Endogenous fluorescence can differentiate the keratoconic cornea.

Area of Science:

• Ophthalmology and Vision Science
• Biophotonics and Spectroscopy
• Biochemistry and Molecular Biology

Background:

• Keratoconus (KC) is a progressive corneal ectasia characterized by stromal abnormalities.
• Endogenous fluorescence spectroscopy offers a non-invasive method to probe tissue biochemistry.
• Understanding biochemical changes in the KC stroma is crucial for diagnosis and management.

Purpose of the Study:

• To investigate the endogenous fluorescence spectra of keratoconic corneas.
• To analyze spectral changes related to keratoconic stroma abnormalities.
• To identify fluorescence parameters that can differentiate between normal and KC corneas.

Main Methods:

• Acquisition of corneal buttons from 22 KC patients and 12 normal controls.
• Recording of fluorescence excitation/emission matrices (EEM) in the UV-Vis range.
• Calculation of relative intensity factors (S1, S2, S3) representing fluorophore contributions.

Main Results:

• Normal and KC corneas exhibited qualitatively similar fluorescence EEM bands.
• Statistically significant differences were found in S1, S2, and S3 parameters between KC and normal corneas.
• Multidimensional distribution analysis revealed significant differences in factor distribution between the groups (p < 0.001).

Conclusions:

• Differences in fluorescence spectra, quantified by relative intensity factors, correlate with KC stromal changes.
• These spectral parameters reflect alterations in collagen cross-links and proteoglycan fractions in KC.
• The calculated fluorescence parameters serve as a valuable tool for differentiating KC from normal corneas.