Anterior Chamber Angle, Volume, and Depth in a Normative Cohort-A Retrospective Cross-Sectional Study.

Purpose: The purpose of the study was to determine the distribution of the anterior chamber angle (ACA) within a population-based study sample in Germany and to find correlations between age, sphere, and biometric parameters of the anterior chamber. Patients and Methods: A total of 500 eyes, approximately 100 eyes per decade starting with patient age of 20 years, of 463 patients with an average age of 45.2 ± 14.1 (±values subsequent represent standard deviation) years without any known history of ocular diseases, surgery, or optic nerve head excavation or hypoplasia were included. ACAs, volume, and depth were correlated to age and sphere. Scheimpflug images (Pentacam, Oculus) with automatically measured ACAs were compared to manually measured angles (Bland Altman analysis) in this healthy population. Results: The mean manually measured ACA was 26.5° ± 3.9°; the highest average angle was found in the temporal position with 28.1° ± 4.9°, while the lowest average angle was found in nasal superior position with 25.7° ± 4.7°. Statistical analysis showed an average difference of +11.4° nasal and +12.1° temporal between the automatic measurements and the manually measured angles (P < 0.01). The analysis also revealed an independent inverted correlation between age (correlation coefficient between -0.28 and -0.38) and sphere (correlation coefficient between -0.44 and -0.51) of the participants and the anterior chamber volume, angle, and anterior chamber depth (P < 0.01 for all correlations). Conclusion: The ACA width manually measured is considerably less compared to automated imaging and formerly reported values. There is a significant difference in the ACA dependent on the position of measurement (superior, nasal, inferior, and temporal) with the average angle being inversely correlated to age and sphere. Abbreviations: AC: anterior chamber ACA: anterior chamber angle ACV: anterior chamber volume ACD: anterior chamber depth AAC: acute angle closure OAG: open-angle glaucoma OCT: optical coherence tomography ACG: angle-closure glaucoma MIGS: microinvasive glaucoma surgery PACS: primary angle-closure suspects.