Accuracy of the Spot and Plusoptix photoscreeners for detection of astigmatism.

PURPOSE: To evaluate the accuracy of the Spot (V2.0.16) and Plusoptix S12 (ROC4, V6.1.4.0) photoscreeners in detecting astigmatism meeting AAPOS referral criteria in students from a population with high prevalence of astigmatism. METHODS: Students attending grades 3-8 on the Tohono O'odham reservation were examined. Screening was attempted with both the Spot and Plusoptix photoscreeners. Results were compared to cycloplegic refraction. Screening attempts providing no estimate of refractive error were considered fail/refer. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for detection of refractive errors were determined using AAPOS referral criteria and receiver operating characteristic area under the curve (ROC AUC) analysis was conducted for measures of astigmatism. Agreement between screening and cycloplegic refraction measurements of astigmatism, spherical equivalent, and anisometropia were assessed using t tests and correlation analyses. RESULTS: A total of 209 students were included. Of the total, 116 (55%) met examination-positive criteria based on cycloplegic refraction, with 105 of those (90%) meeting the criterion for astigmatism. Measurements success rates were 97% for Spot and 54% for Plusoptix. Comparing the Spot and the Plusoptix, sensitivity was 96% versus 100%, specificity was 87% versus 61%, PPV was 90% versus 76%, and NPV was 94% versus 100% for detection of refractive error. Both screeners overestimated astigmatism by 1/3 D to 2/3 D. AUC for astigmatism was 0.97 for Spot and 0.83 for Plusoptix. CONCLUSIONS: In this highly astigmatic population, the Spot and the Plusoptix had similar sensitivity, but the Spot had better specificity and measurement success rates. Compared with results from study samples with lower rates of astigmatism, our results highlight the need to assess the ability of screening instruments to detect individual types of refractive errors.

Refractive status of Chinese with laser-treated retinopathy of prematurity.

PURPOSE: To analyze changes in myopia, astigmatism, and anisometropia after laser treatment of retinopathy of prematurity (ROP), including aggressive posterior retinopathy of prematurity (APROP), in Mainland Chinese children. METHODS: This was a retrospective study of children who had laser treatment for threshold or type 1 prethreshold ROP between January 2004 and October 2012 and age-matched control subjects with spontaneously regressed type 2 prethreshold ROP. One hundred fifteen eyes of 60 patients were included as the laser-treated group, which were further subdivided into APROP and non-APROP groups. Thirty-seven eyes of 20 patients who were diagnosed during the same period were included as the control group. Between 12 and 36 months postnatal age (PA) (mean [±SD], 22.9 [±8.1] months), cycloplegic retinoscopy was performed to measure refractive outcomes. A general linear model was used to analyze refractive changes among different groups at each PA. RESULTS: After adjusting for PA and the correlation between right and left eyes, the magnitude and proportion of astigmatism (p = 0.04 and p = 0.004, respectively) and myopia (p < 0.0001 and p = 0.006, respectively) were greater in the laser-treated group than in the control group. The differences in myopia were even greater in children with APROP than those with non-APROP, whereas the differences in astigmatism were not. Eyes with APROP had higher prevalence of high myopia and spherical anisometropia than the control (p = 0.002 and p = 0.02, respectively) and the non-APROP groups (p < 0.0001 and p = 0.04, respectively). CONCLUSIONS: Children with laser treatment for ROP, including APROP, tended to have higher myopia, astigmatism, and anisometropia, which may progress to amblyopia. These findings highlight the need for regular refractive screening after laser treatment of ROP.

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.

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.

Risk factors for decreased visual acuity in preschool children: the multi-ethnic pediatric eye disease and Baltimore pediatric eye disease studies.

OBJECTIVE: To investigate risk factors associated with unilateral or bilateral decreased visual acuity (VA) in preschool children. DESIGN: Population-based, cross-sectional prevalence study. PARTICIPANTS: Population-based samples of 6504 children ages 30 to 72 months from California and Maryland. METHODS: Participants were preschool African-American, Hispanic, and non-Hispanic white children from Los Angeles, California, and Baltimore, Maryland. Data were obtained by a parental interview and a detailed ocular examination. Logistic regression models were used to evaluate the independent associations between demographic, behavioral, and clinical risk factors with unilateral and bilateral decreased VA. MAIN OUTCOME MEASURES: Odds ratios (ORs) for various risk factors associated with interocular difference (IOD) in VA of ≥2 lines with ≤20/32 in the worse eye, or bilateral decreased VA <20/40 or <20/50 if <48 months of age. RESULTS: In multivariate logistic regression analysis, 2-line IOD with a VA of ≤20/32 was independently associated with Hispanic ethnicity (OR, 2.05), esotropia (OR, 8.98), spherical equivalent (SE) anisometropia (ORs ranging between 1.5 and 39.7 for SE anisometropia ranging between 0.50 to <1.00 diopters [D] and ≥2.00 D), and aniso-astigmatism in J0 or J45 (ORs ranging between 1.4 and ≥5.3 for J0 or J45 differences ranging between 0.25 to <0.50 D and ≥1.00 D). Bilateral decreased VA was independently associated with lack of health insurance (OR, 2.9), lower primary caregiver education (OR, 1.7), astigmatism (OR, 2.3 and 17.6 for astigmatism 1.00 to <2.00 D and ≥2.00 D), and SE hyperopia ≥4.00 D (OR, 10.8). CONCLUSIONS: Anisometropia and esotropia are risk factors for IOD in VA. Astigmatism and high hyperopia are risk factors for bilateral decreased VA. Guidelines for the screening and management of decreased VA in preschool children should be considered in light of these risk associations. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Prevalence and risk factors for refractive errors and ocular biometry parameters in an elderly Asian population: the Singapore Longitudinal Aging Study (SLAS).

PURPOSE: To determine the prevalence rates of refractive errors and pattern of ocular biometry in a multi-ethnic elderly Asian population. METHODS: A population-based study of 1835 residents aged 55-85 years, evaluating the refractive error and ocular biometry parameters, including axial length (AL) and anterior chamber depth. RESULTS: The age-standardized prevalence of myopia, hyperopia, astigmatism, and anisometropia were 30.0% (95% confidence interval (CI): 29.6, 30.4), 41.5% (95% CI: 41.1, 41.9), 43.5% (95% CI: 43.1, 44.0), and 22.1% (95% CI: 21.7, 22.4), respectively. Male gender (P=0.02), age ≥ 75 years (P=0.033), and higher educational level (P<0.001) were significantly associated with higher rates of myopia in multivariate analyses. The prevalence of astigmatism was higher in persons with diabetes (odds ratio (OR) 1.4, 95% CI: 1.03, 1.90, P=0.031). AL was longer in Chinese than other ethnic groups (23.7 vs 23.4 mm, P=0.018), and in men compared with women (24.2 vs 23.4 mm, P<0.001). AL was associated with increasing height (AL increased by 0.3 mm for every 10 cm increase in height, P<0.001). CONCLUSION: There is a high prevalence of myopia in elderly Singaporeans, consistent with trends seen in younger populations in Asia. Male gender and higher education were independent risk factors for myopia. These data suggest that higher rates of myopia in East Asians compared with Caucasians may not be a recent phenomenon.

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

PURPOSE: To determine anisometropia prevalence and associated risk factors in Hispanic and African American preschoolers. DESIGN: Population-based, cross-sectional study. PARTICIPANTS: We included 3030 Hispanic and 2994 African American children aged 6 to 72 months from Inglewood, California. METHODS: Retinomax autorefraction was performed on all participants after cycloplegia. Anisometropia was defined by difference in spherical equivalent (SE), by difference in plus cylinder in any axis (cylindrical), and by difference in cylinder axis vectors (vertical Jackson cross cylinder vector [J0] and oblique Jackson cross cylinder vector [J45] between the eyes. Strabismus was determined by prism-cover testing. A parental questionnaire explored potential risk factors including developmental delay, prematurity, prenatal exposure, and family history. MAIN OUTCOME MEASURES: Anisometropia prevalence stratified by age, gender, and ethnicity. The association of anisometropia with strabismus and other biological risk factors was assessed. RESULTS: The prevalence of SE anisometropia > or =1.0 diopter (D) was 4.3% for Hispanics and 4.2% for African Americans. Prevalence of cylindrical anisometropia > or =1.0 D was 5.6% and 4.5%, respectively. Prevalence of cylindrical or SE anisometropia > or =3.0 D was < or =0.4% for both ethnic groups. Cylinder vector anisometropia > or =0.5 was twice as common as cylindrical anisometropia > or =1.0 D. The SE anisometropia decreased at age 1 year in Hispanics (P = 0.0016) but not African Americans. Cylindrical anisometropia decreased in the first year of life in both ethnic groups (P < or = 0.001). There was no trend in SE or cylindrical anisometropia beyond 1 year of age, but cylinder vector anisometropia steadily decreased beyond 1 year of age in both ethnic groups. Cylinder vector anisometropia was more prevalent among African Americans, but there was no difference in other measurements of anisometropia between ethnic groups. Anisometropia did not vary by gender. Strabismus was associated with all types of anisometropia. No association of anisometropia with gestational age, birth weight, cerebral palsy, family history, or prenatal exposure could be identified. CONCLUSIONS: Spherical and cylindrical anisometropia (> or =1.0 D) each affect 4% to 6% of Hispanic and African American preschoolers. Anisometropia > or =3.0 D is rare. Except for cylinder axis vector, the prevalence of anisometropia does not diminish beyond 1 year of age. Strabismus is associated with all forms of anisometropia. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Anisometropia prevalence in a highly astigmatic school-aged population.

PURPOSE: To describe prevalence of anisometropia, defined in terms of both sphere and cylinder, examined cross-sectionally, in school-aged members of a Native American tribe with a high prevalence of astigmatism. METHODS: Cycloplegic autorefraction measurements, confirmed by retinoscopy and, when possible, by subjective refraction were obtained from 1041 Tohono O'odham children, 4 to 13 years of age. RESULTS: Astigmatism > or =1.00 diopter (D) was present in one or both eyes of 462 children (44.4%). Anisometropia > or =1.00 D spherical equivalent (SE) was found in 70 children (6.7%), and anisometropia > or =1.00 D cylinder was found in 156 children (15.0%). Prevalence of anisometropia did not vary significantly with age or gender. Overall prevalence of significant anisometropia was 18.1% for a difference between eyes > or =1.00 D SE or cylinder. Vector analysis of between-eye differences showed a prevalence of significant anisometropia of 25.3% for one type of vector notation (difference between eyes > or =1.00 D for M and/or > or =0.50 D for J0 or J45), and 16.2% for a second type of vector notation (between-eye vector dioptric difference > or =1.41). CONCLUSIONS: Prevalence of SE anisometropia is similar to that reported for other school-aged populations. However, prevalence of astigmatic anisometropia is higher than that reported for other school-aged populations.

Associations between anisometropia, amblyopia, and reduced stereoacuity in a school-aged population with a high prevalence of astigmatism.

PURPOSE: To describe the relation between magnitude of anisometropia and interocular acuity difference (IAD), stereoacuity (SA), and the presence of amblyopia in school-aged members of a Native American tribe with a high prevalence of astigmatism. METHODS: Refractive error (cycloplegic autorefraction confirmed by retinoscopy), best corrected monocular visual acuity (VA; Early Treatment Diabetic Retinopathy Study logMAR charts), and best corrected SA (Randot Preschool Stereoacuity Test) were measured in 4- to 13-year-old Tohono O'odham children (N = 972). Anisometropia was calculated in clinical notation (spherical equivalent and cylinder) and in two forms of vector notation that take into account interocular differences in both axis and cylinder magnitude. RESULTS: Astigmatism >or= 1.00 D was present in one or both eyes of 415 children (42.7%). Significant increases in IAD and presence of amblyopia (IAD >or= 2 logMAR lines) occurred, with >or=1 D of hyperopic anisometropia and >or=2 to 3 D of cylinder anisometropia. Significant decreases in SA occurred with >or=0.5 D of hyperopic, myopic, or cylinder anisometropia. Results for vector notation depended on the analysis used, but also showed disruption of SA at lower values of anisometropia than were associated with increases in IAD and presence of amblyopia. CONCLUSIONS: Best corrected IAD and presence of amblyopia are related to amount and type of refractive error difference (hyperopic, myopic, or cylindrical) between eyes. Disruption of best corrected random dot SA occurs with smaller interocular differences than those producing an increase in IAD, suggesting that the development of SA is particularly dependent on similarity of the refractive error between eyes.

Amblyogenic anisometropia in the contralateral eye in unicoronal craniosynostosis.

PURPOSE: To describe the prevalence and nature of anisometropic refractive errors in children with unilateral coronal craniosynostosis. METHODS: Retrospective chart review of children with unilateral coronal craniosynostosis who underwent ophthalmic evaluation, including refraction. RESULTS: Refraction was available for 25 of 61 children with unilateral coronal craniosynostosis. Of the 25, 56% had amblyogenic anisometropia. Of these, 79% had the greater refractive error contralateral to the coronal synostosis, mostly (91%) consisting of greater with-the-rule astigmatism in the contralateral eye. Seventy-two percent of Hispanic children had amblyogenic anisometropia, compared with only 14% of non-Hispanic children (p= 0.02). Although Hispanic children tended to receive both surgery and ophthalmic evaluation at older ages than non-Hispanic children, these factors did not appear to account for the difference between ethnicities. There was no detectable association between anisometropia and the timing of fronto-orbital advancement surgery. CONCLUSIONS: Children with unilateral coronal craniosynostosis are at increased risk of developing amblyogenic levels of anisometropia in the eye contralateral to the synostosis and require early evaluation and refraction even in the absence of strabismus.

Distance refractive error among Aboriginal people attending eye clinics in remote South Australia.

PURPOSE: To determine the prevalence of distance refractive error among Aboriginal people attending eye clinics in remote South Australia. METHODS: A clinic-based cross-sectional study was conducted that involved opportunistic sampling of Aboriginal people attending eye clinics in remote South Australia. There were 189 individuals who were invited to participate in the study all of whom underwent ophthalmic examination. This examination included measurement of pinhole-corrected visual acuity and non-cycloplegic autorefraction. RESULTS: Automated refractive error examinations were performed on 148 people within this sample. The mean age was 44.8 +/- 14.5 years and women comprised 57.7% of the sample. The overall mean refractive error was -0.01 +/- 1.8 D (SD). The prevalence of myopia (spherical equivalent (SE) < -0.5 D), high myopia (SE less than or equal to -6.0 D), hypermetropia (SE > 0.5 D), astigmatism (cylinder at least -0.5 D) and anisometropia (difference in SE of >0.5 D) was 31.1%, 0.7%, 33.1%, 55.8% and 45.9%, respectively. Further analyses revealed significant age-related trends with both myopia and hypermetropia. There were no gender associations with any form of refractive error. Of those people with clinically significant refractive error, 51/148 (34%), only four people owned distance spectacles. CONCLUSIONS: There continues to be a level of uncorrected distance refractive error within these patients. This represents a need to screen for refractive error among Aboriginal people in remote locations and to provide them with appropriate spectacle correction.