Anisometropia in Hispanic and african american infants and young children the multi-ethnic pediatric eye disease study

Combination of 2 test methods, single-picture optotype visual acuity chart and spot™ vision screener, in the eye health screening program for 3-year-old children in Tokyo: A retrospective, observational study

To evaluate the usefulness of the Tokyo Metropolitan Government's Eye Health Screening Program for 3-year-old children, which combines the Single-Picture Optotype Visual Acuity Chart (SPVAC) and Spot™ Vision Screener (SVS) tests. This was a retrospective, observational, matched study. Patients who underwent the eye health screening program and had abnormalities were classified into 3 groups according to the outcomes of the SPVAC (SPVAC-passed, SPVAC-P; SPVAC-failed, SPVAC-F) and SVS (SVS-passed, SVS-P; SVS-failed, SVS-F) tests as follows: SPVAC-P/SVS-F, SPVAC-F/SVS-P, and SPVAC-F/SVS-F. We evaluated the age at examination, SPVAC and SVS test success rates, and SVS refractive power. Additionally, the rates of refractive error, amblyopia, and strabismus were compared among the 3 groups. The SPVAC-P/SVS-F, SPVAC-F/SVS-P, and SPVAC-F/SVS-F groups comprised 158, 28, and 74 eyes, respectively. The mean age was 37.4 months. The success rates of the SPVAC and SVS tests were 69.8% and 96.2%, respectively. The mean SVS hyperopia value in the SPVAC-F/SVS-F group (2.71 ± 1.50 D) was significantly higher than that of the SPVAC-P/SVS-F group. The mean SVS astigmatism and myopia values were -2.21 diopter (D) ± 1.09 D and -3.40 ± 1.82 D, respectively; they did not differ significantly from that of the SPVAC-P/SVS-F group. Significant differences were observed in the refractive error, amblyopia, and strabismus rates among the 3 groups. Regarding disease determination, no significant difference was observed among participants who passed and failed the SPVAC test, regardless of the outcome of the other test. However, a significant difference was observed between those passing and failing the SVS tests. The SPVAC method used to screen 3-year-old children should be modified to commence at 42 months of age or be replaced with a single Landolt C test. The SVS test is useful for screening younger patients. Furthermore, the SVS test showed that the degree of hyperopia was higher in patients who did not pass the SPVAC test.

Prevalence of anisometropia and its associated factors in school-age children

PURPOSE

To determine the prevalence of anisometropia and the associated demographic and biometric risk factors in children.

METHODS

This cross-sectional study was conducted on the elementary school children of Shahroud, east of Iran, in 2015. All rural students were recruited, while multistage cluster sampling was used to select the students in urban areas. All children underwent optometric examinations including the measurement of uncorrected and corrected visual acuity, autorefraction, and subjective refraction with cycloplegia. Biometric components were measured using the Allegro Biograph. Myopia and hyperopia were defined as a spherical equivalent ≤-0.5 and ≥ +2.00 diopter, respectively. Students with a history of ocular trauma or lack of cycloplegic refraction at least in one eye were excluded from the study.

RESULTS

Of 6624 selected children, 5620 participated in the study. After applying the exclusion criteria, the data of 5357 students (boys: 52.8%, n = 2834) were analyzed. The mean age of the subjects was 9.2 ± 1.7 years (range: 6-12 years). The prevalence of anisometropia ≥ 1 D was 1.1% (95% CI: 0.8 to 1.4) in all children, 1.0% (95% CI: 0.7-1.3) in boys, 1.3% (95% CI: 0.8-1.7) in girls, 1.1% (95% CI: 0.8-1.4) in urban children, and 1.4% (95% CI: 0.5-2.3) in rural children. The prevalence of anisometropia was 8.8% (95% CI: 5.3-12.2) in myopic and 5.7% (95% CI: 2.8-8.5) in hyperopic children. Axial length asymmetry (OR = 40.9; 95%CI: 10.2-164.1), myopia (OR = 17.9; 95% CI: 9.4-33.9), and hyperopia (OR = 10.1; 95% CI: (5.1-19.7) were associated with anisometropia in multiple logistic regression model. More anisometropia was associated with more severe amblyopia. The odds of amblyopia (OR = 82.3: 38.2-177-3) and strabismus (OR = 17.6: 5.5-56.4) were significantly higher in anisometropic children. The prevalence of amblyopia was 21.7% in children with myopic anisometropia ≥ 3D, 66.7% in children with hyperopic anisometropia ≥ 3D, and 100% in cases with antimetropia ≥ 3D.

CONCLUSION

The prevalence of anisometropia was low in Iranian school children. However, a high percentage of anisometropic students had amblyopia and strabismus. Axial length was the most important biometric component associated with anisometropia.

Temporal trend of anisometropia incidence in Chinese school-aged children before and during the COVID-19 pandemic

Objective

To analyze and compare the temporal trends in the incidence of anisometropia among Chinese school-aged children both before and during the COVID-19 pandemic, and to investigate the impact of the pandemic on the incidence of anisometropia.

Methods

We conducted a retrospective study comprising six distinct and independent longitudinal cohorts, each including children aged 6 to 13 years who visited the Joint Shantou International Eye Center between January 2010 and December 2021. Children were grouped into cohorts based on the year of their first eye clinic visit: 2010, 2012, 2014, 2016, 2018, or 2020. Only children without anisometropia at initial visits, followed for 18 ± 6 months, were included. The cumulative incidence and risk factors of anisometropia were analyzed using Kaplan-Meier estimation and Cox proportional hazards regression models. Subgroup analyses were performed based on sex, age groups, initial refractive error status, and initial interocular SE difference. Anisometropic children were further categorized into myopic and non-myopic, with subsequent subgroup analyses conducted.

Results

Of 11,235 children were recruited from six cohorts (2010: n = 1,366; 2012: n = 1,708; 2014: n = 1,896; 2016: n = 2,354; 2018: n = 2,514; 2020: n = 1,397), 869 children developed anisometropia during a mean follow-up of 17.5 ± 3.7 months. After adjustment of confounding factors, we found that the risk of anisometropia remained relatively stable before 2020 but significantly increased in the 2020 cohort (adjusted HR 2.93, 95% CI 2.23 to 3.86; p < 0.001). This trend persisted in studies of spherical anisometropia (adjusted HR 2.52, 95% CI 1.60 to 3.97; p < 0.001) and cylindrical anisometropia (adjusted HR 2.91, 95% CI 1.69 to 3.62; p < 0.001). Older age and a greater initial difference in SE between the two eyes were also significantly associated with a higher risk of developing anisometropia (p < 0.001). Subgroup analyses consistently showed increased risk in the 2020 cohort.

Conclusion

This study reveals a concerning rise in anisometropia incidence among Chinese school-aged children during the period of the COVID-19 pandemic. These findings highlight the worrisome rise in anisometropia risk during the COVID-19 pandemic and emphasize the importance of early detection and management to safeguard children's visual health.

Anisometropia and its association with refraction development in highly myopic children

CLINICAL RELEVANCE

Anisometropia can affect visual development in children. Investigations of anisometropia in high myopes would explore potential causes related to anisometropia, highlighting the management of anisometropia in high myopia.

BACKGROUND

The prevalence of anisometropia ranged from 0.6% to 4.3% in general paediatric population and from 7% to 14% in myopes. Anisometropia is regarded as an associated factor for myopia development, while myopia progression is a stimulus driving anisometropic development. The purpose of this study was to investigate the prevalence of anisometropia and its association with refraction development in Chinese children with high myopia.

METHODS

In the cohort study, a total of 1,577 highly myopic (spherical equivalent ≤-5.0D) children aged 4-18 years were included. Refractive parameters (dioptre of sphere, dioptre of cylinder, corneal curvature radius, and axial length) of both eyes were measured after cycloplegia. The prevalence and degree of anisometropia were compared among refractive groups (non-parametric tests or chi-square tests), and regression analyses were used to determine associated factors of anisometropia. The statistical significance was set to P < 0.05 (two-tailed).

RESULTS

In highly myopic children with a mean (standard deviation) age of 13.06 (2.80) years, the proportions of spherical equivalent anisometropia, cylindrical anisometropia and spherical anisometropia ≥1.00 D were 34.5%, 21.9% and 39.9%, respectively. There was more spherical equivalent anisometropia associated with more severe astigmatism (P for trend <0.001). In the multivariate regression analysis, more spherical equivalent anisometropia, cylindrical anisometropia and spherical anisometropia were associated with higher degrees of astigmatism (standard beta = -0.175, -0.148 and -0.191, respectively). More spherical anisometropia was associated with better spherical power (standard beta = 0.116).

CONCLUSION

The proportion of anisometropia in highly myopic children was high, compared with previously reported general population, and more severe anisometropia was associated with higher degree of cylindrical power, but not spherical power.

Progression pattern of non-amblyopic Anisomyopic eyes compared to Isomyopic eyes

This study aimed to determine the progression pattern of non-amblyopic anisomyopic children from ages 6 to 16 years. This retrospective study analyzed the electronic medical records of 8680 myopic children who visited Sankara Nethralaya, Chennai, India over eight years (2009 to 2017). A total of 711 records were retrieved based on inclusion criteria. In addition, 423 records out of 711 had consecutive follow-up for three years (baseline plus three follow-up visits) and were considered to determine the progression pattern. The cycloplegic sphero-cylindrical refraction was taken for analysis and converted to vector notation of M (SE), J0, and J45. Anisomyopia referred to the interocular difference of myopic SE of ≥ 1 D whereas isomyopia referred to the interocular difference of myopic SE of < 1 D. Based on the refraction of the less ametropic eye, anisomyopes were further categorized into bilateral anisometropic myopia (BAM) and unilateral anisometropic myopia (UAM). The isomyopic cohort showed a mean annual progression of -0.49 ± 0.54 D (median [IQR] -0.38 D [{-0.75}-0.00]). In BAM, the mean annual progression of the more myopic eye was -0.45 ± 0.55 D (median [IQR] -0.38 D [{-0.75}-0.00]), and the less myopic eye was -0.37 ± 0.55 D (median [IQR] -0.25 D [{-0.63}-0.00]). This difference was significant (t (212) = -2.14, p < 0.05). In UAM, the myopic eyes (-0.39 ± 0.51 D; median [IQR] -0.25 D [{-0.75}-0.00]) showed a statistically significant higher mean annual progression compared to emmetropic eyes (-0.22 ± 0.36 D; median [IQR] 0.00 D [{-0.44}-0.00]; t (96) = -3.30, p < 0.001). In terms of progression trend, in the BAM group, the rate of change of mean SE between the more myopic and the less myopic eyes were similar (-1.12 ± 1.20 D; median [IQR] -1.13 D [{-2.00}-{-0.38}] vs. -1.05 ± 1.25 D; median [IQR] -0.88 D [{-1.75}-{-0.13}]; t (138) = -0.64, p > 0.05). However, the more myopic eyes of UAM showed a higher myopic trend compared to the emmetropic eyes (-1.37 ± 1.06 D; median [IQR] -1.32 D [{-2.13}-{-0.50}] vs. -0.96 ± 1.11 D; median [IQR] -0.75 D [{-1.56}-{-0.25}]; t (61) = -2.74, p < 0.05).   Conclusion: Children with BAM and UAM eyes exhibit different progression patterns from each other. While the rate of the refractive shift in myopic eyes of UAM is similar to isomyopic eyes, BAM eyes present a slower rate of progression than isomyopic eyes. What is Known: • The rate of change of refraction in anisomyopes is higher compared to isomyopic children. • Less myopic eyes tend to shift towards more myopia while more myopic eyes show stable refraction. What is New: • The progression pattern of bilateral anisometropic myopia and unilateral anisometropic myopia differ from one another. • While the rate of the refractive shift in myopic eyes of unilateral anisometropic myopia is similar to isomyopic eyes, bilateral anisometropic myopia eyes present a slower rate of progression than isomyopic eyes. • The pattern of change in the interocular difference of anisometropia depends on the laterality (bilateral or unilateral ametropia), and degree of spherical equivalent in the more ametropic eye.

Refractive outcomes following unilateral laser treatment for type 1 retinopathy of prematurity

PURPOSE

To compare refractive outcomes of infants with type 1 retinopathy of prematurity (ROP) in whom one eye was treated with laser and the fellow eye spontaneously regressed.

METHODS

The medical records of infants who underwent IVB and laser treatment for type 1 ROP or aggressive posterior-ROP between January 2016 and December 2019 were retrospectively evaluated. Infants in whom ROP in the fellow eye regressed and for whom refractive data was available in the record were included in the study. Refractive outcomes of unilaterally treated infants were assessed.

RESULTS

A total of 283 cases were reviewed: of these, 17 experienced spontaneous regression in the fellow eye and were included. All unilateral laser-treated eyes had type 1 ROP in zone Ⅱ. The median age at treatment was 40 weeks' postmenstrual age (IQR, 39-41). The mean spherical equivalent at the last examination was 2.1 ± 2.5 D in treated eyes and 2.50 ± 1.4 D in nontreated eyes, at a mean age of 25.0 ± 9.1 months (P = 0.378). Of the 7 infants who underwent fluorescein angiography, the median of the ratio of the length of the temporal retinal vascularization to the optic disk-to-fovea distance was 3.71 (3.22-3.79) in treated and 4.28 (3.90-4.49) in untreated eyes, at a median age of 18 months (P = 0.018).

CONCLUSIONS

In laser-treated eyes with peripheral zone Ⅱ ROP and with advanced treatment age, we did not observe a significant myopic change compared to the fellow untreated eye.

The UCI EyeMobile Preschool Vision Screening Program: Refractive Error and Amblyopia Results from the 2019-2020 School Year

Purpose

To introduce the University of California Irvine (UCI) EyeMobile for Children preschool vision screening program and describe the ophthalmic examination results of children who failed screening with the PlusoptiX S12C photoscreener during one school year.

Patients and Methods

Children aged 30-72 months were screened with the PlusoptiX using ROC mode 3 during the 2019-2020 school year. Children who failed screening were referred for comprehensive eye examination on the EyeMobile mobile clinic. Presence of amblyopia risk factors (ARFs), amblyopia, and refractive error was determined via retrospective review of records. Amblyopia was defined as unilateral if there was ≥ 2-line interocular difference in the best-corrected visual acuity (BCVA) and as bilateral if BCVA was < 20/50 for children < 4 years old and < 20/40 for children ≥ 4 years old. ARFs were defined using 2021 American Association for Pediatric Ophthalmology and Strabismus (AAPOS) instrument-based screening guidelines.

Results

5226 children were screened during the study period. Of the 546 children who failed screening, 350 (64%) obtained consent and were examined. Mean age of examined children was 4.45 years. Amblyopia was found in 8% of examined children, with unilateral amblyopia seen in 79% of amblyopic subjects. Glasses were prescribed to 246 (70.3%) children. Of the 240 children who received cycloplegic examinations, 43% had hyperopia and 30% had myopia. The positive predictive value (PPV) of the PlusoptiX screening for ARFs in children who received cycloplegic examinations was 70.4%.

Conclusion

A significant proportion of Orange County preschoolers with refractive errors and amblyopia have unmet refractive correction needs. The PlusoptiX S12C photoscreener is an adequate screening device for the UCI EyeMobile for Children program, although modification of device referral criteria may lead to increased PPV. Further research is necessary to understand and overcome the barriers to childhood vision care in our community.

Comparison of Longitudinal Changes in Refractive Error of Hyperopic Children with or without Refractive Accommodative Esotropia

We investigated longitudinal changes in the spherical equivalent refractive error (SE) in hyperopic children with or without refractive accommodative esotropia (AccET). A total of 456 patients met the inclusion criteria: 190 (41.7%) in the hyperopic control group and 266 (58.3%) in the AccET group. All patients received at least 3 years of follow-up after spectacle prescription. Subgroups were divided according to age when spectacles were prescribed, presence of amblyopia, or initial SE. Longitudinal changes in SE in children with hyperopia showed a gradual decrease, although SE of younger children with AccET increased over the first 4 years and then decreased thereafter. SE in eye with higher SE was tended to decrease significantly in patient with Acc ET than hyperopic control group (group × time p = 0.015). Amblyopic eyes showed a greater decreased in SE compared with non-amblyopic eyes, but it was not statistically significant (p = 0.07). SE was significantly decreased in children with more hyperopia (≥ 3 D) compared with children with less hyperopia (<3 D) (p = 0.008). Emmetropization of hyperopia was faster in hyperopic patients without AccET and could be affected by the age of the initial spectacles prescription, initial amount of SE, or presence of amblyopia.

Refractive Error Findings in Students Who Failed School-based Vision Screening

PURPOSE

To report refractive error findings in Baltimore City schoolchildren who failed school-based vision screenings.

METHODS

In this cross-sectional analysis, students pre-kindergarten through 8^th grade who failed screenings during school years 2016-2019 received an eye examination, including non-cycloplegic autorefraction and visual acuity (VA) measurements. Refractive error was identified when there was at least: -0.50 diopter (D) spherical equivalent (SE) myopia, +0.50D SE hyperopia, 1.00D astigmatism, or 1.00D anisometropia in either eye. Generalized estimating equation models were used to identify factors associated with clinically significant refractive error, defined as decreased VA and more severe refractive error.

RESULTS

Of 7520 students who failed screening, 6627 (88%) were analyzed. Clinically significant refractive error and any refractive error were found in 2352 (35.5%) and 5952 (89.8%) students, respectively. Mild myopia (45%, -0.50 D to <-3.00 D SE) and low astigmatism (47%, 1.00 D to <3.00 D cylinder) were the most prevalent types of refractive error. Proportions of students with myopia increased with higher grade levels (P_trend<0.001). Myopia and astigmatism were more common in black and Latinx. Risk factors for clinically significant refractive error included higher grades (odds ratios [OR] ranged from 1.30 to 2.19 compared with 1^st grade, P < .05) and Latinx ethnicity (OR = 1.31, 95%CI: 1.08-1.59).

CONCLUSION

A Baltimore school-based vision program identified a substantial number of students with refractive error in a high-poverty urban community. Over 1/3 students who failed vision screening had clinically significant refractive error, with black and Latinx students at higher risk of having myopia and astigmatism.

Geographic Variation in Strabismus Pattern Among Pediatric Age Group in Lebanon: A Single-Centre Five-Year Observational Study

Background: Strabismus means ocular misalignment. It is also one of the most prevalent types of amblyopia and the leading cause of pediatric visual impairment.

Objective: This study aims to determine the frequency of different types of strabismus and the associated refractive errors and amblyopia in patients younger than 16 years of age. This study also aims to compare the age at presentation and gender between the geographic locations and between different strabismus types.

Materials and methods: A cross-sectional retrospective study was done using the archives of Beirut Eye and ENT specialist hospital between January 2014 and December 2018. Lebanese pediatric patients aged <16 years having strabismus were included in this study.

Results: There was a total of 787 pediatric patients with strabismus, 62.6% of cases had esotropia (ET) and 30.2% exotropia (XT), with ET/XT: 2.07/1. Mt Lebanon had the highest number of cases, whereas Nabatieh was the only governorate with reversed ET/XT ratio. Most patients were diagnosed at the age of 1-5 years, with ET being the most common diagnosis, while XT was mostly found in patients aged 11-15. Hyperopia was the most common (55.4%) refractive error detected in our cohort of strabismus patients, followed by myopia and simple astigmatism. Amblyopia was found in 18.9% of cases, where Nabatieh had the highest count.

Conclusion: Strabismus pattern was investigated for the first time across Lebanon to shed the light on the crucial role of early ophthalmologic examination, to detect early refractive error and strabismus, and to prevent amblyopia.

The biometric parameters of aniso-astigmatism and its risk factor in Chinese preschool children: the Nanjing eye study

Backgrounds

Aniso-astigmatism may hinder normal visual development in preschool children. Knowing its prevalence, biometric parameters and risk factors is fundamental to children eye care. The purpose of this study was to determine the biometric components of aniso-astigmatism and associated maternal risk factors in Chinese preschool children.

Methods

In the population-based, prospective cohort Nanjing Eye Study, children were measured for noncycloplegic refractive error using an autorefractor and for biometric parameters using an optical low-coherent reflectometry. The difference of total astigmatism (TA) between both eyes was calculated using cylinder power (non-vectorial aniso-TA was defined as ≥1.00 Dioptre Cylinder [DC] between both eyes) and by vector analysis (vectorial aniso-TA was defined as a difference of ≥0.5 in J₀ or J₄₅ between both eyes which is equivalent to 1.00 DC). The prevalence of aniso-TA was presented. Interocular biometric parameters were compared between with vs. without aniso-astigmatism group. In addition, risk factors were determined using multivariate logistic regression model.

Results

Of 1131 children (66.90 ± 3.38 months, 53.31% male), the prevalence of non-vectorial aniso-TA was 1.95% (95% Confidence Interval (CI) = 1.14–2.75%), while the prevalence of vectorial aniso-TA was twice as common as non-vectorial aniso-TA, neither varying with sex or age. With aniso-TA eyes were more asymmetric in axial length and corneal curvature radius than without aniso-TA eyes. In multivariate logistic regression model, 5-min Apgar score less than 7 was significantly associated with higher risk of aniso-TA (vectorial aniso-TA: Odds Ratio (OR) = 6.42, 95%CI = 2.63–15.69, P < 0.001; non-vectorial aniso-TA: OR = 4.99, 95%CI = 1.41–17.68, P = 0.01). Being twin or triple was significantly associated with higher risk of vectorial aniso-CA (OR = 2.43, 95%CI = 1.05–5.60, P = 0.04). Pre-term delivery (OR = 2.60, 95%CI = 1.09–6.15, P = 0.03) and post-term delivery (OR = 3.61, 95%CI = 1.31–9.96, P = 0.01) were significantly associated with higher risk of vectorial aniso-CA.

Conclusions

Both corneal curvature radius and axial length asymmetry were correlated with aniso-TA. Children with 5-min Apgar score < 7 were more likely to have aniso-TA, while twin or triple, pre-term or post-term delivery were more likely to have vectorial aniso-CA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-01808-7.

Evidence-Based Clinical Practice Guideline: Comprehensive Pediatric Eye and Vision Examination

Republished with written permission granted from the American Optometric Association, October 2, 2020.

Comparison of Photoscreening to Chart Methodology for Vision Screening

The goal of this study is to assess the referral rate accuracy of photoscreening versus the chart methodology in identifying preschool children at risk of amblyopia and amblyogenic refractive error. Vision screenings using the plusoptiX S12 and the LEA chart were performed on 127 children, aged 3-5 years old. Comprehensive eye exams were performed after screenings. The sensitivity and specificity of the plusoptiX S12 were 80.3% and 92.1% and the LEA chart were 43.6% and 94.8%, respectively. The sensitivity of the plusoptiX S12 is significantly higher than the LEA (p value: <.001). After eye exams, 82.9% were correctly passed by the plusoptiX S12 and 64% were correctly passed by the LEA chart (p value: .009). Objective photoscreening is significantly more accurate in identifying preschool children at risk of developing amblyopia and should be considered best practice. The chart methodology provides an inaccurate report on a preschool child's amblyopic risk.

Relationship between Geography and Refractive Error from the UCLA Preschool Vision Program

PURPOSE

Using the screening data collected through the University of California, Los Angeles Preschool Vision Program (UPVP) that provides free vision screening to children 2.5 to 6 years of age attending public preschools in five Supervisory Districts in Los Angeles County, this paper explores whether geographic location of where children attended preschool affects the vision screening results.

METHODS

62,936 children were screened using a handheld device (Nikon Retinomax) between academic years 2012 and 2015. The criteria for failing the screening was set to sphere of ≤ -3.25 diopters (D), sphere ≥ +1.75 D, or cylinder of ≥1.50 D in either eye, or inter-ocular difference of >2.00 D in spherical error (>1.50D in case of antimetropia) or ≥1.00 D in cylinder error.

RESULTS

Higher fail rates were found among girls, Latino race, and those who primarily spoke Spanish at home. In addition, there was a geographical variance in screening outcomes among Supervisory Districts with District 1 having the highest fail rate and District 4 having the lowest fail rate.

CONCLUSION

This paper provides preliminary evidence of geographic factors contributing to the development of refractive errors among preschoolers which may be used in future studies to address the unmet needs of children with vision impairments in Los Angeles County.

Prevalence and pattern of amblyopia in a rural hospital in Ghana

Amblyopia is a developmental ocular disease of childhood-onset which may lead to persistent sequelae into adulthood. Early detection and management of amblyopia usually result in an improved visual outcome. The purpose of this study was to determine the prevalence and pattern of amblyopia in a rural hospital in Ghana. Clinical records of patients seen (from January 2014 to December 2018) at Westphalian Medical Center, Oyoko, Ashanti Region, Ghana, were reviewed retrospectively. Unilateral amblyopia was defined as a two-line interocular difference or more in visual acuity. Bilateral amblyopia was defined as best-corrected visual acuity (BCVA) of Snellen 6/12 or worse in both eyes, with evidence of bilateral ametropia or obstruction of the visual pathway. Following a review of 12,602 patient records, 258 cases of amblyopia were identified. The mean (±SD) presenting age of amblyopic patients was 24.3 ± 16.1 years, with a male-to-female ratio of 1:1.1. The period prevalence of amblyopia was 2.04%. The period prevalence of unilateral and bilateral amblyopia was 1.38% and 0.66%, respectively. The most prevalent form of amblyopia was refractive with a cumulative prevalence of 1.42%. Strabismic and stimulus deprivation amblyopia accounted for 0.36% and 0.21% of all amblyopic cases, respectively. A major cause of amblyopia in this population was refractive error, hence the use of spectacle correction for its initial management. Repeated assessment after an appropriate period of refractive adaptation would elucidate the proportion of amblyopias needing additional treatment modalities. Vision screening for early detection of amblyopia in childhood with accessible and effective management of amblyopia (including refractive correction and occlusion treatment) is necessary to reduce the impact of amblyopia in Ghana.

Influence of prenatal environment and birth parameters on amblyopia, strabismus, and anisometropia

PURPOSE

To report the prevalence of amblyopia, strabismus, and anisometropia in a young adult population at a single center in Australia and to investigate the underlying prenatal and early-life risk factors.

METHODS

Participants in the Raine Study have been followed from mid-gestation (n = 2,868 newborns) to young adulthood. At age 20 years, 1,344 participants had a comprehensive eye examination, including visual acuity and a detailed orthoptic assessment. Risk factors were determined from medical records and questionnaires completed by the mothers at 18 weeks' gestation. The main outcome measures were the proportions of participants with amblyopia, esotropia, exotropia, or anisometropia (defined as >1 D difference).

RESULTS

Of the 1,125 white participants, 12 (1.1%) had amblyopia, 39 (3.5%) had strabismus, and 33 (2.9%) had anisometropia. In multivariable logistic regression, amblyopia was associated with a maternal history of pregnancy-induced hypertension (OR = 3.80; 95% CI, 1.19-12.13); esotropia, with lower gestational age (OR = 0.97; 95% CI, 0.95-0.97) and a heavier placenta (OR = 1.02; 95% CI, 1.00-1.04); exotropia, with a maternal history of previously treated hypertension (OR = 4.00; 95% CI, 1.06-15.03) and maternal use of recreational drugs during early pregnancy (OR = 3.61; 95% CI, 1.06-15.03); and anisometropia, with older maternal age (OR = 1.07; 95% CI, 1.01-1.14) and an abnormal umbilical cord (OR = 2.39; 95% CI, 1.04-5.47).

CONCLUSIONS

The prevalence of amblyopia, strabismus, and anisometropia in this cohort was similar to that in other studies. Preterm birth and maternal health may have adverse effects on eye development.

Associations between Environmental Tobacco Smoke Exposure in Early Life and Astigmatism among Chinese Preschool Children

This study aimed to investigate the association between environmental exposure to tobacco smoke (ETS) during early life and astigmatism in Chinese preschool children. In this cross-sectional study, information concerning prenatal and postnatal ETS exposure at three stages of early life (during pregnancy, from birth to one year and from one to three years), visual problems of children and parents (including a confirmed diagnosis of astigmatism), socio-demographics and perinatal characteristics were obtained from 27,890 parent-reported questionnaires. Logistic regression analyses were undertaken to yield adjusted odds ratios (OR) for assessing their associations. After adjusting for the potential confounders, children were more likely to exhibit astigmatism when they were exposed to ETS during pregnancy + from one to three years [OR (95% CI) = 1.37 (1.02, 1.84)], or from birth to one year + from one to three years [OR (95% CI) = 1.36 (1.11, 1.66)], or during pregnancy + from birth to one year + from one to three years old [OR (95% CI) = 1.29 (1.16, 1.45)], compared to children without ETS exposure at any stage of early life. In Chinese preschool children, prenatal and postnatal astigmatism was associated with ETS exposure; the greater the ETS dose, the greater the astigmatism risk.

Elucidation of the more myopic eye in anisometropia: the interplay of laterality, ocular dominance, and anisometropic magnitude

This study reveals how, in a myopic anisometrope, the odds of an eye being more myopic are related to laterality, ocular dominance, and magnitude of anisometropia. In 193 subjects, objective refraction was performed with cycloplegia. Sighting, motor, and sensory dominance were determined with the hole-in-the-card test, convergence near-point test, continuous flashing technique, respectively. Multiple logistic regression was used for probability analysis. Seventy percent of the subjects had a right eye that was more myopic, while 30% of them had a more myopic left eye. When the right eye was the sensory dominant eye, the probability of the right eye being more myopic increased to 80% if the anisometropia was less than 3.0 D, and decreased below 70% if anisometropia was beyond 3.0 D. When the left eye was the sensory dominant eye, the probability of the left eye being more myopic increased to above 40% if the anisometropia was less than 4.0 D and decreased below 30% if the anisometropia was beyond 4.0 D. Therefore, between the two eyes of anisometropes, laterality tilts the chance of being more myopic to the right. Being the sensory dominant eye increases an eye’s probability of being more myopic by another 10% if the magnitude of anisometropia is moderate.

Amblyopia risk factors in congenital nasolacrimal duct obstruction: A longitudinal case-control study

Purpose

To investigate longitudinal changes in risk factors for amblyopia in children treated with congenital nasolacrimal duct obstruction (CNLDO).

Methods

Retrospective observational case control study. A total of 446 children under 4 years of age who underwent probing and/or intubation for CNLDO between January 2004 and January 2018, and 446 age-matched controls were included. Cycloplegic refraction and ocular alignment were investigated at the time of treatment and after at least one year of symptom improvement. Children were classified as having amblyopia risk factors on the basis of the American Association for Pediatric Ophthalmology and Strabismus guideline in 2013.

Main outcome measures

The prevalence of amblyogenic refractive errors, and determinants associated with the presence of amblyogenic refractive errors in CNLDO patients.

Results

The prevalence of amblyogenic refractive errors in CNLDO patients (5.4%) was similar to that of the control group (6.5%) (P = 0.571). After one year of symptom improvement in CNLDO patients, the prevalence of amblyogenic refractive errors was 4.7%. There was no difference in the prevalence of amblyogenic refractive errors between unilateral and bilateral CNLDO patients. Multivariate analysis revealed that manifest strabismus was the only risk factor related with the presence of amblyogenic refractive errors (odds ratio = 6.383, confidence interval = 1.205–33.826, P = 0.029).

Conclusions

This study found no evidence to suggest that the prevalence of amblyopia risk factors is higher in CNLDO patients compared with normal controls. Manifest strabismus was the only determinant associated with the presence of amblyogenic refractive errors.

Aniseikonia and anisometropia: implications for suppression and amblyopia

Aniseikonia is a difference in the perceived size or shape of images between eyes, and can arise from a variety of physiological, neurological, retinal, and optical causes. Aniseikonia is associated with anisometropia, as both anisometropia itself and the optical correction for anisometropia can cause aniseikonia. Image size differences above one to three per cent can be clinically symptomatic. Common symptoms include asthenopia, headache and diplopia in vertical gaze. Size differences of three and more impair binocular visual functions such as binocular summation and stereopsis. Above five per cent of aniseikonia, binocular inhibition or suppression tend to occur to prevent diplopia and confusion. Aniseikonia can be measured using a range of techniques and can be corrected or reduced by prescribing contact lenses or specially designed spectacle lenses. Subjective testing of aniseikonia is the only way to accurately measure the overall perceived amount of aniseikonia. However, currently it is not routinely assessed in most clinical settings. At least two-thirds of patients with amblyopia have anisometropia, thus we may expect aniseikonia to be common in patients with anisometropic amblyopia. However, aniseikonia may not be experienced by the patient under normal binocular viewing conditions if the image from the amblyopic eye is of poor quality or is too strongly suppressed for image size differences to be recognised. This lack of binocular simultaneous perception in amblyopia may also prevent the measurement of aniseikonia, as most common techniques require direct comparisons of images seen by each eye. Current guidelines for the treatment of amblyopia advocate full correction of anisometropia to equalise image clarity, but do not address aniseikonia. Significant image size differences between eyes may lead to suppression and abnormal binocular adaptations. It is possible that correcting anisometropia and aniseikonia simultaneously, particularly at the initial diagnosis of anisometropia, would reduce the need to develop suppression and improve treatment outcomes for anisometropic amblyopia.

Preschool Vision Screening: Where We Have Been and Where We Are Going

PURPOSE

To discuss the evolution of instrument-based screening to detect amblyopia and its risk factors, and to summarize the importance of preschool vision screening.

DESIGN

Expert commentary.

METHODS

Author experiences were supplemented by a review and interpretation of pertinent medical literature.

RESULTS

Amblyopia remains a public health problem, as it is a common cause of monocular visual impairment. As a disease, amblyopia detection is best obtained by appropriate vision screening rather than by yearly mandated comprehensive eye examinations for all children; the US Preventative Services Task Force (USPSTF) recently reaffirmed their recommendations for vision screening in preschool children. Vision screening devices have evolved over the past 4 decades ranging from photoscreeners that use instantaneously developing film, to autorefractors that detect amblyopia risk factors, to nerve fiber layer scanners that detect the microtropia that nearly always accompanies amblyopia. When it is detected early, effective treatment for amblyopia can be initiated.

CONCLUSIONS

Amblyopia is a reversible cause of vision loss in children. Vision screening devices and screening programs have been extensively studied-experts and literature agree: vision screening devices and programs are cost-effective, are efficient, and are effective methods for amblyopia detection. The authors support the regular use of instrument-based vision screening in the medical home for all children until they reach a developmental stage where they can participate reliably in optotype-based vision screening.

Oregon Elks Children's Eye Clinic vision screening results for astigmatism

BACKGROUND

In the Elks Preschool Vision Screening program, which uses the plusoptiX S12 to screen children 36-60 months of age, the most common reason for over-referral, using the 1.50 D referral criterion, was found to be astigmatism. The goal of this study was to compare the accuracy of the 2.25 D referral criterion for astigmatism to the 1.50 D referral criterion using screening data from 2013-2014.

METHODS

Vision screenings were conducted on Head Start children 36-72 months of age by Head Start teachers and Elks Preschool Vision Screening staff using the plusoptiX S12. Data on 4,194 vision screenings in 2014 and 4,077 in 2013 were analyzed. Area under the curve (AUC) and receiver operating characteristic curve (ROC) analysis were performed to determine the optimal referral criteria. A t test and scatterplot analysis were performed to compare how many children required treatment using the different criteria.

RESULTS

The medical records of 136 (2.25 D) and 117 children (1.50 D) who were referred by the plusoptiX screening for potential astigmatism and received dilated eye examinations from their local eye doctors were reviewed retrospectively. Mean subject age was 4 years. Treatment for astigmatism was prescribed to 116 of 136 using the 2.25 D setting compared to 60 of 117 using the 1.50 D setting.

CONCLUSIONS

In 2013 the program used the 1.50 D setting for astigmatism. Changing the astigmatism setting to 2.25 D; , 85% of referrals required treatment, reducing false positives by 34%.

Anisometropia and refractive status in children with unilateral congenital nasolacrimal duct obstruction

OBJECTIVE:

The objective of the study was to evaluate the refractive status and thereby assess anisometropia in children with unilateral congenital nasolacrimal duct obstruction (CNLDO).

STUDY DESIGN:

This study design was a descriptive cross-sectional study.

PLACE AND DURATION:

this study was conducted at the Department of Pediatric Ophthalmology and Strabismology, Al-Shifa Trust Eye Hospital, Rawalpindi; from August 2013 to July 2014.

METHODOLOGY:

This study assessed consecutive children with unilateral CNLDO. Cycloplegic refraction on all children with CNLDO was performed followed by appropriate intervention. Refractive errors of the affected and normal eyes were compared.

RESULTS:

One hundred and twenty-four children with a mean age of 29.69 ± 21.12 months (range, 2 months to 8 years) were studied. Based on spherical equivalent (SE), hypermetropia was more common in the affected eyes (P < 0.001). Anisometropia of >1.5 diopters (D) was present in n = 17 (13.7%). Interocular difference was significant for spherical error and SE (P < 0.001) but not cylindrical errors.

CONCLUSION:

Unilateral CNLDO is associated with statistically significant anisometropia, especially anisohypermetropia which has amblyogenic potential. It is vital to perform cycloplegic refraction routinely and counsel parents regarding prognosis and regular follow-ups.

Progression of High Anisometropia in Children

PURPOSE

To investigate the onset and rate of progression of high anisometropia in myopic children younger than 13 years.

METHODS

A retrospective study was performed on children with anisometropia younger than 13 years with myopia of more than 4.00 diopters (D) in the more ametropic eye and a difference in spherical equivalent refraction of 4.00 D between both eyes. All children had a complete ophthalmologic examination, including measurement of visual acuity and cycloplegic refraction every 3 to 6 months for at least 5 years. Change in the spherical equivalent and the cylindrical error for both eyes and changes in the difference in spherical equivalent refraction between both eyes were calculated for each patient at each visit. Linear, polynomial, logarithmic, and exponential fitting models were tested for both eyes and for the anisometropic difference between both eyes. The regression line with the greatest R² value was considered best fit.

RESULTS

Sixty-three patients fulfilled the inclusion criteria. The more ametropic eye grew in a regular fashion during the first 2 years of life, followed by a rapid decrease in the rate of growth to become almost stable after 4 years of age. The increase in myopia best fit a third-degree polynomial (cubic) model (R² = 0.98). The less ametropic eye showed only a small increase in myopia during the follow-up period. The anisometropic difference between both eyes increased gradually during the first 2 years, then remained stable.

CONCLUSIONS

High anisometropic myopia progresses rapidly in the first few years of life before becoming stable. [J Pediatr Ophthalmol Strabismus. 2017;54(5):282-286.].

Pediatric vision screening using the plusoptiX A12C photoscreener in Chinese preschool children aged 3 to 4 years

This study evaluated the performance of plusoptiX A12C in detecting amblyopia risk factors (ARFs) in Chinese children aged 3-to-4-year. PlusoptiX examination was successfully conducted among 1,766 subjects without cycloplegia to detect refractive error, asymmetry and media opacity. Cycloplegic retinoscopy (CR) was conducted on 357 children suspected of having vision abnormalities. Statistical differences between CR and the device were confirmed using the mean spherical value (+1.41 ± 0.87 D versus +1.14 ± 0.81 D), cylindrical value (−0.47 ± 0.64 versus −0.84 ± 0.78) and spherical equivalent (SE) value (+1.17 ± 0.84 D versus +0.72 ± 0.64 D) (all P < 0.0001). In the emmetropia group, the differences were statistically significant for the cylinder and SE (all P < 0.0001) but not the sphere (P = 0.33). In the hyperopia group, the differences were statistically significant for the sphere, cylinder and SE (all P < 0.0001). For refractive and strabismic ARFs detection, the sensitivity, specificity, positive predictive value, and negative predictive value were calculated, respectively.

Prevalence and association of refractive anisometropia with near work habits among young schoolchildren: The evidence from a population-based study

Background

Lifestyle behaviour may play a role in refractive error among children, but the association between near work habits and refractive anisometropia remains unclear.

Methods

We estimated the prevalence of refractive anisometropia and examined its association with near work activities among 23,114 children in the Myopia Investigation Study in Taipei who were grade 2 elementary school students at baseline in 2013 and 2014. Baseline data on demographics, medical history, parental history and near work habits were collected by parent-administered questionnaire survey. Refractive status was determined by cycloplegic autorefraction. Refractive anisometropia was defined as the spherical equivalent difference ≥ 1.0 diopter between eyes.

Results

The prevalence of refractive anisometropia was 5.3% (95% confidence interval [CI], 5.0% to 5.6%). The prevalence and severity of refractive anisometropia increased with both myopic and hyperopic refractive error. Multivariate logistic regression analysis revealed that refractive anisometropia was significantly associated with myopia (odds ratio [OR], 2.98; 95% CI, 2.53–3.51), hyperopia (OR, 2.37; 95% CI, 1.98–2.83), degree of astigmatism (OR, 1.005; 95% CI, 1.005–1.006), amblyopia (OR, 2.54; 95% CI, 2.06–3.12), male gender (OR, 0.88; 95% CI, 0.78–0.99) and senior high school level of maternal education (OR, 0.69; 95% CI, 0.52–0.92). Though anisometropic children were more likely to spend more time on near work (crude OR, 1.15; 95% CI, 1.02–1.29) and to have less eye-to-object distance in doing near work (crude OR, 1.15; 95% CI, 1.01–1.30), these associations became insignificant after additional adjustment for ocular, demographic and parental factors.

Conclusions

The present study provides large-scale, population-based evidence showing no independent association between refractive anisometropia and near work habits, though myopia is associated with refractive anisometropia.

Instrument-based pediatric vision screening

PURPOSE OF REVIEW

The purpose is to review currently available instruments for vision screening in young children.

RECENT FINDINGS

Instrumentation continues to evolve. Although the current generation of photoscreeners and autorefractors strive to identify amblyopia risk factors, newer technology aims to directly identify amblyopia in young children. Acceptance of instrument-based vision screening for this population has led to increased reimbursement for the procedure in primary care practices.

SUMMARY

Instrument-based vision screening in the young child is an accepted method of screening for amblyopia. Innovations in instrumentation will continue to improve its implementation.

Refractive Errors and Amblyopia in the UCLA Preschool Vision Program; First Year Results

PURPOSE

To report the outcomes of full ophthalmic examination for preschool children in LA County who failed screening with the Retinomax Autorefractor.

DESIGN

Retrospective, cross-sectional study.

METHODS

Between August 2012 and May 2013, the University of California Los Angeles (UCLA) preschool vision program screened 11 260 preschool children aged 3-5 years in Los Angeles County using the Retinomax Autorefractor only. Of those, 1007 children who failed the screening were examined by an ophthalmologist on the UCLA Mobile Eye Clinic. Data from the eye examination were recorded for all children. Amblyopia was defined as unilateral if there was ≥2 line interocular difference in the best-corrected visual acuity (BCVA) and as bilateral if BCVA was <20/50 for children <4 years old and <20/40 for children ≥4 years old.

RESULTS

Glasses were prescribed for 740 (74%) of those examined. Uncorrected visual acuity for all examined children was 0.4 ± 0.2 (logMAR mean ± SD), and BCVA was 0.2 ± 0.1. Of the 88% who underwent cycloplegia, 58% had hyperopia (spherical equivalent [SE] ≥+0.50 diopter [D]), mean of +2.50 D, and 21% had myopia (SE ≤-0.50 D), mean of -1.40 D. A total of 69% had astigmatism ≥1.50 D, mean of 1.97 D (range 0-5.75). Spherical and cylindrical anisometropia ≥1.00 D were each found in 26% of those examined. Refractive amblyopia was found in 9% of those examined, or 0.8% of the original population. Of the amblyopic subjects, 77% were unilateral.

CONCLUSIONS

Screening of preschoolers with the Retinomax led to diagnosis and early treatment of uncorrected refractive errors and amblyopia. By treating children early, amblyopia may be prevented, quality of life improved, and academic achievements enhanced.

Nasolacrimal duct obstruction: Does it really increase the risk of amblyopia in children?

Purpose:

To report the prevalence of amblyopia risk factors in children with congenital nasolacrimal duct obstruction.

Methods:

A retrospective review of records of children with the diagnosis of congenital nasolacrimal duct obstruction (NLDO), who underwent probing from January 2009 to October 2011, was done. All of them underwent a complete ophthalmic evaluation including cycloplegic refraction and strabismus evaluation before probing.

Results:

A total of 142 children were included in this study. The mean age at presentation was 22.38 months (sample standard deviation (SSD) – 15.88). Amblyopia risk factors were defined according to two sets of guidelines: The American Association for Pediatric Ophthalmology and Strabismus (AAPOS) referral criteria guidelines and the new AAPOS Vision Screening Committee guidelines. Twenty-eight (20%) children were found to have some form of amblyopia risk factor based on the referral criteria prescribed by AAPOS. However, on applying modified guidelines described by Donahue et al., to analyze the same cohort, 21 children were found to have amblyogenic risk factors. Of these 28 children, 13 had significant astigmatism (>1.50 D), 8 children had hypermetropia (>3.50 D), and six children had anisometropia (>1.50 D). One child had significant cataract (media opacity >1 mm). None of the children in this series had either myopia or strabismus.

Conclusion:

Prevalence of amblyopia risk factor was found to be 20% in our study based on the older guidelines; however, it reduces to 14.78% by applying the modified guidelines. Despite this reduction, importance of a comprehensive ophthalmic examination including cycloplegic refraction in all children presenting with NLDO cannot be overstated. A close follow-up of these children is also essential to prevent the development of amblyopia.

Longitudinal Development of Refractive Error in Children With Accommodative Esotropia: Onset, Amblyopia, and Anisometropia

Purpose

We investigated longitudinal changes of refractive error in children with accommodative esotropia (ET) throughout the first 12 years of life, its dependence on age at onset of ET, and whether amblyopia or anisometropia are associated with defective emmetropization.

Methods

Longitudinal refractive errors in children with accommodative ET were analyzed retrospectively. Eligibility criteria included: initial hyperopia ≥+4.00 diopters (D), initial cycloplegic refraction before 4 years, at least 3 visits, and at least one visit between 7 and 12 years. Children were classified as having infantile (N = 30; onset ≤12 months) or late-onset (N = 78; onset at 18–48 months) accommodative ET. Cycloplegic refractions culled from medical records were converted into spherical equivalent (SEQ).

Results

Although the initial visit right eye SEQ was similar for the infantile and late-onset groups (+5.86 ± 1.28 and +5.67 ± 1.26 D, respectively), there were different developmental changes in refractive error. Neither group had a significant decrease in hyperopia before age 7 years, but after 7 years, the infantile group experienced a myopic shift of −0.43 D/y. The late-onset group did not experience a myopic shift at 7 to 12 years. Among amblyopic children, a slower myopic shift was observed for the amblyopic eye. Among anisometropic children, the more hyperopic eye experienced more myopic shift than the less hyperopic eye.

Conclusions

Children with infantile accommodative ET experienced prolonged hyperopia followed by a myopic shift after 7 years of age, consistent with dissociation between infantile emmetropization and school age myopic shift. In contrast, children with late-onset accommodative ET had little myopic shift before or after 7 years.

Interocular Difference of Peripheral Refraction in Anisomyopic Eyes of Schoolchildren

Purpose

Refraction in the peripheral visual field is believed to play an important role in the development of myopia. The purpose of this study was to investigate the differences in peripheral refraction among anisomyopia, isomyopia, and isoemmetropia for schoolchildren.

Methods

Thirty-eight anisomyopic children were recruited and divided into two groups: (1) both eyes were myopic (anisomyopic group, AM group) and (2) one eye was myopic and the contralateral eye was emmetropic (emmetropic anisomyopic group, EAM group). As controls, 45 isomyopic and isoemmetropic children were also recruited with age and central spherical equivalent (SE) matched to those of the AM and EAM groups. The controls were divided into three groups: (1) intermediate myopia group (SE matched to the more myopic eye of AM group), (2) low myopia group (SE matched to the less myopic eye of AM group and the more myopic eye of EAM group), and (3) emmetropia group (SE matched to the less myopic eye of EAM group). Peripheral refraction at 7 points across the central ±30° on the horizontal visual field with a 10° interval was measured with an autorefractor. Axial length (AL), corneal curvature (CC), and anterior chamber depth (ACD) were also determined by using the Zeiss IOL-Master.

Results

The relative peripheral spherical equivalent [RPR(M)] and relative peripheral spherical value [RPR(S)] of the more myopic eye was shifted more hyperopically than the contralateral eye in both the AM and the EAM groups (both p<0.0001). The RPR(M, S) of the less myopic eyes in the AM and EAM groups showed a relatively flat trend across the visual field and were not significantly different from the emmetropia group. The RPR(M, S) of less myopic eyes in the AM group were shifted less hyperopically than in the isomyopic low myopia group and the more myopic eye of the EAM group [RPR(M), p = 0.007; RPR(S), p = 0.001], although the central SEs of the three groups were not significantly different from each other. However, RPR(M, S) of the more myopic eyes were not different from the corresponding isomyopic groups. There was also no significant difference in the relative peripheral astigmatism [RPR(J0, J45)] between the more and the less myopic eyes in either the AM or the EAM group.

Conclusion

Refraction of anisomyopia differs between the two eyes not only at the central visual field but also at the off-axis periphery. The relative peripheral refraction of the more myopic eye of anisomyopia was shifted hyperopically, as occurs in isomyopia with similar central subjective SE values. Less myopic eyes were much less hyperopically shifted in relative peripheral refraction than the corresponding isomyopic eyes, but are comparable to emmetropic eyes. This emmetropia-like relative peripheral refraction in less myopic eyes might be a factor responsible for slowing down the progression of myopia.

Perceptual learning improves neural processing in myopic vision

Visual performance is jointly determined by the quality of optical transmission of the eye and neural processing in the visual system. An open question is: Can effects of optical defects be compensated by perceptual learning in neural processing? To address this question, we conducted a perceptual learning study on 23 observers with myopic vision, targeting high frequency deficits by training them in a monocular grating detection task in the non-dominant eye near their individual cutoff spatial frequencies. The contrast sensitivity function and visual acuity in both eyes (without optical correction) were assessed for all the observers in the training group before and after training, and for all the observers in the control group twice with a 10-day interval between the tests. In addition, the threshold versus external noise contrast function was measured for five observers in the training group before and after training. We found that (a) training significantly improved contrast sensitivity at the trained spatial frequency, visual acuity, and contrast sensitivity over a wide range of spatial frequencies in both eyes; (b) training did not lead to any significant refractive changes; (c) the mechanism of improvements was a combination of internal additive noise reduction and external noise exclusion; and (d) the improvements in visual acuity and contrast sensitivity were almost fully retained for at least four months in the three observers tested. These results suggest that perceptual learning may provide a potential noninvasive procedure to compensate for optical defects in mild to modest myopia.

Early Childhood Vision Screening in Hawai'i Utilizing a Hand-Held Screener

The goal of early childhood vision screening is to detect subnormal vision and amblyopic risk factors that threaten visual development so that treatment can be initiated early to yield the highest benefit. Hand-held, portable, instrument-based vision screening devices can be used in children as young as 6 months of age. We assessed the feasibility of hand-held photoscreeners to screen for vision disorders in pre-school children in Hawai'i. A total of 137 preschool children on O'ahu in the "Tutu and Me"/Partners in Development program were screened at 6 different locations using the Plusoptix S12 hand-held photoscreener. Once technical issues were resolved, screening was fast and well tolerated. Possible vision abnormalities were found in 11 of the 137 children (8%). Poor compliance for follow-up with formal vision examination limited our ability to confirm these abnormalities. We conclude that photoscreening has the potential to facilitate early childhood vision screening in Hawai'i. The optimal referral criteria for use in Hawai'i will need to be determined after considering the age of the screening population and the available medical resources in Hawai'i. Early detection of treatable eye disorders has far-reaching benefits for the visual development and long term health and well-being of children. A comprehensive early childhood vision screening program in Hawai'i utilizing automated hand-held photoscreeners may have public health value. Such a program should integrate referral to an eye care professional for confirmation and management of vision disorders of at-risk children found on screening.

Smoking during pregnancy and vision difficulties in children: a systematic review

Cigarette smoking during pregnancy is a major public health concern. Intra-uterine exposure to maternal cigarette smoking is associated with increased risks of growth and neurodevelopmental problems during childhood and later life. Few studies have focussed on visual difficulties in children in the context of maternal smoking during pregnancy. A systematic search of online databases was carried out between February and May 2013 to examine the trend in visual outcomes in children exposed to maternal cigarette smoking during intra-uterine life. Twenty-four non-randomized studies were identified. Each study was rated for quality using the Newcastle-Ottawa Scale. Most studies (n = 18) reported fetal exposure to active or passive maternal cigarette smoking to be associated with an increased risk of adverse visual outcomes in children. In particular, there were higher rates of strabismus, refractive errors and retinopathy among children of women who smoked during pregnancy. These findings suggest that fetal exposure to cigarette smoke is a significant risk factor for visual problems during later life and that certain visual faculties, such as the intraocular muscles and retinal neurons, are more affected than others. The findings provide evidence in support of public health policies aimed at reducing fetal exposure to smoking by advising both women and their partners to quit smoking during pregnancy.

Longitudinal increase in anisometropia in older adults

PURPOSE

Anisometropia shows an exponential increase in prevalence with increasing age based on cross-sectional studies. The purpose of this study was to evaluate longitudinal changes in anisometropia in all refractive components in older observers and to assess the influence of early cataract development.

METHODS

Refractive error was assessed at two time points separated by approximately 12 years in 118 older observers (aged 67.1 and 79.3 years at the two test times). Anisometropia defined as greater than or equal to 1.00 D was calculated for all refractive components. The subjects had intact ocular lenses in both eyes throughout the study. Lens evaluations were performed at the second test using the Lens Opacities Classification System III.

RESULTS

All refractive components approximately doubled in prevalence of anisometropia. Spherical equivalent anisometropia changed from 16.1 to 32.2%. Similar changes were found for spherical error (17 to 38.1%), primary astigmatism (7.6 to 17.8%), and oblique astigmatism (14.4 to 29.7%). Many who did not have anisometropia at the first visit subsequently developed anisometropia (e.g., 26.3% for spherical error and 22.9% for oblique cylinder). The onset of anisometropia occurred at all ages within the studied age range, with no particular preference for any one age. A small number lost anisometropia over time. Individual comparisons of refractive error changes in the two eyes in combination with nuclear lens changes showed that early changes in nuclear sclerosis in the two eyes could account for a large proportion of anisometropia (~40%), but unequal hyperopic shift in the spherical component in the two eyes was the primary cause of the anisometropia.

CONCLUSIONS

Anisometropia is at least 10 times more common in the elderly than in children, and anisometropia develops in all refractive components in the oldest observers. Clinicians need to be aware of this common condition that could lead to binocular vision problems and potentially cause falls in the elderly.

Limited change in anisometropia and aniso-axial length over 13 years in myopic children enrolled in the Correction of Myopia Evaluation Trial

PURPOSE

We investigated changes in anisometropia and aniso-axial length with myopia progression in the Correction of Myopia Evaluation Trial (COMET) cohort.

METHODS

Of 469 myopic children, 6 to <12 years old, enrolled in COMET, 358 were followed for 13 years. Cycloplegic autorefraction and axial length (AL) in each eye were measured annually. The COMET eligibility required anisometropia (interocular difference in spherical equivalent refraction) of ≤ 1.00 diopter (D). For each child, a linear regression line was fit to anisometropia data by visit, and the regression slope b was used as the rate of change. Logistic regression was applied to identify factors for significant changes in anisometropia (b ≥ 0.05 D/y, or a cumulative increase in anisometropia ≥ 0.50 D over 10 years). Similar analyses were applied to aniso-AL.

RESULTS

A total of 358/469 (76.3%) children had refractions at baseline and the 13-year visit. The mean (SD) amount of anisometropia increased from 0.24 D (0.22 D) at baseline to 0.49 D (0.46 D) at the 13-year visit. A total of 319/358 (89.1%) had slopes |b| < 0.05 D/y and 39 (10.9%) had slopes |b| ≥ 0.05 D/y, with only one negative slope. Similarly, 334/358 (93.3%) children had little change in aniso-AL over time. The correlation between changes in anisometropia and aniso-AL over 13 years was 0.39 (P < 0.001). The correlation between changes in anisometropia and myopia progression was significant (r = -0.36, P < 0.001). No correlation was found between baseline anisometropia and myopia progression (r = -0.02, P = 0.68).

CONCLUSIONS

Myopia and axial length progressed at a similar rate in both eyes for most children in COMET during the period of fast progression and eventual stabilization. These results may be more generalizable to school-aged myopic children with limited anisometropia at baseline. (ClinicalTrials.gov number, NCT00000113.).

Repeat Retinomax screening changes positive predictive value

PURPOSE

To quantify changes in autorefraction measurement with repeated readings using the Retinomax autorefractor and to investigate the clinical implications of the results.

METHODS

Children referred from a preschool vision screening program for a failed autorefraction screening test received repeat autorefraction as well as a comprehensive eye examination with cycloplegic retinoscopy at later follow-up. The intraclass correlation coefficient between initial and follow-up autorefraction was calculated to quantify changes in repeated measurements to determine whether the second autorefraction significantly changed the predictive value that a referred child would meet case definition. Cases were defined by AAPOS Vision Screening Committee amblyogenic risk factors under cycloplegic retinoscopy.

RESULTS

Repeat Retinomax autorefraction had an intraclass correlation of 0.70 in the right eye and 0.70 in the left eye for mean sphere. Of 636 children who were referred on their initial screening, 169 (26.5%) passed a repeat screening and this subpopulation had 7 cases (4.1%). Of the 467 (73.5%) who again met referral criteria at repeat screening, 268 (57.4%) met case definition. The difference in case rates between these subgroups was highly significant (Fisher exact test, P < 0.001).

CONCLUSIONS

There was clinically significant variability when autorefraction measurements were repeated among those referred from initial screening, allowing further risk stratification. In our study cohort, few children who passed repeat screening required further examination. Significant money and overtreatment risk may potentially be avoided by rescreening children who are initially referred from screening evaluations and only examining those who meet referral criteria after a second screening.

Nearwork-induced transient myopia (NITM) in anisometropia

OBJECTIVE

To assess the magnitude of nearwork-induced transient myopia (NITM) under binocular viewing conditions separately in each eye of individuals with mild to moderate anisometropia to determine the relationship between NITM and their interocular refractive error.

METHODS

Forty-three children and young adults with anisometropia [cycloplegic spherical equivalent (SE) difference >1.00 D] were tested (ages 9-28 years). NITM was measured with binocular viewing separately in each eye after binocularly performing a sustained near task (5 D) for 5 min incorporating a cognitive demand using an open-field, infrared autorefractor (Grand-Seiko, WAM-5500). Data were averaged over 10 s bins for 3 min in each eye. Initial NITM, its decay time (DT), and its decay area (DA) were determined. A-scan ultrasound ocular biometry was also performed to determine the axial length of each eye.

RESULTS

The more myopic eye exhibited increased initial NITM, DT, and DA as compared to the less myopic eye (0.21 ± 0.16 D vs 0.15 ± 0.13 D, p = 0.026; 108.4 ± 64.3 secs vs 87.0 ± 65.2 secs, p = 0.04; and 17.6 ± 18.7 D*secs vs 12.3 ± 15.7 D*secs, p = 0.064), respectively. The difference in DA and the difference in SE between the more versus less myopic eye were significantly correlated (r = 0.31, p = 0.044). Furthermore, 63% (27/43), 56% (24/43), and 70% (30/43) of the more myopic eyes exhibited increased initial NITM, longer DT, and larger DA, respectively, than found in the less myopic eye.

CONCLUSIONS

In approximately two-thirds of the anisometropic individuals, the initial NITM and its decay area were significantly increased in the more myopic eye as compared to the less myopic eye. NITM may play an important role in the development of interocular differences in myopia, although a causal relationship is yet to be established. Furthermore, the findings have potentially important implications regarding accommodative control and interocular accommodative responsitivity in anisometropia, in particular for anisomyopia.

Preschool vision screening: update on guidelines and techniques

PURPOSE OF REVIEW

To discuss the current preschool vision screening (PVS) guidelines and review some of the newest vision screening techniques. The different vision screening practices and barriers to screening are discussed.

RECENT FINDINGS

Vision screening guidelines, which have been developed in response to the advances in technology and increased understanding of the developing visual system, have been recently updated by some of the major medical organizations that endorse vision screening. With advances in vision screening technology, there is a growing trend for screening at younger ages.

SUMMARY

PVS has been widely endorsed by various medical organizations as an effective way to detect preventable and treatable vision problems of childhood. Although PVS is widely recommended, actual screening rates remain low. There are several real and perceived barriers to screening which often prevents successful screening programs. Current vision screening guidelines take into account the recent advances in technology. With the development of new devices, vision screening can effectively be performed at younger ages.

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.

Eye laterality: a comprehensive analysis in refractive surgery candidates

PURPOSE

To explore eye laterality (higher refractive error in one eye) and its association with refractive state, spherical/astigmatic anisometropia, age and sex in refractive surgery candidates.

METHODS

Medical records of 12 493 consecutive refractive surgery candidates were filtered. Refractive error (subjective and cycloplegic) was measured in each subject and correlated with eye laterality. Only subjects with corrected distance visual acuity (CDVA) of >20/22 in each eye were enrolled to exclude amblyopia. Associations between eye laterality and refractive state were analysed by means of t-test, chi-squared test, Spearman's correlation and multivariate logistic regression analysis, respectively.

RESULTS

There was no statistically significant difference in spherical equivalent between right (-3.47 ± 2.76 D) and left eyes (-3.47 ± 2.76 D, p = 0.510; Pearson's r = 0.948, p < 0.001). Subgroup analysis revealed (I) right eye laterality for anisometropia >2.5 D in myopic (-5.64 ± 2.5 D versus -4.92 ± 2.6 D; p = 0.001) and in hyperopic (4.44 ± 1.69 D versus 3.04 ± 1.79 D; p = 0.025) subjects, (II) a tendency for left eye cylindrical laterality in myopic subjects, and (III) myopic male subjects had a higher prevalence of left eye laterality. (IV) Age did not show any significant impact on laterality.

CONCLUSIONS

Over the full refractive spectrum, this study confirmed previously described strong interocular refractive correlation but revealed a statistically significant higher rate of right eye laterality for anisometropia >2.5 D. In general, our results support the use of data from one eye only in studies of ocular refraction.

The relationship between anisometropia and amblyopia

This review aims to disentangle cause and effect in the relationship between anisometropia and amblyopia. Specifically, we examine the literature for evidence to support different possible developmental sequences that could ultimately lead to the presentation of both conditions. The prevalence of anisometropia is around 20% for an inter-ocular difference of 0.5D or greater in spherical equivalent refraction, falling to 2-3%, for an inter-ocular difference of 3D or above. Anisometropia prevalence is relatively high in the weeks following birth, in the teenage years coinciding with the onset of myopia and, most notably, in older adults starting after the onset of presbyopia. It has about one-third the prevalence of bilateral refractive errors of the same magnitude. Importantly, the prevalence of anisometropia is higher in highly ametropic groups, suggesting that emmetropization failures underlying ametropia and anisometropia may be similar. Amblyopia is present in 1-3% of humans and around one-half to two-thirds of amblyopes have anisometropia either alone or in combination with strabismus. The frequent co-existence of amblyopia and anisometropia at a child's first clinical examination promotes the belief that the anisometropia has caused the amblyopia, as has been demonstrated in animal models of the condition. In reviewing the human and monkey literature however it is clear that there are additional paths beyond this classic hypothesis to the co-occurrence of anisometropia and amblyopia. For example, after the emergence of amblyopia secondary to either deprivation or strabismus, anisometropia often follows. In cases of anisometropia with no apparent deprivation or strabismus, questions remain about the failure of the emmetropization mechanism that routinely eliminates infantile anisometropia. Also, the chronology of amblyopia development is poorly documented in cases of 'pure' anisometropic amblyopia. Although indirect, the therapeutic impact of refractive correction on anisometropic amblyopia provides strong support for the hypothesis that the anisometropia caused the amblyopia. Direct evidence for the aetiology of anisometropic amblyopia will require longitudinal tracking of at-risk infants, which poses numerous methodological and ethical challenges. However, if we are to prevent this condition, we must understand the factors that cause it to develop.

Anisometropia and amblyopia in nasolacrimal duct obstruction

PURPOSE

To investigate an association of childhood nasolacrimal duct obstruction (NLDO) with anisometropia and amblyopia.

METHODS

The medical records of patients from newborn to 6 years of age with a diagnosis of NLDO seen from 2000 to 2010 were retrospectively reviewed. Data collected included age at onset of NLDO, laterality of NLDO, cycloplegic refractive error, determination of clinically significant anisometropia (defined as ≥1 D), and diagnosis of amblyopia with amblyopia subtype (anisometropic vs other).

RESULTS

A total of 1,218 patients with NLDO were included. Of these, 887 cases (72.8%) were unilateral; 331 (27.2%), bilateral. Anisometropia was found in 67 (7.6%) unilateral cases and 12 (3.6 %) bilateral cases on initial examination (χ2=5.48, P < 0.01). Same-sided unilateral NLDO was significantly associated with greater hyperopia in the anisometropia patients (χ(2) = 33.01, P < 0.001). Follow-up data were available for 482 NLDO patients and revealed an additional 26 patients with anisometropia for a total of 105 of 1218 (8.6%). Of the 482 patients, 28 (5.8%) developed amblyopia, 16 cases of which were purely attributable to anisometropia. Of 41 patients with anisometropia who were in the follow-up, 9 (22%) developed amblyopia.

CONCLUSIONS

Anisometropia occurred at a greater rate in unilateral NLDO patients compared with bilateral NLDO patients and occurred at a greater rate in this NLDO cohort than expected in the general pediatric population. Several patients with anisometropia developed clinical amblyopia. Measurement of cycloplegic refraction in all NLDO patients at initial examination should be considered. Periodic follow-up is appropriate for patients with NLDO and anisometropia.

Prevalence of anisometropia and its association with refractive error and amblyopia in preschool children

AIM

To determine the age and ethnicity-specific prevalence of anisometropia in Australian preschool-aged children and to assess in this population-based study the risk of anisometropia with increasing ametropia levels and risk of amblyopia with increasing anisometropia.

METHODS

A total 2090 children (aged 6-72 months) completed detailed eye examinations in the Sydney Paediatric Eye Disease Study, including cycloplegic refraction, and were included. Refraction was measured using a Canon RK-F1 autorefractor, streak retinoscopy and/or the Retinomax K-Plus 2 autorefractor. Anisometropia was defined by the spherical equivalent (SE) difference, and plus cylinder difference for any cylindrical axis between eyes.

RESULTS

The overall prevalence of SE and cylindrical anisometropia ≥1.0 D were 2.7% and 3.0%, for the overall sample and in children of European-Caucasian ethnicity, 3.2%, 1.9%; East-Asian 1.7%, 5.2%; South-Asian 2.5%, 3.6%; Middle-Eastern ethnicities 2.2%, 3.3%, respectively. Anisometropia prevalence was lower or similar to that in the Baltimore Pediatric Eye Disease Study, Multi-Ethnic Pediatric Eye Disease Study and the Strabismus, Amblyopia and Refractive error in Singapore study. Risk (OR) of anisometropic amblyopia with ≥1.0 D of SE and cylindrical anisometropia was 12.4 (CI 4.0 to 38.4) and 6.5 (CI 2.3 to 18.7), respectively. We found an increasing risk of anisometropia with higher myopia ≥-1.0 D, OR 61.6 (CI 21.3 to 308), hyperopia > +2.0 D, OR 13.6 (CI 2.9 to 63.6) and astigmatism ≥1.5 D, OR 30.0 (CI 14.5 to 58.1).

CONCLUSIONS

In this preschool-age population-based sample, anisometropia was uncommon with inter-ethnic differences in cylindrical anisometropia prevalence. We also quantified the rising risk of amblyopia with increasing SE and cylindrical anisometropia, and present the specific levels of refractive error and associated increasing risk of anisometropia.

The prevalence of anisometropia and its associated factors in an adult population from Shahroud, Iran

BACKGROUND

The aim of this study was to evaluate the prevalence of anisometropia in an urban adult population in the north of Iran.

METHODS

This cross-sectional study was conducted among the 40-64-year-old population in Shahroud, Iran. Random cluster sampling was applied to select 6,311 people. Following an interview, optometric and ophthalmologic examinations, including objective non-cycloplegic refractions, were carried out. The prevalence of anisometropia was reported according to non-cycloplegic refraction and with cut-off points of 0.50, 1.00, 2.00 and 3.00 D.

RESULTS

Of the sampled people, 5,190 (82.2 per cent) took part in the study. After considering exclusion criteria, data from 4,918 participants were included in the final analysis. Most participants were female (57.6 per cent) and the average age (with standard deviation) was 50.7 ± 6.2 years. The prevalence of anisometropia with cut-off points of 0.50, 1.00 and 2.00 D were 23.1 (95%CI: 22.0-24.3), 7.7 (95%CI: 7.0-8.4) and 3.2 per cent (95%CI: 2.7-3.7), respectively. The prevalence of severe anisometropia (3.00 D or more) was 1.9 per cent (95%CI: 1.5-2.3). The odds ratio (OR) of anisometropia was 1.06 times higher for every year of increasing age. The OR of anisometropia in participants with cataract was 2.78 times more than in those without (p < 0.001). Anisometropia was more frequent among participants with unilateral cataract (21.7 per cent) compared to those with bilateral cataract (13.4 per cent). Anisometropia of 1.00 D or more was significantly more prevalent among myopic participants compared to hyperopic participants (13.8 versus 12.7 per cent, p < 0.001) and there was a stronger association between anisometropia and myopia (OR = 2.93) than hyperopia (OR = 2.23). With increasing educational level, the prevalence of anisometropia decreased significantly (p < 0.001). The prevalence of aniso-astigmatism of 1.00 D or more was 11.1 per cent (95%CI: 10.2-11.9).

CONCLUSION

In the present study, the prevalence of anisometropia in Iran was not negligible; however, it is less than in Eastern Asia. Myopia, cataract, age and educational level were associated with anisometropia.

Guidelines for automated preschool vision screening: a 10-year, evidence-based update

In 2003 the American Association for Pediatric Ophthalmology and Strabismus Vision Screening Committee proposed criteria for automated preschool vision screening. Recent literature from epidemiologic and natural history studies, randomized controlled trials of amblyopia treatment, and field studies of screening technologies have been reviewed for the purpose of updating these criteria. The prevalence of amblyopia risk factors (ARF) is greater than previously suspected; many young children with low-magnitude ARFs do not develop amblyopia, and those who do often respond to spectacles alone. High-magnitude ARFs increase the likelihood of amblyopia. Although depth increases with age, amblyopia remains treatable until 60 months, with decline in treatment effectiveness after age 5. US Preventive Services Task Force Preventative Services Task Force guidelines allow photoscreening for children older than 36 months of age. Some technologies directly detect amblyopia rather than ARFs. Age-based criteria for ARF detection using photoscreening is prudent: referral criteria for such instruments should produce high specificity for ARF detection in young children and high sensitivity to detect amblyopia in older children. Refractive screening for ARFs for children aged 12-30 months should detect astigmatism >2.0 D, hyperopia >4.5 D, and anisometropia >2.5 D; for children aged 31-48 months, astigmatism >2.0 D, hyperopia > 4.0 D, and anisometropia >2.0 D. For children >49 months of age original criteria should be used: astigmatism >1.5 D, anisometropia>1.5 D, and hyperopia >3.5 D. Visually significant media opacities and manifest (not intermittent) strabismus should be detected at all ages. Instruments that detect amblyopia should report results using amblyopia presence as the gold standard. These new American Association for Pediatric Ophthalmology and Strabismus Vision Screening Committee guidelines will improve reporting of results and comparison of technologies.

Refractive surgery in anisometropic adult patients induce plastic changes in primary visual cortex

PURPOSE

To prospectively study the effect of refractive surgery in the primary visual cortex of adult anisometropic and isometropic myopic patients.

METHODS

Two anisometropic and two isometropic myopic patients were examined with multifocal functional magnetic resonance imaging technique (mffMRI) before refractive surgery and at 3, 6, 9 and 12 months postoperatively. Two controls without refractive surgery were also examined with mffMRI in the beginning and in the end of the study. Anisometropic patients had only their more myopic eye operated to correct the anisometropia. The myopic isometropic patients had their both eyes operated.

RESULTS

Operated anisometropic eyes showed 65% reduced amount of active voxels in foveal data at 12 months postoperatively compared with the preoperative situation. In unoperated anisometropic eyes, the corresponding value was 86% and in myopic patients and controls 31% and 1%, respectively. To confirm this finding, the number of activated voxels representing the innermost ring of the stimulus was also calculated, and an exactly similar phenomenon was encountered in the anisometropic patients. Both anisometropic patients improved the best-spectacle-corrected visual acuity in the operated eye after refractive surgery.

CONCLUSION

Our results suggest that plastic changes may take place in the primary visual cortex of anisometropic adult patients after refractive surgery.

Horizontal strabismus worldwide--what are the risk factors?

Horizontal strabismus has constant risk factors of ethnicity, family history, genetic conditions and potentially modifiable risk factors of maternal smoking, prematurity, low birth weight, refractive errors and neurodisability.