refractive Error.

To investigate anterior chamber depth (ACD), lens thickness (LT), vitreous body length (VBL), and axial length (AL) in African American females with long anterior zonules (LAZ) while controlling for refractive error. The eyes of 50 African American females with LAZ were compared with 50 controls matched with age, race, sex, and refractive error. Central ACD, LT, VBL, and AL measurements were obtained in a masked manner using a-scan ultrasonography. LAZ cases had a mean age±SD of 67.1±7.6 years (range, 52 to 85 y) and a mean refractive error of +1.85±1.41 D (-1.75 to +4.75 D). Parameters were similar for controls. Mean ACD for cases was 2.45±0.34 mm and 2.57±0.38 mm for controls. Mean LT for cases was 4.94±0.43 mm and 4.83±0.45 mm for controls. Mean VBL for cases was 15.00±0.72 mm and 15.17±0.76 mm for controls. Mean AL for cases was 22.39±0.82 mm and 22.57±0.76 mm for controls. Using multiple logistic regression to control for any residual differences in age and refractive error, no significant differences were present between LAZ eyes and control eyes relative to the a-scan variables (P>0.1). When refractive error was controlled for, this group of African American females with LAZ did not exhibit clinically significant differences in ACD, LT, VBL, and AL as compared with controls.