Corneal stromal demarcation line determined with anterior segment optical coherence tomography following a very high intensity corneal collagen cross-linking protocol.

PURPOSE: To evaluate corneal stromal demarcation line depth after very high intensity (18 mW/cm) ultraviolet-A irradiation for a 5-minute corneal collagen cross-linking (CXL) protocol with the use of anterior segment optical coherence tomography. METHODS: This prospective interventional study enrolled 14 patients (18 eyes) with progressive keratoconus who underwent CXL with an ultraviolet-A irradiation intensity of 18 mW/cm for 5 minutes. One month postoperatively, corneal stromal demarcation line depth was measured with the use of anterior segment optical coherence tomography by 2 independent observers. The rate of reepithelialization and endothelial cell density at a 3-month follow-up period were also evaluated. RESULTS: No intraoperative or postoperative complications were observed in any of the patients. No statistically significant difference between the 2 observers' measurements was observed (P = 0.989). Mean corneal stromal demarcation line depth was 223 ± 32 µm (range, 159-265 µm). The mean endothelial cell density decreased from 2714 ± 174 preoperatively to 2671 ± 192 at 3 months postoperatively; however, this decrease was not statistically significant (P = 0.221). CONCLUSIONS: Corneal stromal demarcation line depth after a very high intensity 5-minute CXL protocol seems to be shallower than the standard Dresden protocol.

Excessive Corneal Flattening and Thinning After Corneal Cross-linking: Single-Case Report With 5-Year Follow-up.

PURPOSE: To present a case of significant progressive corneal flattening and thinning after corneal cross-linking (CXL), with 5 years of follow-up. METHODS: Case report. RESULTS: A 23-year-old woman presented with bilateral progressive keratoconus and received CXL treatment (Dresden protocol) for both eyes in March 2009. The patient has demonstrated gradual significant corneal thinning (from a preoperative value of 464 µm to 243 µm) and progressive flattening (+11.1-diopter change in spherical equivalent) in her right eye, over a 5-year period. The fellow eye remained stable during the same postoperative period. CONCLUSIONS: This is the first case report of significant progressive corneal flattening and thinning after undergoing CXL treatment for progressive keratoconus.

Long-term follow-up of corneal collagen cross-linking for keratoconus--the Cretan study.

PURPOSE: The aim of this study was to present the long-term results of corneal collagen cross-linking (CXL) in patients with keratoconus. METHODS: In this prospective, interventional case series, patients with progressive keratoconus underwent CXL treatment according to the Dresden protocol. Visual, refractive, and topographic outcomes along with endothelial cell density were evaluated preoperatively and at 1, 2, 3, 4, and 5 years postoperatively. RESULTS: Twenty-one patients (25 eyes) were enrolled. The mean follow-up was 43.7 ± 12.2 (range, 24-60) months. Logarithm of the minimum angle of resolution (logMAR) mean uncorrected visual acuity and the mean best spectacle-corrected visual acuity improved significantly from 0.92 ± 0.54 and 0.29 ± 0.21 preoperatively to 0.63 ± 0.41 (P = 0.010) and 0.18 ± 0.18 (P = 0.011), respectively, at the last follow-up. Mean steep and mean flat keratometry readings reduced significantly from 52.53 ± 6.95 diopters (D) and 48.11 ± 5.98 D preoperatively to 49.10 ± 4.50 D (P < 0.001) and 45.58 ± 3.81 D (P = 0.001), respectively, at the last follow-up. The mean endothelial cell density was 2708 ± 302 cells per square millimeter preoperatively and did not change significantly (P > 0.05) at any postoperative interval (2593 ± 258 cells/mm at the last follow-up; P = 0.149). CONCLUSIONS: CXL seems to be effective and safe in halting progression of keratoconus over a long-term follow-up period up to 5 years postoperatively.

Evaluation of corneal stromal demarcation line depth following standard and a modified-accelerated collagen cross-linking protocol.

PURPOSE: To compare the corneal stromal demarcation line depth using anterior segment optical coherence tomography (AS-OCT) after corneal collagen cross-linking (CXL) using 2 different treatment protocols: the standard Dresden protocol (30 minutes with 3 mW/cm(2)) and a modified-accelerated protocol (14 minutes with 9 mW/cm(2)). DESIGN: Prospective, comparative study. METHODS: Forty-three keratoconic patients (52 eyes) were enrolled. All patients underwent CXL using the same high-intensity ultraviolet-A (UV-A) irradiation device. Twenty-six eyes were treated for 30 minutes with 3 mW/cm(2) according to the standard Dresden protocol (Group 1), while 26 eyes were treated with a novel modified-accelerated CXL protocol for 14 minutes with 9 mW/cm(2) of UV-A irradiation intensity (Group 2). One month postoperatively, corneal stromal demarcation line depth was measured by 2 independent observers using AS-OCT. RESULTS: Corneal stromal demarcation line depth was assessed with no significant difference between observer measurements for both groups (P = .676 for Group 1 and P = .566 for Group 2). Mean corneal stromal demarcation line depth was 337.00 ± 46.46 µm for Group 1 and 322.91 ± 48.28 µm for Group 2. There was no statistically significant difference (P = .243) in the corneal stromal demarcation line depth between the 2 groups. CONCLUSIONS: Corneal stromal demarcation line depth using UV-A with 3 mW/cm(2) for 30 minutes and 9 mW/cm(2) for 14 minutes was similar. A modified-accelerated protocol of 14 minutes of CXL provided the same treatment depth as the classic Dresden protocol.