Corneal stromal demarcation line after 4 protocols of corneal crosslinking in keratoconus determined with anterior segment optical coherence tomography.

PURPOSE: To use anterior segment optical coherence tomography (AS-OCT) to compare corneal stromal demarcation line depth after 4 treatment protocols of corneal crosslinking (CXL).

SETTING

Eye Clinic, Sapienza University of Rome, Terracina (Latina), Italy.

DESIGN

Prospective case series.

METHODS

Patients with progressive keratoconus were delegated to one of the following CXL treatments: (1) conventional epithelium (epi)-off 3 mW/cm2 according to the standard Dresden protocol (C-CXL group), (2) accelerated epi-off 10 mW/cm2 (A-CXL group), (3) transepithelial epi-on 3 mW/cm2 (TE-CXL group), or (4) transepithelial epi-on by iontophoresis 10 mW/cm2 (I-CXL group). Two independent observers measured the corneal stromal demarcation line using AS-OCT.

RESULTS

The study comprised 70 patients (120 eyes, 30 eyes in each group). The corneal stromal demarcation line was identified on AS-OCT scans in 109 eyes (90.8%). One month after the treatment, the mean stromal demarcation line depth was 275.05 μm ± 41.83 (SD) in the C-CXL group, 279.35 ± 33.07 μm in the A-CXL group, 132.60 ± 22.14 μm in the TE-CXL group, and 235.40 ± 37.08 μm in the I-CXL group. The difference in stromal demarcation line depth was not statistically significant between the C-CXL and A-CXL group, but it was statistically significant (P < .05) between the epi-off and epi-on CXL groups and between the 2 epi-on groups, where the demarcation line was significantly deeper in the I-CXL group than in the TE-CXL group.

CONCLUSION

The corneal stromal demarcation line was significantly deeper after epi-off 30-minute standard CXL treatment and after epi-off 9-minute accelerated CXL with high-intensity ultraviolet-A irradiation.