Transepithelial Corneal Cross-linking Research Articles

Transepithelial photorefractive intrastromal corneal crosslinking versus photorefractive keratectomy in low myopia

To compare the outcomes of transepithelial photorefractive intrastromal corneal crosslinking (CXL) and photorefractive keratectomy (PRK) in eyes with low myopia. Purpan Hospital, Toulouse, France. Prospective case series. Myopic patients with a manifest refraction spherical equivalent (MRSE) of -1.00 to -2.50 diopters (D) and a cylindrical component of plano to -0.75 D were included. The dominant eye had PRK (PRK eyes). The nondominant eye had transepithelial photorefractive intrastromal CXL with riboflavin (ParaCel Part 1 and 2), 30mW/cm2 pulsed ultraviolet-A irradiation centered on the pupil (Mosaic System) for 16minutes and 40seconds, and a supplemental oxygen delivery mask (CXL eyes). The primary outcome measure wasthe change in the MRSE. Other outcome measures werethe uncorrected (UDVA) and corrected (CDVA) distance visual acuities, mean keratometry, and endothelial cell count (ECC) over a 6-month follow-up. Adverse events were assessed. Nineteen patients were included. By 6months, the mean MRSE had decreased by 0.72 D ± 0.42 (SD) in CXL eyes and by 1.35±0.46 D in PRK eyes (P<.001). The mean change in UDVA was -0.35±0.21 logarithm of the minimum angle of resolution (logMAR) in CXL eyes and -0.66±0.19 logMAR in PRK eyes (P<.001). No complications were reported. The change in the ECC and CDVA was not statistically significant. Photorefractive keratectomy provided better visual and refractive outcomes than transepithelial photorefractive intrastromal CXL. Transepithelial photorefractive intrastromal CXL, however, showed the potential refractive effect of CXL but with a limited magnitude of myopic correction.

Two-year topographic and densitometric outcomes of accelerated (45\u2009mW/cm2) transepithelial corneal cross-linking for keratoconus: a case-control study

BackgroundConventional corneal cross-linking is effective for retarding the progression of keratoconus. However the long-term efficacy and safety of accelerated (45 mW/cm2) transepithelial corneal cross-linking (ATE-CXL) on progressive keratoconus (KC) treatment is not fully understood. The purpose of this study is to evaluate the 2-year changes in corneal topographic parameters and densitometry values after ATE-CXL for KC.MethodsTwenty-five progressive eyes of 25 KC patients (KC group) and 25 eyes of 25 myopes without KC (control group) were enrolled. Corneal topography and densitometry values were evaluated pre-operatively and at 6, 12 and 24 months post-operatively in the KC group.ResultsThe mean values of flat keratometry (K1), steep keratometry (K2), mean keratometry (Km), corneal astigmatism (CA), maximum keratometry (Kmax), central corneal thickness (CCT), thinnest corneal thickness (TCT), anterior corneal elevation (ACE) and posterior corneal elevation (PCE) all remained unchanged over time (all P values > 0.05). The densitometry values of the anterior, central, posterior and total layers over the annular diameters 0 mm to 2 mm (Φ0-2 mm) and Φ2–6 mm all decreased significantly (all P values < 0.05). At post-operative month 24, except for the densitometry value of the posterior layer (Φ0-2 mm), which was significantly lower than that of the control group (post hoc P = 0.010), all densitometry values obtained from the remaining locations of the KC eyes were equal to those of the control group (All post hoc P values > 0.05). Subgroups with Km ≥ 50.30D or ACE ≥35.3 μm progressed significantly when compared with those with Km < 50.30D (F = 8.167, P = 0.004) or ACE< 35.3 μm (F = 5.207, P = 0.022).ConclusionsK1, K2, Km, CA, Kmax, CCT, TCT, ACE, and PCE values may remain stable but severer KC patients tend to have poorer long-term outcomes. The densitometry values of the full corneal thickness (total layer over Φ0-2 mm and Φ2–6 mm) may decrease to normal levels at 2 years after ATE-CXL for KC.

Oxygen Diffusion May Limit the Biomechanical Effectiveness of Iontophoresis-Assisted Transepithelial Corneal Cross-linking

To evaluate the impact of varying treatment time on the efficacy of iontophoresis-assisted transepithelial corneal cross-linking (I-CXL) in ex vivo porcine corneas. One hundred twelve porcine corneas with intact epithelium were divided into 7 groups and analyzed. Groups 1, 2, and 3 received standard epitheliumoff CXL (S-CXL) with hypo-osmolaric 0.1% riboflavin and 30 minutes of ultraviolet-A (UV-A) irradiation at 3 mW/cm2, 10 minutes at 9 mW/cm2, or were not irradiated (controls). Groups 4, 5, 6, and 7 received I-CXL for either 60 minutes at 1.5 mW/cm2, 30 minutes at 3 mW/cm2, 10 minutes at 9 mW/cm2, or were not irradiated (controls). Elastic modulus and stress after relaxation of 5-mm wide corneal strips were analyzed. In the S-CXL groups, significant differences (P ≤ .05) in stress-strain extensometry were found between controls and 3 mW/cm2 for 30 minutes (group 1) and between controls and 9 mW/cm2 for 10 minutes (group 2). In the I-CXL groups, only the 1.5 mW/cm2 for 60 minutes setting (group 4) showed a significant stiffening effect. All epithelium-off groups provided a stiffening effect significantly stronger than I-CXL: with a stiffening effect of 149% and 112%, groups 1 and 4 were the groups with greater elastic modulus between the S-CXL and I-CXL groups, respectively. The biomechanical effect of I-CXL increased significantly when using a low irradiance/long irradiation setting. Oxygen diffusion thus represents a limiting factor even when riboflavin penetration is improved via iontophoresis. Still less effective than S-CXL, this modification may help establish transepithelial CXL as a treatment option in selected cases. [J Refract Surg. 2018;34(11):768-774.].

Combined wavefront-guided transepithelial photorefractive keratectomy and corneal crosslinking for visual rehabilitation in moderate keratoconus

To present 24-month results from the transepithelial photorefractive keratectomy (PRK)-corneal crosslinking (CXL) trial using simultaneous accelerated CXL and a new tissue-saving ocular wavefront-guided transepithelial PRK algorithm aiming to reverse visual loss in early-stage keratoconus without compromise to stabilization of disease progression. Moorfields Eye Hospital, London, United Kingdom. Prospective case series. Patients with progressive grades I to III keratoconus and logarithm of the minimum angle of resolution (logMAR) corrected distance vision acuity (CDVA) worse than 0.00 (20/20) were included. Consecutive matched historical controls treated only with accelerated CXL were the control group. The main outcome measure was change in logMAR CDVA. The study group comprised 47 eyes of 47 patients (mean age 24.6years±3.8 [SD]). The CDVA improved from 0.28±0.21 logMAR (20/60) preoperatively to 0.15±0.14 logMAR (20/30) 24months after transepithelial PRK-CXL (P<.001). Twelve eyes gained and 1 eye lost 2 lines or more of CDVA. The mean stromal ablation depth at the cone apex was 35±15μm. Significant reductions in the maximum keratometry (K) reading and coma were evident in topographic comparison maps. The controls (n=47) had no significant changes in CDVA, higher-order aberrations, or K values. The mean K values in both groups were stable from 6months after treatment. Ocular wavefront-guided transepithelial PRK-CXL resulted in significant gains in CDVA without compromising CXL efficacy over a 24-month follow-up.

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.

Conventional and transepithelial corneal cross-linking for patients with keratoconus.

Previous studies investigating the effectiveness of conventional corneal collagen cross-linking (CXL) and transepithelial CXL in keratoconus treatment have reported conflicting outcomes. Therefore, we conducted a meta-analysis to compare the effectiveness of these treatments. We searched MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials for prospective randomized controlled trials (RCTs) with no restrictions. We included visual acuity (corrected distance visual acuity, uncorrected distance visual acuity) and corneal keratometry (K) as primary outcome parameters, and spherical equivalent, central corneal thickness (CCT), and endothelial cell density, as secondary parameters. We finally included seven reports (including six RCTs involving 305 participants and 344 eyes). Our analysis revealed significant postoperative differences in average K and CCT values between conventional and transepithelial CXL-treated patients [K: weighted mean difference (WMD) = 0.79, 95% confidence interval (CI) = 0.04–1.53, p = 0.04; CCT: WMD = 4.53, 95% CI = 0.42–8.64, p = 0.03]. In contrast, we did not find any significant differences in visual acuity, flattest K value, steepest K value, cylinder K value, apex K value, spherical equivalent, or endothelial cell density between groups. In conclusion, transepithelial CXL has a more protective influence on corneal thickness than conventional CXL, and results in lesser postoperative corneal flattening. Further investigation of the clinical outcomes of transepithelial CXL is required.

Results of ethanol-assisted epithelium-on corneal cross-linking with and without intrastromal corneal ring implantation.

To evaluate the topographic, refractive, and pachymetric changes after ethanol-assisted transepithelial corneal cross-linking (CXL) to stabilize progression of keratoconus (KC). This study retrospectively evaluated the long-term topographic, refractive, and pachymetric changes in patients diagnosed with KC who underwent corneal cross-linking and/or intrastromal corneal ring segment (ICRS) implantation. The subjects were divided into three groups, corresponding to eyes treated with CXL alone (group1), CXL and ICRS at the same time (group2), and CXL after ICRS implantation (group3). Corrected visual acuity and refraction, steep keratometry (SteepK) values, steepest keratometry reading on sagittal curvature map, and corneal thickness were recorded preoperatively and at each visit. Changes between measurements were assessed during follow-up. Corrected distant visual acuity (CDVA) values improved in all groups compared with baseline, but the differences were not statistically significant except for the first year (p>0.05). In groups1 and 3, SteepK values did not change statistically significantly during the entire follow-up (p>0.05). In group2, SteepK values statistically significantly decreased at all follow-up examinations compared with baseline, determined as the first month after ICRS implantation (p<0.05). Complication rates were acceptable without any need for surgical intervention. Single-session ethanol-assisted transepithelial CXL with or without ICRS implantation was a safe and effective procedure to halt progression of KC.

Quantitative analysis of corneal stromal riboflavin concentration without epithelial removal

To compare the corneal stromal riboflavin concentration and distribution using 2 transepithelial corneal crosslinking (CXL) systems. Absorption Systems, San Diego, California, USA. Experimental study. The stromal riboflavin concentration of 2 transepithelial CXL systems was compared in rabbit eyes invivo. The systems were the Paracel/Vibex Xtra, comprising riboflavin 0.25% solution containing TRIS and ethylenediaminetetraacetic acid and an isotonic solution of riboflavin 0.25%, (Group 1) and the CXLO system (Group 2). Manufacturers' Instructions For Use were followed. The intensity of riboflavin fluorescence by slitlamp observation 10, 15, and 20minutes after instillation was graded on a scale of 0 to 5. The animals were humanely killed and the corneal stromal samples analyzed with liquid chromatography and mass spectrometry. The mean riboflavin fluorescence intensity grades inGroup 1 (4 eyes) were 3.8, 4.8, and 4.8 at 10, 15, and 20minutes, respectively. The mean grades in Group 2 (3 eyes) were 2.0, 2.3, and 2.0, respectively. The riboflavin distribution was uniform in Group 1 but not in Group 2. The mean riboflavin concentration by liquid chromatography and mass spectrometry was 27.0μg/g stromal tissue in Group 1 and 6.7μg/g in Group 2. A stromal riboflavin concentration theoretically adequate for CXL, 15μg/g, was achieved in all eyes in Group 1 and no eyesin Group 2. Slitlamp grading correlated well with liquidchromatography and mass spectrometry concentration (R2=0.940). The system used in Group 1 produced corneal riboflavin concentrations that were theoretically adequate for effective transepithelial CXL (≥15μg/g), while the system in Group 2 did not. Slitlamp grading successfully estimated the corneal riboflavin concentration and can be used to ensure an adequate concentration of riboflavin in the cornea for transepithelial CXL.

Standard, transepithelial and iontophoresis corneal cross-linking: clinical analysis of three surgical techniques.

To evaluate the clinical results of standard, transepithelial (TE) and iontophoresis (I) corneal cross-linking (CXL), in patients with progressive keratoconus. Thirty eyes of 30 patients with progressive keratoconus treated by CXL (10 by standard-CXL, 10 by TE-CXL and 10 by I-TE-CXL) with 12months of follow-up. Pre- and postoperative ophthalmologic testing were: uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive examination (spherical error, spherical equivalent), corneal topography (corneal astigmatism, simulated maximum, minimum and average keratometry), aberrometry (coma and spherical aberration), pachymetry and endothelial cell density. In all groups, UDVA and CDVA improved significantly after treatment. Furthermore, a significant improvement in spherical error, spherical equivalent, topographic and aberrometric outcomes was observed in 3 groups at 1year posttreatment. No significant variations were recorded in corneal thickness and endothelial cellular density. Our results showed efficacy, clinical and refractive stability after standard-CXL, TE-CXL and iontophoresis-CXL.

Early epithelial complications of accelerated trans-epithelial corneal crosslinking in treatment of keratoconus: a case series.

To report a case series of early postoperative complications following combined accelerated corneal crosslinking (CXL) and trans-epithelial technique in keratoconus. Eleven eyes underwent accelerated trans-epithelial CXL (18mW/cm2 for 5min). Seven eyes (64%) developed complications in the first week postoperatively. Five eyes had large epithelial defects, and two eyes were complicated with diffuse punctate epithelial erosions. Early transient stromal haze was seen in eyes with epithelial complications. Anterior segment optical coherence tomography showed a faint demarcation line in six eyes (55%) with epithelial complications. A significant number of eyes developed epithelial complications shortly after combined accelerated trans-epithelial CXL, which defeated the benefits of leaving the epithelium intact.

Higher order optical aberrations and visual acuity in a randomized controlled trial comparing transepithelial versus epithelium-off corneal crosslinking for progressive keratoconus.

PurposeThe purpose of this study was to compare the effects of transepithelial crosslinking (trans-CXL) versus epithelium-off crosslinking (epi-off CXL) for progressive keratoconus with respect to the development of higher order aberrations (HOAs) and their effects on visual acuity.Materials and methodsA total of 61 patients were randomized and examined preoperatively and 1, 3, 6, and 12 months postoperatively in an academic referral center. Total corneal HOAs were compared between the two treatment groups using mixed linear modeling. Types of HOAs (coma, trefoil, and spherical aberration) that differed between groups were entered in a multivariable analysis to test their effect on uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA).ResultsThe epi-off CXL group had more flattening in maximal keratometry compared to the trans-CXL group (P=0.02). UDVA did not differ significantly between the groups (P=0.59); however, CDVA was significantly more improved in the trans-CXL group (P=0.02). Horizontal trefoil improved more in the epi-off group compared to the trans-CXL group (P=0.04), whereas the other HOAs were virtually unchanged in both groups. Differences in changes in HOAs between the two groups had no effect on either UCVA (P=0.76) or CDVA (P=0.96).ConclusionAlthough HOAs are clinically relevant determinants of vision quality in keratoconus patients, the change in total HOAs post treatment did not differ between the trans-CXL and epi-off CXL groups. Only horizontal trefoil differed significantly post treatment between the trans-CXL and epi-off CXL groups. However, this difference did not independently affect either UDVA or CDVA. Trans-CXL provides no benefit over epi-off CXL regarding visual relevant HOAs.

Visual and Topographical Outcomes Following Accelerated Trans-Epithelial Corneal Crosslinking in Progressive Keratoconus.

To assess the visual and topographical outcomes following accelerated trans-epithelial corneal crosslinking (TE-CXL) in progressive keratoconus. Case series. Laser Vision Centre, Karachi, from January 2015 to December 2016. Forty-five eyes of 25 patients affected with progressive keratoconus and treated with accelerated TE-CXL with riboflavin (vitamin B2) and ultra-violet A(UV-A) irradiation were enrolled in this study. The visual outcome was measured by ETDRS chart as improvement in best corrected visual acuity (BCVA) of at least one line or more as compared to pre-CXLBCVA. The topographical outcome was measured as decrease in maximum simulated keratometry values, astigmatism and spherical equivalent (SE) and an increase in central corneal thickness (CCT). K-max was defined as the steepest radius of curvature of the anterior corneal surface. SE was measured by subjective refraction, and K-max, astigmatism and CCTby scanning-slit corneal topography. Patients were followed-up 12 months post-treatment. At the end of follow-ups, mean BCVAshowed improvement of one line from LogMAR 0.58 ±0.067 to LogMAR 0.48 ±0.077. Seven (15.5%) eyes showed two lines of improvement while 3 (6.7%) eyes showed worsening of one line in BCVA. The mean K-max flattened by 0.7D. Mean astigmatism and SE decreased up to -0.5D and -0.4D, respectively. Mean preoperative CCTwas 454.31 ±36.34 µm, whereas mean postoperative CCTwas 456.47 ±35.60 µm with an average increase of 2.15 µm. No postoperative complications were reported. Based on topographical outcomes, accelerated TE-CXL is effective in preventing the progression of keratoconus without any safety concerns with improvement of vision in majority of cases.

The Effect of Ascorbic Acid (Vitamin C) on Transepithelial Corneal Cross-Linking in Rabbits.

To evaluate the effects of ascorbic acid (vitamin C), the main antioxidant agent in the cornea on transepithelial corneal cross-linking (CXL) where the main mechanism is oxidation. Twenty eyes of 20 rabbits were divided into 3 groups: Group 1 (7 eyes) had transepithelial corneal CXL after being fed with normal diet; Group 2 (7 eyes) had corneal CXL after once-daily subcutaneous injections of 200 mg of ascorbic acid in addition to normal diet; and the control group (6 eyes) was fed with normal diet but did not have corneal CXL performed. Ascorbic acid levels were measured in aqueous humor and plasma, and biomechanical measurements were applied to the cornea. There was a significant difference in ascorbic acid levels of plasma (P = 0.008) and aqueous humor (P = 0.006) between group 1 and 2. The Young's modulus values of group 1 and 2 were similar (P = 0.741) and were significantly higher than the control group (P = 0.02 and P = 0.01). The increase rate in Young's modulus values was 37.3% in group 1 and 43.9% in group 2 compared to control group. The ultimate strain values in group 1 and 2 were similar (P = 0.632) and were significantly higher than control group (P = 0.04, P = 0.03). The ultimate stress values in group 1 and 2 were similar (P = 0.836) and were significantly lower than control group (P = 0.001, P = 0.001). Systemic vitamin C does not appear to decrease effectiveness of transepithelial corneal CXL. Therefore, there is no reason to stop or reduce vitamin C supplementation before corneal CXL therapy.

Assessment of stromal riboflavin concentration–depth profile in nanotechnology-based transepithelial corneal crosslinking

To determine the intrastromal concentration of riboflavin in nanotechnology-based transepithelial corneal crosslinking. Consiglio Nazionale delle Ricerche, Messina, Italy. Experimental study. Six human donor sclerocorneal tissues were used to evaluate penetration of nanotechnology-based riboflavin 0.1% solution in the stroma through the intact epithelium. Three additional tissues were deepithelialized and soaked with dextran 20.0%-enriched riboflavin 0.1% solution for 30minutes. After corneal soaking with riboflavin, all tissues were irradiated using a 10mW/cm2 device for 9minutes. Two-photon emission fluorescence (TPEF) axial scanning measurements were collected in all specimens before treatment and immediately after corneal soaking with riboflavin and ultraviolet-A (UVA) irradiation of the cornea. The absorbance spectra of each tissue were collected at the same time intervals. The TPEF signals and absorbance spectra were used to calculate the concentration-depth profile of riboflavin in the corneal stroma during treatments. The mean stromal riboflavin concentration was 0.008%±0.003% (SD) and 0.017%±0.001% after transepithelial soaking with the nanotechnology-based solution and standard soaking, respectively (P=.001). After UVA irradiation of the cornea, the mean consumption of riboflavin was 52%±13% and 67%±2% in the study group and control group, respectively (P<.01). The nanotechnology-based platform was effective in enriching the anterior stroma with riboflavin through the intact epithelium, although the riboflavin concentration-depth profile rapidly decreased across the mid and posterior stroma. The treatment-induced stiffening effect on the corneal stroma was not assessed in this study.

Randomized Controlled Trial Comparing Transepithelial Corneal Cross-linking Using Iontophoresis with the Dresden Protocol in Progressive Keratoconus

To compare clinical outcomes of transepithelial corneal cross-linking using iontophoresis (T-ionto CL) and standard corneal cross-linking (standard CL) for the treatment of progressive keratoconus 12 months after the operation. Prospective randomized controlled clinical trial. Thirty-four eyes of 25 participants with progressive keratoconus were randomized into T-ionto CL (22 eyes) or standard CL (12 eyes). T-ionto CL was performed using an iontophoresis device with dextran-free 0.1% riboflavin-5-phosphate solution with enhancers and by irradiating the cornea with a 10 mW/cm2 ultraviolet A device for 9 minutes. Standard CL was performed according to the Dresden protocol. The primary outcome measure was stabilization of keratoconus after 12 months through analysis of maximum simulated keratometry readings (Kmax, diopters). Other outcome measures were corrected distance visual acuity (CDVA, logarithm of the minimum angle of resolution [logMAR]), manifest spherical equivalent refraction (D), central corneal thickness (CCT, micrometers) and endothelial cell density (ECD). Follow-up examinations were arranged at 3 and 7 days and 1, 3, 6, and 12 months. Twelve months after T-ionto CL and standard CL, Kmax on average flattened by-0.52±1.30 D (P=0.06) and-0.82±1.20 D (P= 0.04), respectively. The mean change in CDVA was-0.10±0.12 logMAR (P=0.003) and-0.03±0.06 logMAR (P= 0.10) after T-ionto CL and standard CL, respectively. The manifest spherical equivalent refraction changed on average by+0.71±1.44 D (P= 0.03) and+0.21±0.76 D (P= 0.38), respectively. The CCT and ECD measures did not change significantly in any group at 12 months. Significant differences in the outcome measures between treatments were found in the first week postoperatively. No complications occurred in the T-ionto CL group; 1 eye (8%) had sterile corneal infiltrates, which did not affect the final visual acuity, in the standard CL group. Significant visual and refractive improvements were found 12 months after T-ionto CL, though the average improvement in corneal topography readings was slightly lower than the Dresden protocol in the same period.

Ex Vivo Study of Transepithelial Corneal Cross-linking

To perform in vitro assessment of different techniques of transepithelial corneal cross-linking (CXL) and to compare the results to deepithelialized CXL. Transepithelial CXL was performed after pre-treatment with or without penetration enhancers (gum cellulose, 0.44% sodium chloride, and 0.01% benzalkonium chloride) for 15 or 60 minutes. Deepithelialized corneas underwent CXL after pretreatment with riboflavin for 15 minutes, according to the Dresden protocol. All corneas were incubated in 0.3% collagenase A solution and the time to total dissolution was measured. Corneas were also imaged with confocal microscopy to evaluate the corneal epithelium, subbasal nerve plexus, and depth of stromal keratocyte nuclei as a means of measuring the depth of collagen CXL. Deepithelialized CXL corneas with 15 minutes of pretreatment dissolved after 15.4 ± 3.1 hours, significantly longer (P = .001) than deepithelialized untreated corneas (8.5 ± 0.6 hours). Transepithelial CXL corneas with 15 minutes of pretreatment with or without penetration enhancers dissolved after 8.3 ± 2.1 and 7.4 ± 1.6 hours, respectively. A longer pretreatment of 60 minutes with penetration enhancers resulted in greater resistance to degradation of the transepithelial CXL corneas (14.6 ± 2.2 hours), which was similar to deepithelialized CXL corneas. The results of the biological assay correlated well with the imaging results obtained by confocal microscopy. Corneas treated by transepithelial CXL with an extended pretreatment time of 60 minutes and penetration enhancers exhibited similar characteristics as corneas treated by the deepithelialized CXL approach. By confocal imaging, the transepithelial approach with extended pretreatment time demonstrated evidence of epithelial damage, which may have improved the treatment effect of this group. [J Refract Surg. 2017;33(3):171-177.].

Biomechanical Strengthening of the Human Cornea Induced by Nanoplatform-Based Transepithelial Riboflavin/UV-A Corneal Cross-Linking

The purpose of this study was to investigate the biomechanical stiffening effect induced by nanoplatform-based transepithelial riboflavin/UV-A cross-linking protocol using atomic force microscopy (AFM). Twelve eye bank donor human sclerocorneal tissues were investigated using a commercial atomic force microscope operated in force spectroscopy mode. Four specimens underwent transepithelial corneal cross-linking using a hypotonic solution of 0.1% riboflavin with biodegradable polymeric nanoparticles of 2-hydroxypropyl-β-cyclodextrin plus enhancers (trometamol and ethylenediaminetetraacetic acid) and UV-A irradiation with a 10 mW/cm2 device for 9 minutes. After treatment, the corneal epithelium was removed using the Amoils brush, and the Young's modulus of the most anterior stroma was quantified as a function of scan rate by AFM. The results were compared with those collected from four specimens that underwent conventional riboflavin/UV-A corneal cross-linking and four untreated specimens. The average Young's modulus of the most anterior stroma after the nanoplatform-based transepithelial and conventional riboflavin/UV-A corneal cross-linking treatments was 2.5 times (P < 0.001) and 1.7 times (P < 0.001) greater than untreated controls respectively. The anterior stromal stiffness was significantly different between the two corneal cross-linking procedures (P < 0.001). The indentation depth decreased after corneal cross-linking treatments, ranging from an average of 2.4 ± 0.3 μm in untreated samples to an average of 1.2 ± 0.1 μm and 1.8 ± 0.1 μm after nanoplatform-based transepithelial and conventional cross-linking, respectively. The present nanotechnology-based transepithelial riboflavin/UV-A corneal cross-linking was effective to improve the biomechanical strength of the most anterior stroma of the human cornea.

Accelerated transepithelial corneal cross-linking for progressive keratoconus: a prospective study of 12 months

Background/aimsTo evaluate the clinical results of accelerated transepithelial corneal cross-linking (CXL) in Japanese patients with progressive keratoconus (KCN).MethodsThirty eyes of 19 patients (16 male, 3 female patients) with progressive KCN...

Transepithelial corneal crosslinking in treatment of progressive keratoconus: 12 months' clinical results.

Objective:The purpose of this study was to evaluate the safety and efficacy of transepithelial corneal collagen cross linking (TE-CXL) with modified riboflavin and accelerated UVA irradiance in thin corneas with pachymetry less than 400 microns at thinnest point, untreatable by epithelium off corneal collagen cross linking (CXL) in adult Pakistani population with progressive keratoconus.Methods:This quasi experimental study included twenty six eyes of 26 patients with progressive keratoconus who underwent accelerated transepithelial CXL in Armed forced institute of ophthalmology with 12 months follow up. Modified riboflavin, ParaCel ((riboflavin 0.25%, Benzalkonium chloride, EDTA, Trometamol, hydroxypropyl methylcellulose) and vibeX Xtra (riboflavin 0.25%) (Avedro, USA)) were applied to cornea in two stages. Uncorrected and Corrected Distant Visual Acuities (UDVA, CDVA), spherical equivalent (SE), astigmatism, pachymetry at thinnest point (Pachy thin), apex keratometry (Kmax), simulated and steep keratometry (Sim K, steep K) were measured at baseline and at 3, 6 and 12 months post operatively. The cornea was then exposed to accelerated UVA irradiance of 9mW/cm2 for 10 min (total dose 30 mW/cm2).Results:The mean age of the patient was 24.54±5.16 years. UDVA, CDVA, SE, astigmatism significantly improved at all postoperative test points (p=0.000, 0.004, 0.000, 0.004 respectively). Kmax and pachy thin were significantly reduced over baseline at 1 year (p=0.000, 0.004 respectively). Topographic indices Sim K and steep K did not show significant changes. No intra or post-operative complications were reported.Conclusion:Transepithelial accelerated CXL with modified riboflavin is a safe and effective procedure which halt disease progression in thin corneas with progressive keratoconus.

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