Dimitrios A. Liakopoulos

Corneal stroma demarcation line after standard and high-intensity collagen crosslinking determined with anterior segment optical coherence tomography

Purpose To use anterior segment optical coherence tomography (AS‐OCT) to compare corneal stroma demarcation line depth after corneal collagen crosslinking (CXL) with 2 treatment protocols. Setting Vardinoyiannion Eye Institute of Crete, Faculty of Medicine, University of Crete, Heraklion, Crete, Greece. Design Prospective comparative interventional case series. Methods Corneal collagen crosslinking was performed in all eyes using the same ultraviolet‐A (UVA) irradiation device (CCL‐365). Eyes were treated for 30 minutes with 3 mW/cm2 according to the standard Dresden protocol (Group 1) or for 10 minutes with 9 mW/cm2 of UVA irradiation intensity (Group 2). One month postoperatively, 2 independent observers measured the corneal stroma demarcation line using AS‐OCT. Results Sixteen patients (21 eyes) were enrolled. Group 1 comprised 7 patients (9 eyes) and Group 2, 9 patients (12 eyes). The mean corneal stroma demarcation line depth was 350.78 &mgr;m ± 49.34 (SD) (range 256.5 to 410 &mgr;m) in Group 1 and 288.46 ± 42.37 &mgr;m (range 238.5 to 353.5 &mgr;m) in Group 2; the corneal stroma demarcation line was statistically significantly deeper in Group 1 than in Group 2 (P=.0058, t test for unpaired data). Conclusion The corneal stroma demarcation line was significantly deeper after a 30‐minute CXL treatment than after a 10‐minute CXL procedure with high‐intensity UVA irradiation. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Correlation of the Corneal Collagen Cross-Linking Demarcation Line Using Confocal Microscopy and Anterior Segment Optical Coherence Tomography in Keratoconic Patients

PURPOSE To evaluate and compare the depth of the corneal stromal demarcation line after corneal collagen cross-linking (CXL) using 2 different methods: confocal microscopy and anterior segment optical coherence tomography (AS OCT). DESIGN Prospective, comparative, interventional case series. METHODS Seventeen patients (18 eyes) with progressive keratoconus were enrolled. All patients underwent uneventful CXL treatment according to the Dresden protocol. One month after surgery, corneal stromal demarcation line depth was measured in all patients by 2 independent observers using confocal microscopy and AS OCT. RESULTS Mean corneal stromal demarcation line depth measured using confocal microscopy by the first observer was 306.22 ± 51.54 μm (range, 245 to 417 μm) and that measured by the second observer was 303.5 ± 46.98 μm (range, 240 to 390 μm). The same measurements using AS OCT were 300.67 ± 41.56 μm (range, 240 to 385 μm) and 295.72 ± 41.01 μm (range, 228 to 380 μm) for the first and second observer, respectively. Pairwise comparisons did not reveal any statistically significant difference between confocal microscopy and AS OCT measurements for both observers (P = .3219 for the first observer and P = .1731 for the second observer). CONCLUSIONS Both confocal microscopy and AS OCT have similar results in evaluating the depth of the corneal stromal demarcation line after CXL.

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.

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/mm2 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.

Safety of high-intensity corneal collagen crosslinking

Purpose To evaluate the safety of a new high‐intensity corneal collagen crosslinking (CXL) treatment protocol for keratoconus. Setting Vardinoyiannion Eye Institute of Crete, Faculty of Medicine, University of Crete, Heraklion, Crete, Greece. Design Prospective interventional case series. Methods Patients with progressive keratoconus had CXL using a new treatment protocol with 9 mW/cm2 irradiance for duration of 10 minutes. The rate of reepithelialization, endothelial cell density (ECD), corrected distance visual acuity (CDVA), and steep and flat keratometry (K) values were evaluated preoperatively and 3 months postoperatively. Results Nine patients (10 eyes) were enrolled. No intraoperative or early postoperative complications were observed in any patient. The ECD did not change significantly 3 months postoperatively (P=.169). The CDVA improved from 0.19 logMAR ± 0.20 (SD) preoperatively to 0.10 ± 0.16 logMAR 3 months postoperatively; however, the improvement did not attain significance (P=.141). No eye lost lines of CDVA. The mean steep K readings decreased significantly from 48.04 ± 2.57 diopters (D) preoperatively to 46.51 ± 2.81 D 3 months postoperatively (P=.047); the mean flat K readings did not change significantly postoperatively (P=.285). Conclusions Corneal collagen crosslinking at 9 mW/cm2 irradiance for 10 minutes did not cause significant changes in ECD or intraoperative or early postoperative complications. None patient lost a line of CDVA 3 months after the procedure. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Combined topical application of a regenerative agent with a bandage contact lens for the treatment of persistent epithelial defects.

Purpose: The aim of this study was to report 3 cases of persistent epithelial defects (PEDs) successfully treated with the combined topical application of a regenerative agent (RGTA; Cacicol20, OTR3, Paris, France) with a bandage contact lens (BCL). Methods: This is a case series. Results: Three patients suffering from a PED for 4–8 weeks and unresponsive to conventional therapy were treated with the combined application of an RGTA (Cacicol20) and a silicone hydrogel BCL. The PED healed in all patients after 4–21 days, and no side effects were noted. Conclusions: The combination of an RGTA (Cacicol20) with a BCL seems to be an effective treatment for PED.

Corneal Stromal Demarcation Line Depth Following Standard and a Modified High Intensity Corneal Cross-linking Protocol

PURPOSE To compare the corneal stromal demarcation line depth using anterior segment optical coherence tomography (AS-OCT) after corneal cross-linking (CXL) using two different treatment protocols: the standard Dresden protocol (30 minutes with 3 mW/cm(2)) and a modified high intensity protocol (7 minutes with 18 mW/cm(2)), corresponding to a total surface dose of 5.4 and 7.5 J/cm(2), respectively. METHODS This prospective, comparative, interventional case series included 29 keratoconic patients (32 eyes). All patients underwent CXL using the same high intensity ultraviolet-A (UV-A) irradiation device (CCL-365; Peschke Meditrade GmbH, Huenenberg, Switzerland). Sixteen eyes were treated for 30 minutes with 3 mW/cm(2) according to the standard Dresden protocol, whereas 16 eyes were treated with a novel modified high intensity CXL protocol for 7 minutes with 18 mW/cm(2) of UV-A irradiation intensity. One month postoperatively, corneal stromal demarcation line depth was measured by two independent observers using AS-OCT. RESULTS There was no significant difference in corneal stromal demarcation line depth between observer measurements for both groups (P = .645, Dresden protocol group; P = .715, high intensity group). Mean corneal stromal demarcation line depth was 341.81 ± 47.02 µm for the Dresden protocol group and 313.37 ± 48.85 µm for the high intensity protocol group. There was no statistically significant difference (P = .104) in the corneal stromal demarcation line depth between the two groups. Mean endothelial cell density did not change significantly in either group (P = .090, Dresden protocol group; P = .103, high intensity group). No intraoperative or postoperative complications were noted. CONCLUSIONS Corneal stromal demarcation line depth using UV-A irradiance with 3 mW/cm(2) for 30 minutes and 18 mW/cm(2) for 7 minutes was similar. It seems that the current modified accelerated CXL protocol provided the same treatment depth as the standard Dresden protocol.

Effect of the Regenerative Agent Poly(Carboxymethylglucose Sulfate) on Corneal Wound Healing After Corneal Cross-Linking for Keratoconus.

Purpose: To evaluate the effect of a regenerative agent (RGTA) [Cacicol20—poly(carboxymethyl glucose sulfate); OTR3, Paris, France] on corneal reepithelialization and pain after corneal cross-linking (CXL) for keratoconus. Methods: In this prospective comparative (contralateral) clinical study, patients with bilateral progressive keratoconus underwent CXL treatment. The corneal epithelium during CXL was removed using transepithelial phototherapeutic keratectomy (Cretan protocol). One eye of each patient was randomly instilled with an RGTA (Cacicol20) once a day (study group), whereas the fellow eye was instilled with artificial tears (control group). Patients were examined daily until complete reepithelialization. Postoperative examinations included slit-lamp biomicroscopy to assess the epithelial defect size and subjective evaluation of pain. Results: The study enrolled 18 patients (36 eyes). The mean epithelial defect size for study and control groups was 19.6 ± 4.2 mm2 versus 21.5 ± 2.8 mm2, respectively, at day 1 (P = 0.019) and 6.4 ± 3.4 mm2 versus 7.9 ± 4.3 mm2, respectively, at day 2 (P = 0.014). At day 3 postoperatively, 61.1% of study eyes were fully reepithelialized, compared with 11.1% of control eyes (P = 0.002). Conclusions: RGTA (Cacicol20) instillation seems to result in faster corneal reepithelialization after CXL in this study. However, there was no significant effect in subjective pain/discomfort.

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 &mgr;m to 243 &mgr;m) 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.

Topography-based keratoconus progression after corneal collagen crosslinking.

Purpose: The aim of this study was to report 2 cases with topographic keratoconus progression despite stability for a long-term period after corneal collagen crosslinking (CXL). Methods: This is a case report. Results: Two patients with progressive keratoconus underwent CXL treatment. Four and 5 years postoperatively, a topographic examination revealed an increase in the keratometric values indicating keratoconus progression. Conclusions: Post-CXL, topographic keratoconus progression may occur several years after, despite stability for a long-term period.