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Investigation of Age-Related Changes in Iris Curvature Among Japanese Participants
Yuki Takagi1,2, Ryo Asano3,4, Kanna Yamashita2
1Department of Ophthalmology, Japan Community Healthcare Organization Kanitounou Hospital, Kani, Gifu, Japan.
Purpose:
Angle-closure glaucoma is more common among Asians, including Japanese individuals, and iris curvature (I-Curv) is reportedly useful for its diagnosis. To investigate age-related changes in iris configuration and their associated factors in Japanese participants using I-Curv measured using anterior segment optical coherence tomography (AS-OCT).
Patients And Methods:
A total of 480 healthy Japanese individuals aged 20-99 years were enrolled. The anterior segment parameters of the anterior chamber, angle, and iris were measured using AS-OCT (CASIA2). The relationships between I-Curv and other parameters were assessed using Spearman's rank correlation coefficient. Differences in the I-Curv among age groups were analyzed using the Kruskal-Wallis test, followed by pairwise comparisons with Bonferroni correction. Multiple regression analysis was performed with I-Curv as the dependent variable and age, refractive error, sex, axial length, and anterior segment parameters as the independent variables. Further, eyes were classified into concave and convex groups based on the sign of I-Curv, and clinical characteristics were compared between these groups.
Results:
I-Curv tended to increase (become more anteriorly convex) with age, showing significant differences among age groups (P < 0.001). However, no significant differences were observed between the adjacent age groups. Spearman correlation revealed significant negative correlations between I-Curv and angle/anterior chamber parameters such as AOD500 and ACD, and positive correlations with LV, age, and refractive error. Multiple regression analysis identified AOD500, ARA500, LV, refractive error, age, and pupil diameter as significant factors influencing the I-Curv (R² = 0.824, P = 0.043). Compared with the convex group, the concave group was significantly younger, had greater myopia, wider anterior chambers and angles, and tended to include more males (P < 0.05).
Conclusion:
The iris tended to become more anteriorly convex with increasing age, and these changes appeared to be strongly influenced by angle configuration.
