Standard Corneal Collagen Cross-linking Research Articles

Comparative analysis of clinical and functional parameters in patients with stable stage II-III keratoconus after implantation of corneal segments and fitting of scleral rigid contact lenses

This study compares the effect of implantation of intrastromal corneal ring segment (ICRS) and fitting of individual scleral rigid contact lenses (RCLs) on visual functions in patients with stage II-III KC after previously performed corneal collagen cross-linking. The Helmholtz National Medical Research Center of Eye Diseases examined and treated 34 patients (69 eyes) aged 18 to 33 years with stage II-III KC. The study included patients who had previously undergone standard corneal collagen cross-linking. Depending on the type of optical correction, the patients were divided into two groups: patients in group 1 underwent ICRS implantation using a femtosecond laser; patients in group 2 were fitted with individual scleral RCLs. Improvement in clinical and functional parameters was observed in both groups. A higher clinical and functional result was achieved in group 2. For patients with stable stage II-III KC, it is advisable to recommend fitting of individual scleral RCLs for visual rehabilitation.

Comparison of Accelerated and Standard Corneal Collagen Cross-Linking Treatments in Experimental Fungal Keratitis for Aspergillus fumigatus.

Introduction To compare accelerated and standard corneal collagen cross-linking (CXL) treatments in experimental Aspergillus keratitis models. Methods Twenty-six New Zealand rabbits were divided into two groups: a 1% voriconazole combined with standard CXL group, and a 1% voriconazole combined with accelerated CXL group. The ulcer area, corneal opacity, and corneal neovascularization score were measured via slit-lamp imaging, and the corneal and corneal epithelial thickness and ulcer depth were measured via anterior segment optical coherence tomography (AS-OCT). The duration of the hyphae was observed via in vivo confocal microscopy (IVCM), and the cornea was taken for pathological examination after modeling and at the end of the study to determine the hyphae and corneal repair. The observation times were as follows: at successful modeling (day 0) and at 1, 4, 7, 14, 21, and 28 days after the intervention. Results The area and depth of the ulcer decreased in both groups after CXL (all P < 0.05). Interestingly, the ulcer area in the accelerated CXL group still tended to increase on the first day after CXL although the difference was not statistically significant (P=0.6649). On the 21st and 28th days after CXL, the ulcer area and depth of the standard CXL group were larger and deeper than those of the accelerated CXL group (all P < 0.05). The ulcer healing time in the accelerated CXL group was 18.67 ± 6.21 days, while that in the standard CXL group was 23.55 ± 4.72 days, and the difference was statistically significant (P=0.0475). Conclusions Both accelerated and standard CXL can significantly inhibit the progression of Aspergillus keratitis corneal ulcers and promote ulcer healing. The accelerated CXL was superior to the standard CXL, which could control infection faster and promote ulcer healing. However, it is important to note that there may be a risk of early deterioration of the ulcer with accelerated CXL.

Three-year follow-up of accelerated versus standard corneal cross-linking in paediatric Keratoconus.

Standard corneal collagen cross-linking (S-CXL) is an effective treatment to arrest Keratoconus (KC) progression in children. Less is known on the long-term efficacy of accelerated CXL (A-CXL) in paediatric populations. A historical cohort analysis of paediatric patients (≤18 years) with KC who underwent S-CXL and A-CXL at two tertiary referral centres in Israel between 2010-2017. Preoperative and 3-year postoperative evaluation included changes in visual acuity (best spectacle corrected [BSCVA]) and uncorrected [UCVA]), refractive errors, and keratometric data. Ninety-three eyes of 93 patients were analysed (A-CXL: n = 39; S-CXL: n = 54). Baseline characteristics were similar between groups. Both groups showed a significant improvement in visual acuity compared to baseline (S-CXL: 0.810-0.602 LogMAR UCVA; A-CXL: 0.890-0.306 LogMAR UCVA, p < 0.05 for both). Improvement in BSCVA and UCVA following A-CXL was non-inferior to S-CXL (< ± 0.2 LogMAR). Kmax decreased by a mean of 0.98 ± 5.56 dioptres following S-CXL (p = 0.02) and by 1.48 ± 8.4 dioptres following A-CXL (p = 0.015). Thinnest pachymetry decreased following both treatments (S-CXL: by 26.8 ± 40.7 µm, p = 0.001, A-CXL: by 10.2 ± 13.4 µm, p = 0.028), the difference between groups was within the non-inferiority margin (< ± 10 µm). Paediatric patients followed for three years after A-CXL showed improved visual function, reduced corneal astigmatism and Kmax, and decreased thinnest corneal thickness. A-CXL was non-inferior to S-CXL at three years in terms of best-corrected and uncorrected visual acuity, thinnest pachymetry, and astigmatism. For Kmax, non-inferiority could not be concluded.

Assessment of two-year clinical outcomes after keratoconus treatment using two different crosslinking protocols.

This study aims to compare the long-term outcomes of standard corneal collagen crosslinking with accelerated corneal collagen crosslinking (CXL) for progressive keratoconus. This prospective, comparative study included 79 eyes with progressive keratoconus, which were randomly assigned: 42 eyes received a standard CXL procedure, and 37 eyes were treated with the accelerated CXL protocol. We evaluated the following parameters, before the procedure and 1 month, 6 months, 12 months and 24 months postoperatively: best corrected visual acuity (BCVA), manifest refraction spherical equivalent (MRSE), cylindrical values, corneal dioptric powers on the steepest meridian (Kmax), central corneal thickness (CCT); demarcation line depth (DLD) preoperatively and 1 month after the CXL procedure. The BCVA, MRSE, cylindrical values, Kmax, CCT improved significantly, after both the accelerated and the standard CXL procedure. Throughout the 24-months follow-up, BCVA improvement was achieved sooner in the accelerated group (after 1 month, vs. after 3 months). However, there were no statistically significant differences between the two groups in these aspects. The DLD-to-CCT was significantly greater in the standard group (66% vs. 62%, p = 0.02). Standard and accelerated CXL are effective in stabilizing keratoconus progression in the long term. In clinical practice, the accelerated protocol has the added benefit of a faster visual recovery, in addition to the known reduced treatment time and increased comfort.

Стандартный кросслинкинг роговичного коллагена в сравнении с одномоментной топографически ориентированной фоторефракционной кератэктомией в сочетании с ускоренным кросслинкингом роговичного коллагена в лечении кератоконуса I-II стадии

Стандартный кросслинкинг роговичного коллагена в сравнении с одномоментной топографически ориентированной фоторефракционной кератэктомией в сочетании с ускоренным кросслинкингом роговичного коллагена в лечении кератоконуса I-II стадии

Corneal endothelial changes evaluation using specular microscope following collagen cross-linking in treatment of keratoconus

Objective The aim of this study was to evaluate the corneal endothelial changes following corneal collagen cross-linking treatment of keratoconus using a specular microscope.Patients and methods The study included 30 eyes of 30 patients with keratoconus, comprsing 16 males and 14 females, with a mean age of 28 years. Patients had a standard corneal collagen cross-linking after removal of the corneal epithelium. They were evaluated before and 1 month after the procedure using the specular microscope.Results The mean preoperative central corneal thickness of the patients was 477.5±35.57 µm, and at 1 month postoperatively, it was 477.9±36.88 µm, with no statistically significant change (P=0.7821). The mean preoperative value of cell density was 2963.1±364.1 cells/mm2 and became 2956.96±363 cells/mm2 1 month postoperatively, with no statistically significant change (P=0.7091). The mean preoperative coefficient of variation value was 36.3±5.9%, whereas 1 month postoperatively, it became 36.2±5.6%, with no statistically significant change (P=0.6951). The mean preoperative value of hexagonal cells was 49.93±7.9% and became 48.5±7.3% 1 month postoperatively, with no statistically significant change (P=0.2078).Conclusion There were no significant changes in human corneal endothelial parameters, as evaluated with the specular microscope, following cross-linking in keratoconic eyes.

Sterile keratitis following standard corneal collagen crosslinking: A case series and literature review

Standard corneal collagen crosslinking (S-CXL) is a safe, approved procedure, but it may result in severe pain, early vision loss and possible complications, such as infectious or sterile keratitis, in some cases. We describe four cases of sterile infiltrates after uneventful S-CXL for keratoconus, from diagnosis to medical management with six months of follow-up, reporting their pathophysiological features, and comparing our findings with published reports. We discuss various possibilities for diagnosing sterile infiltration more rapidly. In terms of the pathophysiology of sterile infiltrate formation, we separated our patients into two types, one with sterile infiltrate from an antigen reaction and the other with sterile infiltrate due to excessive scarring. Early local steroid treatment resulted in a good visual outcome in our cases.

Accelerated versus standard corneal collagen cross-linking in pediatric keratoconus patients: 24 months follow-up results

To compare the 24 month visual, refractive, topographic and aberrometric results of the accelerated and standard corneal collagen cross-linking (CXL) in pediatric keratoconus patients. 87 eyes of 64 consecutive keratoconus patients under 18 years old with 24 month follow-up period following standard or accelerated CXL were included. 38 eyes received standard CXL (3 Mw/cm2, 30 min), while 49 eyes had accelerated CXL (9 mW/cm2, 10 min). Changes in the uncorrected (UCVA) and best corrected visual acuity (BCVA), spherical equivalent (SE), manifest astigmatism (MA), corneal topographic parameters, and corneal aberrations such as spherical aberration (SA), high order aberrations (HOAs), horizontal and vertical coma were evaluated. Corneal haze was graded and progression rate was assessed. The difference between baseline and 24 months postoperative UCVA, BCVA, SimK (keratometry)-1, SimK-2, Kmax, and the corneal aberrations were not significantly different between the two groups (p > 0.05 for all). The mean reduction in thinnest corneal pachymetry from baseline to 24 months after CXL was higher in accelerated CXL group (p = 0.007). The progression rate was 13.1% in standard and 16.3% in accelerated group (p = 0.754). There were no differences in the grade of corneal haze between the two groups (p = 0.249). No complications were observed in the both groups. The 24 month results of accelerated and standard CXL revealed that, the efficacy and safety of accelerated CXL were the same with standard CXL in pediatric keratoconus patients. As being a rapid procedure, accelerated CXL appears to be more benefical for pediatric patients.

Long-term efficacy and safety after corneal collagen crosslinking in pediatric patients: Three-year follow-up.

To evaluate the effectiveness of standard corneal collagen crosslinking for children with progressive keratoconus. Prospective study including 26 eyes of 26 patients younger than 18 years old with progressive keratoconus at Oftalmosalud Instituto de Ojos, Lima, Peru. Standard epi-off corneal crosslinking was performed in all eyes between January 2012 and January 2013. Pre- and postoperative evaluation (at 3 years) included uncorrected and best-corrected visual acuity and Scheimpflug analysis. Crosslinking failure was defined as an increase in maximum keratometry (Kmax) of more than 1 diopter after 1 year or more. Mean uncorrected visual acuity improvement was 0.24 LogMAR (p = 0.07) and mean best-corrected visual acuity improvement was 0.18 LogMAR (p = 0.01). None of the eyes lost more than one line in the best-corrected visual acuity. Four eyes (15.38%) lost two lines in the uncorrected visual acuity at 3 years postoperative. Mean steeper keratometry improvement was 1.14 diopters (p = 0.60). Progression rate was 23.07%. Standard epi-off corneal collagen crosslinking is safe and effective to halt the progression of the keratoconus with significant improvement in the best-corrected visual acuity at 3-year follow-up.

Transepithelial versus standard corneal collagen cross-linking for treatment of grades 1–3 keratoconus

Purpose The purpose of this article was to assess the safety and efficacy of transepithelial corneal collagen cross-linking (epithelial on) versus standard (epithelial off) technique in halting the progression of keratoconus. Patients and methods A prospective nonrandomized interventional comparative standard technique was conducted, which divided 40 patients into two groups: in group A, 34 eyes of 24 patients were enrolled and treated by transepithelial cross-linking, and in group B, 28 keratoconus eyes of 16 patients were included and treated by the standard technique. In group A, a solution of riboflavin 0.1%, dextran T500, trometamol, and EDTA (trans-Ribo) was instilled. In group B the epithelium was removed and riboflavin 0.1 solution (10 mg of riboflavin-5-phosphate in a 20% dextran T500 10 ml solution Ricrolin was instilled. Ultraviolet A irradiation (Food and Drug Administration approval) Avedro system was used with total energy 7.2, power intensity 30 mW, induction time 10 min, ultraviolet time continuous 4 min, and ultraviolet time pulse 8 min, but in transepithelial cross-linking, the intensity was 45 mW. Preoperative and postoperative assessments were performed at baseline and 3, 6, and 12 months postoperatively. Results Group A showed statistically highly significant differences between mean uncorrected visual acuity (UCVA) and mean UCVA at first, sixth, and 12th months postoperatively. In group B, there were statistically highly significant differences between mean UCVA preoperatively and the mean UCVA at first, sixth, and 12th months postoperatively. In group A, there were statistically significant differences between mean Km (mean k power) preoperatively and mean Km at the first and at 12th months postoperatively, whereas in group B, there were statistically significant differences between mean Km preoperatively and the mean Km at first month and statistically insignificant difference at third, sixth, and 12th months postoperatively. Conclusion Both epithelial-on and epithelial-off techniques appeared to correct best-corrected visual acuity but epithelial-off technique was more effective in reduction of KM, astigmatism, Q-value and anterior elevation. Moreover, epithelial off showed to halt keratoconus progression more than epithelial-on technique.

Efficacy and safety of transepithelial corneal collagen crosslinking surgery versus standard corneal collagen crosslinking surgery for keratoconus: a meta-analysis of randomized controlled trials

BackgroundThe aim of this study was to evaluate the efficacy and safety of transepithelial corneal collagen crosslinking (transepithelial CXL) versus standard corneal collagen crosslinking (epithelium-off CXL) on keratoconus.MethodsEligible studies were identified by systematically searching PubMed, the Cochrane Library and Embase. Topographic parameters, corrected distant visual acuity (CDVA), uncorrected distant visual acuity (UDVA), and corneal thickness (CT) were assessed by the pooled weighted mean differences (WMDs) of the change from baseline to the end of follow up. Quality was assessed according to Cochrane handbook. And we used Review Manager to analysis the included trials.ResultsThree trials involving 244 eyes were evaluated, with 111 eyes in the standard CXL group and 133 eyes in the transepithelial CXL group. The pooled results showed that there were significant differences between the two groups in maximum keratometry (mean difference = 1.05D, 95% CI 0.19 to 1.92, P = 0.02)),and the standard CXL is more effective in decreasing the maximum keratometry at least 12 months after operation; the transepithelial CXL group gained more improvement in CDVA (mean difference = −0.07, 95% CI -0.12 to −0.02, P = 0.007);there were no significant differences in uncorrected distant visual acuity (UDVA) between the two groups (mean difference = −0.03, 95% CI -0.20 to 0.15, P = 0.75). A similar change was found in corneal thickness (mean difference = 4.35, 95% CI -0.43 to 9.13, P = 0.07)).ConclusionsThe standard CXL is more effective in decreasing the maximum keratometry than the transepithelial CXL; the transepithelial CXL provided favorable visual outcomes; they both exhibit similar safety.

Corneal Cross-Linking With Verteporfin and Nonthermal Laser Therapy.

To test whether verteporfin with a nonthermal laser increases corneal mechanical stiffness and resistance to enzymatic degradation ex vivo. Thirty human corneas (n = 5 per group) were treated with verteporfin alone (V), irradiated with nonthermal laser therapy (689 nm) alone (NTL), or received combined treatment of verteporfin with nonthermal laser therapy for 1 sequence (V+NTL1) or 6 sequences (V+NTL6) of 1 minute of NTL exposure. Positive controls were pretreated with 0.1% riboflavin/20% dextran every 3 to 5 minutes for 30 minutes and irradiated with ultraviolet light type A (λ = 370 nm, irradiance = 3 mW/cm) for 30 minutes using the Dresden protocol (R+UVA). Untreated corneas were used as negative controls. The corneal biomechanical properties were measured with enzymatic digestion, compression, creep, and tensile strength testing. V+NTL6- and R+UVA-treated corneas acquired higher rigidity and more pronounced curvature than untreated corneas. The stress-strain tests showed that V+NTL6 and R+UVA corneas became significantly stiffer than controls (P < 0.005). The V+NTL6 group seemed to be slightly stiffer than the R+UVA group, although the differences were not statistically significant. V+NTL6 corneas were found to have a significantly lower absolute creep rate (-1.87 vs. -3.46, P < 0.05) and significantly higher maximum stress values (7.67 vs. 3.02 P < 0.05) compared with untreated corneas. Verteporfin-NTL (V+NTL6) increases corneal mechanical stiffness and resistance to enzymatic collagenase degradation. Although a clinical study is needed, our results suggest that V+NTL6 induces corneal cross-linking and corneal biomechanical changes that are similar to those induced by standard corneal collagen cross-linking.

A case of in vivo iontophoresis-assisted corneal collagen cross-linking for keratoconus: An immunohistochemical study

The standard corneal collagen cross-linking (CXL), that includes the removal of corneal epithelium to permit adequate penetration of riboflavin in the stroma, is an established procedure to halting keratoconus progression. However, as epithelial removal may cause postoperative pain and an increased risk of corneal infection, new therapeutic approaches have been proposed. Iontophoresis is a recently developed non-invasive technique which provides the use of electrical current during CXL to enhance transepithelial penetration of riboflavin into the corneal stroma. Here, we describe for the first time the morphological changes of the corneal stromal compartment in a patient with keratoconus who underwent in vivo iontophoresis-assisted CXL (ionto-CXL) before full-thickness corneal transplantation. Immunohistochemistry for type I collagen and CD34 was performed to investigate the stromal distribution of collagen fibers and keratocytes, respectively. The histology of ionto-CXL-treated keratoconic cornea, collected 6 months after the intervention, was compared with that of healthy corneas and either untreated or standard CXL-treated keratoconic corneas. An attempt to restore a normal stromal architecture was observed in the ionto-CXL-treated cornea compared with untreated keratoconic corneas. In particular, the ionto-CXL-treated cornea showed a parallel distribution of type I collagen fibers, although fiber interweaving appeared less organized than in healthy corneas and standard CXL-treated keratoconic corneas. Moreover, the distribution of CD34-positive keratocytes was improved in keratoconic corneas following ionto-CXL treatment, though a scattered CD34 immunoreactivity was still noticeable in the subepithelial stroma. This study provides histological evidence that ionto-CXL may represent a non-invasive alternative in the management of progressive keratoconus in adults.

Сравнительный анализ клинико-функциональных и морфологических результатов фемтосекундного, трансэпителиального и стандартного кросслинкинга роговичного коллагена

Сравнительный анализ клинико-функциональных и морфологических результатов фемтосекундного, трансэпителиального и стандартного кросслинкинга роговичного коллагена

Effect of a Matrix Therapy Agent on Corneal Epithelial Healing After Standard Collagen Cross-linking in Patients With Keratoconus: A Randomized Clinical Trial.

Corneal abrasions are frequent after standard (epithelium-off [epi-off]) corneal collagen cross-linking (CXL) in patients with progressive keratoconus. A new matrix therapy agent (ReGeneraTing Agent [RGTA]) has been developed to promote corneal wound healing. To assess the effect of the new type of matrix therapy agent on corneal wound healing after epi-off CXL in patients with keratoconus. This double-masked randomized clinical trial enrolled 40 patients with keratoconus undergoing epi-off CXL from July 18, 2014, to October 21, 2015, when the last follow-up was completed. The analysis of the intention-to-treat population was performed at the Department of Clinical Pharmacology in cooperation with the Center for Medical Physics and Biomedical Engineering and the Department of Ophthalmology and Optometry of the Medical University of Vienna. Patients were randomized to receive the matrix therapy agent or hyaluronic acid-containing eyedrops, 0.1%, every other day starting immediately after surgery. The size of the corneal defect was measured using ultrahigh-resolution optical coherence tomography (OCT) and slitlamp photography (SLP) with fluorescein staining. Corneal wound healing rate, defined as the size of the defect over time. Among the 40 patients undergoing epi-off CXL (31 men; 9 women; mean [SD] age, 31 [10] years), wound healing was significantly faster in the matrix therapy agent group compared with the hyaluronic acid group (4.4 vs 6.1 days; mean difference, 1.7 days; 95% CI, 0.25-3.15 days; P = .008). The defect size was smaller in the matrix therapy agent group than in the hyaluronic acid group as measured with OCT (12.4 vs 23.9 mm2; mean difference, 11.6 mm2; 95% CI, 0.8-23.5 mm2; P = .045) and SLP (11.9 vs 23.5 mm2; mean difference, 11. 6 mm2; 95% CI, 1.3-22.9 mm2; P = .03). A correlation between the defect size measured with OCT and SLP was found (r = 0.89; P < .001). No ocular or serious adverse events occurred. Use of a new matrix therapy agent appears to improve corneal wound healing after CXL in patients with keratoconus. Monitoring of corneal wound healing using ultrahigh-resolution OCT might be an attractive alternative to SLP because OCT provides an objective and 3-dimensional evaluation of the corneal defect. clinicaltrials.gov Identifier: NCT02119039.

Corneal Collagen Cross-linking in Advanced Keratoconus: A 4-Year Follow-up Study.

To analyze the safety and efficacy of standard corneal collagen cross-linking (CXL) in advanced cases of progressive keratoconus after 4 years of follow-up. A retrospective case series of patients with advanced progressive keratoconus (stages 3 and 4 of Amsler-Krumeich classification) underwent standard CXL treatment. The parameters examined were changes in uncorrected visual acuity (UDVA), corrected visual acuity (CDVA), keratometry values (mean, flat, steep, and apical), pachymetry, and endothelial cell count at the baseline and at 12, 24, and 48 months postoperatively. Forty eyes of 40 patients were enrolled in the study. The mean patient age was 22.5 years (range: 15 to 37 years). Both mean UDVA and CDVA remained stable during the time points; no statistically significant change was noted. Although a slight reduction was observed in all keratometric readings, a statistically significant reduction was only reached in the apical keratometry (P = .037) at 4 years after CXL. A significant reduction in the corneal thickness was also found (ultrasonic: 388 ± 49 to 379 ± 48 μm; slit-scanning: 362 ± 48 to 353 ± 51 μm); however, this change was likely not clinically meaningful. Endothelial cell count was not significantly different at the end of the study. Treatment failure or progression was noted in two patients (5%) over the follow-up period. Standard CXL treatment was safe and able to stabilize both visual acuity and topographic parameters at 4 years of follow-up in eyes with advanced keratoconus. [J Refract Surg. 2016;32(7):459-464.].

Accelerated versus standard corneal collagen crosslinking combined with same day phototherapeutic keratectomy and single intrastromal ring segment implantation for keratoconus

AimTo compare the results of same day transepithelial phototherapeutic keratectomy (t-PTK) and single inferior intracorneal ring segment (ICRS) combined with standard versus accelerated corneal collagen crosslinking (CXL) for keratoconus.MethodsAll consecutive...

BAC-EDTA transepithelial riboflavin-UVA crosslinking has greater biomechanical stiffening effect than standard epithelium-off in rabbit corneas

Studies suggest that standard corneal collagen crosslinking (CXL) is a safe and effective treatment to stiffen the cornea for keratoconus and other ectatic corneal disorders. The purpose of the present study was to compare the biomechanical effects of transepithelial benzalkonium chloride-EDTA (BAC-EDTA) riboflavin-UVA crosslinking to standard epithelium-off riboflavin-UVA crosslinking in a rabbit model. Corneal stiffness was quantified using optical coherence elastography at two months after treatment. The mean lateral-to-axial displacement ratio for the BAC-EDTA transepithelial CXL group was lower (greater stiffness) [0.062 ± 0.042, mean ± SD] than epithelium-off CXL (mean ± SD: 0.065 ± 0.045) or untreated control eyes (0.069 ± 0.044). Using ANOVA with Tukey correction, a statistically significant difference was found between the BAC-EDTA transepithelial CXL group and standard epithelium-off CXL (p = 0.0019) or the untreated control (p < 0.0001) groups. A graph of the probability density functions for biomechanical stiffness also showed a greater shift in stiffening in the BAC-EDTA transepithelial CXL group than the standard epithelium-off CXL or untreated control group. These results demonstrated that the biomechanical stiffening effect produced by BAC-EDTA transepithelial CXL was greater than that produced by standard epithelium-off CXL in a rabbit model.

Changes in Forward and Backward Light Scatter in Keratoconus Resulting From Corneal Cross-Linking.

To study the forward and backward light scatter in keratoconic corneas before and after cross-linking. An institutional, prospective, cross-sectional study was conducted. This study includes 35 eyes of 25 patients with keratoconus scheduled for either standard corneal collagen cross-linking with riboflavin (CXL) or transepithelial corneal cross-linking (TE-CXL). A group of 26 healthy myopic eyes from 26 prerefractive patients was included as normal reference. Before and 6 months after cross-linking, forward light scatter was measured using the compensation comparison method, whereas backward light scatter was measured using Scheimpflug imaging. In keratoconic eyes, backward light scatter originating from the corneal stroma was [mean (SD)] 27.2% (8.2%) higher than in the normal eyes (P < 0.001). In the anterior stroma, this increased backscatter was significantly correlated with the maximum corneal curvature Kmax as a measure of keratoconus severity (Pearson ρ = 0.582, P = 0.003). For forward light scatter, no significant difference was seen between the normal and keratoconus groups, nor was there any correlation with keratoconus severity. After CXL, the backscatter increased significantly by [mean (SD)] 33.0% (9.5%) in the entire corneal stroma (P = 0.001), whereas for TE-CXL, no significant increase was seen. Forward scatter increased significantly by [mean (SD)] 0.10 (0.10) log units (P = 0.009) and 0.09 (0.10) log units (P = 0.003) for CXL and TE-CXL, respectively, which is near the detection limit for an average patient. Unlike TE-CXL, CXL increases the already-elevated stromal backscatter in keratoconus. Forward scatter increases equally for both techniques.

Corneal melting after collagen cross-linking for keratoconus: a case report

IntroductionCorneal collagen cross-linking is a rather new technique that uses riboflavin and ultraviolet A light for collagen fiber stabilization in keratoconus corneas. Other than reversible side effects, the preliminary results of corneal collagen cross-linking studies suggest that it is a rather safe technique. In this report, we demonstrate a case of corneal melting after corneal collagen cross-linking for keratoconus corneas associated with an acute inflammatory response.Case presentationA 23-year-old Caucasian man with keratoconus cornea stage 1 to 2 underwent uneventful corneal collagen cross-linking treatment according to the Dresden protocol. The next day the patient had intense photophobia, watering and redness of the eye, and his visual acuity was limited to counting fingers. Slit lamp biomicroscopy revealed severe corneal haze accompanied by non-specific endothelial precipitates following an acute inflammatory response. Mild inflammation could be detected in the anterior chamber. Moreover, the re-epithelialization process could barely be detected. His corneal state gradually deteriorated, resulting in descemetocele and finally perforation.ConclusionIn this report, we present a case of a patient with corneal melting after standard corneal collagen cross-linking treatment for keratoconus corneas following an acute inflammatory response. Despite modifying postoperative treatment, elaboration of all apparent associated causes by the treating physicians and undergoing extensive laboratory testing, the patient developed descemetocele, which led to perforation. Our report suggests that further research is necessary regarding the safety of corneal collagen cross-linking in keratoconus corneas.