Accelerated Corneal Cross-linking Research Articles

Efficacy of Conventional Versus Accelerated Corneal Cross-linking in Pediatric Keratoconus: Two-Year Outcomes.

To compare the efficacy and safety of accelerated corneal cross-linking (CXL) with conventional CXL in pediatric patients with keratoconus. Consecutive patients with keratoconus received either accelerated CXL (9 mW/cm2 irradiance for 10 minutes) or conventional CXL (3 mW/cm2 irradiance) for 30 minutes. Visual acuities (uncorrected [UDVA] and corrected [CDVA] distance visual acuity, logMAR), spherical error, cylindrical error, spherical equivalent, and keratometric values were recorded. Follow-up measurements were compared with baseline values. The study enrolled 48 eyes: 22 eyes had accelerated CXL (mean age: 16.0 ± 1.7 years) and 26 eyes had conventional CXL (mean age: 15.7 ± 1.6 years). Compared with preoperative values, all mean keratometric values significantly improved in the accelerated CXL group (flat [K1]: Δ = -0.64 D, P < .0001, steep [K2]: Δ = -0.63 D, P = .009 and Kmax: Δ = -0.55 D, P = .028), but no significant changes were observed in the mean UDVA and CDVA. In the conventional CXL group, all mean keratometric values and CDVA significantly improved (K1: Δ = -0.65 D, P = .017, K2: Δ = -0.87 D, P = .006, Kmax: Δ = -1.47 D, P = .011). No significant changes were observed in refractive error in either CXL group. There were no significant differences in the keratometric readings, visual acuities, or refractive error between the two groups at the 2-year follow-up. Both conventional and accelerated CXL protocols appear to be effective in stabilizing keratoconus progression in pediatric patients. Improved CDVA was also observed in the conventional CXL group. Accelerated CXL, with its advantage of shorter treatment duration, may be an alternative in pediatric patients. [J Refract Surg. 2020;36(4):265-269.].

Prospective two year study of changes in corneal density following transepithelial pulsed, epithelium-off continuous and epithelium-off pulsed, corneal crosslinking for keratoconus

PurposeTo compare the corneal densitometry changes after transepithelial pulsed (t-ACXL), epithelium-off continuous (c-ACXL) and epithelium-off pulsed (p-ACXL), accelerated corneal crosslinking for patients with progressive keratoconus. MethodsProspective, interventional case series at a university hospital tertiary referral center. Forty eyes received t-ACXL, 40 eyes received c-ACXL, and 40 eyes received p-ACXL. Corneal tomography, densitometry and visual acuity were evaluated preoperatively and at 1, 3, 6, 12 and 24 months postoperatively. ResultsTotal densitometry values of the total layer over the annular diameters 0–12 mm expressed in grayscale units (GSU) showed no significant change after t-ACXL and p-ACXL but increased significantly after c-ACXL at 1 month (16.76 ± 2.38, P value < 0.01) and 3 months (16.12 ± 2.22, P value 0.04), returning to baseline levels at month 6 (14.97 ± 2.13, P value 0.99) and remained stable until final follow-up. At 1 month, the mean change in total densitometry value of the t-ACXL group (-0.53 ± 2.08) was significantly lower than the p-ACXL (0.70 ± 1.96 P value 0.04) and c-ACXL (1.97 ± 2.65 P value < 0.01). There was no statistical difference in the mean change in total densitometry between the three groups from 6 to 24 months. In the c-ACXL group, a higher degree of CXL-induced corneal haze at 1 month was observed in patients with steeper preoperative keratometry readings and in individuals where a greater flattening effect was achieved at 24 months. ConclusionsContinuous epithelium-off accelerated cornea crosslinking appears to induce more corneal haze than pulsed epithelium-off and transepithelial pulsed cornea crosslinking in the early postoperative period. Differences resolve by six-months.

Accelerated corneal cross-linking with hypo-osmolar riboflavin in thin keratoconic corneas: 2-year follow-up.

This study was performed to evaluate the outcomes of accelerated corneal cross-linking in keratoconic corneas with thinnest pachymetry values of <400 µm. The study included 28 eyes of 24 patients. The uncorrected and best-corrected visual acuities (logMAR), flattest and steepest keratometric readings, central corneal thickness at the thinnest point, corneal higher-order aberrations, and contrast sensitivity were assessed before and at 1, 3, 6, 12, and 24 months after corneal cross-linking. The mean best-corrected visual acuity and contrast sensitivity increased (p=0.02, p=0.03, respectively), whereas the mean uncorrected visual acuity did not significantly differ (p>0.05) at 24 months after corneal cross-linking, compared with measurements before corneal cross-linking. Although the mean flattest keratometric reading showed no significant change (p=0.58), the mean steepest keratometric reading was reduced when compared with its value before corneal cross-linking (p=0.001). No change was observed in the mean central corneal thickness at the thinnest point at 24 months after corneal cross-linking, compared with its value before corneal cross-linking (p=0.12). Accelerated corneal cross-linking in keratoconic eyes with thin corneas could halt the progression of keratoconus in corneas thinner than 400 µm at 24 months after treatment.

Protective Role of Xtra‐Factor in Refractive Surgery

AbstractCombination of refractive surgery procedures (i.e. LASIK) with high‐fluence, accelerated corneal crosslinking (Xtra) has been proposed and introduced in clinical practice, aiming to restore corneal strength, increase stability of visual outcomes, and potentially lower the refractive enhancement rate. However, there is no consensus in the literature regarding the beneficiary effect of this procedure.This presentation will review current clinical evidence on the topic, highlight advantages and disadvantages of this method and, finally, deliver relevant practical tips for young corneal surgeons.

Comparison of Femto-LASIK With Combined Accelerated Cross-linking to Femto-LASIK in High Myopic Eyes: A Prospective Randomized Trial

To evaluate the safety and efficacy of femtosecond (fs) laser-assisted insitu keratomileusis (LASIK) combined with accelerated corneal cross-linking (LASIK Xtra) compared to conventional fs-LASIK (convLASIK) in high myopic patients. Prospective, randomized, fellow-eye controlled clinical trial. Setting: Department of Ophthalmology, Goethe University, Frankfurt/Germany. StudyPopulation: Twenty-six patients with high myopia and/or myopic astigmatism received randomized treatment with LASIK Xtra (30 mW/cm2, 90 seconds with continuous ultraviolet-A) in 1 eye and convLASIK in the other eye. MainOutcomeMeasures: Uncorrected distance visual acuity (UDVA), best spectacle-corrected VA (BSCVA), manifest refractive spherical equivalent (MRSE), endothelial cell count (ECC), and corneal thickness. The UDVA improved from 1.26 ± 0.13 logMAR preoperative to-0.02 ± 0.15logMAR in LASIK Xtra eyes and from 1.27 ± 0.12 logMAR to 0.01 ± 0.15 logMAR in the convLASIK eyes (P > .05). The MRSE changed from-7.35 ± 1.15 diopters (D) and-7.5 ± 1.12 D to-0.17 ± 0.43 D and-0.25 ± 0.46 D, respectively. There was no significant difference in outcomes between both groups during the 12months follow-up except for the convLASIK eyes' showing slightly better BSCVA after 1week (P < .05). ConvLASIK eyes revealed a nonsignificant trend toward myopic regression from 3 to 12months postoperative with a change in MRSE of-0.15 D compared to-0.1 D in LASIK Xtra eyes. Topography showed stability of corneal curvature with no signs of keratectasia in both groups at 12months. While apparently safe, LASIK Xtra showed no advantages over conventional LASIK. At 12months, both groups showed no difference regarding UDVA and refractive stability, and no signs of keratectasia.

Study of Demarcation Line Depth in Transepithelial versus Epithelium-Off Accelerated Cross-Linking (AXL) in Keratoconus

Aim This is a prospective interventional clinical trial to assess the depth of the demarcation line in transepithelial versus epithelium-off accelerated corneal cross-linking (AXL) in keratoconus patients. Methods This prospective clinical trial was conducted on 40 eyes of 20 patients. Each patient had transepithelial AXL in one eye and epithelium-off AXL in the contralateral eye applying UVA light with an irradiance of 45 mW/cm2 for 2.4 minutes and 30 mW/cm2 for 4 minutes. The depth of the demarcation line was measured using anterior segment OCT (Topcon 3D OCT-2000) one month postoperative for both eyes. Results The demarcation line was patchy in 50% of the transepithelial AXL eyes, the other half showing a demarcation line at a mean depth of 183 ± 41.6 μm. In the epithelium-off AXL technique, the demarcation line was well defined in all cases with a mean depth of 219 ± 27.3 μm. There was a statistically significant difference in corneal demarcation line depth between transepithelial and epithelium-off techniques (P = 0.008 and P < 0.05). The shallower demarcation line in the transepithelial group suggests that it is less effective. Conclusion Based on the depth of the demarcation line, the cross-linking effect of epi-off AXL seems more efficacious than after transepithelial AXL. The future will show if the biomechanical effect will be sufficient to stop progression of keratoconus similarly after standard CXL. This trial is registered with NCT04045626.

Two-year changes in corneal stiffness parameters after accelerated corneal cross-linking

The objective of this non-randomized trial was comparison of two-year changes in dynamic corneal response (DCR) between 18 mW/cm2 (5- min) and 9 mW/cm2 (10-min) cross-linking (CXL) protocols, using novel stiffness parameters and correlating them to clinical indices. The two groups were evaluated before and 2 years after the procedure using Corvis ST (Oculus Optikgeräte GmbH, Germany) and DCR parameters such as deformation amplitude ratio at 1 mm and 2 mm (DA ratio-1 mm and DA ratio-2 mm) and integrated radius and stiffness parameters at A1 (SP-A1). Two-year follow-up was completed for 16 of the 30 eyes in the 5-min group and 21 of the 25 eyes in the 10-min group; data from those who were lost to follow-up was not included in the analyses. Mean age at baseline was 21.7 ± 4.9 and 21.5 ± 5.2 years in the 5- and 10-min groups, respectively (P = 0.895). At 2 years after CXL, in the 5-min group, the reduction in integrated radius (−1.12 ± 1.27 mm, P = 0.003) was significant, and the increase in SP-A1 (7.11 ± 14.86 mmHg/mm, P = 0.075) was borderline, while in the 10-min group, the decrease in DA ratio-2 mm (−0.43 ± 0.58, P = 0.003) and integrated radius (−1.89 ± 1.72 mm, P < 0.001), and increase in SP-A1 (7.67 ± 10.92 mmHg/mm, P = 0.004) were significant. In both groups, the strongest and significant correlation was observed between DCR parameters and changes in radius of curvature. In conclusion, results indicated corneal strengthening with both protocols especially with the 9 mW/cm2. Corvis ST indices can provide “in vivo” biomechanical evidence on the efficacy of CXL that may occur prior to clinical indices.

Different accelerated corneal collagen cross-linking treatment modalities in progressive keratoconus

BackgroundTo compare the outcomes of two different protocols of accelerated corneal crosslinking (CXL) on visual, corneal high order aberrations (HOA) and topographic parameters in patients with progressive keratoconus.MethodsIn this prospective comparative study, sixty-six eyes of 66 patients with progressive keratoconus were divided into two groups; 37 eyes in Group 1 received 18 mW/cm2 for five minutes, and 29 eyes in Group 2 were treated with 9 mW/cm2 for 10 min. The uncorrected distant visual acuity (UCVA), best-corrected distant visual acuity (BCVA), corneal HOAs and topography parameters were measured preoperatively and postoperatively at the end of 12 months. The data for the two groups were compared statistically.ResultsThe mean UCVA and BCVA were significantly improved at the postoperative 12 months compared with the preoperative values in both groups (P < 0.05 for all). A significant improvement in corneal HOAs was observed in both groups (P < 0.05 for all). The change in corneal coma value was significantly higher in Group 2 (P < 0.05). The change in keratometric values K1, K2, AvgK and maximum keratometry (AKf) were significantly higher in Group 2 (P < 0.05 for all). The regression model showed that the most important factor predicting the change in AKf was the type of CXL (β = − 0.482, P = 0.005).ConclusionsAccelerated CXL using 10 min of UVA irradiance at 9 mW/cm2 showed better topographic improvements and coma values than five minutes of UVA irradiance at 18 mW/cm2 independent of keratoconus severity.

Local Antioxidant Status in Patients with Keratoconus after Ultraviolet Corneal Crosslinking

The article presents the study results of the local antioxidant status in patients with progressive keratoconus and its dynamics after the ultraviolet corneal crosslinking. Purpose: to study the oxidative activity in the tear of the patients with keratoconus and its dynamics after ultraviolet cornea crosslinking. Patients and methods. To assess the local level of oxidative activity in keratoconic patients according to the levels of total antioxidant status (TAS) and superoxide dismutase (SOD) in the tear fluid, as well as their dynamics after UV crosslinking were investigated. The study included 38 patients (38 eyes) with keratoconus stage I–II (classification according to Amsler), men — 24 (63.1 %), women — 14 (36.9 %). The standard UV crosslinking group (S-CXL) was 20 eyes, and the pulsed accelerated protocol (I-CXL) — 18 eyes. The average age of patients was 32.4 ± 6.8 years. As a control group, 12 practically healthy individuals were selected. The time of observation is before the operation, on the 3rd, 7th, 14th and 30th days after the procedure. Results: On the basis of the conducted studies, it was revealed that keratoconus patients showed a statistically significant decrease in the initial indicator of TAS by 40 % and amounted to 1.68 ± 0.21 mmol/l, compared to healthy people — 2.82 ± 0.15 mmol/l. The SOD level in tears in patients with keratoconus was also lower by 19 % — to 96.7 ± 11.3 ng/ml, compared to the control — 119.1 ± 16.5 ng/ml. The use of S-CXL of the cornea caused a decrease in TAS during the first 3 days with the subsequent restoration of its level. The use of pulse A-CXL also showed a decrease in this indicator, but by the end of 1st month the level of TAS was higher than preoperative and better than when using the standard protocol. A decrease in SOD level after treatment was noted during the first 3 days, however, the use of S-CXL caused a more significant collapse of this indicator compared to the pulsed accelerated corneal crosslinking protocol. Conclusion. TAS data and SOD level had shown a decrease in local antioxidative status in patients with keratoconus. Ultraviolet corneal crosslinking causes the maximum decrease in SOD and TAS on the 3rd day after the procedure, and from the 14th day their gradual recovery to the initial level is observed. The standard protocol contributed to a more pronounced development of local cross-linking damage in patients with keratoconus. It manifests itself in the antioxidant status reduction of the tear compared to the pulsed accelerated method.

This issue of Acta

This issue of Acta

Simultaneous Transepithelial Topography-Guided Photorefractive Keratectomy and Accelerated Cross-Linking in Keratoconus: 2-Year Follow-Up

Purpose To evaluate the visual, refractive, and topographic outcomes after simultaneous topography-guided transepithelial photorefractive keratectomy (transepithelial TG-PRK) using the Amaris Excimer laser platform and accelerated corneal cross-linking (CXL) in eyes with keratoconus. Materials and Methods Patients with 2 years of follow-up were included in this retrospective case series. Manifest refraction (MR), uncorrected (UDVA) and corrected (CDVA) distance visual acuity, corneal topography, and pachymetry were evaluated at 1, 3, 6, 12, and 24 months after surgery. The root-mean-square of total higher-order aberrations (total HOA-RMS), coma (Coma-RMS), and spherical aberration (SA-RMS) were calculated for 4- and 6-mm diameters. Results Forty-six eyes of 46 patients were included in the study. Stromal ablation was ≤50 μ in all patients. MR was −3.78±3.26 preoperatively and −1.39±1.82 postoperatively. Significant improvements were seen in the UDVA and Coma-RMS values at 1 month, CDVA and total HOA-RMS values at 3 months, and SA-RMS values at 1 year compared to preoperative levels. UDVA values further improved after 2 years, compared to the 1-year values. No patient lost two or more lines and keratoconus progression was not observed in any patient. Conclusion Simultaneous transepithelial TG-PRK and accelerated CXL resulted in significant gains in CDVA without compromising CXL efficacy.

Simultaneous Accelerated Corneal Crosslinking and Laser In situ Keratomileusis for the Treatment of High Myopia in Asian Eyes

Background LASIK Xtra is a recently described technique which combines LASIK and accelerated corneal cross-linking(CXL) in the same setting. Its long-term outcome in Asians with high myopia is not well described. Objectives To compare the efficacy, predictability and safety of LASIK Xtra with LASIK in patients with high myopia. Method This is a retrospective study comparing 50 consecutive eyes undergoing LASIK Xtra for the correction of high myopia and/or myopic astigmatism (-6.63 to -15.50 D manifest spherical equivalent) with a matched control group of 50 eyes undergoing LASIK alone for correction of high myopia (-6.00 to -12.25 D manifest spherical equivalent). Mean follow-up was 5.7 months (range, 1.5-13.3 months) for LASIK Xtra and 3.6 months (range, 1.7-4.2 months) for LASIK only. Outcome measures included Uncorrected Distance Visual Acuity (UDVA), Corrected Distance Visual Acuity (CDVA), refraction and intraoperative and postoperative complications. Results At post-operative 3 months, all eyes achieved UDVA of 20/40 or better, and 80.0% of LASIK Xtra eyes achieved UDVA of 20/20 or better, compared to 66.0% of LASIK only eyes (p = 0.115). Efficacy indices were 0.99±0.17 for LASIK Xtra and 0.94±0.17 for LASIK only (p = 0.164). The proportion of eyes within ±0.50 D of attempted correction was 84% in the LASIK only group and 72% in the LASIK Xtra group at post-operative 3 months (p = 0.148). Safety indices were 1.11±0.19 and 1.11±0.18 in the LASIK Xtra and LASIK only groups, respectively (p = 0.735). Conclusion LASIK Xtra achieved comparable safety, predictability and efficacy as LASIK in patients with high myopia. Good refractive stability was attained at 6-12 months. Further long term studies are required to determine whether simultaneous CXL is able to reduce postoperative LASIK keratectasia in high-risk individuals.

Simultaneous Accelerated Corneal Crosslinking and Laser In situ Keratomileusis for the Treatment of High Myopia in Asian Eyes.

Background:LASIK Xtra is a recently described technique which combines LASIK and accelerated corneal cross-linking(CXL) in the same setting. Its long-term outcome in Asians with high myopia is not well described.Objectives:To compare the efficacy, predictability and safety of LASIK Xtra with LASIK in patients with high myopia.Method:This is a retrospective study comparing 50 consecutive eyes undergoing LASIK Xtra for the correction of high myopia and/or myopic astigmatism (-6.63 to -15.50 D manifest spherical equivalent) with a matched control group of 50 eyes undergoing LASIK alone for correction of high myopia (-6.00 to -12.25 D manifest spherical equivalent). Mean follow-up was 5.7 months (range, 1.5-13.3 months) for LASIK Xtra and 3.6 months (range, 1.7-4.2 months) for LASIK only. Outcome measures included Uncorrected Distance Visual Acuity (UDVA), Corrected Distance Visual Acuity (CDVA), refraction and intraoperative and postoperative complications.Results:At post-operative 3 months, all eyes achieved UDVA of 20/40 or better, and 80.0% of LASIK Xtra eyes achieved UDVA of 20/20 or better, compared to 66.0% of LASIK only eyes (p = 0.115). Efficacy indices were 0.99±0.17 for LASIK Xtra and 0.94±0.17 for LASIK only (p = 0.164). The proportion of eyes within ±0.50 D of attempted correction was 84% in the LASIK only group and 72% in the LASIK Xtra group at post-operative 3 months (p = 0.148). Safety indices were 1.11±0.19 and 1.11±0.18 in the LASIK Xtra and LASIK only groups, respectively (p = 0.735).Conclusion:LASIK Xtra achieved comparable safety, predictability and efficacy as LASIK in patients with high myopia. Good refractive stability was attained at 6-12 months. Further long term studies are required to determine whether simultaneous CXL is able to reduce postoperative LASIK keratectasia in high-risk individuals.

Survival Analysis of Corneal Densitometry After Collagen Cross-Linking for Progressive Keratoconus.

To evaluate the history of densitometric data in patients with keratoconus undergoing corneal cross-linking. Twenty-two eyes of 22 patients with keratoconus were included. Corneal tomography and densitometry measurements were performed before and after accelerated corneal cross-linking. The duration of corneal haze was defined as the time between cross-linking and densitometry measurements returning to the preoperative value. Survival analysis of corneal haze after cross-linking was performed. Preoperative and postoperative corneal densitometry, maximum keratometry (Kmax), and central corneal thickness were compared. The duration of corneal haze was 18.2 ± 3.8 months at the first zone of 0 to 2 mm and 10.9 ± 2.5 months at the second zone of 2 to 6 mm. There was no change in Kmax between the preoperative period and the time at which corneal haze resolved (P = 0.394 at the first zone; P = 0.658 at the second zone). Compared with the measurement taken at resolution of corneal haze, Kmax at 1 year after haze resolution was lower (62.0 ± 9.9 D to 61.2 ± 9.9 D, P = 0.008 at the first zone; 63.6 ± 10.9 D to 62.5 ± 10.1 D, P = 0.016 at the second zone). There was a decrease of central corneal thickness between the preoperative period and the time at which corneal haze resolved (470.8 ± 34.1 μm to 464.8 ± 34.5 μm, P = 0.047 at the first zone; 465.0 ± 35.3 μm to 454.7 ± 37.2 μm, P = 0.001 at the second zone), but it remained unchanged after haze resolution (P = 0.146 at the first zone; P = 0.067 at the second zone). Corneal cross-linking halted keratoconus progression when detectable haze was present. There was continuous corneal flattening measured at 1 year after haze resolution. Thinning of the cornea was seen only when haze was detectable after cross-linking.

A comparative, randomized, contralateral study between the use of Mitomycin-C and accelerated cross-linking as adjuvant therapy after trans-epithelial all surface laser ablation for moderate to high myopia (ASLA-MMC vs. ASLA-XTRA): a pilot study

ABSTRACTObjectives: The purpose of our study is to compare accelerated corneal cross-linking (CXL) against topical application of Mitomycin-C (MMC), in patients undergoing all-surface laser ablation (ASLA) for moderate-to-high myopia and/or myopic astigmatism contralaterally and evaluate the efficacy of this technique in the prevention of postoperative corneal haze formation as well as the efficacy of refractive results.Methods: This prospective study consisted of 34 eyes of 17 myopic (range: −4.00 to −10.5 D, SD: 2.11) patients (8 males, 9 females). Mean age was 26.88 years (SD: 6.04, range: 19–36 years). One eye was randomly selected to ASLA with MMC while the contralateral eye underwent ASLA with accelerated CXL.Results: There was no statistically significant difference in the UDVA between the two groups at all postoperative time intervals (1,3,6, and 12 months). The keratometric values of the eyes and the haze score showed no statistically difference between the two groups at any time point.Conclusion: ASLA combined with accelerated CXL(ASLA-XTRA) appears to be a safe alternative to the use of MMC as an adjuvant treatment in moderate and high myopia. The potential additional benefits of this modality are the stabilizing effect of the refractive result and its sterilization effect on the treated cornea.

Mechanical versus transepithelial phototherapeutic keratectomy epithelial removal followed by accelerated corneal crosslinking for pediatric keratoconus: Long-term results

To compare the 36-month outcomes of mechanical or transepithelial phototherapeutic keratectomy (PTK) epithelial removal before accelerated corneal crosslinking (CXL) for pediatric keratoconus. Atatürk Training and Research Hospital, Ankara, Turkey. Retrospective case series. Eyes that had accelerated CXL after mechanical (Group 1) or transepithelial PTK (Group 2) epithelial removal were evaluated preoperatively and 12, 24, and 36months postoperatively. The uncorrected (UDVA) and corrected distance visual acuities, spherical equivalent (SE), manifest astigmatism, and corneal tomographic and aberrometric parameters were assessed. The study included 40 eyes of 35 consecutive keratoconus patients younger than 18years with a 36-month follow-up. Group 1 comprised 15 patients, and Group 2 comprised 20 patients. Both groups had a significant improvement in UDVA (P=.001 and P=.02, respectively) and a significant decrease in maximum keratometry (K) and thinnest corneal thickness (all P<.001) 36months postoperatively. The improvements in maximum K, topographic astigmatism, and spherical aberration were greater in Group 2 than in Group 1 at 12months (P=.03, P=.01, and P=.04, respectively). After 12months, the outcomes in the 2 groups were more similar. The initial visual and topographic outcomes of transepithelial PTK ablation were better than those of mechanical epithelium removal before accelerated CXL in pediatric patients with keratoconus. Over the long-term, the results were similar between the 2 groups.

Influence of the beam profile crosslinking setting on changes in corneal topography and tomography in progressive keratoconus: Preliminary results

To evaluate the effect of accelerated corneal crosslinking (CXL) with a "higher peripheral intensity" profile setting compared with a standard "top hat" profile setting performed using different CXL systems. Department of Ophthalmology, University Hospital Carl Gustav Carus, Dresden, Germany. Retrospective case series. Eyes from patients with progressive keratoconus were included. Group 1 included eyes treated with the higher peripheral intensity profile. Group 2 included eyes treated with the top hat profile. Accelerated CXL was performed based on the modified Dresden protocol (9mW/cm2, 10minutes). Corneal-topography and tomography are characterized using the Pentacam Scheimpflug system. The study comprised 45 eyes (25 eyes in Group 1, 20 eyes in Group 2) from 45 patients. The keratometry (K) at the apex (maximum K) decreased significantly from 54.95 diopters (D)±6.73 (SD) to 53.21±6.05 D for Group 1 (P<.001) and from 57.29±7.16 D to 56.48±6.88 D for Group 2 (P=.01). In Group 1, flat K (K1) and steep K (K2) decreased significantly after treatment (P<.05). The thinnest corneal thickness decreased significantly by -17.5 ± 21.9μm (P=.001) in Group 1. In Group 2, no significant flattening was observed in K1 and K2 (P>.05), and the thinnest corneal thickness showed a slight but not significant thinning (P=.097). In Group 1 (the higher peripheral intensity group), the corneal topographic and tomographic parameters improved significantly after accelerated CXL. The higher peripheral intensity profile effect on keratoconic cornea flattening seemed to be more pronounced compared with the top hat profile.

Corneal Allogenic Intrastromal Ring Segments (CAIRS) Combined With Corneal Cross-linking for Keratoconus.

To describe a new technique for the treatment of keratoconus using corneal allogenic intrastromal ring segments (CAIRS). CAIRS trephined from donor cornea using a double-bladed trephine were implanted into mid-depth femtosecond laser-dissected channels in the cornea of patients with keratoconus in the 6.5-mm optic zone, followed by accelerated corneal cross-linking (A-CXL)-either conventional or contact lens-assisted CXL (A-CACXL), depending on minimum corneal thickness. Twenty patients (24 eyes) with stage 1 to 4 keratoconus (Amsler-Krumeich grading) were included. Mean follow-up was 11.58 ± 3.6 months (range: 6 to 18 months). There was significant improvement in uncorrected (2.79 ± 2.65 lines; range: 0 to 8 lines) and corrected (1.29 ± 1.33 lines; range: 0 to 5 lines) distance visual acuity, spherical equivalent, simulated maximum keratometry, steepest keratometry, topographic astigmatism, anterior and posterior best fit spheres, and mean power in the 3- and 5-mm zones. No eye showed progression during the entire follow-up. All segments remained well positioned and no segment-induced complications were seen. No other major intraoperative or postoperative complications were observed. This pilot study indicates that CAIRS with CXL may be a simple, safe, and effective option for treating keratoconus. Further studies are recommended to determine long-term outcomes. [J Refract Surg. 2018;34(5):296-303.].

Corneal crosslinking (CXL) with 18-mW/cm2 irradiance and 5.4-J/cm2 radiant exposure-early postoperative safety.

To investigate safety of accelerated corneal crosslinking during the first postoperative month. In this retrospective study, 76 eyes of 60 patients with verified progressive keratectasia were enrolled in this study and followed for 1month after accelerated CXL (18mW/cm2 for 5min, radiant exposure 5.4J/cm2) (A-CXL(5*18)). Preoperatively, objective refraction, slit lamp inspection, and corneal tomography were performed. Early postoperative slit lamp examinations were performed on days 1 and 4. At 1month, objective refraction, slit lamp inspection, and corneal tomography were performed. Gender distribution was m:f = 55:21, OD:OS was 40:36, and the average age was 26.5 ± 8.6years at surgery. Only 71 of the 76 eyes completed the 1-month follow-up, indicating a dropout rate of 6.6%. In 7.0% (n = 5), sterile infiltrates were observed; 5.6% of eyes (n = 4) showed delayed epithelial healing (> 4days) in 2.8% (n = 2); an infection occurred and in 1 eye (1.4%), a stromal scar was detected; no other complications, neither a loss of two or more Snellen lines at 1month postoperatively, were observed. As a risk factor for sterile infiltrates, thin preoperative pachymetry could be identified (p = 0.027). This study revealed no difference in early postoperative safety between CXL using 18mW/cm2 and standard corneal CXL. Thinner preoperative pachymetry could be identified predicting a higher rate of postoperative sterile infiltrates.

Continuous-light versus pulsed-light accelerated corneal crosslinking with ultraviolet-A and riboflavin

To determine whether the pulsed-light ultraviolet-A (UVA) accelerated corneal crosslinking (CXL) procedure is more efficacious and selective than its continuous-light counterpart in rabbits. School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China. Experimental study. Fifty-four rabbits were divided into 2 groups. Group 1 had continuous-light accelerated CXL using 9mW/cm2 UVA for 10minutes (5.4J/cm2). Group 2 had pulsed-light accelerated CXL by exposing them to 9mW/cm2 UVA for 20minutes (1second on/1second off). Corneal stromal demarcation line depth, invivo confocal microscopic analysis, biomechanical stiffness, endothelial cell density, and keratocyte apoptosis were measured after performing these CXL procedures. The mean stromal demarcation line depth was 254.7μm±47.4 (SD) in Group 1 and 341.1±36.1μm in Group 2 (P<.01). One day after CXL, confocal analysis and histological staining identified keratocyte apoptotic fragments in the anterior stroma in the Group 2 corneas whereas all cells were obliterated in Group1. Seven days after treatment, the thicknesses in Group 1 were significantly greater than those in Group 2 (P<.05). Endothelial cell losses were reversible; however, in Group 1, some losses were still evident on day 7. Increases in both the stress-strain relationship and tangent modulus in Group 2 were greater than those in Group1. The pulsed-light accelerated CXL protocol was less injurious and more efficacious at inducing CXL than the continuous-light accelerated CXL protocol in rabbit corneas.