Optical characterization of ocular collagen microstructure and anisotropy in animal and human eyes.

Second-harmonic generation (SHG) microscopy enabled label-free, high-resolution visualization of ocular collagen structures in mouse, rabbit, and human pterygium tissues. Quantitative analyses using fast Fourier transform (FFT), gray-level co-occurrence matrix (GLCM), and polarization-resolved SHG revealed regional variations in collagen alignment, texture anisotropy, and optical polarization dependence. The results demonstrate that SHG imaging can sensitively capture microstructural organization and pathological remodeling within corneal and conjunctival tissues. This study highlights the potential of SHG microscopy as a powerful noninvasive technique for quantitative assessment of collagen integrity and early detection of structural abnormalities in ocular diseases.