Abstract
Purpose:
To investigate whether OCT epithelial mapping may improve detection of forme fruste keratoconus.
Methods:
We retrospectively reviewed the OCT RTVue 5.5 (Optovue, Fremont, CA), Orbscan IIz (Bausch & Lomb, Rochester, NY), and Pentacam Scheimpflug system 1.15 (Pentacam Comprehensive Eye Scanner Oculus Optikgerate GmbH) data from 62 eyes from 62 patients with normal cornea (control group, n= 21), forme fruste keratoconus (n =21), and keratoconus (n =20). Forme fruste keratoconic corneas featured normal slit-lamp examination, normal Orbscan data (K<47D, I-S<1.4) and negative Pentacam indices (KI, KCI, and TKC) with evidence of keratoconus in the contralateral eye. Keratoconic corneas were characterized by presence of clinical signs, K >47D, I-S>1.4 and positive KI, KCI, and TKC. A pachymetry+Cpwr scan pattern (6 mm scan diameter, 8 radials, 1024 axial scans each, repeated 5 times) centered at the pupil center was used to map both the corneal and epithelial thickness.
Results:
There were no significant differences in K, I-S, KI, KCI, and TKC indices between the forme fruste group and the control group (p>0.05). The average epithelial thickness in the thinnest corneal zone was 49.3±3.8 µm in forme fruste keratoconic corneas, 42.4± 4.4 µm in keratoconic corneas, and 54.2±3.4 µm in normal corneas (ANOVA, p<0.0001). Compared with normal and keratoconic corneas, forme fruste corneas featured, respectively, significantly lower and higher epithelial thickness in the thinnest corneal zone (p<0.0001).
Conclusions:
The epithelial thickness in the thinnest corneal zone provided by the OCT epithelial mapping may be useful for early diagnosis of forme fruste keratoconus.
Keywords: 482 cornea: epithelium •
574 keratoconus •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)