Demarcation line evaluation of iontophoresis-assisted transepithelial corneal collagen cross-linking for keratoconus.

PURPOSE: To evaluate the visualization and depth of the demarcation line with anterior segment optical coherence tomography (AS-OCT) after iontophoresis-assisted transepithelial corneal collagen cross-linking (CXL). METHODS: This prospective, consecutive, single center, non-randomized clinical study involved 15 eyes of 12 patients with keratoconus who underwent an AS-OCT scan (Spectralis; Heidelberg Engineering, Inc., Carlsbad, CA) to search for a demarcation line and its depth at 1 month after iontophoresis-assisted transepithelial CXL. AS-OCT scan measurements were performed by two independent examiners. RESULTS: No intraoperative or postoperative complications were observed. Kappa coefficient estimation for operator agreement in demarcation line visualization (whether it was visualized) was 70.6%. The corneal stromal demarcation line was identified in 9 eyes (60%) by both examiners. Mean depth of the corneal stromal demarcation line was 246.67 ± 50.72 µm (range: 183 to 339 µm) for the first examiner and 241.89 ± 62.52 µm (range: 163 to 358 µm) for the second examiner. There were no statistically significant differences for the measurements of the paired comparisons between the two examiners (P = .61). The Pearson correlation coefficient between the measurements was 0.910. CONCLUSIONS: Iontophoresis-assisted transepithelial CXL creates a demarcation line that can be visualized with AS-OCT, which seems less easily distinguishable and shallower than in conventional CXL. However, its depth and visualization seems to be more similar to conventional CXL than transepithelial CXL.

Reproducibility of macular ganglion cell-inner plexiform layer thickness measurement with cirrus HD-OCT in normal, hypertensive and glaucomatous eyes.

AIM: To evaluate the intraobserver and interobserver reproducibility of macular retinal ganglion cell-inner plexiform layer (GC-IPL) thickness measurement by automated detection on Optical Coherence Tomography (OCT) images in normal, hypertensive (ocular hypertensive (OHT)) and glaucomatous eyes. METHODS: A total of 138 eyes were enrolled in three groups: 69 normal, 35 OHT and 34 primary open-angle glaucoma eyes. All patients underwent a complete ocular examination, 24-2 automated perimetry, biometry and pachymetry. Macular imaging was performed in each eye using the Cirrus HD-OCT 4000 with software V.6.0. (Carl Zeiss Meditec, Dublin, California, USA) three times on the same day by each of two observers, and the GC analysis (GCA) algorithm provided parameters expressed as average, minimum and six sectoral GC-IPL thicknesses. Reproducibility was assessed by intraclass correlation coefficient (ICC), coefficient of variation (CV) and test-retest variability (TRTV) calculated as 1.96 times the SD. RESULTS: Mean GC-IPL thickness was 82.27 ± 7.37 µm, 76.84 ± 7.01 µm and 66.16 ± 11.16 µm in normal, OHT and glaucoma groups, respectively. GC-IPL thickness was significantly lower in glaucomatous eyes than in normal and OHT eyes (p<0.0001 for all parameters). In all groups, ICC ranged from 96.4 to 99.9% and 92.5 to 99.8%, CV ranged from 0.41 to 2.24% and 0.55 to 1.67%, and TRTV ranged from 0.61 to 2.64 µm and 0.83 to 2.22 µm for intraobserver and interobserver reproducibility, respectively. CONCLUSIONS: To the best of our knowledge, this is the first study of GCA algorithm reproducibility in normal, OHT and glaucomatous eyes. The reproducibility of GC-IPL thickness measurements using the Cirrus HD-OCT GCA algorithm was found to be highly satisfactory. GC-IPL thickness may be a promising new OCT parameter for analysis of ganglion cell damage in glaucoma.