Prevalence of anisometropia in children and adolescents

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.

Observation of peripheral refraction in myopic anisometropia in young adults

AIM

To investigate the differences in retinal refraction difference values (RDVs) of adult patients with myopic anisometropia compared with those without myopic anisometropia, and to investigate the relationship between ocular biometric measurements and relative peripheral refraction.

METHODS

This clinical observation study included 130 patients with myopia (-0.25 to -10.00 D) between October 2022 and January 2023 aged between 18 and 40y. The patients were divided into anisometropia (n=63; difference in binocular anisometropia ≥1.00 D) and non-anisometropia (n=67; difference in binocular anisometropia <1.00 D) groups accordingly. Ocular biometric measurements were performed by optical biometrics and corneal topography to assess the steep keratometry (Ks), flap keratometry (Kf), axial length (AL), corneal astigmatism (CYL; Ks-Kf), surface regularity index (SRI), surface asymmetry index (SAI), and central corneal thickness (CCT). The RDV was measured at five retinal areas from the fovea to 53 degrees (RDV-0-10, RDV-10-20, RDV-20-30, RDV-30-40, and RDV-40-53), the total RDV (TRDV) of 53 degrees, and four regions, including RDV-superior, RDV-inferior, RDV-temporal, and RDV-nasal. An analysis of Spearman correlation was carried out to examine the correlation between RDV and the spherical equivalent (SE) and ocular biological parameters.

RESULTS

Within RDV-20-53, both groups showed relative hyperopic defocus, and the increase in RDV corresponds to the increase in eccentricity. In the myopic anisometropia group, the TRDV, RDV-20-53, RDV-superior, and more myopic eyes had significantly higher RDV-temporal values than less myopic eyes. (P<0.05). In the non-anisometropia group, there was no significant difference in the RDV between the more and less myopic eyes at different eccentricities (P>0.05). There was a negative correlation between SE and TRDV (r=-0.205, P=0.001), RDV-20-53 (r=-0.281, -0.183, -0.176, P<0.05), RDV-superior (r=-0.251, P<0.001), and RDV-temporal (r=-0.230, P<0.001), a negative correlation between CYL and RDV-10-30 (r=-0.147, -0.180, P<0.05), and a negative correlation between SRI and RDV-0-20 (r=-0.190, -0.170, P<0.05). AL had a positive correlation with RDV-20-30 (r=0.164, P=0.008) and RDV-temporal (r=0.160, P=0.010).

CONCLUSION

More myopic eyes in patients with myopic anisometropia show more peripheral hyperopic defocus. Diopter and corneal morphology may affect peripheral retinal defocus.

Effectiveness and the nomogram of small incision lenticule extraction in the correction of myopic anisometropia in adults

AIM

To evaluate the safety, effectiveness, and predictability of small incision lenticule extraction (SMILE) for the treatment of anisometropia, and to explore the personalized design scheme of SMILE in correcting adult myopia anisometropia based on the nomogram.

METHODS

It's a prospective cohort study. Patients with anisometropic myopia of refractive difference ≥ 2.0 diopters (D) who underwent SMILE between September 2020 and March 2021 were enrolled. Clinical features and visual function were assessed preoperatively and at 1wk, 1, 3, and 6mo after the operation. The examination included tests for uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive errors, effectiveness index (preoperative CDVA/postoperative UDVA), safety index (postoperative CDVA/preoperative CDVA), nomogram and stereoscopic function. Paired t-test, Wilcoxon signed-rank test and repeated-measures analyses of variance were used for continuous variables, and Pearson Chi-squared test was used for categorical variables.

RESULTS

The study involved 45 consecutive patients (average age: 25.0±6.9y; 82 out of 90 eyes underwent SMILE, while 8 eyes were not operated). The average preoperative spherical equivalent (SE) was -4.74±0.22 D. Six months after surgery, the effectiveness index was 1.05±0.12, and the safety index was 1.09±0.11. Seventy eyes (85.4%) exhibited SE correction error within ±0.5 D. The percentage of eyes with Titmus stereoscopic function equal to or less than 200″ significantly increased from 55.6% preoperatively to 88.9% postoperatively (P<0.05). There was statistically significant difference between higher myopia eyes and contralateral eyes in average nomogram value/spherical refraction ratio.

CONCLUSION

SMILE is safe, effective and predictable in correcting myopic anisometropia, and it improves stereoscopic visual function of anisometropia patients. The precise and individualized design of the nomogram is a vital element to ensure the balance of both eyes after SMILE.

A large-scale analysis of refractive errors in students attending public primary schools in Mexico

A cross-sectional, retrospective study was conducted from September 2013 through July 2014 to determine the prevalence of refractive errors among students attending public primary schools in Mexico. Among 3,861,156 students at 14,566 public primary schools in all 32 states of Mexico, teachers identified reduced visual acuity in 1,253,589 (32.5%) using visual acuity measurement. Optometrists confirmed 391,498 [31.2%, mean (SD) age: 8.8 (1.9) years; 204,110 girls (52.9%)] had refractive errors using visual acuity measurement and noncycloplegic static retinoscopy. Among 288,537 (72.4%) of children with previous eyeglasses usage data reported, 241,505 (83.7%) had uncorrected refractive errors. Before prescription eyeglasses were provided, 281,891 students (72%) had logMAR visual acuity ≤ 0.2; eyeglasses corrected vision loss in 85.6% (n = 241,352) of them. Simple myopic astigmatism was the most frequent refractive error (25.7%, n = 100,545). Astigmatism > - 1.00 diopters was present in 54.6% of all students with ametropia. The anisometropia rate based on spherical equivalent difference between right and left eye ≥ 1.50 diopters was 3.9% (n = 15,402). Uncorrected refractive errors are an important issue in primary school students in Mexico. An updated study is needed to analyze the evolving trends over the past decade.

Prevalence of anisometropia and influencing factors among school-age children in Nantong, China: a cross-sectional study

Objective

To investigate the prevalence of anisometropia and associated parameters among school-aged children in Nantong, China.

Methods

This school-based, cross-sectional study examined students from primary schools, junior high schools, and senior high schools in an urban area of Nantong, China. Univariate and multivariate logistic regression analyses were used to investigate the specific correlations between anisometropia and related parameters. Non-cycloplegic autorefraction was assessed for each student. Anisometropia was defined as the spherical equivalent refraction (SE) difference ≥ 1.0 D between eyes.

Results

A total of 9,501 participants were validated for analyses, of which 53.2% (n = 5,054) were male, and 46.8% (n = 4,447) were female. The mean of age was 13.32 ± 3.49 years, ranging from 7-19 years. The overall prevalence of anisometropia was 25.6%. Factors such as myopia, scoliosis screening positive, hyperopia, female sex, older age, and higher weight had a significantly higher risk of anisometropia (p < 0.05).

Conclusion

There was a high prevalence of anisometropia in school-age children. Some physical examination parameters are closely related to children's anisometropia, especially myopia and scoliosis. Preventing myopia and controlling its progression may be the most important ways to reduce the prevalence of anisometropia. Correcting scoliosis may be an important factor in controlling the prevalence of anisometropia, and maintaining good reading and writing posture may be helpful in controlling the prevalence of anisometropia.

Ophthalmic manifestations in children with Down Syndrome in Bogotá, Colombia

BACKGROUND

To describe the ocular features of a cohort of children with Down Syndrome (DS) in Bogotá, Colombia.

METHODS

We performed a cross-sectional study, evaluating 67 children with DS. A pediatric ophthalmologist performed a complete optometric and ophthalmological evaluation of each child, including visual acuity, ocular alignment, external eye examination, biomicroscopy, auto-refractometry, retinoscope in cycloplegia, and fundus examination. Results were reported as frequency distribution tables with percentages for categorical variables and means and standard deviation or median and interquartile ranges for continuous variables, according to their distribution. We used the Chi-square test or Fisher's exact test for categorical variables and ANOVA or Kruskal-Wallis for continuous variables when indicated.

RESULTS

A total of 134 eyes from 67 children were evaluated. Males represented 50.7%. The children's age ranged from 8-16 years, with a mean of 12.3 (SD 2.30). The most frequent refractive diagnosis per eye was hyperopia (47%), followed by myopia (32.1%) and mixed astigmatism (18.7%). The most frequent ocular manifestations were oblique fissure (89.6%), followed by amblyopia (54.5%) and lens opacity (39.4%). Female sex was associated with strabismus (P = 0.009) and amblyopia (P = 0.048).

CONCLUSION

Our cohort had a high prevalence of disregarded ophthalmological manifestations. Some of these manifestations, such as amblyopia, can be irreversible and severely affect the neurodevelopment of DS children. Therefore, ophthalmologists and optometrists should be aware of the visual and ocular affection of children with DS to assess and provide appropriate management. This awareness could improve rehabilitation outcomes for these children.

Ten-Year Outcomes of LASIK for Pediatric Myopic Anisometropia

Purpose

To evaluate long-term safety, effectiveness, and stability of unilateral LASIK in pediatric myopic anisometropic amblyopia.

Methods

This retrospective study included children who received unilateral LASIK for myopic anisometropia of >6 D, after mandatory 6-month occlusion/penalization therapy. They were evaluated at 6 months, 1 year, 2 years and biannually until 10 years. Outcome measures included visual acuity, refraction, ocular alignment, stereopsis, corneal clarity, and corneal topography.

Results

32 patients (16 girls) with mean age of 8.6 ± 2.3 years completed 10 years of follow up after unilateral LASIK. Mean preoperative spherical equivalent refraction (SER) was -10.3D ±2.0D in the affected eye, with anisometropic difference of -9.5D ±1.7D. Mean post-LASIK SER was -1.3D±0.8D (p<0.001). Anisometropia significantly decreased to 0.3D±0.8D, 0.4D±1.0D, and 1.0±2.5D at 6 months, 1 year and 10 years respectively (p<0.001). 11 patients (34%) who had preoperative intermittent exotropia (< 15°) regained orthophoria in all gazes, while 5 of 10 who had constant exotropia with large angle (>30°) required strabismus surgery for ocular alignment. BCVA improved from 0.04±0.6 Decimal at baseline to 0.6 ±0.2 after LASIK and occlusion therapy (p< 0.001). Despite insignificant refractive regression in both eyes, patients have maintained orthophoria, improved stereopsis, clear cornea, and the topography showed no evidence of post-LASIK ectasia.

Conclusion

LASIK appears safe, effective, and stable for correcting refractory pediatric myopic anisometropia, in which conventional measures fail or endanger normal visual development. Eliminating anisometropic aniseikonia consequently restores binocular vision and stereopsis which, along with amblyopia therapy, would reverse amblyopia and prevent recurrence.