CXL For Keratoconus Research Articles

Corneal Crosslinking: Present and Future.

Keratoconus is a progressive corneal thinning disorder that can lead to vision loss. In the last 2 decades, corneal crosslinking (CXL) has emerged as an effective method to halt the progression of keratoconus and reduce the number of patients requiring keratoplasty. The procedure has been adopted globally and has evolved to become a part of combination treatments to regularize the cornea and improve visual outcomes. CXL has even been extrapolated in managing other ocular pathologies such as progressive myopia, infectious keratitis, and bullous keratopathy. This review aims to summarize the current role of CXL in keratoconus and its alternative uses, and provide insights into future developments in this fast-developing field.

Çocuk ve erişkin Keratokonus hastalarında hızlandırılmış çapraz bağlama tedavisi sonrası Scheimpflug Kornea Dansitometri analizi

Amaç: On sekiz yaş altı ve 18 yaş üstünde keratokonus nedeniyle çapraz bağlama tedavisi (ÇB) uygulanan hastalardaki korneal dansitometri değişimlerini karşılaştırmalı olarak değerlendirmektir. Yöntem: Keratokonus tanısıyla ÇB uygulanan 55 hastanın 74 gözü çalışmaya alındı. 18 yaş ve altındaki hastalar grup 1’e dahil edilirken, 18 yaş üstündeki hastalar grup 2’ye dahil edildi. Hastaların ÇB öncesinde ve sonrasında Pentacam Scheimpflug görüntüleme sistemi ile kornea kalınlığı ve korneal dansitometri değerleri ölçülerek kaydedildi. Çapraz bağlama sonrası tüm hastaların kornea kalınlıkları ultrasonik pakimetri ile de ölçüldü ve Scheimpflug sistem ölçümleri ile karşılaştırma yapıldı. Bulgular: Grup 1’de ÇB öncesindeki korneal dansitometri değeri 19.84±2.67 GSU iken, işlem sonrası 21.54±3.32 GSU idi ve aradaki fark istatistiksel olarak anlamlıydı (p=0.048). Benzer şekilde Grup 2’deki dansitometri değeri ÇB öncesinde 18.74±1.56 GSU iken, işlem sonrasında 24.53±10.46 GSU idi ve aradaki fark anlamlıydı (p<0.0001). Grup 1’de Scheimpflug görüntüleme sistemi ile ÇB öncesi ölçülen kornea kalınlığı 473.04±24.23 µ iken, grup 2’de 467.89±29.09 µ idi. Her iki grupta ÇB sonrası kornea kalınlıkları sırasıyla 461.88±27.64 µ ve 446.42±32.76 µ idi ve aradaki fark iki grupta da istatistiksel olarak anlamlıydı (sırasıyla p=0.003, p<0.0001). Sonuç: Keratokonus hastalarında, ÇB sonrasında, çocuk ve erişkinlerde korneal bulanıklık oluşmaktadır. Erişkinlerde çocuklara göre daha fazla bulanıklık olmaktadır. Bulanıklığın takibinde korneal dansitometri objektif veriler sunar. Bulanıklık olan kornealarda kalınlık takibi için ultrasonik pakimetri, Scheimpflug kameraya göre daha doğru ölçümler sunabilir.

Flattening of Central, Paracentral, and Peripheral Cones After Non-accelerated and Accelerated Epithelium-off CXL in Keratoconus: A Multicenter Study.

To assess the flattening of central, paracentral, and peripheral cones following non-accelerated (non-A-CXL) and accelerated (A-CXL) epithelium-off corneal cross-linking with 10 times higher intensity. In this multicenter study of 200 eyes (100 in each group), following 10 minutes of soak time with riboflavin 0.1%, continuous CXL was performed for 30 minutes (intensity: 3 mW/cm2, fluence: 5.4 J/cm2) in the non-A-CXL group and 3 minutes (intensity: 30 mW/cm2, fluence: 5.4 J/cm2) in the A-CXL group. Anterior and posterior cone flattening were compared at 12 months. Multiple regression analysis was performed to establish correlation of age, sex, cone location, and preoperative maximum keratometry (Kmax) values with postoperative flattening at 12 months. In the non-A-CXL and A-CXL groups, central cones were the steepest, followed by paracentral and peripheral cones. Both groups showed significant flattening in central (1.54 ± 1.94 and 1.09 ± 1.79 diopters [D]) and paracentral (0.62 ± 1.59 and 0.55 ± 0.98 D) cones only. In the non-A-CXL group, there was a positive correlation between postoperative flattening and preoperative Kmax values, whereas paracentral and peripheral cone locations were negatively related. In the A-CXL group, only paracentral location was negatively correlated to postoperative flattening and showed posterior cone steepening at 12 months. Although central cones were the steepest in both groups, there was no difference in postoperative flattening between the groups for all cone locations. In the non-A-CXL group, postoperative flattening was proportional to preoperative Kmax values in central cones and was less with paracentral and peripheral locations. With A-CXL, postoperative flattening was less only with paracentral location. In the A-CXL group, significant posterior cone steepening was noticed only in paracentral cones. [J Refract Surg. 2022;38(5):310-316.].

Corneal Cross-Linking as Treatment in Pediatric Keratoconus: Comparison of Two Protocols.

Introduction Keratoconus is a progressive corneal disease commonly treated by collagen cross-linking (CXL). Accelerated protocols have recently become common. This study sought to compare the outcomes of accelerated and standard CXL in terms of visual acuity, keratometry, and tomographic parameters in pediatric population. Methods We retrospectively reviewed the files of pediatric patients who underwent standard and accelerated CXL for keratoconus in our hospital, between October 2014 and March 2018. Changes in uncorrected distance visual acuity (UCDVA), best corrected distance visual acuity (BCDVA), tomographic keratometry parameters (Kmax, Ksteep, Kflat, Kmean), and endothelial density count (EDC) were assessed before and at 6 and 12 months following treatment. The analysis included intergroup and intragroup comparisons. Results This study included 53 eyes (44 patients). Fourteen eyes were treated with standard CXL (S-CXL, 3 mW/cm2, 30 min), while 39 underwent accelerated CXL (A-CXL, 9 mW/cm2, 10 min). Intergroup comparison found insignificant differences between groups, with the exception of better results for UCDVA in the S-CXL group after 12 months (P = 0.03). In this study, there was no significant difference between the two protocols postoperatively in BCDVA, Kmax, Kmean, pachymetry, or corneal astigmatism. Conclusion A-CXL is as safe and effective as S-CXL for stabilizing progressive keratoconus in pediatric population. Larger-sample-size studies with a longer follow-up time are required. Considering the long-term results of 9 mW A-CXL and its safety and efficacy profile, it should be preferred to S-CXL for reducing treatment time and improving patients' comfort.

Структурні зміни рогівки, виявлені за допомогою конфокальної мікроскопії, у пацієнтів з кератоконусом після прискореного кросслінкінгу

Структурні зміни рогівки, виявлені за допомогою конфокальної мікроскопії, у пацієнтів з кератоконусом після прискореного кросслінкінгу

Combined surface ablation+CXL for keratoconus

AbstractKeratoconus treatment should be aimed to improve the optical inefficiency of the irregular cornea and halt the disease progression that may lead to the need for corneal transplantation. Corneal collagen cross‐linking (CXL) using Riboflavin and ultraviolet A has been used to stabilize the cornea with progressive keratoconus or ectatic corneal disorders after corneal refractive procedures. Studies demonstrated that the simultaneous wavefront optimized (WG PRK) or topography guided (TG PRK) approach of photore‐fractive keratectomy (PRK) plus CXL offers improvements in uncorrected distance acuity (UDA), best distance acuity(BDA), and topographic irregularity, even if the surgical goal is not a refractive end point. Combining photorefractive keratectomy (PRK) with CXL or accelerated CXL offers keratoconus patients both stability and improvement in functional vision. However, different excimer laser platforms have different ablation patterns and different algorithms for topography‐guided ablation. Additionally, mechanical and laser debridement of the corneal epithelium (PRK versus transepithelial PRK) may result in different patterns of ablation and different clinical results. Though the conventional refractive components of sphere and cylinder may be simultaneously incorporated into the treatment profile, in the treatment of keratoconus, tissue sparing is the prime consideration, and therefore, PRK typically limits the maximum depth of tissue ablation to less than 50mm. Several CXL protocols result in more cross‐linking and a greater increase in Young's modulus, less corneal cross‐linking (a smaller increase in Young's modulus) may still have the same clinical effect (in terms of disease stabilization). In other words, the optimum CXL parameters to produce the clinically desired effect (in terms of stabilization or prophylaxis) are not known. A reduction in HOA after TG‐PRK in keratoconus eyes (with or without the addition of CXL) is not surprising and is a consistent finding in published studies. Diffuse corneal haze, which emerges in a few days after CXL in virtually all eyes, generally resolves over time. It is identified as a dust‐like change in the stroma. In addition, some patients suffer from scarring that persists and can decrease visual acuity. However, these two words— “haze” and “scar”—are sometimes used interchangeably in the literature.

Appropriate Sequence of Combined Intracorneal Ring Implantation and Corneal Collagen Cross-Linking in Keratoconus: A Systematic Review and Meta-Analysis.

To compare surgical sequences of combined intracorneal ring segment (ICRS) implantation and corneal collagen cross-linking (CXL) in keratoconus and corneal ectasia in terms of visual, refractive, and keratometric outcomes. A comprehensive electronic search (in PubMed, Web of Science, Scopus, Embase, and Cochrane Library) was conducted in accordance with the PRISMA statement to find articles on combined ICRS implantation and CXL in keratoconus and corneal ectasia. The search period was from the inception of the database up to April 2017. Eligible articles were categorized into 3 surgical sequences (same day, ICRS first, and CXL first) and assessed qualitatively. Articles with 12 months of follow-up data after combined surgery were included in the meta-analysis. The initial search identified 120 related articles, of which 17 were included in the review after screening. The quality assessment showed that visual, refractive, and keratometric improvement was observed in all studies in all 3 groups of combined surgery. Meta-analysis on 6 studies that reported 12-month follow-up outcomes showed no significant differences between the 3 groups regarding uncorrected and best-corrected visual acuity and cylindrical refractive error. However, results with simultaneous surgery were superior to the CXL-first technique in terms of spherical refractive errors and flat-K (P = 0.011 and P = 0.0001, respectively) and to both CXL first and ICRS first in terms of steep-K (P = 0.002 and P = 0.007, respectively). Simultaneous ICRS implantation and CXL may provide better outcomes than staged techniques for improving the corneal shape.

Corneal Collagen Cross-Linking in the Management of Keratoconus in Canada: A Cost-Effectiveness Analysis

To use patient-level microsimulation models to evaluate the comparative cost-effectiveness of early corneal cross-linking (CXL) and conventional management with penetrating keratoplasty (PKP) when indicated in managing keratoconus in Canada. Cost-utility analysis using individual-based, state-transition microsimulation models. Simulated cohorts of 100 000 individuals with keratoconus who entered each treatment arm at25 years of age. Fellow eyes were modeled separately. Simulated individuals lived up to a maximum of 110 years. We developed 2 state-transition microsimulation models to reflect the natural history of keratoconus progression and the impact of conventional management with PKP versus CXL. We collected data from the published literature to inform model parameters. We used realistic parameters that maximized the potential costs and complications of CXL, while minimizing those associated with PKP. In each treatment arm, we allowed simulated individuals to move through health states in monthly cycles from diagnosis until death. For each treatment strategy, we calculated the total cost and number of quality-adjusted life years (QALYs) gained. Costs were measured in Canadian dollars. Costs and QALYs were discounted at 5%, converting future costs and QALYs into present values. We used an incremental cost-effectiveness ratio (ICER= difference in lifetime costs/difference in lifetime health outcomes) to compare the cost-effectiveness of CXL versus conventional management with PKP. Lifetime costs and QALYs for CXL were estimated to be Can$5530 (Can$4512, discounted) and 50.12 QALYs (16.42 QALYs, discounted). Lifetime costs and QALYs for conventional managementwith PKP were Can$2675 (Can$1508, discounted) and 48.93 QALYs (16.09 QALYs, discounted). The discounted ICER comparing CXL to conventional management was Can$9090/QALY gained. Sensitivity analyses revealed that in general, parameter variations did not influence the cost-effectiveness of CXL. CXL is cost-effective compared with conventional management with PKP in the treatment of keratoconus. Our ICER of Can$9090/QALY falls well below the range of Can$20 000 to Can$100 000/QALY and below US$50 000/QALY, thresholds generally used to evaluate the cost-effectiveness of health interventions in Canada and the United States. This study provides strong economic evidence for the cost-effectiveness of early CXL in keratoconus.

Therapeutic effect and safety of accelarated transepithelial riboflavin-ultraviolet corneal collagen crosslinking for keratoconus

Background Researches showed that classic corneal collagen crosslinking (CXL) can effectively control the progression of keratoconus and corneal ectasia, but its adverse responses and complications are common due to the de-epithelial procedure. A transepithelial riboflavin-ultraviolet CXL surgery has applied in ophthalmology, but its effectiveness and safety evaluation is less. Objective This study was to evaluate the effectiveness and safety of rapid transepithelial riboflavin-ultraviolet CXL for keratoconus. Methods A prospective self-controlled study was designed. Forty-six eyes of 28 keratoconus patients scheduled to receive the rapid transepithelial riboflavin-ultraviolet CXL in Beijing Tongren Hospital from March to October in 2014 under the approval of this hospital and informed consent with a follow-up duration for one year. The spherical equivalent (SE), astigmatic power, central corneal thickness (CCT), endothelial cell count, corneal topography parameters, the parameters from the anterior segment optical coherence tomography (AS-OCT) and corneal biomechanical parameters were examined before surgery and 1 week, 1 month, 3 months, 6 months and 12 months after surgery, and the results were compared among different time points to assess the effectiveness of transepithelial riboflavin-ultraviolet CXL for keratoconus. The postoperative irritation symptoms and adverse response were observed to evaluate the safety of surgery. Results No intraoperative complication and serious adverse postoperative infection were found in all the operated eyes. Slight irritation symptoms occurred in operated eyes 1 day after surgery and disappeared 3 days after surgery. A little reducing was seen in the spherical equivalent 1 month later, without significant difference among various time points (F=0.722, P=0.614). However, a significant reducing was found in astigmatic power in 12 months after surgery compared with before surgery (t =3.242, P=0.004). No considerably differences were seen in corneal endothelial cell (CEC) density, variation coefficient of CEC area and hexagonal CEC ratio among different time points (F=0.246, 0.465, 0.981; all at P>0.05). The corneal thickness values in postoperative 3 and 6 months were (467.86±52.92)μm and (468.51±52.96)μm, which were insignificantly higher than (453.91±45.78)μm in preoperation (t=0.236, 0.469; both at P>0.05), however, the corneal thickness value in postoperative 12 months([488.67±51.44]μm) was significantly increased in comparison with preoperation (t=3.681, P=0.002). The maximal corneal curvature value (Ks), minimal corneal curvature value (Kf) and average corneal curvature value (Avek) were not significantly lower 3, 6 and 12 months after surgery than those before surgery (F=0.592, 0.897, 1.029, all at P>0.05). High reflective light band of corneal stroma was found in OCT images in 39 eyes (84.78%) with the mean depth of (214.38±31.92)μm. No significant differences were found in corneal hysteresis (CH) and corneal resistance factor (CRF) before and after surgery (F=1.268、0.894, both at P>0.05). Conclusions Rapid transepithelial riboflavin-ultraviolet CXL for keratoconus can increase corneal thickness, flatten corneal curvature and therefore arrest the development of keratoconus corneas. In addition, this therapy does not alter the shape and function of corneal epithelial and endothelial cells with mild irritation to eyes. Key words: [Key words] Keratoconus/drug therapy; Photochemotherapy/methods; Photosensitizing agents/therapeutic use; Riboflavin/therapeutic use; Ultraviolet rays; Biomechanics, corneal; Accelerated transepithelial riboflavin-ultraviolet corneal collagen crosslinking

Corneal Biomechanical and Anterior Chamber Parameters Variations after 1-year of Transepithelial Corneal Collagen Cross-linking in Eyes of Children with Keratoconus.

Aim:To assess the changes in corneal hysteresis (CH) and corneal resistance factor (CRF) 1-year following transepithelial corneal collagen cross-linking (CXL) treatment in eyes of children with keratoconus.Methods:This case series was conducted in 22 eyes of 22 children. Children aged < 18 years with progressive keratoconus were included. They were treated with transepithelial CXL. Corneal biomechanical and anterior chamber parameters such as CH, CRF, and peak 1 were noted using ocular response analyzer, Pentacam, intraocular lens master, and anterior segment optical coherence tomography before and 1, 3, 6, and 12 months after treatment.Results:Our series had 22 eyes of 22 children with a mean age 15.7 ± 2.1 years. The CH and CRF 1-year after treatment declined (difference of mean 0.1 mmHg (95% confidence interval [CI] 0.04–0.24), P = 0.2] and (difference of mean 0.1 mmHg [95% CI 0.04–0.30], P = 0.3), respectively. Peak 1 and peak 2 increased (difference of mean 0.1 mmHg [95% CI 0.006–0.008], P = 0.2) and (difference of mean 0.1 mmHg [95% CI 0.007–0.006], P = 0.3), respectively. The uncorrected distance visual acuity improved from 0.95 ± 0.34 logMAR to 0.68 ± 0.45 logMAR (P < 0.05). No statistically significant changes during 12 months follow-up were observed in axial length, corneal volume, anterior chamber volume, and anterior chamber depth (P > 0.05).Conclusion:Transepithelial CXL in keratoconus in pediatric age group seems to have good stability in corneal biomechanical parameters after 1-year. Further studies with a larger sample and better study design are recommended to confirm our findings.

Non-topography–guided Photorefractive Keratectomy for the Correction of Residual Mild Refractive Errors After ICRS Implantation and CXL in Keratoconus

To evaluate the safety and clinical outcomes of non-topography-guided photorefractive keratectomy (PRK) for the treatment of residual mild refractive errors 6 months after sequential intracorneal ring segment (ICRS) implantation and corneal collagen cross-linking (CXL) in stable keratoconus. This retrospective study included 17 eyes of 14 patients with mild to moderate keratoconus. The ICRS implantation and CXL were performed sequentially with a 4-week interval and non-topography-guided PRK was performed at least 6 months after CXL. Data were collected preoperatively and at the 6-month follow-up visits. ICRS implantation and CXL induced a significant decrease in keratometry and refraction and an increase in visual acuity. At the 6-month follow-up after ICRS implantation and CXL, uncorrected and corrected distance visual acuity (UDVA and CDVA) significantly improved from 1.17 ± 0.38 and 0.44 ± 0.09 logMAR preoperatively to 0.45 ± 0.11 and 0.17 ± 0.08 logMAR (P = .001) postoperatively, respectively. The mean spherical error decreased from -5.45 ± 1.64 to -2.57 ± 1.15 D (P = .01) and the mean cylinder from 3.86 ± 1.15 to 2.13 ± 1.11 D (P = .01). At the 6-month follow-up after PRK, UDVA significantly improved to 0.18 ± 0.06 logMAR and CDVA was 0.15 ± 0.05 logMAR. The mean spherical error and mean cylinder significantly decreased to -1.10 ± 0.41 D (P = .02) and 0.98 ± 0.37 D (P = .046), respectively. No intraoperative or postoperative complications occurred. At the 6-month follow-up, non-topography-guided PRK after ICRS implantation and CXL was found to be an effective and safe option for correcting residual refractive error and improving visual acuity in patients with moderate keratoconus.

Effects and adverse events after CXL for keratoconus are independent of age: a 1-year follow-up study

To compare the effect, failure rate and the risks of corneal cross-linking (CXL) in keratoconus patients aged ≥35 years to patients <35 years. In 141 eyes of 116 keratoconus patients we compared the changes in best phoropter-corrected visual acuity (BCVA) and maximum keratometry values (Kmax) before and 12 months after CLX in patients aged ≥35 years (n=34, 38 eyes) to the cohort of patients below 35 years of age. Overall, CXL significantly improved BCVA from 0.487 logMAR (95% confidence interval (CI) 0.426-0.548) by -0.197 logMAR (95% CI -0.243 to -0.150; P<0.001) and reduced Kmax from 48.96 diopter (Dpt) by -1.33 Dpt (95% CI -1.85 to -0.81: P<0.001). Age ≥35 years had no effect on the changes of BCVA (-0.02 (95% CI -0.13 to 0.09); P=0.757) or Kmax (0.58 (95%CI -0.51 to 1.68); P=0.294) as compared with younger patients. In 54 patients (55 eyes, 38.5%) aged <35 years and in 18 patients (18 eyes, 47.4%) aged ≥35 years, BCVA increased by ≥2 Snellen lines. Failure (increase in Kmax ≥1 Dpt) was observed in 17 eyes (16.5%) of patients aged <35 years and in 3 eyes (7.9%) of patients aged ≥35 years during the 12-month follow-up period. Adverse outcomes (loss of ≥2 Snellen lines) occurred in 4 (3.9%) eyes of patients aged <35 years and 1 (2.6%) eye of a patient aged ≥35 years. Effects and adverse events of CXL treatment do not seem to differ between subjects younger or older than 35 years.

Increased corneal hysteresis after corneal collagen crosslinking: a study based on applanation resonance technology.

A reliable tool for quantification of the biomechanical status of the cornea in conjunction with corneal collagen crosslinking (CXL) treatment is needed. To quantify the biomechanical effects of CXL in vivo. A prospective, open, case-control study was conducted at the Department of Ophthalmology, Umeå University, Umeå, Sweden. Participants included 28 patients (29 eyes) aged 18 to 28 years with progressive keratoconus and corresponding age- and sex-matched healthy individuals serving as controls. All participants were monitored during a 6-month period between October 13, 2009, and November 5, 2012. Corneal hysteresis after CXL for keratoconus. A difference in corneal hysteresis between the control group and the patients with keratoconus was found at baseline, both with an applanation resonance tonometer (ART) and an ocular response analyzer (ORA), at mean (SD) values of -1.09 (1.92) mm Hg (99% CI, -2.26 to 0.07; P = .01) and -2.67 (2.55) mm Hg (99% CI, -4.05 to -1.32; P < .001), respectively. Increased corneal hysteresis was demonstrated with an ART 1 and 6 months after CXL, at 1.2 (2.4) mm Hg (99% CI,-0.1 to 2.5; P = .02) and 1.1 (2.7) mm Hg (99% CI, -0.3 to 2.6; P = .04), respectively, but not with ORA. A decrease in corneal thickness was seen 1 and 6 months after treatment (-24 [26] µm, P < .001; and -11 [21] µm, P = .01, respectively), and a corneal flattening of -0.6 (0.7) diopters was seen at 6 months (P < .001). No significant change in intraocular pressure was identified in patients with keratoconus with any method, except for an increase at 1 month with Goldmann applanation tonometry (P = .005). To our knowledge ART is the first in vivo method able to assess the increased corneal hysteresis after CXL treatment. Given the large-scale use of CXL in modern keratoconus treatment, a tool with this capacity has a great potential value. Refinement of the ART method of measuring and quantifying corneal biomechanical properties will be a subject of further studies.

Corneal collagen cross-linking for correction of low myopia?

DOI:10.1097/ICU.0b013e3283622cb1 Corneal collagen cross-linking (CXL) was first described in 1997 by Sporl et al. [1]. Since then, it has been increasingly used in the treatment of postlaser-assisted in situ keratomileusis (LASIK) keratectasia as well as keratoconus [2–6]. Recently, this technique has been used as an adjunct to refractive surgery, such as LASIK, to provide increased structural stability following correction of refractive error [7]. Given the corneal flattening that occurs with CXL, the possibility of using this particular technique alone as a method to correct low myopia has been proposed [8]. In this issue of Current Opinion in Ophthalmology, Nguyen and Chuck [9] review the application of CXL in a variety of keratoplastic procedures, including photorefractive keratectomy , LASIK, thermal keratoplasty, and orthokeratology. This review highlights numerous instances in which CXL has been shown to halt regression and even produce additional effects in all of the above keratoplastic procedures, with the exception of orthokeratology. If the addition of CXL to these procedures results in these prolonged and/or additional effects, the potential effects of using CXL alone should be considered. In 2011, Hersh et al. [2] demonstrated significant improvement in both uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) at 1 year in eyes that had undergone CXL in keratoconus or corneal ectasia patients. Their results revealed an improvement in mean UDVA from 0.84 logMAR 0.34 (SD) (20/137) to 0.77 0.37 logMAR (20/117) and an improvement in mean CDVA from 0.35 0.24 log MAR (20/45) to 0.23 0.21 logMAR (20/34). Brooks et al. [10] also suggested that patients experience subjective improvement in visual function, such as night driving, difficulty reading, diplopia, glare, halo, starbursts, and foreign-body sensation, after undergoing CXL for keratoconus and corneal ectasia, corroborating the objective results described by Hersh et al. These results included the following: a decrease in the mean maximum keratometry value by 2.0 D or more in 31% of patients, an increase in the mean maximum keratometry value by 2.0 D or more in 4.2% of

Clinical Results of Topography-based Customized Ablations in Highly Aberrated Eyes and Keratoconus/Ectasia With Cross-linking

To report results of a series of highly aberrated corneas treated with a topography-guided excimer laser ablation. Retrospective, nonrandomized, consecutive series of eyes treated with topography-guided photorefractive keratectomy (TG-PRK) with the customized topographical neutralization technique (TNT). Cases included postoperative refractive surgery decentered ablations, optical zone enlargement, asymmetrical astigmatism, postoperative radial keratotomy (RK), postoperative keratoplasty, keratoconus combined with collagen cross-linking (CXL), and postoperative LASIK ectasia combined with CXL. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and manifest refraction were analyzed preoperatively and 6 months postoperatively. In decentered ablation cases, 94% of 37 eyes were within 1.00 diopter (D) of the attempted refractive outcome, with 76% within 0.50 D. Mean topographic, central, optical zone of uniform (monodioptric) power increased from 3.5 to 5.2 mm in 25 eyes. Thirty-one eyes treated for asymmetrical astigmatism showed improvement in cylinder from mean 1.31 to 0.52 D. Ten of 11 eyes treated for previous RK astigmatism achieved postoperative UDVA 20/40 or better. Twenty-seven eyes with postoperative keratoplasty astigmatism were treated, with 7 (25.9%) eyes gaining > or = 2 lines and 12 (44.4%) eyes gaining > or = 1 line of CDVA. Of eyes with keratoconus that were treated using TG-PRK with CXL, 42 (58%) eyes had UDVA 20/40 or better, and 66 (92%) eyes had CDVA 20/40 or better. Twelve (71%) of 17 eyes treated for postoperative LASIK ectasia using TG-PRK with CXL had UDVA 20/40 or better. Nine (53%) eyes gained > or = 2 lines of CDVA. Topography-guided laser treatment with custom TNT, combined with CXL in keratoconus and ectasia, is an effective, safe, and increasingly predictable option for highly aberrated corneas.

Endothelial Failure After Collagen Cross-Linking With Riboflavin and UV-A

To report a case of endothelial decompensation after a collagen cross-linking (CXL) procedure for keratoconus. An 18-year-old boy had CXL for keratoconus in the right eye. He developed keratouveitis with generalized corneal edema seen 3 weeks after the procedure. Polymerase chain reaction for aqueous humor Herpes simplex virus was negative. The patient was treated with topical steroids. Specular microscopy revealed mildly reduced density of endothelial cells. On follow-up to 6 months, corneal edema increased with the formation of epithelial bullae. Penetrating keratoplasty was performed. Possible causes for this complication are discussed. Clinical and histopathological analyses revealed generalized loss of endothelial cells along with signs of inflammation. Although it is considered very safe, collagen CXL can cause severe keratouveitis and endothelial failure.

Simultaneous wavefront-guided photorefractive keratectomy and corneal collagen crosslinking after intrastromal corneal ring segment implantation for keratoconus

To study the results of simultaneous photorefractive keratectomy (PRK) and corneal collagen crosslinking (CXL) in keratoconus after previous intrastromal corneal ring segment (ICRS) implantation. Enaim Laser Center, Jerusalem, Israel. Case series. This study comprised patients with moderate keratoconus who had previous Intacs ICRS implantation with the Intralase laser at least 6 months before PRK-CXL. Wavefront-guided PRK and ultraviolet-A CXL were performed simultaneously. Refraction, uncorrected (UDVA) and corrected (CDVA) distance visual acuities, keratometry (K) values, endothelial cell count (ECC), pachymetry, corneal resistance factor (CRF), and corneal hysteresis (CH) were assessed 3, 6, and 12 months postoperatively. Twelve months after PRK-CXL, the mean decimal UDVA improved significantly from 0.20 ± 0.12 (SD) to 0.55 ± 0.15 (P<.01). The mean decimal CDVA improved from 0.58 ± 0.13 to 0.77 ± 0.17 (P=.01). The mean cylinder decreased from -3.60 ± 1.70 to -1.30 ± 1.10 diopters (D) (P<.001). The mean apex K decreased from 50.91 ± 5.50 D to 46.61 ± 4.52 D (P<.005). The other corneal parameters did not change significantly after treatment. No significant difference was found between the 6-month and 12-month results. No patient lost lines of CDVA. Mild haze remained in 11.1% of eyes 12 months after treatment. Simultaneous wavefront-guided PRK and CXL for keratoconus after ICRS implantation was safe and effective. It significantly improved the UDVA, CDVA, and central K value, and consequently the visual function, of patients with moderate keratoconus.

Sterile keratitis after corneal collagen crosslinking in a child

Corneal collagen crosslinking (CXL) is a non invasive technique used in halting the progression of keratoconus. Complications with this modality are rare. We report a case of an 8-year-old child who developed sterile infiltrates in the immediate postoperative period after uneventful corneal collagen crosslinking for keratoconus. The infiltrates resolved with topical steroid therapy. There was also present coexisting vernal keratoconjunctivitis (VKC) which was controlled with topical 2% cyclosporine A eye drops prior to crosslinking treatment. This case highlights importance of controlling VKC prior to CXL in keratoconus as it adds to the risk of developing post operative sterile keratitis.

Corneal Collagen Cross-linking Demarcation Line Depth Assessed by Visante OCT After CXL for Keratoconus and Corneal Ectasia

To report the demarcation line depth after corneal collagen cross-linking (CXL) for keratoconus and postoperative LASIK ectasia with Visante (Carl Zeiss Meditec) optical coherence tomography (OCT) and investigate correlations between this depth and preoperative parameters and postoperative visual and keratometry outcomes. Retrospective interventional case series of 40 eyes with keratoconus or postoperative LASIK ectasia treated with riboflavin ultraviolet-A CXL. Ophthalmic evaluation included uncorrected distance visual acuity, corrected distance visual acuity (CDVA), corneal topography (Pentacam, Oculus Optikgeräte GmbH), and postoperative anterior segment OCT. Correlation analyses were performed. Statistical significance was indicated by P<.05. At 6 months postoperative, mean demarcation line depth was 281.4±53.3 μm. Thinner minimal corneal thickness (r=0.413, P=.008), older age (r=-0.490, P=.001), higher grading of ectasia (for both keratoconus and postoperative LASIK ectasia) (r=-0.332, P=.044), female sex (r=0.343, P=.030), postoperative LASIK ectasia (r=-0.420, P=.007), and longer duration of disease (r=-0.377, P=.023) were correlated with shallower demarcation line depth. Forward stepwise multiple linear regression analysis showed that among all preoperative factors, minimal corneal thickness (standardized β=0.473, P=.003) and age (standardized β=-0.317, P=.036) were significantly associated with demarcation line depth. The CXL demarcation line depth and change in CDVA (r=-0.16, P=.325) and change of the steepest keratometry at 6 months (r=0.084, P=.637) were not correlated. The Visante OCT can be used for assessing CXL demarcation line depth. The demarcation line depth may decrease with the severity of ectasia and age.

Patient subjective visual function after corneal collagen crosslinking for keratoconus and corneal ectasia

To assess subjective visual function after corneal collagen crosslinking (CXL). Cornea and refractive surgery subspecialty practice. Prospective randomized controlled clinical trial. Patients completed a subjective questionnaire regarding visual symptoms administered preoperatively and 1 year after CXL. Patients ranked self-reported symptoms of photophobia, difficulty night driving, difficulty reading, diplopia, fluctuations in vision, glare, halo, starburst, dryness, pain, and foreign-body sensation on a scale from 1 to 5. Possible associations of symptoms with changes in corrected distance visual acuity (CDVA) and maximum keratometry were also analyzed. One hundred seven eyes of 76 patients had CXL for keratoconus (n = 71) or ectasia (n = 36). The mean preoperative to 1-year postoperative changes in night driving (3.2 ± 1.5 [SD] to 2.8 ± 1.5), difficulty reading (3.1 ± 1.5 to 2.9 ± 1.3), diplopia (2.5 ± 1.3 to 2.1 ± 1.2), glare (3.1 ± 1.4 to 2.7 ± 1.2), halo (2.9 ± 1.4 to 2.5 ± 1.3), starbursts (2.6 ± 1.5 to 2.4 ± 1.4), and foreign-body sensation (1.8 ± 1.1 to 1.6 ± 0.9) were statistically significant. There were no associations between the change in any symptom and changes in CDVA. There was a weak association between the change in night driving, pain, and foreign-body sensations and the change in maximum keratometry. After CXL, patients noted subjective improvement in visual symptoms, specifically night driving, difficulty reading, diplopia, glare, halo, starbursts, and foreign-body sensation. These subjective outcomes corroborate quantitative clinical improvements seen after CXL.