Collagen Cross-linking In Patients Research Articles

Dynamics of Corneal Swelling With Hypoosmolar Riboflavin After Induction During Corneal Collagen Crosslinking in Patients With Progressive Keratoconus.

To evaluate the rate of corneal swelling induced by hypoosmolar riboflavin in patients with progressive keratoconus (KCN) with corneal thickness <400 µm after the induction phase using riboflavin with 20% dextran during epithelium-off corneal crosslinking (CXL). Prospective, nonrandomized, single-center consecutive case series. Preoperative assessments included tomography, specular microscopy, and hysteresis. After epithelial debridement, riboflavin with 20% dextran (Photrexa Viscous; Glaukos, Burlington, MA) was applied at 2-min intervals during a 30-min induction phase. Eyes that dehydrated to a minimum corneal thickness (MCT) of <400 µm after induction (postinduction pachymetry) were recruited. Hypoosmolar riboflavin 0.146% (Photrexa; Glaukos) was used every 10 s to induce stromal swelling, with pachymetry performed every 30 s until the MCT was ≥400 µm (postswelling pachymetry). Corneal swelling rate was compared with variables using regression analysis. In 31 eyes of 31 patients, mean postinduction pachymetry was 338.4 ± 28.7 μm. Hypoosmolar riboflavin induced a postswelling pachymetry of 413.4 ± 15.0 μm over a mean of 5.2 ± 3.2 min, and the average stromal swelling rate was 10.3 ± 8.7 μm/30 s. All eyes reached a postswelling pachymetry MCT ≥400 µm and no cases were aborted. Eyes with highly severe KCN (Kmax >70 and Belin/Ambrosio enhanced ectasia display final D score >17) experienced quicker swelling (14.4 ± 12.8 μm/30 s and 14.9 ± 12.4 μm/30 s, respectively; P < 0.05 for both). A thicker postinduction pachymetry was moderately associated with a faster rate of swelling (rs = 0.389; P = 0.030). Hypoosmolar riboflavin 0.146% can be safely employed in thinner corneas, allowing for swelling to ≥400 µm for epithelium-off CXL. Associations between swelling rate, KCN severity, and postinduction pachymetry were determined, allowing for a more accurate prediction of procedure time during CXL.

Corneal collagen cross-linking in patients with keratoconus from the Dresden protocol to customized solutions: theoretical basis.

Keratoconus is an ectatic condition characterized by gradual corneal thinning, corneal protrusion, progressive irregular astigmatism, corneal fibrosis, and visual impairment. The therapeutic options regarding improvement of visual function include glasses or soft contact lenses correction for initial stages, gas-permeable rigid contact lenses, scleral lenses, implantation of intrastromal corneal ring or corneal transplants for most advanced stages. In keratoconus cases showing disease progression corneal collagen crosslinking (CXL) has been proven to be an effective, minimally invasive and safe procedure. CXL consists of a photochemical reaction of corneal collagen by riboflavin stimulation with ultraviolet A radiation, resulting in stromal crosslinks formation. The aim of this review is to carry out an examination of CXL methods based on theoretical basis and mathematical models, from the original Dresden protocol to the most recent developments in the technique, reporting the changes proposed in the last 15y and examining the advantages and disadvantages of the various treatment protocols. Finally, the limits of non-standardized methods and the perspectives offered by a customization of the treatment are highlighted.

A Novel approach for Corneal Remodeling of Laser Asymmetric Keratectomy with Collagen Cross Linking in Patients with Keratoconus Suspect

Background True Keratoconus Suspect (KCS) is an absolute contraindication to LASIK or Photorefractive Keratectomy (PRK) due to postoperative ectasia. Objective To evaluate the effectiveness of laser asymmetric keratectomy with collagen cross-linking (L-LAK-CXL) in myopic patients with suspected keratoconus (KCS). Methods This study included 40–44-year-old four myopic (-2.50 to -5.50 D) patients (4 eyes), of KCS with focal corneal steepening over +47.0 D and peripheral asymmetric corneal thickness. L-LAK-CXL was performed for both original ablation of refractive errors and crescentic customized ablation of the thicker peripheral cornea selectively and myopic changes due to the ablation of the peripheral thicker cornea simultaneously, followed by CXL without the epithelium. We compared preoperative and postoperative ocular findings, including corneal symmetry (total differences of the corneal thickness in four directions (SUM) and decentration of the thinnest point (DISTANCE)) and tear break-out time (TBUT). Results From preoperative to postoperative, spherical equivalent (D, average) decreased from -3.38 to -0.34, uncorrected distance visual acuity (LogMAR) increased from 0.53 to 0.00, and Kmax (average D) had decreased from +48.3 to +43.95, central pachymetry (CP, µm, average) decreased from 574 to 511. Postoperative corneal symmetry increased markedly owing to decreased SUM and DISTANCE scores. TBUT increased over 15 s postoperatively. No post-operative corneal ectasia was observed. Conclusion L-LAK-CXL improved corneal symmetry in myopic patients with KCS by reducing SUM, decreasing DISTANCE and Kmax, increasing TBUT, and demonstrating good postoperative visual outcomes.

Results of corneal collagen cross-linking in patients with corneal ectasia after laser refractive surgery—A prospective study

PurposeTo evaluate the safety and efficacy of epithelium-off (epi‑off) corneal cross-linking (CXL) in patients with post-LASIK corneal ectasia (PLE) SettingPrivate clinical practice DesignProspective clinical trial Methods82 eyes of adult patients post-LASIK, ages 21–67, with a topography pattern consistent with corneal ectasia, corrected distance visual acuity (CDVA) worse than 20/20, and minimum corneal pachymetry > 400 µm underwent epi‑off CXL. Exclusion criteria were patients with corneas that were thinner than 400 μm or demonstrated central corneal scarring, history of herpetic eye disease, pregnancy or nursing. Follow up examinations of spherical equivalent, uncorrected distance visual acuity (UDVA), CDVA, steep keratometry (KSteep) and minimum pachymetry occurred on different but highly overlapping subsets of the operated eyes yearly until 5 years post-CXL. ResultsOver the 5 years of follow up, spherical equivalent did not significantly change while UCVA and CDVA stabilized or improved to a non-significant degree. KSteep and minimum pachymetry continued to be decreased to a statistically significant degree (p < 0.05 at 5 years). ConclusionsCXL in PLE patients is safe and efficacious: it halts progression of PLE and may improve visual function. KSteep and minimum pachymetry decrease post-CXL. Patients with PLE should be encouraged to stop progression of the disease by undergoing epi‑off CXL once progression is established.

Efficacy and safety of accelerated corneal collagen cross-linking in patients with keratoconus

AIM: To study the efficacy and safety of accelerated collagen cross-linking in keratoconus. METHODS: Medical records of keratoconic corneas underwent accelerated collagen cross-linking at King Chulalongkorn Memorial Hospital, Thailand between April 2015 and August 2018 were reviewed. Preoperative and postoperative data at 1y of visual acuity, auto-refraction, corneal topography, higher-order aberrations (HOA), topometric indices and corneal densitometry were evaluated. Age of 24-30 (mean age 23.43±7.26)y, maximum keratometric value (Kmax) of 55 D, and baseline best corrected visual acuity (BCVA) of 20/40 (or 0.3 in LogMAR unit) were used as cut-off values to highlight the cross-linking effects. The effect of age, preoperative Kmax and BCVA were analyzed. The association between the change of corneal densitometry and other factors including preoperative Kmax, Kmean, manifest refraction spherical equivalent (MRSE), visual acuity, thinnest pachymetry, the change in Kmax, and the change of those parameters were also analyzed. P&lt;0.05 was considered statistically significant. RESULTS: One hundred and fifty-five patients (185 eyes) were included. Male to female ratio was 3:31. According to Amsler-Krumeich classification, stage 1 and 2 were dominant (37.84% and 35.14% respectively). At 1y, mean LogMAR uncorrected visual acuity (UCVA) improved by 0.1 (P&lt;0.05). The number of eyes of which postoperative BCVA improved more than 0.2 LogMAR was higher in the worse baseline BCVA group (preoperative BCVA ≥0.3) compared to the better baseline BCVA group (preoperative BCVA &lt;0.3) (78.26% vs 21.74%, P&lt;0.05). Mean Kmax decreased from baseline by 2.36 diopters (D) (P&lt;0.05). Seventy-three percent of the eyes of which Kmax reduced more than 2.0 D had preoperative Kmax ≥55 D. Q-value showed less prolate by 0.06 (P&lt;0.05). Corneal HOA at 6 mm from corneal apex decreased by 0.40 (P&lt;0.05). Corneal densitometry at 0-6 mm zone increased at 1mo and persisted 1y postoperatively (P&lt;0.05). The relationship of the increase in densitometric value and the decrease of thinnest pachymetry at 1y were in linear fashion. Index of surface variance, index of vertical asymmetry, keratoconus index, index of height decentration decreased at 1y (P&lt;0.05). Success rate at 1y was 90.24%. Postoperative corneal haze was found 11.35%, 30.27%, 15.67%, 10.27% and 2.16% at 1wk, 1, 3, 6mo and 1y respectively. No eyes developed corneal edema. There was one case of sterile keratitis. CONCLUSION: Accelerated collagen cross-linking in keratoconus was effective to flatten, reshape the cornea, improved visual acuity, HOA and topometric indices. Great Kmax reduction was found in advanced keratoconus. The magnitude of Kmax reduction is also greatest among previous reports.

Corneal densitometry before and after corneal collagen cross-linking in patients with keratoconus

Background Keratoconus is an ectatic corneal disorder characterized by progressive corneal thinning that results in corneal protrusion, irregular astigmatism, and decreased vision. Objective To evaluate changes in corneal density following corneal cross-linking (CXL) in keratoconic patients. Patients and methods This was a prospective case series study including all patients with keratoconus (50 eyes) undergoing CXL. The number of male patients in the study was 13 (26 eyes) cases, while female patients represented 12 (24 eyes) cases; the study was conducted at the outpatient clinic of the Ophthalmology Department at Al Azhar University Hospital. Results There was no statistically significant correlation between corneal densitometry and K1, K2, K-max, or thinnest corneal thickness preoperatively. There was no statistically significant correlation between corneal densitometry and K1, K2, K-max or thinnest corneal thickness at 1 month postoperatively. There was no statistically significant correlation between corneal densitometry and K1, K-max, or thinnest corneal thickness at 3 months postoperatively. Also, the table shows that there was statistically significant positive correlation between corneal densitometry and K2 with P value of 0.037 and r=0.296. There was no statistically significant correlation between corneal densitometry and K1, K2, K-max, or thinnest corneal thickness at 6 months postoperatively. Conclusion After CXL, the Scheimpflug corneal densitometry and clinical corneal haze peaked at 1 month followed by a gradual decline reaching baseline by 6 months after operation. Corneal thinning was correlated inversely with the corneal haze at 1 month postoperatively. Lens densitometry was not affected by CXL.

Efficacy and safety of accelerated corneal collagen cross-linking in patients with keratoconus

Efficacy and safety of accelerated corneal collagen cross-linking in patients with keratoconus

Еvaluate the Effectiveness of Accelerated Collagen Crosslinking in the Treatment of Corneal Endothelial Decompensation

The article discusses the effectiveness of accelerated collagen crosslinking in the treatment of patients with corneal diseases, a common basic pathogenetic link of which is endothelial corneal decompensation. This method was used to treat patients with bullous keratopathy and endothelial dystrophy of Fuchs’ cornea with a long postoperative follow-up. In connection with the controversial results of researchers, reflecting the positive dynamics of the postoperative period, the question of the expediency of accelerated collagen cross-linking in patients with this pathology as a monotherapy is discussed.The study included 25 patients (26 eyes) with mean age 69.10 ± 10.61 years (40 to 82 years). There was Fuchs corneal endothelial dystrophy in 16 patients (17 eyes), in 9 patients (10 eyes) — stage II, in 7 patients (7 eyes) — stage III. Bullous keratopathy was present in 9 patients (9 eyes). All patients underwent treatment according to the method of accelerated collagen corneal crosslinking. In patients with bullous keratopathy (9 eyes), the data on the central thickness of the cornea and the maximum corrected visual acuity did not differ from the initial data at any of the postoperative visits, and did not differ from each other (p &gt; 0.83). On the contrary, in some patients the dystrophic process progressed in the form of the appearance of fibrotic changes in the stroma of the cornea. Corneal transplantation was recommended to all patients under observation after treatment at different periods of observation. In patients with Fuchs endothelial dystrophy, a significant difference in the maximum corrected visual acuity from the initial data was observed only 6 months after surgery.The expediency of accelerated collagen cross-linking in the treatment of patients with corneal diseases accompanied by endothelial decompensation as monotherapy is very doubtful. The study of combined surgical methods for treating this complex corneal pathology using cross-linking as an auxiliary method seems promising.

Long-term results of corneal collagen crosslinking with ectatic forms of corneal dystrophy

Corneal collagen crosslinking is one of the most effective methods of prophylactics and treatment of progressive corneal ectasias. In the literature, there are occasional data related to remote results concerning only the most common form of ectasias keratoconus. In published studies, no remote results are met concerning the efficacy of corneal collagen crosslinking in other forms of corneal ectasias, which are now on the rise, including secondary ectasias that became more frequent with refractive surgery. The number of diagnosed cases of pellucid marginal degeneration increased as well. The literature shows no data on comparative analysis of remote results concerning the efficacy of this method in treatment of various forms of corneal ectasias.&#x0D; The aim of the investigation was to evaluate the efficacy of corneal collagen crosslinking based on the analysis of long-term results of this treatment method for various forms of corneal ectasias.&#x0D; Materials and methods. The results of corneal collagen crosslinking in patients with various forms of corneal ectasia 6 years after surgery were analyzed. The nosological structure of the study included patients with keratoconus, pellucid marginal degeneration, and secondary ectasia. The group of patients with keratoconus included 30 patients (30 eyes), that with pellucid marginal degeneration 30 patients (30 eyes), and that with secondary ectasia 30 patients (30 eyes). Corneal collagen crosslinking was performed by the same specialist, during the first or the second year of follow-up. Then changes in the state of the cornea and visual functions were monitored for 6 years. To assess the efficacy, preoperative examination results and interim data were used.&#x0D; Results. In all groups, there was an increase in the best corrected visual acuity, a decrease in the index of asymmetry of the corneal surface and its refractive power in the center of ectasia. However, best corneal collagen crosslinking results were obtained in groups of patients with keratoconus and secondary corneal ectasia.

Prospective study on a novel treatment for leaking cystic bleb: Efficacy and safety of collagen crosslinking.

Management of cystic bleb leak is difficult. It would be essential to look for a method to strengthen the original pathological conjunctiva and reverse bleb leak. To evaluate the long-term efficacy and safety of collagen crosslinking in patients with leaking cystic bleb. Prospective interventional case series at a university-based hospital. Twelve eyes in 12 subjects with late-onset bleb leak from cystic bleb, without indications for prompt surgical interventions were included. The subjects underwent crosslinking with 0.1% riboflavin application to bleb surface, followed by ultraviolet irradiation for 30 minutes. The subjects were followed up at baseline and at 1 week, 1 month, 3 months, 6 months post-treatment and then every 6 months afterwards. Interval from treatment to cessation of bleb leak, recurrence rate of bleb leak and side effects of treatment. The mean follow-up after crosslinking was 29.33 ± 12.45 months. Bleb leak subsided in 11 (92%) of 12 patients after a single session of crosslinking, after 1 to 8 weeks (median 3 weeks). Time to leak cessation was significantly correlated with the number of prior glaucoma interventions (R = .71, P = .014). Bleb wall at 3 months was significantly thicker than at baseline (0.70 ± 0.67 vs 0.81 ± 0.62 mm, P = .008). None of the patients experienced any complications. Crosslinking achieves resolution of cystic bleb leak which lasts for at least 12 months, without the need of subsequent surgical interventions. Crosslinking is a simple, non-invasive treatment for bleb leak. It aims to restore the integrity of conjunctiva.

Results of confocal microscopy examinations after epithelium-off collagen cross-linking in patients with keratoconus

Results of confocal microscopy examinations after epithelium-off collagen cross-linking in patients with keratoconus

Assessment of the changes in corneal biomechanical properties after collagen cross-linking in patients with keratoconus

PurposeTo assess the changes in biomechanical properties of the cornea after treatment of keratoconus patients with UV-A/riboflavin corneal collagen cross-linking (CXL) using Corvis ST (Oculus, Wetzlar, Germany) and Ocular Response Analyzer (ORA; Reichert Ophthalmic Instruments, Inc., Buffalo, NY, USA) devices. MethodsIn this prospective, observational case series, 48 eyes from 48 consecutive patients with progressive keratoconus were enrolled. Patients with history or signs of ocular disorders other than keratoconus, previous eye surgery, systemic diseases, or inability to cooperate with any measurement device were excluded. Corvis ST and ORA images were obtained at baseline and 4 months after CXL. The primary outcome measures comprised Corvis ST corneal biomechanical factors [time of highest concavity (T), time of applanation 1 (T1), time of applanation 2 (T2), length of applanation 1 (L1), length of applanation 2 (L2), velocity of applanation 1 (V1), velocity of applanation 2 (V2), deformation amplitude (DA), peak distance (PD), and radius (R)] and the ORA parameters [corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-related IOP (IOPg), cornea-compensated IOP (IOPcc), and waveform score (WS)]. ResultsThe mean [± standard deviation (SD)] age of patients was 20 ± 5 years, and 27 (56%) were male. At baseline, the averages of the refraction, mean keratometry, and keratometric astigmatism were −3.0 ± 1.8 diopter (D), 47.0 ± 1.8 D, and 3.5 ± 1.5 D, respectively. According to Corvis ST, L2 increased from 0.83 ± 0.25 mm at baseline to 1.15 ± 0.57 mm after CXL; and V2 decreased from −0.81 ± 0.08 to −0.94 ± 0.26 m/s (P = 0.001 and P = 0.032, respectively). ORA parameters showed significant decrease in the CRF (from 7.82 ± 1.72 to 7.21 ± 1.05 mmHg; P = 0.036) and increase in the WS (from 4.58 ± 2.55 to 6.12 ± 1.92; P = 0.002). ConclusionsAccording to in vivo observation with Corvis ST and ORA, CXL induces significant changes in corneal biomechanical properties in cases with keratoconus. The parameters with significant changes (L2 and V2) may reflect increased stiffness of the treated cornea. The importance of such observations should be elucidated in future studies.

Transepithelial accelerated versus conventional corneal collagen crosslinking in patients with keratoconus: a comparative study.

PurposeTo systematically compare the efficacy of transepithelial accelerated corneal collagen crosslinking (TE-ACXL) with conventional corneal collagen crosslinking (C-CXL) in patients with progressive keratoconus.MethodsEyes of patients with progressive keratoconus who were treated with C-CXL (3 mW/cm2 for 30 minutes) were compared with those who underwent TE-ACXL (6 mW/cm2 for 15 minutes). Best-corrected visual acuity (BCVA), keratometry values, corneal thickness, and topometric indexes were compared before CXL, and at 2 months, 6 months, and 12 months postoperatively.ResultsThe study enrolled 26 eyes of which 16 had TE-ACXL and 10 had C-CXL. Both groups were comparable at baseline and 12 months in terms of BCVA (P=0.16 and P=0.57), Kmax (maximum keratometry) (P=0.31 and P=0.73), pachymetry (P=0.75 and P=0.37), index of surface variance (ISV) (P=0.45 and P=0.86), index of vertical asymmetry (IVA) (P=0.26 and P=0.61), and index of height decentration (IHD) (P=0.27 and P=0.86, respectively). We did not observe significant differences between preoperative and 12-month postoperative readings in within-group analysis: ΔKmax (TE-ACXL, −2.13±5.41, P=0.25 vs C-CXL, 0.78±1.65, P=0.17), Δpachymetry (TE-ACXL, 4.10±14.83, P=0.41 vs C-CXL, −8.90±22.09, P=0.24), ΔISV (TE-ACXL, −8.50±21.26, P=0.24 vs C-CXL, 3.80±12.43, P=0.36), ΔIVA (TE-ACXL, −0.12±0.31, P=0.26 vs C-CXL, 0.03±0.18, P=0.61), and ΔIHD (TE-ACXL, −0.03±0.07, P=0.18 vs C-CXL, −0.01±0.03, P=0.88).ConclusionBoth TE-ACXL and C-CXL were similarly effective. Further follow-up is required to determine whether these techniques are comparable in the long-term.

The Outcome of Corneal Collagen Cross-Linking in Patients with Advanced Progressive Keratoconus: A 2-Year Follow-up Study.

PURPOSE:The aim of this study was to evaluate the safety and efficacy of collagen cross-linking (CXL) in advanced progressive keratoconus with a maximum keratometry (Kmax) value of more than 58 diopters (D).METHODS:This prospective interventional case series involved patients with advanced progressive keratoconus with a Kmax of more than 58 D. The best-corrected visual acuity (BCVA), uncorrected visual acuity (UCVA), Kmax, mean keratometry (Kmean) value, corneal astigmatism, and thinnest corneal thickness before surgery and 24 months after CXL were determined for 30 eyes of 27 patients. A Pentacam was used to measure the paraclinical parameters.RESULTS:The mean age of the patients was 24.47 ± 3.33 years. The mean logarithm of the minimum angle of resolution (logMAR) of the uncorrected visual acuity UCVA decreased from 0.73 ± 0.36 D at baseline to 0.48 ± 0.30 D (P = 0.01), while the mean thinnest point thickness of the cornea decreased from 438.65 ± 40.11 μm to 431.43 ± 61.92 μm (P = 0.005) after 24 months. The decreases in the mean logMAR of the BCVA, Kmax and Kmean values, and corneal astigmatism were not statistically significant (P > 0.05) at the 24-month follow-up. Progression was halted in 29 eyes (96.6%); only 1 eye (3.3%) showed an increase in the Kmax value of more than 2.0 D, which was indicative of treatment failure. In contrast, most other eyes showed a decrease in the Kmax value although it was not statistically significant. There were no major complications in any of the patients during the study period.CONCLUSION:Standard CXL treatment was safe and stabilized both the visual acuity and tomographic parameters at the 2-year follow-up in eyes with advanced progressive keratoconus.

A Comparative Study of Age-Related Level of Sclera Collagen Crosslinking in Patients with Different Stages of Primary Open Angle Glaucoma

A Comparative Study of Age-Related Level of Sclera Collagen Crosslinking in Patients with Different Stages of Primary Open Angle Glaucoma

Pentacam topographic changes after Epithelium-off collagen cross-linking versus Epithelium-on collagen cross-linking in patients with keratoconus

Keratoconus is a bilateral non-inflammatory disease .One of its characteristics is reduction of biomechanical strength of cornea and stromal thinning , which gradually decreases corneal thickness and induces irregular astigmatism , myopia , corneal scaring, andreduction of visual acuity.(1)For early stages of keratoconus , one would use spectacles and contact lenses though the progression of the disease can lead to irregular astigmatism or corneal scaring, leaving no other option but corneal transplantation in about 20% of patients.(2)Corneal transplantation is an expensive procedure with many complications such as high astigmatism and graft rejection; hence, seeking for a way to halt this progressive disease seems to be of crucial importance.(3) For more than a decade, corneal cross-linking (CXL) has been considered as the only method for improvingcorneal biomechanical power.(4)Corneal collagen cross-linking (CXL) is a low-invasive treatment aimed to improve biomechanical stability in eyes with keratectasia.(5) The “standard CXL protocol” described by Wollensak and colleagues includes removal of the corneal epithelium in a diameter of 9 mm , followed by saturation of the corneal stroma using 0.1% isotonic riboflavin solution in 20% dextran.(6)This procedure is proved to be effective in increasing corneal stiffness , stabilization of keratoconus , and in some cases in improving the refractive and topographic features.Even so, the epithelial removal may lead to serious complications that include infection(7),stromal haze (8), and corneal melting (9)in addition to severe pain and decrease in vision occurring during the first days after the treatment.To avoid such complications, Boxer Wachler et al. suggested a modification of the technique by keeping the epithelium intact (epithelium-on or transepithelial CXL) (10).In this study, we sought to compare keratoconus indices before and after crosslinking either epi-off or epi-on CXL by Pentacam criteria.

Corneal collagen crosslinking in patients treated with dextran versus isotonic hydroxypropyl methylcellulose (HPMC) riboflavin solution: a retrospective analysis

BackgroundCorneal collagen crosslinking (CXL) is a widely used treatment for halting the progression of keratoconus. Although initial studies of CXL were performed with a riboflavin solution containing dextran, recent protocols for CXL have indicated the use of a riboflavin solution containing isotonic hydroxypropyl methylcellulose (HPMC). This study was performed to investigate differences in visual outcomes and Scheimpflug (Pentacam) analysis in patients who have undergone epithelium-off CXL with riboflavin solution containing either 20% dextran versus 1.1% HPMC.MethodsAll patients in this non-randomized, non-masked, retrospective cohort analysis were treated at Edward S. Harkness Eye Institute, Columbia University Medical Center, New York, NY, USA. Thirty-seven eyes of 33 patients were crosslinked with a dextran solution and 19 eyes of 19 patients crosslinked with an isotonic HPMC solution, both using an epithelium-off 30-min, 3 mW/cm2 protocol. All patients had a diagnosis of keratoconus or post-refractive surgery ectasia. Best spectacle corrected visual acuity (BSCVA) and Pentacam parameters were compared at all follow up visits (1, 6, 12, and 24 months). Differences between groups treated with HPMC and dextran were compared using student’s t-test. Differences between treated eye and fellow eye were calculated and compared between HPMC and dextran groups using paired t-test.ResultsPatients treated with a dextran solution had significantly greater improvement in BSCVA at 1, 6, and 24 months (p < 0.05) compared to the isotonic HPMC-treated group. Kmax increased in both groups at 1 month; however, HPMC-treated patients had a greater increase compared to dextran-treated patients (p = 0.01). Kmax decreased in both groups at 6 and 12 months, although this finding was only significant in the HPMC-treated group at 12 months.ConclusionsOur data suggest that crosslinking with the dextran solution may result in significantly better visual outcomes (demonstrated by visual acuity) compared to the isotonic HPMC riboflavin solution. Dextran solutions may have other potential advantages intrinsic to its biochemical properties facilitating more efficient crosslinking. Further research and long-term evidence regarding the use of dextran versus HPMC riboflavin solutions in collagen crosslinking is necessary.

Evaluation of Corneal Biomechanical Changes After Collagen Crosslinking in Patients with Progressive Keratoconus by Ocular Response Analyzer

Objectives:To evaluate corneal biomechanics before and after collagen crosslinking (CXL) in patients with progressive keratoconus.Materials and Methods:In this prospective study, CXL was performed under topical anesthesia after removal of the epithelium (epi-off technique) by applying ultraviolet A (UVA) light at a wavelength of 365 nm and power of 3 mW/cm2 or 5.4 joule/cm2. Isoosmolar 0.1% riboflavin solution was administered before and during UVA irradiation. In addition to ophthalmologic examination, ocular response analyzer measurements were performed pre- and postoperatively. Corneal hysteresis (CH), corneal resistance factor (CRF), corneal compensated intraocular pressure (IOPcc), Goldmann-correlated intraocular pressure (IOPg), and central corneal thickness (CCT) were recorded.Results:The study included 35 eyes of 30 patients with progressive keratoconus. The mean age was 28.2±6.5 years and postoperative follow-up time was 20.2±14.7 months (range: 6-74 months). The mean CH was 8.60±1.23 mmHg preoperatively, 8.96±2.05 mmHg in the early postoperative period (1-6 months), (p=0.28) and 8.96±1.28 mmHg in the late postoperative period (10-29 months) (p=0.48). Mean CRF was 7.13±1.50 mmHg preoperatively, 8.48±2.16 mmHg in the early postoperative period (p=0.009), and 7.71±1.29 mmHg in the late postoperative period (p=0.40). Mean IOPcc was 12.78±2.34 mmHg preoperatively, 15.38±4.21 mmHg in the early postoperative period (p=0.12) and 13.68±3.61 mmHg in the late postoperative period (p=0.48). Mean IOPg was 9.56±2.73 mmHg preoperatively, 13.01±4.45 mmHg in the early postoperative period (p=0.046), and 10.86±3.47 mmHg in the late postoperative period (p=0.44). Mean CCT was 484.43±41.26 µm preoperatively, 474.16±64.74 µm in the early postoperative period (p=0.70), and 470.38±33.64 µm in late postoperative period (p=0.71).Conclusion:CXL is a treatment modality believed to affect corneal biomechanics in keratoconus, but the results of larger patient series with longer follow-up periods may enable a better evaluation.

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

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

Analysis of long-term results of collagen corneal cross-linking in patients with ectatic forms of corneal dystrophy

Corneal collagen cross-linking became a permanent part of complex treatment for patients with different forms of corneal ectasia. In periodical literature, there are anecdotal reports concerning long-term results of this corneal disease therapy method, which is an isolated variant of photodynamic therapy.&#x0D; Purpose. To carry out a retrospective study of corneal collagen cross-linking long-term results in various ectatic corneal diseases.&#x0D; Materials and methods. Results of corneal collagen cross-linking in patients with ectatic forms of corneal dystrophy 6 years after surgery were analyzed. The nosological structure of the study included a group of patients with primary keratoconus, pellucid marginal corneal degeneration, secondary ectasias. The group with primary keratoconus includes 30 patients (31 eyes), that with pellucid marginal degeneration 10 patients (10 eyes), that with secondary ectasias 10 patients (10 eyes). Data of the diagnostic examination before surgery, intermediate data of the dynamic follow-up during 6 years of observation were used for the analysis. Corneal collagen cross-linking was performed in the first or second year of follow-up, followed by monitoring of changes in the state of the cornea after corneal collagen cross-linking for 4-5 years.&#x0D; Results. A statistically significant increase in visual acuity was observed after the corneal collagen cross-linking in patients with primary and secondary ectasias. In patients diagnosed with pellucid marginal degeneration, there was no statistically significant increase of visual function. A decrease in the corneal asymmetry index was revealed in all groups and confirmed by statistical analysis.