Biometric Measurement of Iridocorneal Angle Parameters in a Sample of Healthy Saudi Eyes

Iridocorneal angle (ICA) or anterior chamber angle is the anatomical structure responsible for aqueous humor outflow and regulating intraocular pressure inside the eye.

The study aims to evaluate iridocorneal angle parameters in healthy Saudi eyes using the spectral domain located in the anterior segment optical coherence tomography (AS-OCT) and to describe their correlation with other factors.

For precise measurements of ICA, anterior segment imaging was executed with the aid of spectral-domain AS-OCT MS-39^®. The measurements of the iridocorneal angle included angle opening distance (AOD) and trabecular-iris space area (TISA), located 500 and 750 μm away from the actual scleral spur from nasal and temporal angles.

The comparison of temporal and nasal angle parameters showed significantly higher AOD500 values in the temporal compared to the nasal angle (p=0.005). The study also evaluated correlations with a grade of the angle, and no correlations were found between gender, refractive error, iris thickness, and angle parameters. Multiple linear regression with backward elimination of non-significant factors found age (p=0.002), angle grade (p<0.001), predicting factors for nasal AOD₅₀₀ (Adjusted R²=0.772, p<0.001), and angle grade (p<0.001) and temporal iris thickness (p=0.004) predicting factors for temporal AOD₅₀₀ (Adjusted R2=0.511, p<0.001). IOP (p =0.026) and angle grade (p<0.001) were found to predict factors for nasal TISA₅₀₀ (Adjusted R2=0.639, p<0.001), and angle grade (p<0.001) and temporal iris thickness was found predicting factors for temporal TISA₅₀₀ (Adjusted R2=0.314, p<0.001).

AS-OCT is a valuable, easy, non-aggressive method to evaluate the iridocorneal angle.