Correlation between myopic ametropia and stereoacuity in school-aged children in Taiwan

Binocular balance across spatial frequency in anisomyopia

Purpose

Anisomyopia is prevalent in myopia and studies have reported it exhibits impaired binocular function. We investigated the binocular balance across spatial frequency in adults with anisomyopia and compared it to in individuals with less differences in refractive error, and examined whether ocular characteristics can predict binocular balance in anisomyopia.

Methods

Fifteen anisomyopes, 15 isomyopes and 12 emmetropes were recruited. Binocular balance was quantitatively measured at 0.5, 1, 2 and 4 c/d. The first two groups of the observers were tested with and without optical correction with contact lenses. Emmetropes were tested without optical correction.

Results

Binocular balance across spatial frequency in optically corrected anisomyopes and isomyopes, as well as emmetropes were found to be similar. Their binocular balance nevertheless still got worse as a function of spatial frequency. However, before optical correction, anisomyopes but not isomyopes showed significant imbalance at higher spatial frequencies. There was a significant correlation between the dependence on spatial frequency of binocular imbalance in uncorrected anisomyopia and interocular difference in visual acuity, and between the dependence and interocular difference in spherical equivalent refraction.

Conclusion

Anisomyopes had intact binocular balance following correction across spatial frequency compared to those in isomyopes and emmetropes. Their balance was weakly correlated with their refractive status after optical correction. However, their binocular balance before correction and binocular improvement following optical correction were strongly correlated with differences in ocular characteristics between eyes.

Comparison of stereoacuity in patients of anisometropia, isometropia and emmetropia

Purpose

To compare the stereoacuity in patients with anisometropia, isometropia, and emmetropia.

Methods

A cross-sectional study was conducted on 1403 subjects (range: 5-45 years) divided into anisometropes (n = 403), isometropes (n = 500), and emmetropes (n = 500). There were 258 amblyopic eyes among anisometropes and 156 amblyopic eyes among isometropes. Stereoacuity was measured using the Titmus stereo test consisting of a combination of contour targets.

Results

There were 675 males and 728 females. A significant (P < 0.001) reduction in stereoacuity was found in anisometropes as compared to isometropes and emmetropes. The stereoacuity was even worse in amblyopes as compared to non-amblyopes. Most patients with anisometropia of <3.0 D had fair stereoacuity. However, as the degree of anisometropia increased to >3.0 D, stereoacuity deteriorated gradually. Marked reduction of stereoacuity was observed in severe degree of anisometropia (>6.0 D). Overall, an anisometropia of ≥2.12 D was associated with reduced stereoacuity. Among the anisometropes, it was found to be the poorest in myopia, followed by myopia with astigmatism, hypermetropia with astigmatism, and hypermetropia.

Conclusion

The level of stereoacuity was worse in anisometropes as compared to isometropes and emmetropes. Amblyopes had a greater reduction in stereoacuity than non-amblyopes. Stereoacuity decreased as the degree of anisometropia increased. Among the anisometropes, myopes had worst stereoacuity than hypermetropes.

Stereopsis after corneal refractive surgeries: a systematic review and meta-analysis

PURPOSE

To systematically review the published manuscripts on stereopsis after corneal refractive surgery.

METHODS

The Web of Science, PubMed, Scopus, ProQuest, Clinical Key, Embase, and Cochrane Library were searched for relevant articles published until August 2020. The fixed- or random-effects models were used to estimate the Weighted mean difference (WMD) or Relative risk (RR) and 95% Confidence interval (CI) for postoperative stereopsis changes and incidence when applicable. Meta-regression was conducted for adjusting the effects of potential confounders.

RESULTS

Seven studies (1266 eyes) in adults and ten studies in pediatrics (259 eyes) were included. In adults, stereopsis improved significantly compared to the preoperative state (WMD = - 27.4, 95% CI = - 40.0, - 14.7; I² = 97.8%; P < 0.001). In pediatrics, proportion of patients with stereoacuity postoperatively was 2.18 times compared to preoperative evaluation. (RR = 2.18, 95% CI = 1.2, 3.9; I² = 68.6%, P < 0.001).

CONCLUSIONS

Stereopsis improves after corneal refractive surgery in adults and pediatrics.

Study on stereoacuity and associated factors in school children aged 7 to 14 years

Purpose:

The study aimed to estimate the prevalence of subnormal stereoacuity in school children and to assess the factors associated with it.

Methods:

In this prospective cross-sectional study, a total of 2,376 school children without amblyopia and manifest squint were screened by the titmus fly test, Snellen chart, tests for heterophoria, anterior segment examination, and fundoscopy. Children with a manifest squint, amblyopia (best-corrected visual acuity [BCVA] <6/18), and history of ocular trauma or surgery, and one-eyed children were excluded. Cycloplegic refraction was done in children with uncorrected or undercorrected refractive errors, and stereoacuity was assessed again with spectacle correction.

Results:

The prevalence of normal stereoacuity by titmus fly test was 93.18% with correction of refractive errors. Girls had slightly better stereopsis compared with boys. The subnormal stereoacuity was significantly associated with refractive error (P < 0.00001, significant at P < 0.05), unilateral refractive error (P < 0.00001, significant at P < 0.05), bilateral refractive error (P < 0.00001, significant at P < 0.05), anisometropia (P < 0.00001, significant at P < 0.05), ametropia (P < 0.00001, significant at P < 0.05), lower BCVA (P < 0.00001, significant at P < 0.05), hyperopia (P < 0.05, significant at P < 0.05), and heterophoria (P = 0.014, significant at P < 0.05). The subnormal stereoacuity was positively correlated with the magnitude of refractive error of the eyes.

Conclusion:

This study underlines the significant impact of identification and correction of refractive errors and squints in school children. The measurement of stereoacuity will be of immense importance and must be included in the screening programs for children.

Stereoacuity and its determinants in 7-year-old children: the Lhasa Childhood Eye Study

PURPOSE

To explore the distribution of stereoacuity and to examine its determinants in school-age children in Tibetan plateau, Southwest China.

METHODS

This is the cross-sectional part of a school-based cohort study of 7-year-old children in Lhasa, Tibet Autonomous Region, Southwest China. Children in first year of primary school were invited to undergo a comprehensive examination, including height, weight, visual acuity, cycloplegic autorefraction (1% cyclopentolate), anterior segment, cover and uncover test, and stereoacuity (Titmus Stereo Test).

RESULTS

A total of 1833 eligible subjects were included, with a mean age of 6.82 ± 0.46 years. Mean stereoacuity was 1.78 ± 0.21 in log units (median: 60 arcsec). Children with stereoacuity equal to 40 arcsec and stereoacuity worse than 100 arcsec accounted for 29.24% and 8.18% of the cohort, respectively. Tibetan ethnicity (OR = 1.98; 95%CI, 1.30-3.03), astigmatism (OR = 1.65; 95%CI, 1.26-2.17), strabismus (OR = 2.92; 95%CI, 1.38-6.18), and amblyopia (OR = 3.77; 95%CI, 1.14-12.49) were risk factors for normal stereoacuity (= 40 arcsec). Shorter height, younger age, strabismus, and worse BCVA (P < 0.05 for all) were both related to lower stereoacuity in Spearman correlation analysis and associated with lower stereoacuity in multivariate regression analysis.

CONCLUSION

Stereoacuity maturation does not appear fully completed in 7-year-old children, while few children present stereoacuity worse than 100 arcsec (8.18%). Lower stereoacuity was associated with younger age, shorter height, strabismus, and lower best-corrected visual acuity.

Stereoacuity Among Patients with Refractive Error at University of Gondar, Northwest Ethiopia

PURPOSE

This study aimed to assess the level of stereopsis, proportion of poor stereopsis, and factors influencing stereopsis in adults with refractive error.

METHODS

This was a cross-sectional, descriptive study conducted on 153 adults with refractive error at Gondar University Hospital Tertiary Eye Care Center from April 08 to June 07, 2019. Structured questionnaires and ophthalmic instruments (Retinoscope, Worth Four Dot test and TNO Stereo plates) were used to collect the data. Data were entered and analyzed with Statistical Package for Social Sciences (SPSS) version 20. The result was summarized using summary statistics such as mean. Chi-squared test of association was applied between stereopsis and independent variables.

RESULTS

The level of stereopsis after correction of refractive error ranged from 1.89 to 2.65 log arc second. Before correction of refractive error, poor stereopsis was observed in 46.4% of the participants, while after correction, it dropped to 39.8% (CI: 95%: 31.1%-47.8%). Stereopsis after correction had a significant association with age, best visual acuity, type of refractive error, and fusional status at distance with a p value < 0.05.

CONCLUSION

Given refractive error corrected, the mean stereopsis in patients with refractive error was 2.42 log arc second. Proportion of poor stereopsis was noted in 39.8% of the participants corrected for refractive error. Age, best corrected visual acuity, type of refractive error, and fusional status had a significant association with stereopsis. Further studies on stereoacuity on a large scale are recommended.

Stereoacuity and Related Factors in Healthy Preschool Children: The Nanjing Eye Study

Purpose: To assess the distribution of stereoacuity and related factors in healthy preschool children aged 48-60 months in eastern China. Methods: This cross-sectional study was part of the Nanjing Eye Study, a longitudinal population-based cohort study. In 2016, preschool children without any neurological problems or ophthalmological abnormalities completed comprehensive eye examinations, including visual acuity, ocular alignment and movements, cycloplegic refraction, axial length, interpupillary distance, Titmus stereotest, anterior segment, and fundus examination. Multivariate linear regression model was used to determine the factors associated with stereoacuity score, and logistic regression model was used to determine the factors associated with subnormal stereoacuity (worse than 40 arc-seconds). Results: Among 942 healthy preschool children (mean age = 55 months), the mean (SD) stereoacuity was 81 (2.3) arc-seconds with majority (76.5%) worse than 40 arc-seconds. In the multivariate analysis, older age (p = 0.001) and better presenting visual acuity (PVA) (p = 0.01) were independently associated with better stereoacuity score. Older age was also associated with low risk of subnormal stereoacuity (odds ratio = 0.37,p < 0.001 for age 57-60 months compared to age 48-51 months). Conclusions: The maturation of stereopsis has not completed by the age of 48-60 months. Age and PVA should be taken into account when evaluating stereopsis in healthy preschoolers. The significant associations of age and PVA with stereoacuity provide valuable insights into possible intervention for healthy preschool children with poor stereoacuity.

Threshold Values of Myopic Anisometropia Causing Loss of Stereopsis

Purpose

The aim of the study was to determine the threshold values of myopic anisometropia that lead to the loss of stereoacuity in most of patients.

Materials and Methods

Forty healthy subjects were included in the study. The inclusion criteria were as follows: lack of any functional or morphological ophthalmological disorders, or detectable damage to the visual system, anisometropia equal or less than 0.25 D in a spherical equivalent, and full stereoscopic vision for near and for distance. Myopic anisometropia was evoked by placing different focusing lenses in front of the right eye of the subject in the trial frame. Stereoscopic vision was assessed with the use of the Titmus test (dots) (Stereo Fly Test Stereo Optical Co. Inc.) for near and the Randot test for distance (Distance Randot Stereotest Stereo Optical Co. Inc.).

Results

The threshold values for different types of myopic anisometropia for the loss of stereopsis in more than 50% of patients were determined. For near, this value was 3 D for sphere and “against the rule astigmatism” and 4 D for “with the rule astigmatism”. For distance, the values were 2 D for sphere and “against the rule astigmatism” and 3 D for “with the rule astigmatism.” Conclusions. Myopic anisometropia of more than 2 D can cause a significant impairment of binocular vision. Stereoacuity at distance is more sensitive to myopic anisometropia than stereoacuity at near. Myopic anisometropia involving “against the rule” astigmatism potentially affects binocularity more than anisometropia with regular astigmatism. A prompt correction of anisometropia of more than 2 D is needed in children to prevent the development of amblyopia.

Validation of dynamic random dot stereotests in pediatric vision screening

PURPOSE

Stereo vision tests are widely used in the clinical practice for screening amblyopia and amblyogenic conditions. According to literature, none of these tests seems to be suitable to be used alone as a simple and reliable tool. There has been a growing interest in developing new types of stereo vision tests, with sufficient sensitivity to detect amblyopia. This new generation of assessment tools should be computer based, and their reliability must be statistically warranted. The present study reports the clinical evaluation of a screening system based on random dot stereograms using a tablet as display. Specifically, a dynamic random dot stereotest with binocularly detectable Snellen-E optotype (DRDSE) was used and compared with the Lang II stereotest.

METHODS

A total of 141 children (aged 4-14, mean age 8.9) were examined in a field study at the Department of Ophthalmology, Pécs, Hungary. Inclusion criteria consisted of diagnoses of amblyopia, anisometropia, convergent strabismus, and hyperopia. Children with no ophthalmic pathologies were also enrolled as controls. All subjects went through a regular pediatric ophthalmological examination before proceeding to the DRDSE and Lang II tests.

RESULTS

DRDSE and Lang II tests were compared in terms of sensitivity and specificity for different conditions. DRDSE had a 100% sensitivity both for amblyopia (n = 11) and convergent strabismus (n = 21), as well as a 75% sensitivity for hyperopia (n = 36). However, the performance of DRDSE was not statistically significant when screening for anisometropia. On the other hand, Lang II proved to have 81.8% sensitivity for amblyopia, 80.9% for strabismus, and only 52.8% for hyperopia. The specificity of DRDSE was 61.2% for amblyopia, 67.3% for strabismus, and 68.6% for hyperopia, respectively. Conversely, Lang II showed about 10% better specificity, 73.8% for amblyopia, 79.2% for strabismus, and 77.9% for hyperopia.

CONCLUSIONS

The DRDSE test has a better sensitivity for the detection of conditions such as amblyopia or convergent strabismus compared with Lang II, although with slightly lower specificity. If the specificity could be further improved by optimization of the stimulus parameters, while keeping the sensitivity high, DRDSE would be a promising stereo vision test for screening of amblyopia.

Stereoacuity and refractive, accommodative and vergence anomalies of South African school children, aged 13–18 years

Aim: The aim of this study was to explore possible associations between stereoacuity and refractive, accommodative and vergence anomalies.Methods: The study design was cross-sectional and comprised data from 1056 high school children aged between 13 and 18 years; mean age and standard deviation were 15.89 ± 1.58 years. Using a multi-stage random cluster sampling, participants were selected from 13 high schools out of a sample frame of 60 schools in the municipality concerned. In the final sample, 403 (38%) were males and 653 (62%) females. Refractive errors, heterophoria, near point of convergence, fusional vergences and accommodative functions (amplitude, facility, response and relative) were evaluated. Stereoacuity was evaluated using the Randot stereotest and recorded in seconds of arc where reduced stereoacuity was defined as worse than 40 s arc.Results: Overall, the mean stereoacuities (in seconds of arc) of the children with anomalies were the following: those with refractive errors (52.6 ± 36.9), with accommodative anomalies (53.1 ± 34.1) and with vergence anomalies (48.29 ± 31.1). The mean stereoacuity of those with vergence anomalies was significantly better than that of those with either refractive errors or accommodative anomalies (p = 0.02). In the refractive error category, only anisometropia had significantly reduced mean stereoacuity compared to emmetropia (Mann–Whitney U: p = 0.01). The mean stereoacuity of cases of accommodative anomalies was significantly reduced compared to those without such anomalies (Mann–Whitney U: p = 0.01). Similarly, the mean stereoacuity of cases with vergence anomalies was significantly reduced compared to those without vergence anomalies (p = 0.02).Conclusion: Refractive errors, accommodative or vergence anomalies are more likely to have reduced mean stereoacuity than cases without such anomalies. Refractive errors or accommodative anomalies had significantly more reduced stereoacuity than vergence anomalies. These findings suggest that the Randot stereotest could be used to identify those with such anomalies, and this study extends knowledge regarding the possible use of stereoacuity as a useful tool to screen for binocular anomalies.

Stereoacuity and Related Factors: The Shandong Children Eye Study

Objective

To assess stereoacuity in a population-based sample of children and to examine ocular and systemic parameters related to stereoacuity.

Methods

Using a random cluster sampling method, four- to 18-year-old children from kindergartens, elementary schools, junior high schools and senior high schools from a rural area and an urban area in the East Chinese province of Shandong were included in the school-based cross-sectional study. All participants underwent a comprehensive eye examination including assessment of cycloplegic refraction and measurement of stereoacuity using the Titmus Stereo test.

Results

Out of 6364 eligible children, 5780 (90.8%) children with a mean age of 10.1 ± 3.2 years (range: 4 to 18 years) participated. Mean (± standard deviation) stereoacuity was 50.2 ± 50.6 arc seconds. Stereoacuity improved significantly (P<0.01) from the age group of 4 years to the age group of 6 to 7 years, then showed a plateau, deteriorated (P = 0.001) for both sexes from the age group of 9 years to the age group of 12 years (P<0.001), after which it improved (P = 0.001) again in the age group of 16 years or older to the pre-puberty values. In multivariate analysis, larger angle of binocular disparity (i.e., lower stereoacuity) was significantly associated with lower best corrected visual acuity (logMAR; P<0.001), higher intereye difference in refractive error (spherical equivalent) (P<0.001), higher cylindrical refractive error (P<0.001), higher refractive error (spherical value; P<0.001), higher intereye difference in best corrected visual acuity (logMAR) (P = 0.001), higher intereye difference in axial length (P = 0.001), and rural region of habitation (P = 0.006).

Conclusions

Stereoacuity as tested with the Titmus Stereo test improved significantly from an age of 4 years to an age of 6 and 7 years, then remained constant, temporarily deteriorated for both sexes in pre-puberty and puberty, after which it improved again to pre-puberty or better values at the age of 16 years or older. Lower stereoacuity was associated with lower best corrected visual acuity and higher intereye difference in best corrected visual acuity, higher cylindrical and spherical refractive errors, higher inter-eye difference in refractive error, higher intereye difference in axial length, and rural region of habitation.