Shape analysis of rectus extraocular muscles with age and axial length using anterior segment optical coherence tomography

Purpose This study aimed to evaluate the shape of the extraocular muscles (EOMs) in normal subjects using the en-face images of anterior segment optical coherence tomography (AS-OCT). The EOM insertion and the direction of the muscle fibers were investigated. Subjects and methods A total of 97 healthy normal subjects (194 eyes) at Okayama University Hospital (age, 47.1±21.5 years; range, 8–79 years) participated in the study. A series of 256 tomographic images of the rectus EOMs were captured using the C-scan function of the AS-OCT (CASIA2, TOMEY Co., Japan), and the images were converted to en-face images in multi-TIFF format. The anterior chamber angle to EOM insertion distance (AID) and the angle of the muscle fibers from the insertion site (angle of muscles) were measured from the images. The correlations of AID and angle of muscles with age and axial length were investigated and evaluated. Results AID and angle of muscles were significantly correlated with age or axial length in some EOMs. The AIDs of medial rectus (MR) (P = 0.000) and superior rectus (SR) (P = 0.005) shortened with age. The AIDs of MR (P = 0.001) and inferior rectus (IR) (P = 0.035) elongated with axial length, whereas lateral rectus (LR) (P = 0.013) shortened. The angles of MR (P = 0.001) and LR (P = 0.000) were found to have a more downward direction toward the posterior in older subjects. Conclusion En-face images can be created by AS-OCT, and the shape of the EOMs in normal subjects using these image measurements was available. With the ability to assess the EOMs, AID and angle of muscles are expected give useful information for treating and diagnosing strabismus-related diseases

A nationwide survey of newly certified visually impaired individuals in Japan for the fiscal year 2019: impact of the revision of criteria for visual impairment certification

Purpose　To determine the status of visual impairment certification in Japan in the fiscal year 2019 and the impact of revising the criteria for visual impairment certification implemented in 2018. Study Design　Observational cross-sectional study. Methods　We requested welfare offices throughout Japan to submit data of age, sex, causative diseases, and visual impairment grades for newly certified visually impaired individuals aged ≥ 18 years during the fiscal year 2019. The certification was based on criteria of the Act on Welfare of Physically Disabled Persons. Results　Altogether, data were collected for 16,504 newly certified visually impaired individuals. The most common age group was 80–89 years (29.6%), followed by 70–79 (28.2%) and 60–69 (15.3%) years. The most common causative disease was glaucoma (40.7%), followed by retinitis pigmentosa (13.0%), diabetic retinopathy (10.2%), and macular degeneration (9.1%). The most common impairment grade was grade 2 (40.8%), followed by 5 (21.2%) and 1 (17.0%). Compared to the fiscal year 2015, there was a considerable increase in the number of individuals certified with glaucoma in the fiscal year 2019. Moreover, there was a significant increase in the number of individuals with certified grades 1 and 2 visual impairment, with a decrease in the number of individuals with certified grade 6 visual impairment. Conclusion　The changes revealed in this study were primarily due to the revised certification criteria implemented in July 2018, indicating that it is important to review the certification criteria and to repeat surveys similar to the present study

Accuracy of ultrasound vs. Fourier-domain optic biometry for measuring preoperative axial length in cases of rhegmatogenous retinal detachment

Purpose　To identify a method for accurately measuring preoperative axial length (AL) in cases of rhegmatogenous retinal detachment (RRD). Study design　Retrospective study. Methods　This retrospective study included 83 eyes of 83 patients who underwent vitrectomy for RRD and had both preoperative and postoperative data for AL. Preoperative AL measurements for the affected eye were obtained using ultrasound (aUS-AL) and compared with those for affected and fellow eyes measured using optical biometry (aOB-AL and fOB-AL, respectively). Absolute differences between preoperative aUS-AL, aOB-AL, or fOB-AL measurements and postoperative AL (aPost-AL) were examined. Results　In the 41 eyes without macular detachment, the absolute difference between aOB-AL and aPost-AL (0.06±0.07 mm) was significantly smaller than between aUS-AL and aPost-AL (0.21±0.18 mm) and that between fOB-AL and aPost-AL (0.29±0.35 mm) (P = 0.017 and P Conclusion　The current findings suggest that aOB-AL is more accurate than aUS-AL or fOB-AL in cases of RRD without macular detachment, while aUS-AL or fOB-AL is more accurate than aOB-AL in cases with macular detachment