Prevalence and Incidence of Strabismus by Age Group in Japan: A Nationwide Population-Based Cohort Study.

PURPOSE: To investigate the prevalence and incidence of strabismus in the Japanese population by age group and to estimate the subtype proportions. DESIGN: A nationwide population-based cohort study. METHODS: This study investigated the number of cases with previous and new diagnoses of strabismus by age group between 2009 and 2020 using the National Database of Health Insurance Claims and Specific Health Checkups of Japan, which includes almost all (≥95%) medical claims data. We calculated the strabismus prevalence and 1-year incidence in 2019 and analyzed the proportion of each strabismus subtype. RESULTS: The strabismus prevalence was 2.154% (2 709 207/125 708 000; 95% CI, 2.152%-2.157%). It showed a bimodal distribution, with a high proportion in school and old ages (especially ≥75 years). Exotropia, esotropia, and cyclovertical strabismus proportions were 67.3%, 26.0%, and 6.7%, respectively. Cyclovertical strabismus was uncommon in patients aged ≤18 years (1.4%) and more common (10.2%) in those aged >18 years. The strabismus incidence in 2019 was 321 per 100 000 person-years (403 093/125 708 000; 95% CI, 320-322). The annual incidence proportion of cyclovertical strabismus as opposed to whole strabismus subtypes in patients aged >18 years (13.1%) was higher than that in those aged ≤18 years (1.4%). CONCLUSIONS: This is the first nationwide population-based cohort study to demonstrate strabismus's overall prevalence and incidence. The high prevalence of cyclovertical strabismus in adults compared with children may suggest that cyclovertical strabismus is a primarily age-related strabismus. The high prevalence of exotropia may indicate a genetic difference between Japanese and other ethnicities.

Effect of Duration of Macular Detachment on Visual Prognosis after Surgery for Macula-Off Retinal Detachment: Japan-Retinal Detachment Registry.

PURPOSE: To evaluate the association between the duration of macular detachment (DMD) and visual prognosis in patients with macula-off rhegmatogenous retinal detachment (RD). DESIGN: Prospective observational cohort study. PARTICIPANTS: This study analyzed 719 eyes with macula-off rhegmatogenous RD registered with the Japan-Retinal Detachment Registry created by the Japan Retina and Vitreous Society. METHODS: We included patients with macular detachment without a history of prior surgery, except cataract surgery and vitrectomy. Reoperation cases, hereditary RD, and macular hole RD were excluded. We compared the visual prognosis between patients with DMD of N days or less and those with DMD of N + 1 days or more (N = 2-5). For these 4 comparisons, the inverse probability of treatment weighting (IPTW) methodology was employed, to balance 20 baseline characteristics between the shorter and longer DMD groups. The baseline characteristics included age, sex, axial length, baseline visual acuity, operative procedures, and detailed characteristics of RD. P-values < 0.01 were considered statistically significant. MAIN OUTCOME MEASURES: The best-corrected visual acuity (BCVA) 6 months after surgery. RESULTS: The final analysis included 719 eyes. For all comparisons, the patients' backgrounds were well balanced after IPTW with standardized differences < 0.10. The IPTW regression analysis revealed that the BCVA after 6 months was significantly better after surgeries for DMD of ≤ 2 days than that for DMD of ≥ 3 days. Similarly, the 6-month BCVA for surgeries for DMD of ≤ 3 days was significantly better than that for surgeries for DMD of ≥ 4 days (differences in logarithm of the minimum angle of resolution: -0.113, P = 9.1 × 10-7; -0.076, P = 1.6 × 10-3, respectively). On the other hand, there were no statistically significant differences for the other comparisons. CONCLUSIONS: Earlier surgical treatment within 3 days from the onset of macular detachment should be considered, after accounting for social circumstances, such as weekends. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any materials discussed in this article.

Genome-Wide Association Study of Age-Related Macular Degeneration Reveals 2 New Loci Implying Shared Genetic Components with Central Serous Chorioretinopathy.

PURPOSE: To investigate the genetic architecture of age-related macular degeneration (AMD) in a Japanese population. DESIGN: Genome-wide association study (GWAS). PARTICIPANTS: Three thousand seven hundred seventy-two patients with AMD and 16 770 control participants from the Japanese population were enrolled in the association analyses. METHODS: We conducted a meta-analysis of 2 independent GWASs that included a total of 2663 patients with AMD and 9471 control participants using the imputation reference panel for genotype imputation specified for the Japanese population (n = 3541). A replication study was performed using an independent set of 1109 patients with AMD and 7299 control participants. MAIN OUTCOME MEASURES: Associations of genetic variants with AMD. RESULTS: A meta-analysis of the 2 GWASs identified 6 loci significantly associated with AMD (P < 5.0 × 10-8). Of these loci, 4 were known to be associated with AMD (CFH, C2/FB, TNFRSF10A, and ARMS2), and 2 were novel (rs4147157 near WBP1L and rs76228488 near GATA5). The newly identified associations were confirmed in a replication study (P < 0.01). After the meta-analysis of all datasets, we observed strong associations in these loci (P = 1.88 × 10-12 and P = 1.35 × 10-9 for meta-analysis for rs4147157 and rs76228488, respectively). When we looked up the associations in the reported central serous chorioretinopathy (CSC) GWAS conducted in the Japanese population, both loci were associated significantly with CSC (P = 4.86 × 10-3 and P = 4.28 × 10-3 for rs4147157 and rs76228488, respectively). We performed a genetic colocalization analysis for these loci and estimated that the posterior probabilities of shared causal variants between AMD and CSC were 0.39 and 0.60 for WBP1L and GATA5, respectively. Genetic correlation analysis focusing on the epidemiologically suggested clinical risk factors implicated shared polygenic architecture between AMD and smoking cessation (rg [the measure of genetic correlation] = -0.33; P = 0.01; false discovery rate, 0.099). CONCLUSIONS: Our findings imply shared genetic components conferring the risk of both AMD and CSC. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Rescue of exotropia subsequent to pulled-in-two syndrome of the medial rectus muscle occurring during surgery for high myopic strabismus fixus: A case report.

RATIONALE: Pulled-in-two syndrome is one of the significant complications of strabismus surgery. This study aimed to report a case of pulled-in-two syndrome of the contractured medial rectus muscle (MR) that occurred during strabismus surgery for strabismus fixus due to high myopia, and to describe a rescue of this complication. PATIENT CONCERNS: A woman in her 60s presented to our Ophthalmology Department with the main complaint of unilateral high myopia and severe myopic strabismus fixus. Esotropia exceeded 45° and hypotropia exceeded 15° in her right eye in the Hirschberg test. Right eye duction was markedly limited in every gaze direction. Orbital magnetic resonance images showed rupture of the superior rectus to lateral rectus band ligament and lengthening of the distance between the SR and LR muscles in the right eye. DIAGNOSIS: Due to the patient's ophthalmic examination and imaging results, she was diagnosed with high myopic strabismus fixus. INTERVENTIONS: We performed MR recession and Yokoyama surgery to correct right eye hypoesotropia. In the MR recession procedure, pulled-in-two syndrome (MR muscle tear) occurred. Thus, no additional procedure was performed on the MR. After the surgery, she presented 45 prism diopter exotropia and 18 prism diopter residual right hypotropia in a Krimsky test. We performed a second surgery, combining MR muscle advancement and inferior rectus (IR) muscle recession, 3 months after the first surgery. OUTCOMES: One and a half years after the second surgery, she presented exotropia of 14 prism diopters without hypotropia in the Krimsky test and was satisfied with her ocular position and improved motility. LESSONS: We experienced pulled-in-two syndrome in a case with severe myopic strabismus fixus and achieved a good outcome by performing additional surgery 3 months later, in which the lost MR muscle was advanced. This case underscores that, if the lost muscle cannot be found during surgery, one should maintain composure and perform a reoperation a few months after the initial surgery, if necessary. This case report can aid in making rescue treatment decisions when pulled-in-two syndrome occurs.

Myopia Prevalence and Ocular Biometry Features in a General Japanese Population: The Nagahama Study.

PURPOSE: To describe the distribution of ocular biometry and refraction in Japanese adults. DESIGN: Cross-sectional analysis of a prospective cohort study. PARTICIPANTS: A total of 9850 individuals participated in the first follow-up of the Nagahama Prospective Cohort for Comprehensive Human Bioscience (the Nagahama Study) conducted between 2013 and 2016. Participants were between 34 and 80 years of age. METHODS: All participants underwent axial length (AL; in millimeters), anterior chamber depth (ACD; in millimeters), corneal diameter (white to white; in millimeters), and central corneal thickness (CCT; in micrometers) measurement (IOL Master; Carl Zeiss Meditec, Dublin, CA) and refraction (spherical equivalent [SE]; in diopters [D]) and corneal curvature (CC; in millimeters) measurement (ARK-530A; Nidek, Aichi, Japan). Distribution of these ocular biometric parameters and prevalence of myopia, high myopia, and extreme myopia were summarized. MAIN OUTCOME MEASURES: Distribution of ocular biometry and refraction. RESULTS: After standardization to the national population of 2015, estimates of mean AL and SE were 24.21 mm and -1.44 D, respectively. Estimates of mean CC, corneal diameter, CCT, and ACD were 7.69 mm, 12.01 mm, 543.96 µm, and 3.21 mm, respectively. After standardization of age and gender, the prevalence of myopia (SE, ≤-0.5 D) and high myopia (SE, ≤-6.0 D) were 49.97% and 7.89%, respectively. Approximately 70% of the younger participants (34-59 years of age) showed myopia, whereas high myopia was observed in approximately 10%. Although the number of individuals with myopia or high myopia was higher in the younger age groups, the prevalence of more extreme phenotypes remained stable across all ages, especially in women. Axial length of more than 30 mm was observed only in older women (n = 5 [0.05%]). CONCLUSIONS: We showed detailed distributions of various ocular biometry and refraction parameters using a large general Japanese cohort. Prevalences of myopia and high myopia from 2013 through 2016 were higher than those in earlier studies, which reflects recent environmental change. However, constant prevalence of extreme myopia across all ages suggests high genetic predisposition of the extreme phenotype.

One-Year Outcome Predictors of Strabismus Surgery from Anterior Segment Optical Coherence Tomography with Multiple B-Scan Averaging.

Strabismologists are eager to identify preoperative or intraoperative strabismus surgery outcome predictors because of the variable effects in each patient. Conjunctival closure position recession after rectus muscle recession is effective for correcting large angle strabismus. The elasticity of the conjunctiva and Tenon's capsule is important for strabismus surgery management. In this longitudinal study, we evaluated the prognosis of conjunctiva and Tenon's capsule thickness (CTT) near the limbus 1 year after strabismus surgery with a limbal conjunctival incision using swept-source anterior segment optical coherence tomography with multiple B-scan averaging. Also, we identified preoperative and/or intraoperative parameters associated with corrective effects 1 year after surgery in 15 consecutive treatment-naïve patients with exotropia or esotropia who underwent recession and resection. The 1-year CTT was greater than the preoperative CTT on the resection side (269 ± 111 vs 183 ± 53 µm, P < 0.001) but was smaller on the recession side (137 ± 54 vs 183 ± 71 µm, P = 0.02). The corrective effect of surgery (1.6 ± 0.3°/mm) was most strongly correlated with preoperative CTT on the recession side (P = 0.005, ß = -0.73). Hence, CTT on the recession side may provide adjunctive information for strabismus treatment.