Normative assessment of corneal thickness and iridocorneal angle parameters in guinea pigs (Cavia porcellus) using spectral-domain optical coherence tomography

Guinea pigs (Cavia porcellus) are valuable models for ophthalmic research due to their ocular similarities to humans. Optical coherence tomography (OCT) provides a non-invasive, high-resolution method for detailed, cross-sectional imaging of the ocular structures across species. This study aimed to establish normative biometric parameters of the cornea and iridocorneal angle in guinea pigs using spectral-domain optical coherence tomography (SD-OCT). Twenty eyes from ten clinically healthy adults underwent complete ophthalmic examination followed by anterior segment SD-OCT imaging without sedation. Central corneal thickness (CCT), central epithelial thickness (CET), iridocorneal angle (ICA), and angle opening distance at 500 μm from the scleral spur (AOD500) were quantified. Data distribution was assessed using the Shapiro-Wilk test, and parametric or non-parametric analyses were applied accordingly. The mean (± SD) CCT was 234.45 ± 16.53 μm, with the inferior quadrant being the thickest and the central region the thinnest. CET averaged 50.35 ± 5.81 μm, representing 21.54 ± 2.58% of CCT, with no significant correlation between CET and CCT (r = 0.24, p = 0.31). ICA and AOD500 averaged 39.2 ± 10.1° and 435.6 ± 111.3 μm, respectively, displaying a strong positive correlation (r = 0.89, p < 0.001). No significant interocular differences were observed for any parameter (p > 0.05). The present results provide the first SD-OCT-based references for corneal and angle biometry in guinea pigs, facilitating their use as a translational model in ophthalmic research and aiding in the diagnosis and monitoring of anterior segment diseases in exotic pet medicine.