Using Ultra High-Resolution Imaging Of Collagen Properties To Choose The Right Refractive Procedure.

To determine and correlate collagen fiber distribution and Bowman layer thickness (BLT) in differentiating healthy from suspect corneas, aiding in the selection of suitable refractive surgery.

Tertiary Eye Centre, India.

Fifty healthy, fifty suspect, and fifty keratoconus corneas were imaged using ultra-high-resolution polarization-sensitive optical coherence tomography (PS-OCT) operating at a center wavelength of 840 nm and spectral bandwidth of 100 nm. Phase Retardation (PR) enface maps from the posterior corneal surface (10×8 mm) at the 2mm central zone and in annular outer zones through the depth of the stroma, along with the BLT (8×8 mm), were generated. The epithelium, Bowman's layer (BW), and stroma were segmented by PS-OCT to obtain True BLT.

Eyes with a healthy topography depicted uniform BLT with a healthy PR distribution. Suspicious eyes showed irregular BLT. Suspect and ectatic corneas exhibited a loss of normal collagen orientation and irregular BLT thinning. BLT in healthy eyes was 15 ± 2 µm, while BLT in healthy eyes with corneal thickness <500 µm was 11–13 µm.

Changes in collagen fiber orientation and BLT outline the differences between normal and suspicious corneas, indicating potential weaker biomechanics. PS-OCT can be utilized to obtain ultra-high-resolution images of the cornea, aiding in the diagnosis of keratoconus in suspect corneas and decision-making for refractive surgery.