The Relationship Between Corneal Stiffness Distribution and Tomography in Keratoconus Patients

Area of Science:

• Ophthalmology
• Biomechanical Engineering
• Corneal Imaging

Background:

• Keratoconus (KC) is a progressive thinning disorder of the cornea.
• Understanding the biomechanical properties of the cornea is crucial for KC diagnosis and management.
• Regional variations in corneal stiffness may contribute to disease progression.

Purpose of the Study:

• To map the regional distribution of corneal stiffness in patients with keratoconus.
• To investigate the relationship between regional corneal stiffness and established tomographic parameters.

Main Methods:

• A prospective, cross-sectional study involving 111 eyes of 111 KC patients.
• Corneal stiffness was assessed using air-puff tonometry and Scheimpflug-based tomography (Pentacam and Corvis).
• Stress-Strain Index (SSI) maps were generated to quantify regional and overall corneal stiffness, and correlated with keratometric and pachymetric indices.

Main Results:

• Corneal stiffness (SSI) was non-uniform, with the lowest values predominantly in the inferior-temporal region.
• Overall SSI correlated weakly with tomographic parameters, but regional SSI showed stronger correlations.
• The strongest correlations between regional SSI and tomographic indices (Kmax and Pmin) were observed in the central and inferior-temporal regions.

Conclusions:

• Biomechanical weakening in keratoconus exhibits significant regional heterogeneity.
• Regional corneal stiffness, particularly in the central and inferior-temporal areas, is strongly associated with keratoconus severity (Kmax and Pmin).
• These findings underscore the importance of regional mechanical properties and collagen structure in corneal deformation in KC.