Agreement And Interchangeability Of Corneal Topography And Anterior Segment Optical Coherence Tomography In Primary Open-Angle Glaucoma

To evaluate the agreement and interchangeability between corneal topography and anterior segment optical coherence tomography (AS-OCT) in measuring iridocorneal angle parameters in primary open-angle glaucoma (POAG) eyes and to determine whether the two modalities can be used interchangeably at the individual patient level.

Glaucoma Unit, Department of Ophthalmology, Kartal Dr. Lütfi Kırdar City Hospital, a tertiary referral center, Istanbul, Turkey.

This cross-sectional study included 58 POAG eyes. Eyes with incomplete measurements (n = 7) were excluded, and 51 eyes were analyzed. Iridocorneal angle (ICA) measurements were obtained using corneal topography in nasal and temporal sectors. AS-OCT provided angle measurements in degrees and angle opening distance at 500 µm (AOD500). Pearson correlation analysis assessed inter-device relationships. Multivariable linear regression evaluated the independent effect of anterior chamber depth (ACD) on AOD measurements. Agreement was further analyzed using Bland–Altman plots.

Strong correlations were observed between topographic ICA and AS-OCT angle measurements both nasally (r = 0.71, p < 0.001) and temporally (r = 0.77, p < 0.001). Moderate correlations were found between ICA and AOD500 (nasal: r = 0.46, p = 0.0007; temporal: r = 0.52, p < 0.001). In multivariable analysis, ICA remained independently associated with temporal AOD500 (p = 0.01), whereas ACD was not a significant independent predictor. Bland–Altman analysis showed minimal mean bias but wide limits of agreement.

Corneal topography and AS-OCT demonstrate strong correlation in angular degree measurements in POAG eyes. However, wide limits of agreement indicate that the two modalities are not interchangeable at the individual patient level. AS-OCT remains superior for precise anatomical quantification of angle opening.