Age-related change and sex difference over 60s in disc-fovea angle in Japanese population: the Nagahama Study

Age-related nonparalytic hypertropia: Clinical features

PURPOSE

Age-related nonparalytic hypertropia (ARNH) is reported to be involved in sagging eye syndrome, where excyclotorsion is large and the lower eye is more extorted. The primary aim of this study was to describe the clinical profiles of patients with ARNH. The secondary aim was to compare cyclotorsion in patients with ARNH with that in normal individuals.

METHODS

Inclusion criteria for ARNH were insidious onset of diplopia at distance after 50 years of age, nonparalytic hyperdeviation and follow-up >6 months. Objective cyclotorsion was measured as the disc-to-fovea angle (DFA) on fundus photographs obtained from two groups: 75 patients with ARNH (age, 74.1 ± 7.9 years) and 75 sex- and age-matched normal controls (73.9 ± 8.1 years).

RESULTS

The hypertropia angle was 4.6 ± 2.8 prism dioptres. One patient also experienced diplopia at near-gaze. DFA in ARNH (right/left eye; 11.0 ± 4.8°/11.6 ± 3.9°) was larger than that of the control (6.6 ± 3.7°/9.2 ± 3.5°) (p < 0.0001). The DFA in the non-dominant eye (12.5 ± 4.1°) was larger than that in the dominant eye (10.2 ± 4.3°) (p = 0.0003). The lower eye did not have the larger DFA in 29 patients.

CONCLUSION

The angle of hyperdeviation in patients with ARNH was small. The DFA in the ARNH group was larger than that in the normal group. The lower eye was not the eye with a larger DFA in 39% of ARNH, inconsistent with sagging eye syndrome. Decreased phoria adaptation (fusional ability) may trigger diplopia in patients with ARNH.

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.

Objective excyclotorsion increases with aging in adults

INTRODUCTION

It has been reported that the disc-fovea angle (DFA), a measure of objective cyclotorsion, increases with age. DFA was measured in three age groups of adults and the effects of age, sex, and laterality on DFA is reported.

METHODS AND SUBJECTS

A retrospective study was performed on patients who had a glaucoma checkup or who visited for suspected cataract, who underwent fundus photography between 2013 and 2021. Patients with visual acuity <0.7, axial length >27 mm, strabismus or ocular diseases affecting fusion were excluded. DFA was measured from digital fundus photographs obtained from 249 participants comprising three age groups (group I, 44.4 ± 0.5 years, n = 58; group II, 63.7 ± 3.6 years, n = 129; group III, 81.0 ± 3.8 years, n = 62). The sum of right- and left-eye DFAs is named as total DFA.

RESULTS

Dunnett's post-hoc test after ANOVA showed that the left-eye DFA and total DFA of group III were significantly larger than those of group I (p = .01 and p < .01, respectively). Total DFA of female participant (15.6 ± 4.7°, n = 168) was significantly larger than that of male participant (13.9 ± 4.3°, n = 81) (p < .01). The DFA of the left eye (8.2 ± 3.5°, n = 249) was significantly larger than that of the right eye (6.8 ± 3.3°, n = 249) (p < .001). Group III was subdivided based on eye dominance (right eye dominance, n = 36; left eye dominance, n = 13; NA, n = 13). The DFA in the nondominant eye (9.7 ± 4.6°) was significantly larger than that in the dominant eye (7.4 ± 3.7°) (p < .01).

DISCUSSION

This study found a slight increase of DFA with age. Furthermore, DFA in female or DFA in the left-eye was larger than DFA in male or in the right-eye.

Comparison of subjective cyclofusion ranges and objective ocular torsion in normal participants according to age

PURPOSE

To investigate the relationship between subjective cyclofusion ranges and objective ocular torsion in normal participants according to age.

METHODS

This cross-sectional study included 120 participants aged ≥ 20 years with no ocular diseases. The subjective cyclofusion ranges were measured centrifugally and centripetally in the direction of excyclotorsion and incyclotorsion, respectively, concurrently with rotational diplopia production by rotation using synoptophore. Disc fovea angle (DFA) was defined as the angle formed by two lines: a line passing through the center of the optic nerve papilla and fovea and a horizontal line passing through the center of gravity of the optic papilla using fundus photographs.

RESULTS

The participants were aged 49.1 ± 17.7 years. The total cyclofusion centrifugal (sum of extorsion and intorsion) and centripetal ranges were 10.9 ± 2.2° and 7.2 ± 1.8°, respectively, both of which decreased in participants in their 60 s and 70 s (p < 0.01). The DFA was - 7.0 ± 3.4° in the right eye (- : excyclo, + : incyclo) and - 8.0 ± 3.2° in the left, which was associated with age (p < 0.001). The correlation between the DFA and centrifugal (r =  - 0.13, p = 0.16) and centripetal (r =  - 0.002, p = 0.99) cyclofusion ranges of extorsion was not significantly different. The centrifugal (r = 0.37, p < 0.001) and centripetal (r = 0.40, p < 0.001) cyclofusion ranges of intorsion were positively correlated.

CONCLUSION

Subjective cyclofusion ranges decreased in both extorsion and intorsion in the elderly. Objective ocular torsion showed excyclotorsion with age. When strabismus surgery is performed in elderly patients with torsional strabismus, the decrease in subjective cyclofusion ranges should be considered.

Objective excyclotorsion in age-related distance esotropia

Age-related distance esotropia (ARDE) is thought to be caused by sagging eye syndrome. Sagging of the lateral rectus derives from the naturally occurring aging process and induces excyclotorsion of the eye. To date, no study has compared the cyclodeviation in ARDE with that in the age-matched individuals without strabismus. This study aimed to measure the objective cyclotorsion on fundus photographs of ARDE patients and compare the findings with those for normal age-matched individuals. Objective cyclotorsion was measured by determining the disc-to-fovea angle (DFA) on fundus photographs, which were obtained from two groups: 38 consecutive patients with ARDE (age, 74.1 ± 7.9 years), 76 normal age-matched controls (age, 73.9 ± 8.1 years). DFA in ARDE patients was not different from that in the control group (Welch's t-test: ARDE vs Control, right eye; 7.7° ± 2.9° vs 6.8° ± 3.9°, p = .18. Left eye; 10.0° ± 4.5° vs 9.4° ± 3.6°, p = .54. Sum of both eyes; 17.6° ± 5.8° vs 16.2° ± 4.7°, p = .21). These findings suggest sagging of the lateral rectus is not the sole cause of ARDE. Another aging-related factor, such as decreased phoria adaptation, might also be responsible for ARDE.

Assessment of objective ocular cyclodeviation under monocular condition and binocular condition using fundus photography

Objective

The relationship between retinal structure and function of glaucomatous eyes has attracted a great deal of research attention. However, visual field tests are conducted under monocular condition, and ophthalmic imaging was performed in patients without occlusion. We aimed to assess the objective ocular cyclodeviation between monocular occlusion and binocular conditions using fundus photography.

Methods and analysis

This study included 76 healthy participants. We obtained six photos of the right eye of each patient using fundus photography. Three of the photographs were taken under monocular conditions, and the other three, under binocular conditions. We measured the optic disc margin-fovea angle (MFA) of the line connecting one point of the disc limbus and the fovea. One-way repeated analysis of variance was used to compare the angles under both conditions. We also examined the direction of ocular rotation under the binocular condition regarding the monocular condition.

Results

The MFAs were 12.12°±3.83° and 12.19°±3.95° under the monocular and binocular conditions, respectively. There was no significant difference in both MFAs (F=1.19, p=0.28). The mean cyclodeviation was 0.07°±0.80° (range: −2.40° to +2.75°). A total of 38 eyes showed excycloduction, while another 38 showed incycloduction.

Conclusion

Significant cyclodeviation did not occur regardless of the existence of an occlusion. When examining the relationship between retinal structure and function, the difference in rotation angle under both conditions need not be taken into consideration if the other disease did not cause pathological cyclodeviation.

[Gender medicine in ophthalmology : The "small difference" between women and men]

Gender-specific or sex-specific medicine is part of "personalized" medicine. After differences in heart diseases between women and men were first identified and increasingly published in the field of cardiology since the 1980s, differences between the sexes have also become the focus of interest in other disciplines. Immunological and hormonal aspects indicate significant differences, e.g. in the severity of the disease or the response to treatment. Even in ophthalmology epidemiological differences in some diseases are known but so far these do not lead to a different approach in the practical treatment of patients. This CME article aims to raise awareness of gender medicine also in the field of ophthalmology and at the same time to promote understanding of these differences by presenting the fundamental differences between the sexes.

Cohort Profile: The Ganka-Ekigaku Network (GEN), a Network of Japanese Ophthalmological Epidemiology Studies

PURPOSE

Japan has been known as a super-aged society, and ageing is a well-known risk factor for blinding eye diseases. However, epidemiological studies in ophthalmology are still scarce in Japan, and the sizes of the cohorts are relatively small. "Ganka-Ekigaku Network" (GEN, an acronym for the epidemiological network in ophthalmology in Japanese) is established to develop a capacity to boost each epidemiological study and enrich a potential inter-study collaboration to identify risk factors of visual impairment in aged society.

METHODS

We reviewed cohort studies in Japan with the inclusion criteria as: (1) at least n = 1000 at baseline, (2) multiple modalities of ophthalmic data, and (3) diagnosis reviewed by ophthalmologist(s), and (4) ophthalmologists are involved in the investigators group. As of January 2020, GEN includes 4 individual Japanese epidemiological studies namely, Hisayama study, Yamagata Study (Funagata), Tsuruoka Metabolomics Cohort study, and the Nagahama Prospective Genome Cohort for Comprehensive Human Bioscience.

RESULTS

GEN includes approximately 25,000 Japanese participants. The baseline surveys started from 1998 to 2012, and since then the data has been prospectively collected approximately every 5 years. A variety of ophthalmic measurements and other factors have been collected in each study in GEN: ophthalmic measurements (fundus photography, optical coherence tomography, etc.), systemic conditions (laboratory data, etc.), and others (DNA, etc.).

CONCLUSION

GEN is an open platform for observational ophthalmic epidemiological studies to share standardized methodologies. While each study in GEN pursues specific and original research questions, standardization of the methods will enable us to conduct reliable meta-analysis/pooled data analyses.

Bilateral Fundus Excyclotorsion in Unilateral Superior Oblique Palsy Confirmed by MR Imaging

Purpose: To determine whether bilateral fundus excyclotorsion is helpful in distinguishing bilateral superior oblique palsy (SOP) from unilateral SOP by investigating bilateral fundus excyclotorsion in unilateral SOP and comparing the features with bilateral SOP using fundus photographs. Methods: This retrospective cohort study included a total of 212 subjects who were diagnosed with unilateral SOP with hypoplasia of a single superior oblique (SO) muscle and 7 subjects with clinically diagnosed bilateral SOP. Fundus excyclotorsion measured by modified fovea–disc angles and inter-eye differences in cyclotorsion angles (the difference in fundus excyclotorsion angles: paretic eye or hypertropic eye in primary gaze–fellow eye), and subjective cyclotorsion were compared between groups of unilateral SOP with bilateral fundus excyclotorsion (SOP_BE) and bilateral SOP. Results: Bilateral fundus excyclotorsion was found in 18 out of 212 patients (8.5%) in the unilateral SOP group, and 7 out of 7 patients (100%) in the bilateral SOP group. Among the 25 patients with bilateral fundus excyclotorsion, the mean angle of excyclotorsion (5.7° ± 4.7° vs. 7.6° ± 4.3°, p = 0.125) and the inter-eye differences (0.7° ± 3.6° vs. 0.5° ± 5.8°, p = 0.615) were not significantly different between the unilateral SOP_BE and bilateral SOP groups. The degree of subjective excyclotorsion was significantly larger in the bilateral SOP group compared with the unilateral SOP_BE group (16.0 ± 5.5 vs. 4.6 ± 4.3, p = 0.002). Conclusion: Bilateral fundus excyclotorsion was demonstrated not only in bilateral SOP, but also in unilateral SOP at a rate of 8.5%. Bilateral fundus excyclotorsion alone did not prove to be a specific sign in distinguishing bilateral SOP from unilateral SOP.