Scheimpflug tomographic changes across the keratoconus spectrum based on the modified Rabinowitz-McDonnell...

Area of Science:

• Ophthalmology
• Corneal Imaging
• Biomedical Engineering

Background:

• Keratoconus is a progressive corneal ectasia characterized by thinning and steepening.
• Accurate classification and characterization of keratoconus stages are crucial for patient management.
• Scheimpflug tomography offers advanced imaging for detailed corneal analysis.

Purpose of the Study:

• To analyze spectrum-dependent changes in Scheimpflug tomographic parameters in normal, keratoconus suspect, and keratoconus eyes.
• To correlate tomographic findings with keratoconus classification using the modified Rabinowitz-McDonnell index.
• To elucidate the sequence of tomographic alterations in keratoconus development.

Main Methods:

• Retrospective analysis of 115 eyes from a tertiary ophthalmology clinic.
• Classification into control (n=37), keratoconus suspect (n=51), and keratoconus (n=27) groups based on the modified Rabinowitz-McDonnell index.
• Evaluation of Scheimpflug tomographic data including anterior/posterior keratometry, corneal thickness, volume, anterior chamber depth, and pupil diameter.

Main Results:

• Progressive increase in anterior and posterior corneal curvature from control to keratoconus groups (p<0.001).
• Significant curvature differences between control and suspect groups, while pachymetry remained comparable until the keratoconus stage.
• Corneal volume was higher in suspect eyes; anterior chamber depth increased, and pupil diameter decreased in keratoconus eyes.

Conclusions:

• Scheimpflug tomography demonstrates stage-dependent corneal changes in keratoconus.
• Corneal curvature alterations precede significant thinning, validating curvature-based classification.
• Tomographic parameters enhance the characterization of keratoconus across its spectrum.