Three-Dimensional Epithelial Assessment in Keratoconus
Narrative Responses:
Purpose
To evaluate applicability of spectral domain optical coherence tomography (AS-OCT) of epithelial thickness patterns in the diagnosis of keratoconus, and to compare with Scheimpflug imaging keratoconus severity.
Methods
250 healthy (group A) and 155 untreated keratoconic (Group Β) eyes were subjected to anterior segment OCT three-dimensional epithelial thickness imaging. Comparative statistical analysis of patterns was performed, investigating central, minimum, inferior, posterior, and topographic variability of epithelial thickness. Epithelial thickness characteristics were correlated to established Scheimpflug imaging–derived keratoconus classification and anterior surface irregularity indices.
Results
Intra-individual repeatability of epithelial thickness was for group A ±1.13 μm, for group B ±1.78 μm for center and average ±1.67 μm (center, superior, inferior, maximum and minimum).
In group A, center epithelial was 52.54±3.23 μm, maximum 55.33±3.27 μm and minimum 48.50±3.98 μm. In group B, center thickness was 51.75±7.02 μm, maximum and minimum were 63.54±8.85 μm and 40.73±8.51 μm. Topographic variability was 6.07±3.55 μm (range -22.81±12.55 μm) for the keratoconic group, while for the control group 1.59±0.79 μm (-6.86±3.33 μm). Both epithelial thickness variability and range were increased with keratoconus severity and correlated well with keratoconus severity.
Conclusion
AS-OCT may offer high predictability of 3 dimensional epithelial assessment in keratoconus. Overall epithelial thickness in keratoconic eyes appears significantly different to normal even in lower stages of keratoconus. Increased overall thickness correlated remarkably with keratoconus severity, obtained by established Scheimpflug imaging-derived anterior-surface irregularity indices.