Transepithelial Corneal Collagen Cross-linking Research Articles

Transepithelial (Epi-on) Corneal Collagen Cross-linking with Supplemental Oxygen as a Treatment for Patients with Progressive Keratoconus in Oman: 1-year Results

Transepithelial (Epi-on) Corneal Collagen Cross-linking with Supplemental Oxygen as a Treatment for Patients with Progressive Keratoconus in Oman: 1-year Results

The effect of transepithelial corneal collagen cross-linking treatment on optical quality of the cornea in keratoconus: 12-month clinical results.

To evaluate the effect of transepithelial corneal collagen crosslinking (CXL) treatment on the optical performance of the cornea at 12-month follow-up after CXL in patients with progressive keratoconus. One hundred and ten eyes of 67 patients were included. The following corneal optical aberrations over the 4-mm-diameter pupil were recorded via Sirius dual-scanning corneal tomography: total, anterior and posterior amount of corneal higher order aberrations [HOAs], vertical coma, horizontal coma, vertical trefoil, oblique trefoil, and spherical aberration, and Strehl ratio of point spread function (PSF). There were significant improvements in mean root mean square error values for corneal total HOA, total coma, anterior HOA, anterior coma, and vertical coma following CXL (P > 0.05, for all). No significant changes were found in the posterior aberometric parameters.PSF value did not change after CXL (P > 0.05). The corneal topographic measurements not revealed a change in the mean simulated keratometry-1, simulated keratometry-2, and maximum keratometry compared with the baseline measurements (P > 0.05, for all). At 12months, there was a significant improvement in the uncorrected (UCVA) and best corrected (BCVA) visual acuity (P < 0.001, both). Most corneal aberrations correlated significantly with postoperative BCVA, but changes in HOAs were not statistically associated with improvements in visual acuity. Transepithelial CXL was effective in stabilizing the keratometric indices and improving the most corneal aberrations in keratoconic eyes 1year after the procedure. While the healing effect on aberrations after CXL was in total and anterior parameters, no significant changes were observed in the posterior surface. In addition, it was observed that transepithelial CXL treatment did not cause a significant change in PSF distribution data.

Topography-guided transepithelial corneal collagen cross-linking by sequential ultraviolet A irradiation in different diameters for progressive keratoconus in adults

Objective: To compare the efficacy and safety of a novel customized topography-guided transepithelial corneal collagen cross-linking (TG-CXL) procedure by sequential ultraviolet A irradiation in different diameters and conventional transepithelial corneal collagen cross-linking (TE-CXL) in adult patients with progressive keratoconus. Methods: A prospective cohort study was conducted. Adult patients diagnosed with progressive keratoconus in the Affiliated Xiamen Eye Center of Xiamen University were continuously recruited and randomly assigned to receive the TG-CXL or TE-CXL procedure from March 2020 to March 2021. Patients in the TE-CXL group were irradiated in the central 9-mm zone of the cornea (total energy, 7.2 J/cm2; irradiance, 45 mW/cm2), while patients in the TG-CXL group were first irradiated with the protocol used in the TE-CXL group, and further irradiated in the central 6-mm zone (total energy, 3.6 J/cm2; irradiance, 9 mW/cm2). The subjective symptom of pain and corneal fluorescein sodium staining were scored within postoperative 3 days. Slit lamp examination, measurements of uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), corneal topography, anterior segment optical coherence tomography, in vivo corneal confocal microscopy, corneal endothelial cell count, and non-contact tonometry were performed before surgery and at 3, 6, and 12 months after surgery. Results: A total of 66 patients were enrolled (mean age, 23.0±3.3 years old), with 33 patients (33 eyes) in each group. No statistically significant differences were found in age, gender, and maximum keratometry (Kmax) between the two groups (P>0.05). On day 1 after surgery, the average pain score of the TG-CXL group (2.21±0.45) was significantly higher than that of the TE-CXL group (1.32±0.33) (P<0.05). The pain was rapidly alleviated in both groups on days 2 and 3. On days 1 and 2, the corneal fluorescein sodium staining scores in the TG-CXL group (4.15±0.83 and 2.21±0.60, respectively) were significantly higher than those in the TE-CXL group (1.76±0.56 and 0.85±0.51, respectively, P<0.001), while there was no significant difference between the two groups at day3 (P=0.184). The UCVA and BCVA of the TG-CXL group at 3, 6, and 12 months after surgery were significantly improved when compared with the baseline. At 3, 6, and 12 months, the BCVA (LogMAR) of the TG-CXL group (0.21±0.15, 0.22±0.16, and 0.22±0.16, respectively) were significantly improved when compared with those of the TE-CXL group(0.32±0.15, 0.34±0.15, and 0.36±0.16, respectively, P<0.01). However, there was no significant difference in UCVA between groups at any time point after surgery (P>0.05). The spherical and cylindrical power values of the TG-CXL group were improved when compared with the baseline (P<0.05). However, no significant difference in spherical power values was found between the two groups at any time point after surgery (P>0.05). Meanwhile, there were significant differences in cylindrical power values between the two groups at 6 and 12 months after surgery (P<0.05). The Kmax in the TG-CXL group was improved at all of the time points after surgery when compared with the baseline (P<0.001), while no significant difference in Kmax was found at any time point after surgery in the TE-CXL group when compared with the baseline (P>0.05). At 6 and 12 months after surgery, the Kmax values in the TG-CXL group were significantly lower than the TE-CXL group (P<0.05). No significant differences were found in flat keratomety, steep keratometry, the minimal thickness of the cornea, endothelial cell density, and intraocular pressure between the two groups at any time point after surgery (P>0.05). Within one month after surgery, optical coherence tomography revealed the increased density in the anterior stroma in both groups. In most patients in the TG-CXL group, a demarcation line was visible in the central and para-central corneal stroma, representing a clear and continuous, high-signal arc-shaped linear structure, which was deeper in the central cornea than the para-central cornea. In contrast, a demarcation line, fuzzy and focally discontinuous, was visible only in a few patients in the TE-CXL group, with an almost uniform depth in the central and the para-central cornea. Confocal microscopy demonstrated an apparent mesh-like cross-linked collagen structure in the superficial and intermediate corneal stroma at all time points after surgery in the TG-CXL group, with thickening stromal collagen fibers and an increased number of interconnections. In contrast, the mesh-like structure and number of interconnections in the superficial corneal stroma were significantly reduced at 12 months after surgery in the TE-CXL group, with no cross-linking structure in the intermediate corneal stroma at any time point after surgery. No serious complications such as corneal infection, sterile corneal ulcer, and persistent epithelial defect were observed in both groups during the follow-up of 12 months. Conclusions: The TG-CXL procedure by sequential irradiation in two different diameters with ultraviolet A light was effective and safe in the management of progressive keratoconus in adults, achieving significant refractive improvement. This might be a good technical alternative for refractive corneal cross-linking surgery.

Crosslinking for post-laser-assisted in situ keratomileusis corneal ectasia: Transepithelial flap-on 30 minute and flap-lift 4 minute protocol.

To evaluate the outcomes of transepithelial corneal collagen crosslinking (CXL) for management of corneal ectasia after laser-assisted in situ keratomileusis (LASIK). CXL was performed on 18 eyes of 16 patients either with LASIK flap lift (n = 9; 365 nm, 30 mW/cm2, 4 minutes, pulse) or with transepithelial flap-on (n = 9 eyes; 365 nm, 3 mW/cm2, 30 minutes) technique. Postoperative change in maximum keratometry (Kmax), anterior elevation, posterior elevation, spherical equivalent (SE), logMAR uncorrected distance visual acuity (UDVA), aberrations, and central corneal thickness (CCT) were evaluated at 12 months postoperatively. A total of 18 eyes of 16 patients (11 males, 5 females) were included. Overall, Kmax flattened more after flap-on CXL (P = 0.014) compared to flap-lift CXL. The endothelial cell density and posterior elevation were stable throughout the follow-up period. Index of vertical asymmetry (IVA), keratoconus index (KI), and central keratoconus index (CKI) decreased after flap-on CXL at 12 months, postoperatively (P < 0.05), whereas there were no statistically significant changes in these parameters after flap-off CXL group. The spherical aberrations and total root mean square decreased after flap-lift CXL at 12 months, postoperatively (P < 0.05). In our study, transepithelial collagen crosslinking was successfully used to halt disease progression in post-LASIK keratectasia. We recommend flap-on surgical technique for these cases.

Comparison of Efficacy and Safety Between Standard, Accelerated Epithelium-Off and Transepithelial Corneal Collagen Crosslinking in Pediatric Keratoconus: A Meta-Analysis

PurposeThe purpose of the study is to compare the efficacy of standard epithelium-off CXL (SCXL), accelerated epithelium-off CXL (ACXL), and transepithelial crosslinking CXL (TECXL) for pediatric keratoconus.MethodsA literature search on the efficacy of SCXL, ACXL, and TECXL [including accelerated TECXL (A-TECXL)] for keratoconus patients younger than 18 years was conducted using PubMed, Cochrane Library, ClinicalTrials.gov, and EMBASE up to 2021. Primary outcomes were changes in uncorrected visual acuity (UCVA) and maximum keratometry (Kmax) after CXL. Secondary outcomes were changes in best-corrected visual acuity (BCVA), mean refractive spherical equivalent (MRSE), and central corneal thickness (CCT). Estimations were analyzed by weighted mean difference (WMD) and 95% confidence interval (CI).ResultsA number of eleven identified studies enrolled 888 eyes (SCXL: 407 eyes; ACXL: 297 eyes; TECXL: 28 eyes; A-TECXL: 156 eyes). For pediatric keratoconus, except for a significant greater improvement in BCVA at 24-month follow-up in SCXL (WMD = –0.08, 95%CI: –0.14 to –0.01, p = 0.03, I2 = 71%), no significant difference was observed in other outcomes between the SCXL and ACXL groups. SCXL seems to provide greater changes in UCVA (WMD = –0.24, 95% CI: –0.34 to –0.13, p < 0.00001, I2 = 89%), BCVA (WMD = –0.09, 95% CI: –0.15 to –0.04, p = 0.0008, I2 = 94%), and Kmax (WMD = –1.93, 95% CI: –3.02 to –0.85, p = 0.0005, I2 = 0%) than A-TECXL, with higher incidence of adverse events.ConclusionFor pediatric keratoconus, both SCXL and ACXL appear to be comparable in the efficacy of visual effects and keratometric outcomes; SCXL seems to provide greater changes in visual and pachymetric outcomes than A-TECXL.

EVALUATION OF CHANGES IN VISUAL ACUITY AND CONTRAST SENSITIVITY IN PATIENTS WITH KERATOCONUS AFTER CORNEAL COLLAGEN CROSS-LINKING

Objective: To evaluate changes in visual acuity and contrast sensitivity in patients with keratoconus after corneal collagen cross-linking.&#x0D; Study Design: Quasi-experimental study.&#x0D; Place and Duration of Study: Armed Forces Institute of Ophthalmology, Rawalpindi, Pakistan, from May 2019 to Apr 2020.&#x0D; Methodology: A total of 48 eyes of 30 patients with progressive keratoconus were included in this study. Baseline uncorrected distance visual acuity, corrected distance visual acuity and contrast sensitivity were recorded, following which transepithelial corneal collagen cross-linking with topical riboflavin and ultraviolet A light was performed. Uncorrected distance visual acuity, corrected distance visual acuity and contrast sensitivity measurements were repeated and recorded 6-months postoperatively.&#x0D; Results: Mean preoperative uncorrected distance visual acuity was 0.56 ± 0.27 logarithm of the minimum angle of resolution which improved to 0.51 ± 0.26 at 6 months after the procedure (p=0.002). Mean corrected distance visual acuity was 0.30 ± 0.19 preoperatively, improving to 0.24 ± 0.18 (p=0.001) at 6 months after corneal collagen cross-linking, thereby depicting a statistically significant improvement. Treated eyes also showed a significant improvement in contrast sensitivity (p=0.001) of 0.05 ± 0.08 logarithmic units of contrast sensitivity, from a mean preoperative contrast sensitivity of 1.72 ± 0.10 to 1.77 ± 0.09 when evaluated 6 months after corneal collagen cross-linking.&#x0D; Conclusion: Corneal collagen cross-linking is a promising advancement in the treatment of keratoconus. It was found effective in significantly improving visual acuity as well as contrast sensitivity, thus enhancing visual outcomes in keratoconus.

The Effect of Sodium Iodide on Stromal Loading, Distribution and Degradation of Riboflavin in a Rabbit Model of Transepithelial Corneal Crosslinking.

PurposeTo evaluate effects of sodium iodide (NaI) on riboflavin concentration in corneal stroma before and during ultraviolet A (UVA) light exposure using a novel transepithelial corneal collagen crosslinking (CXL) procedure (EpiSmart CXL system, CXL Ophthalmics, Encinitas CA).MethodsRiboflavin solutions with NaI (Ribostat, CXL Ophthalmics, Encinitas CA) and without NaI were used for CXL in rabbits using EpiSmart. A pilot study determined sufficient riboflavin loading time. Four rabbits were dosed and monitored. Riboflavin fluorescence intensity was assessed from masked slit-lamp photos. A 12 min loading time was selected. Sixteen additional rabbits received the two formulae in contralateral eyes for CXL. Riboflavin uptake was assessed at 0, 10, 15, 20, 25, and 30 min of UVA exposure using a scale for riboflavin fluorescence previously validated against stromal concentration. Post sacrifice, corneal stromal samples were analyzed for concentrations of riboflavin and riboflavin 5ʹ-phosphate.ResultsEyes dosed with NaI riboflavin had higher riboflavin grades compared to eyes dosed with the NaI-free riboflavin formulation immediately after riboflavin loading and persisting throughout UVA exposure, with significantly higher (P < 0.01 to < 0.05) riboflavin grades from 15 through 25 min of UVA exposure. Riboflavin grades decreased more slowly in eyes dosed with NaI riboflavin through 25 minutes of UVA exposure. Minor conjunctival irritation was noted with or without NaI.ConclusionThe addition of NaI to riboflavin solution is associated with increased riboflavin concentration in corneal stroma throughout a clinically relevant time course of UVA exposure. This effect may be a combination of enhanced epithelial penetration and reduced riboflavin photodegradation and should enhance intrastromal crosslinking.

Epithelium-Off vs. transepithelial corneal collagen crosslinking in progressive keratoconus: 3 years of follow-up

PurposeTo compare the efficacy of epithelium-off corneal collagen crosslinking (CXL) with transepithelial CXL in patients with progressive keratoconus with a follow-up of 3 years, taking into account the patients’ age and the location of the corneal ectasia. MethodsIn this prospective study participated 64 eyes with progressive keratoconus were included in this long-term study, of which 31 eyes were treated by epithelium-off CXL and 33 by transepithelial CXL. All of the patients with a follow-up of 36 months were evaluated for visual variables (corrected distance visual acuity (CDVA), corneal aberrations, and corneal densitometry), structure variables (astigmatism, keratometry, corneal asphericity, maximum posterior elevation, corneal thickness, and corneal volume), and keratoconus index variables. ResultsAfter corneal CXL, CDVA improved significantly in both central and paracentral keratoconus, with greater improvement in the centrals (p = 0.001), asphericity at 6 mm improved in central keratoconus (p = 0.047). In the epi-off group, there was a significant improvement in coma-like (p = 0.038), higher-order aberrations (p = 0.036), asphericity at 8 mm (p = 0.049), asphericity at 10 mm (p = 0.049), and index of surface variance (p = 0.049). ConclusionAlthough both techniques halted and stabilized the progression of keratoconus, epithelium-off CXL was more effective. In addition, after the corneal CXL, there was a greater degree of regularization of the corneal surface and, therefore, a greater improvement in the CDVA with central keratoconus than with paracentral keratoconus.

Three-year clinical observation of the outcomes of transepithelial and epithelial-off accelerated corneal collagen crosslinking treatment for different types of progressive keratoconus.

In the present study, the clinical and long-term effects of accelerated transepithelial corneal collagen crosslinking (ATE-CXL) and accelerated epithelial-off corneal collagen crosslinking (A-CXL) for the treatment of different types of progressive keratoconus were compared. A total of 70 patients, including 96 eyes with advanced keratoconus, were enrolled in the study. ATE-CXL or A-CXL was performed on one or two eyes of each subject according to corneal thickness, keratoconus type and surgical approach. Patients were divided into the following four groups: Group A, ATE-CXL for central keratoconus; group B, A-CXL for central keratoconus; group C, ATE-CXL for peripheral keratoconus; and group D, A-CXL for peripheral keratoconus. Uncorrected distant visual acuity (UDVA), best-corrected distant (BD)VA and corneal astigmatism (CA) were evaluated in all patients by routine ophthalmology pre-operatively and 3 years post-operatively. Topographical features, including maximum corneal curvature (Kmax), thinnest corneal thickness (TCT), anterior corneal elevation (ACE) and corneal endothelial cell density (ECD) were also compared across groups. The results suggested that pre- and post-operative UDVA, BDVA, Kmax, CA and ACE values differed in all four groups (P<0.05), whereas no differences were observed between pre- and post-operative TCT and ECD (P>0.05). Concordant results were obtained between groups A and C and groups B and D. ATE-CXL achieved better control of central keratoconus UDVA, Kmax and CA as compared with A-CXL. The difference between pre- and post-operative UDVA, Kmax and CA as compared with A-CXL was highly correlated with the change in intraocular pressure and treatment effectiveness. There was a statistically significant improvement in BDVA with ATE-CXL for treatment of central keratoconus compared with that after A-CXL treatment (P=0.032). There were statistically significant improvements in BDVA (P=0.047), CA (P=0.045) and ACE (P=0.012) with A-CXL treatment of peripheral keratoconus when compared with ATE-CXL treatment. Central, and to a lesser extent, peripheral, keratoconus may be effectively controlled by either approach, with disease stabilization 3 years later. ATE-CXL is suggested to be the most suitable treatment for keratoconus of <400 µm with a corneal thickness of >400 µm; however, A-CXL yields superior long-term outcomes.

Corneal Haze After Transepithelial Collagen Cross-linking for Keratoconus: A Scheimpflug Densitometry Analysis.

To quantitate corneal haze and analyze the postoperative time course of corneal haze after transepithelial corneal collagen cross-linking (TECXL) in patients with keratoconus. Patients underwent TECXL and were randomized into 2 groups. One group received intraoperative riboflavin 0.10% every minute, and the second group received riboflavin 0.10% every 2 minutes during ultraviolet exposure. Scheimpflug densitometry was measured preoperatively, and at 1, 3, 6, and 12 months to assess the postoperative time course. Densitometry measurements were also correlated with visual acuity, pachymetry, and topography outcomes. Fifty-nine eyes of 43 patients with keratoconus were analyzed. Preoperative mean corneal densitometry was 20.45 ± 2.79. Mean densitometry increased at 1 month (22.58 ± 3.79; P < 0.001), did not significantly change between 1 and 3 months (22.64 ± 3.83; P = 0.8), and significantly improved between 3 and 12 months postoperatively (mean6 21.59 ± 3.39; P = 0.002, mean12 20.80 ± 3.27; P = 0.002). There was no difference between preoperative and 1-year densitometry measurements (P = 0.21). There was no significant difference between the 1-minute and 2-minute subgroups. In addition, corneal densitometry at either 3 months or 1 year did not correlate with uncorrected distance visual acuity (P = 0.4), corrected distance visual acuity (P = 0.1), or maximum keratometry (P = 0.5), 1 year after corneal collagen cross-linking (CXL). After TECXL, corneal haze increased slightly at 1 month, plateaued between 1 and 3 months, and returned to baseline between 3 and 12 months. In general, corneal haze in this study was substantially less than the haze previously reported for the standard cross-linking procedure. CXL-associated corneal haze did not correlate with the postoperative visual or topographic outcomes 1 year after CXL.

Combined femtosecond laser-assisted intrastromal corneal ring segments implantation and corneal collagen cross-linking for treatment of pellucid-like keratoconus

Purpose To evaluate the safety and efficacy of combined femtosecond laser-assisted intrastromal corneal ring segments implantation plus accelerated transepithelial corneal collagen cross-linking (ATE-CXL) in cases of pellucid-like keratoconus (PLK). Patients and methods This retrospective study included 25 eyes of 13 patients with PLK. Cases were divided into two groups: group 1 consisted of 13 eyes (seven patients) that had been treated by femtosecond laser-assisted Kerarings implantation and ATE-CXL in the same session, whereas group 2 included 12 eyes (six patients) that had been treated with ATE-CXL alone. Results After 1 year of surgery, the mean uncorrected visual acuity (UCVA) of group 1 improved from 0.94±23 (logMAR) to 0.73±18, whereas the mean best-corrected visual acuity improved from 0.75±16 to 0.49±0.22. The mean preoperative maximum keratometry (Kmax) was 65.23±5.03 D, whereas the mean postoperative Kmax was 53.92±4.21 D. However, in group 2, the preoperative mean UCVA was 0.63±0.31 and the postoperative UCVA was 0.55±0.29, whereas the mean best-corrected visual acuity changed from 0.31±0.26 to 0.23±0.19. The mean preoperative Kmax was 51.38±3.73 D, whereas the mean postoperative Kmax was 48.43±2.98 D. Conclusion Combined femtosecond laser-assisted Kerarings implantation and ATE-CXL is safe and effective in the treatment of PLK.

Transepithelial versus epithelium-off corneal collagen cross-linking for corneal ectasia: protocol for a systematic review, meta-analysis and trial sequential analysis of randomised controlled trials

IntroductionCorneal ectasias are progressive, degenerative ocular diseases defined by abnormal structural changes in the cornea, leading to distortion of vision and substantial reduction in quality of life. Corneal collagen cross-linking...

Transepithelial versus Epithelium off Crosslinking for Treating Keratoconus among Jordanians

Background: The progression of keratoconus is stabilized with the help of corneal collagen cross-linking (CXL) supported through photosynthesized riboflavin. Objective: This study aims to compare the effectiveness of the transepithelial procedure and epithelium off procedure of corneal collagen crosslinking among keratoconus patients in Jordan. Methods: The study recruited 80 patients suffering from progressive keratoconus, from a tertiary care setting in Jordan. These participants were randomly divided into two groups; group 1 with 40 participants subjected to transepithelial (Corneal collagen cross-linking) CXL; and 40 participants in group 2 received conventional epithelium off CXL. Results: Improvement was observed in the mean contact lens, which corrected distance visual acuity (CDVA) from logMAR 0.332 ± 0.09 (group 1), 0.35 ± 0.09 (group 2) to 0.241 ± 0.07 (group 1), 0.21 ± 0.07 (group 2), respectively at the end of follow-up (12 months). The mean pachymetry improved from 429.81 ± 18.96 μm (group 1), 430.08 ± 17.05 μm (group 2) to 436.5 ± 15.49 μm (group 1), 436.44 ± 12.53 μm (group 2), respectively, after twelve months. Additionally, the mean Sim K astigmatism declined from 7.0 ± 2.0 (group 1), 6.73 ± 1.98 (group 2) to 5.97 ± 1.88 (group 1), 5.53 ± 0.08 (group 2) respectively at twelve months post-treatment. Majority of the patients in group 2 experienced more pain as compared to group 1 participants. Conclusion: The effectiveness of a cross-linking procedure related to keratometry readings and corneal thickness showed that conventional (epithelium off) CXL method is more effective than transepithelial CXL.

Combined transepithelial phototherapeutic keratectomy and corneal collagen cross-linking for corneal ectasia after small-incision lenticule extraction\u2014preoperative and 3-year postoperative results: a case report

BackgroundCorneal ectasia after small-incision lenticule extraction (SMILE) is uncommon. To our knowledge, this is the first report of 3-year results of combined phototherapeutic keratectomy (PTK) and corneal collagen cross-linking (CXL) for corneal ectasia after SMILE.Case presentationHerein, we describe a case of prominent corneal ectasia after SMILE treated with PTK combined with CXL 3 years ago. After surgery, maximum corneal keratometry, mean corneal keratometry, spherical equivalent and uncorrected distance visual acuity were significantly improved at follow-up intervals.ConclusionsTransepithelial PTK combined with CXL for corneal ectasia after SMILE may be an effective and safe treatment in the long term.

Assessment of Corneal Higher Order Aberrations Before and After Corneal Collagen Cross-Linking in Patients with Keratoconus

Purpose: This study aimed at assessing the shortterm effect of corneal collagen crosslinking on higher order aberrations of cornea in patients with keratoconus using corneal topography. Patients and Methods: The study was a prospective cohort study that was conducted in a private specialized eye hospital on 40 eyes of 28 keratoconus patients. Each patient was fully assessed preoperatively including doing corneal topography using Pentacam® HR. Transepithelial accelerated CXL was done to all patients. Postoperative corneal topography was done at six months and data was retrieved and analyzed. Results: RMS HOA recorded a higher mean value preoperatively, with a high statistically significant difference (p=0.00). All elements of HOAs showed lower postoperative values except for trefoil 30o. The difference was statistically significant in comma 0o, comma 90o, spherical aberrations and fifth order comma 90° (p=0.026, p= 0.003, p=0.005, and p=0.001 respectively). Conclusion: Transepithelial corneal collagen cross-linking improves corneal higher order aberrations. The maximum effect of the procedure is on comma 0o, comma 90o, spherical aberrations and fifth order comma 90° elements.

Comparison of Epithelium-Off Versus Transepithelial Corneal Collagen Cross-Linking for Keratoconus: A Systematic Review and Meta-Analysis.

To systematically compare standard epithelium-off corneal collagen cross-linking (SCXL) and transepithelial corneal collagen cross-linking (TECXL) for treating keratoconus. PubMed, EMBASE, the Cochrane Library, the US trial registry (ClinicalTrials.gov), VIP Database, Wanfang Databse, and China National Knowledge Infrastructure searches up to February 2017 were conducted. Primary outcomes were changes at 1 year in uncorrected distance visual acuity, maximum keratometry (Kmax), and mean keratometry (mean K). Secondary outcomes were changes at 1 year in corrected distance visual acuity, mean refractive spherical equivalent, central corneal thickness, endothelial cell density, and the occurrence of adverse events. Eight studies with a total of 455 eyes were included. For primary outcomes, SCXL showed a greater reduction in mean K [standardized mean difference (SMD) 0.28; 95% confidence interval (CI), 0.03-0.53; P = 0.03] compared with TECXL. Subgroup analysis indicated that SCXL had a comparable effect on reducing mean K with TECXL protocols using chemical enhancers (SMD 0.05; 95% CI, -0.36 to 0.45; P = 0.82) but a greater reduction in mean K compared with TECXL with current iontophoretic protocols (SMD 0.43; 95% CI, 0.10-0.75; P = 0.01). For the other outcomes, there were no statistically significant differences. With the exception of less reduction in mean K with current iontophoretic protocols, analysis of the limited number of comparative studies available seems to demonstrate that SCXL and TECXL have a comparable effect on visual, refractive, pachymetric, and endothelial parameters at 1 year after surgery. Further follow-up is required to determine whether these techniques are comparable in the long-term.

Trans-epithelial corneal collagen cross-linking with iontophoresis for progressive keratoconus

To evaluate the efficacy of trans-epithelial corneal collagen cross-linking (CXL) with Iontophoresis among patients with progressive keratoconus. It is a prospective interventional study, which is based on 41 eyes of 23 patients, suffering from progressive keratoconus and treated with trans-epithelial corneal cross-linking, using iontophoresis with ETDA and trometamol-enriched riboflavin 5 phosphates 0.1% hypotonic solution (Ricrolin+, Soot Italia SpA, Italy). The mean of uncorrected distance visual acuity and best corrected distant visual acuity was improved at 6months with statistically significant differences from baseline (p < 0.05). There was no statistically significant difference in keratometric values, including K1, K2, Km, topographic astigmatism, and central corneal thickness. Patients, who had completed 1year (21 eyes of 12 patients) of the treatment, showed similar results. The data indicated that corneal collagens cross-linking with iontophoresis using Ricroli+ may be an effective method in halting the progression of keratoconus without the side effects of epithelial removal, which may be encountered in the standard epi-off CXL procedure.

One-year follow-up of accelerated transepithelial corneal collagen cross-linking for progressive pediatric keratoconus

BackgroundKeratoconus typically presents in the teenage years and is more advanced in younger patients when compared with adults. In the present study, we aimed to assess the safety and efficacy of accelerated transepithelial corneal collagen cross-linking (ATE-CXL) in children with progressive keratoconus.MethodsIn this retrospective consecutive study, 18 eyes were enrolled from 17 pediatric patients (15 boys and 2 girls) with a mean age of 14.44 ± 1.98 years. Manifest refraction, best-corrected visual acuity (BCVA), steepest meridian keratometry (K1), flattest meridian keratometry (K2), maximum keratometry (Kmax), thinnest corneal thickness (TCT), posterior central elevation (PCE), and posterior mean elevation (PME) were measured before and after ATE-CXL. The patients were followed-up at 1, 6, and 12 months. Repeated measures analysis of variance was used for statistical analysis. P < 0.05 was considered statistically significant.ResultsThere were no complications in any case during or after ATE-CXL. BCVA improved from 0.64 ± 0.32 preoperatively to 0.69 ± 0.32 at 1-year postoperatively. The Kmax value was 56.67 ± 9.60 D before the treatment and 56.19 ± 8.55 D, 56.08 ± 8.85 D, and 55.94 ± 8.46 D at 1, 6, and 12 months postoperatively, respectively. No statistically significant differences were present in K1, K2, Kmax, PCE, and TCT before and after ATE-CXL during the 12-month follow-up (P > 0.05).ConclusionsATE-CXL is a safe and effective treatment in pediatric progressive keratoconus patients. The long-term effects need further observation.Trial registrationRetrospectively registered. Registration number: ChiCTR-OIC-16008181. Registered 29 March 2016.

Transepithelial corneal collagen crosslinking in patients with progressive keratoconus

To assess the effectiveness of transepithelial collagen crosslinking (CXL) in patients with keratoconus. The study involved 44 patients (44 eyes) with stage I-II progressive keratoconus. Patients were divided into two groups. The 1st group included 22 patients that had underwent transepithelial CXL. The 2nd group included 22 patients that had underwent traditional CXL. All patients of the group 2 all patients had corneal syndrome, which lasted 2-4 days. In the 1st group, 98% of the patients did not have corneal syndrome and their visual acuity (VA) was same as preoperative on the next day after the surgery. In the 2nd group, the mean level of postoperative pain was 1.7 times higher than in group 1 (p<0.05). Six months after the treatment, uncorrected VA (UCVA) in the 1st group has increased by 52%, the best corrected VA (BCVA) - by 17%, in the 2nd group UCVA increased by 53%, BCVA - by 20% (p<0.05). The demarcation line in the 2nd group was 2.2 times deeper than in the 1st group (p<0.05). Six months after the treatment in the 1st group mean K1, K2 and Km decreased by 1.5%, 2.3% and 1.7% respectively (p>0.05); in the 2nd group - by 3.6%, 3.9% and 4.1% (p<0.05) compared with the data before the surgery. One year after the treatment, mean Kmax in the 1st group decreased by 2.1%, in the 2nd group - by 3.9%. Differences with preoperative values were statistically significant only in the 2nd group. Transepitelial CXL is a safe procedure well tolerated by patients and leading to a rapid restoration of visual function. Transepithelial CXL proved to have reduced effectiveness in inducing improvement in keratometric values, its effect on visual acuity was likely to be similar to that of epithelium-off CXL.

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.