Corneal Collagen Research Articles

Long-term Safety and Efficacy of Corneal Collagen Crosslinking in a Pediatric Group With Progressive Keratoconus: A 7-year Follow-up

To assess effectiveness and safety of corneal crosslinking (CXL) to reduce keratoconus (KC) progression and improve visual acuity among children with progressive KC and to analyze the use of 20% dextran-based (Dextran) and 1% hydroxypropyl methylcellulose-based (HPMC) riboflavin. Prospective, clinical cohort study METHODS: Standard CXL (SCXL) was performed in 74 eyes (58 patients, 45 males, mean age 13.0 ± 2.1 years): 53 eyes with HPMC and 21 with Dextran. Examinations were performed at baseline, 3 and 6 months, and 1, 2, 3, 4, 5, and 7 years of follow-up, including uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), a complete ophthalmologic examination, anterior segment ocular coherence tomography, Scheimpflug corneal tomography, and specular microscopy. UDVA and CDVA improved at all periods with statistically significant differences in CDVA at 1, 2, and 3 years. Compared with baseline, maximum K (Max K) reduced throughout the 7-year follow-up. Mean thinnest pachymetry (Th Pachy) decreased significantly at 3 months and remained low; in the Dextran group, the Th Pachy mean value returned to baseline 6 months postoperatively. After CXL, 1.5 diopter progression in max K was 1.4% to 14.6% of eyes; worsening was found at 4 to 7 years postoperatively. SCXL reduced KC progression in children up to 7 years of follow-up and revealed improvement and stability of UDVA and CDVA in 82% of eyes. For visual acuity and KC stability, no statistically significant difference was observed between Dextran-HPMC. The HPMC group showed persistent cornea thinning, raising concerns about its use in SCXL.

Safety of transglutaminase-induced corneal collagen cross-linking on the central cornea thickness and intraocular pressure in vivo

Background: Corneal collagen cross-linking (CXL) is a procedure for making bonds that connect polymer chains to one another. Corneal CXL aims to slow or stop the progression of keratoconus by using photooxidative therapy so as to increase stromal rigidity. Transglutaminase enzymes are currently widely used in the food industry. Recent studies have shown that mRNA, fibronectin, and transglutaminase were found to be more abundant in human corneal keratocytes treated with UVA and riboflavin. Transglutaminase is considered to reduce discomfort caused by UVA irradiation. Methods: A total of 21 white New Zealand rabbits were divided into three groups, namely, transglutaminase-induced CXL group, epithelial-off CXL group, and transepithelial CXL group. The ocular surface was treated with a 1 U/mL microbial transglutaminase solution, and both the epithelial-off and transepithelial groups were exposed to clinical ultraviolet A-riboflavin (UVA/RF). The efficacy of each group was evaluated on the 14th day after the procedures. The central corneal thickness (CCT) and intraocular pressure (IOP) were evaluated using Corneal Visualization Scheimpflug Technology (Corvis ST). Results: The transglutaminase-induced CXL group exhibited the highest mean CCT (370.14 ± 38.85) in comparison with the UVA/RF epithelial-off group (368.00 ± 25.48) and the UVA/RF transepithelial group (369.86 ± 23.43). The transglutaminase-induced CXL group had the highest IOP mean (8.50 ± 3.02) compared with the UVA/RF epithelial-off (6.50 ± 3.07) and UVA/RF transepithelial groups (7.00 ± 1.90). There were no significant differences in CCT (p = 0.990) or IOP (p = 0.563) between the groups. Conclusions: The findings of this study suggest that there are no significant differences between the transglutaminase-induced CXL group and the UVA/RF CXL group. The safety of transglutaminase-induced CXL could be comparable to that of UVA/RF CXL in terms of altering CCT and IOP, which are two factors contributing to corneal rigidity.

Penetrating keratoplasty following Tenon's patch graft

This report aims to describe the histopathological changes in the cornea following Tenon's patch graft. A 51-year-old male underwent Tenon's patch graft (TPG) for corneal perforation following Therapeutic penetrating keratoplasty which was performed twice for non-resolving microbial keratitis and graft infiltrate, respectively. The infection resolved following TPG resulting in formation of a vascularised scar. An Optical penetrating keratoplasty was performed six months after the TPG. Postoperative period was uneventful. Histo-pathological evaluation of the excised corneal tissue revealed excellent integration of the tenon tissue with the surrounding corneal stromal collagen. Histo-pathological evidence suggests that, tenon's tissue integrates well with surrounding corneal stromal collagen and is probably capable of regenerating new collagen and thus aid in corneal wound healing

Topical losartan inhibits corneal scarring fibrosis and collagen type IV deposition after Descemet's membrane-endothelial excision in rabbits

Topical losartan inhibits corneal scarring fibrosis and collagen type IV deposition after Descemet's membrane-endothelial excision in rabbits

Coincidental occurrence of severe hydrops after corneal collagen cross-linking

This case report describes a case of acute corneal hydrops (ACH) within 4 days following collagen cross-linking that was done to arrest the progression of keratoconus in a 15-year-old girl. She developed pain, redness, and watering in the left eye within 4 days of undergoing an uneventful bilateral corneal collagen cross-linking. The diagnosis of ACH was made and was managed medically with a course of topical steroids. A large fluid-filled stromal pocket with iris adhering to the posterior surface was observed that resolved with stromal scarring after the treatment. Thus, ACH may be precipitated by cross-linking and needs to be managed appropriately.

Effect of Corneal Collagen Cross Linking For Keratoconus on The Ocular Higher Order Aberrations Corneal Collagen Cross Linking effect

Effect of Corneal Collagen Cross Linking For Keratoconus on The Ocular Higher Order Aberrations Corneal Collagen Cross Linking effect

The outcome of corneal collagen cross-linking in progressive keratoconus: A 24-month follow-up

Purpose: The purpose of this study is to evaluate the effect of corneal collagen cross-linking on visual acuity and corneal parameters like keratometry and pachymetry. Methods: It was a retrospective, noncomparative, open-label study conducted at a tertiary eye care center. The eyes that underwent epithelium-off CXL (corneal collagen cross-linking) for progressive keratoconus between 2018 January and 2019 December, and who completed 24 months' post-CXL follow-up, were included in the study. Data regarding uncorrected and best spectacle-corrected visual acuity (UCVA and BSCVA) and corneal topography parameters, that is, K max, K min, and pachymetry at thinnest point, were collected prior to the procedure and 2 years after the procedure. Results: A total of 92 eyes of 65 patients were included in the study. There was a significant improvement of logMAR BCVA from preoperative 0.40 ± 0.24 to 0.28 ± 0.19 at 24 months after CXL (P < 0.001). UCVA also increased from preoperative value of logMAR 0.70 ± 0.28 to 0.61 ± 0.26 2 years postoperatively (P < 0.001). The number of eyes achieving BCVA of 0.3 logMAR or better significantly increased from 54 (58.7%) preoperatively to 72 (78.26%) at 2 years and it was found to be statistically significant (P < 0.001). There was a significant improvement in K max 49.38 ± 3.70 to 49.07 ± 3.45 (P = 0.0005) and K min 45.65 ± 2.69 to 45.19 ± 2.46 (P < 0.001) following CXL. Conclusion: Corneal collagen cross-linking is a treatment modality to stabilize and even improve UCVA in patients with mild-to-moderate keratoconus.

Морфологические изменения роговицы у мелких домашних животных под влиянием кросслинкинга

The article presents morphological changes of the cornea in small domestic animals during crosslinking. The research was carried out on the basis of the Department of Anatomy and Histology of Animals named after Professor A. F. Klimov, as well as the Center for Veterinary Ophthalmology of Dr. Shilkin A.G. Morphological studies were performed in the Department of Pathomorphology of the FSAU «MNTC «Eye Microsurgery» named after Academician S. N. Fedorov». The objects of the study were selected cats (n=10) aged 4 to 6 years and dogs (n=10) aged 4 to 6 years of the Yorkshire Terrier breed (n=5) and Chihuahua (n=5), admitted to the «Center of Veterinary Ophthalmology of Dr. A. Shilkin.G.», euthanized as a result of received polytrauma incompatible with life. Analysis of the data obtained allowed us to conclude that corneal collagen crosslinking affects changes in the morpho-functional features of the corneal stroma. The data on changes in the anterior layers of the stroma, which are expressed by a compact packing of fibers without signs of edema, as well as a demarcation line separating the impact area from the indifferent zone, are scientifically substantiated. The results obtained are basic in the development of new methods of therapeutic strategy and tactics in the treat-ment of animals with keratopathies of various genesis.

Analysis of the results of modified personalized topographically and tomographically oriented technique of ultraviolet corneal collagen crosslinking

The study aims to develop a modified personalized topographically and tomographically oriented technique of ultraviolet corneal collagen cross-linking (UVCXL) to affect the area of the cornea with weakest biomechanical properties as determined by mathematical modeling. Modeling of the biomechanics of keratoconic cornea under conditions of external diagnostic action was done using COMSOL Multiphysics® software. Finite-element analysis procured 3D images of stress/deformation distribution pattern throughout the cornea. Matching these 3D images with primary topographic and tomographic Pentacam AXL maps and Corvis ST findings allowed determining localization and dimensions of impaired regions of the cornea. The acquired data helped develop the modified corneal collagen cross-linking technique, which was applied in the treatment of 36 persons (36 eyes) with degrees I and II keratoconus. Uncorrected and best-corrected visual acuity (UCVA and BCVA logMAR) in all patients after modified UVCXL increased after the follow-up period lasting 6-12 months by 0.2±0.19 (23%) and 0.1±0.14 (29%) (p<0.05), respectively, in comparison with preoperative values. Maximum keratometry (Kmax) decreased by 1.35±1.63% (3%; p<0.05) in all cases at 6-12 months follow-up. Improvement of corneal biomechanical strength was determined by statistically significant increase in corneal stiffness index (SP-A1) and corneal stress-strain index (SSI) measured with Pentacam AXL and Corvis ST at 6-12 months follow-up by 15.1±5.04 (18%) and 0.21±0.20 (23%) (p<0.05), respectively. Effectiveness of the developed UVCXL technique is also confirmed by the appearance of a characteristic morphological marker - «demarcation line» at the cross-linking site in keratoconus projection at the depth of 240±10.2 µm. The developed personalized topographically and tomographically oriented UVCXL technique provides an evident stabilizing effect on the cornea in the form of an increase in its biomechanical strength, improvement of clinical, functional indicators and safety of keratoconus treatment.

Short- and long-term safety and efficacy of corneal collagen cross-linking in progressive keratoconus: A systematic review and meta-analysis of randomized controlled trials.

The purpose of the study is to evaluate the safety and outcomes of corneal collagen cross-linking (CXL) and different CXL protocols in progressive keratoconus (PK) population at short and long-term. A systematic review and meta-analysis was conducted. A total of eight literature databases were searched (up to February 15, 2022). Randomized controlled trials (RCTs) comparing CXL versus placebo/control or comparing different CXL protocols in the PK population were included. The primary objective was assessment of outcomes of CXL versus placebo and comparison of different CXL protocols in terms of maximum keratometry (Kmax) or Kmax change from baseline (Δ), spherical equivalent, best corrected visual acuity (BCVA), and central corneal thickness (CCT) in both at short term (6 months) and long term (1st, 2nd, and 3rd year or more). The secondary objective was comparative evaluation of safety. For the meta-analysis, the RevMan5.3 software was used. A total of 48 RCTs were included. Compared to control, CXL was associated with improvement in Δ Kmax at 1 year (4 RCTs, mean difference [MD], -1.78 [-2.71, -0.86], P = 0.0002) and 2 and 3 years (1 RCT); ΔBCVA at 1 year (7 RCTs, -0.10 [-0.14, -0.06], P < 0.00001); and Δ CCT at 1 year (2 RCTs) and 3 years (1 RCT). Compared to conventional CXL (C-CXL), deterioration in Δ Kmax, ΔBCVA and endothelial cell density was seen at long term in the transepithelial CXL (TE-CXL, chemical enhancer). Up to 2 years, there was no difference between TE-CXL using iontophoresis (T-ionto) and C-CXL. At 2 and 4 years, C-CXL performed better compared to accelerated CXL (A-CXL) in terms of improving Kmax. Although CCT was higher in the A-CXL arm at 2 years, there was no difference at 4 years. While exploring heterogeneity among studies, selection of control eye (fellow eye of the same patient vs. eye of different patient) and baseline difference in Kmax were important sources of heterogeneity. CXL outperforms placebo/control in terms of enhancing Kmax and CCT, as well as slowing disease progression over time (till 3 years). T-ionto protocol, on the other hand, performed similarly to C-CXL protocol up to 2 years.

Keratoconus: main lines of research

Keratoconus (KC) research focuses on studying pathogenesis, advancing diagnostic techniques and methods of correction and treatment. The working hypothesis for KC etiopathogenesis is based on abnormalities in distribution of microelements in the cornea and its potential influence on the processes of stromal collagen disorganization. Improvement of early diagnosis of KC is associated with evaluation of microstructural changes in the cornea using computerized methods such as Scheimpflug camera and high-definition optical methods for visualization of initial signs of a pigment ring. The main optimization directions of KC contact correction are associated with increasing gas permeability of the material, improving lens design and methods of lens fitting. Customized fitting of gas-permeable scleral hard contact lenses with consideration of topographic features of the anterior corneal surface allows achieving stable lens positioning and preserving the tear gap between the lens and the cornea. Alternative methods of correcting the refraction component of KC are associated with surgical interventions involving increase in corneal volume in the paracentral area. Implantation of corneal ring segments should be considered as an alternative to correction of refractive errors in cases with unsatisfactory individual subjective tolerance and insufficient patient compliance with contact correction. Femtolaser-assisted implantation of intrastromal allotransplants along with a decrease in the degree of spherical and astigmatic components of refractive errors contribute to prevention of KC progression. Advancement of techniques of corneal collagen cross-linking for prevention of KC progression is aimed at reducing the risk of developing post-operative complications directly related to the extent of intraoperative deepithelization. Limiting corneal ectatic area by implantation of intrastromal allotransplants can be considered an alternative approach. Deep anterior lamellar keratoplasty and penetrating keratoplasty are the surgeries of choice in replacing altered corneal layers in KC. With regard to the modern trends in selective keratoplasty, selective replacement of the cornea in lamellar keratoplasty reduces the rate of injuries and the risk of tissue reaction.

Herpes Zoster Dermatitis after Corneal Collagen Cross-Linking with Riboflavin: A Case Report

A middle-aged female presented with complaints of decreased vision in both eyes OD (right eye) &gt; OS (left eye), since 6 months, and eye rubbing. Due to steep keratometry readings on an automated keratometer, pentacam was done, and the findings were suggestive of keratoconus in OD and formefruste keratoconus in OS. As best corrected visual acuity (BCVA) decreased only since 6 months and pentacam readings were suggestive of keratoconus, the patient was treated with corneal collagen cross-linking with riboflavin (C3R) in OD, to halt the progression. On post-op day 5, the patient presented with erythema, small papulovesicular lesions over the right half of the face and forehead, suggestive of herpetic skin lesions. She was prescribed topical eye drops for post-C3R haze and oral acyclovir for skin lesions, which were regressed within 1 week. Early diagnosis and appropriate treatment of herpes zoster dermatitis prevent worsening of signs and decrease further risk of herpetic keratitis and associated complications. Thus in this case, ultraviolet (UV)-A irradiation acted as a trigger for herpes zoster virus reactivation.

Effect of corneal collagen cross linking on crystalline lens clarity graded by Pentacam Nucleus Staging Software

Effect of corneal collagen cross linking on crystalline lens clarity graded by Pentacam Nucleus Staging Software

Evaluation of corneal demarcation line and associated parameters in patients with keratoconus following transepithelial, epithelial scoring and epithelium-off accelerated corneal collagen crosslinking

Introduction: Keratoconus is a progressive corneal ectatic disorder with thinning, protrusion and poor vision. Corneal collagen crosslinking (CXL) is a minimally invasive procedure used to prevent progression. CXL is performed either after epithelial debridement (Epi-Off) or with the epithelium in-situ (transepithelially).Objective: To evaluate corneal demarcation line and associated parameters in patients with keratoconus following accelerated CXL using the described methods. Materials and methods: Retrospective data of twelve consecutive eyes (n=12) which underwent CXL using the method described by the authors was compared with randomized data of sixteen eyes (n=11) which underwent transepithelial CXL and eighteen eyes (n=14) which underwent Epi-Off CXL. An accelerated CXL protocol was used (UVA 9mW/cm2 for 10 min) in all patients after instillation of 0.1% riboflavin solution for 30 minutes. The surgeon made linear full thickness epithelial abrasions in the modified technique. Visual acuity, keratometry, pachymetry were evaluated preoperatively and at one month postop. Specular microscopy and AS-OCT was performed at one month postop.Results: Preoperative Kmax, Kmean and cylinder power were similar in all groups. However, patients who underwent the modified technique had poorer UCDVA and BCDVA at baseline (MRSEQ-4.41) and average pachymetry of 450 μm. Postoperatively, patients who underwent the modified technique had mild stromal haze, a well visible stromal demarcation line on AS-OCT and a higher average endothelial cell count on specular microscopy. Keratometry and pachymetry values were stable in all groups.Conclusion: Preliminary data indicate that the method described by the authors can be used in thinner corneas to improve efficacy of CXL compared to the transepithelial approach.

Evaluation of effects of riboflavin and/or ultraviolet-A on survival of rat limbal epithelial stem cells in ex-vivo.

To investigate the effects of riboflavin and/or ultraviolet-A (UV-A) irradiation on the cell viability of ex-vivo-cultured rat limbal stem cells (LSCs). LSCs of male Wistar rats (N = 12 eyes) were cultured, and immunofluorescence staining was performed to evaluate them. After characterization, these cells were assigned to four groups of control (C), a group that was exposed to UV-A radiation (UV), a group that was treated with riboflavin (R), and a group that cotreated with both UV-A and riboflavin (UV+R). To determine the cell viability of LSCs, these cells were subjected to MTT assay on days 1, 3, and 7 after exposure to UV-A and/or riboflavin. The duration of exposure to UV-A and riboflavin was similar to levels used during the conventional corneal collagen cross-linking procedure. Compared with the viable cells in the control group, there was a significant decrease (P < 0.0001) in the number of LSCs in the UV group during all study days. In the R group, the level of viable LSCs was as same as the level of viable LSCs in the C group. Combined treatment with UV-A plus riboflavin significantly decreased the survival of LSCs on days 1 and 3 (P < 0.0001, P < 0.001, respectively) compared with the control group. Interestingly, in the UV+R group, the photosensitizing effect of riboflavin significantly decreased the cytotoxic effect of UV irradiation 7 days after exposure. These results suggest that the administered UV energy in the presence or absence of riboflavin can damage LSCs. Likewise, riboflavin could decrease the toxic effect of UVA on LSCs.

Corneal stromal demarcation line depth after corneal collagen cross-linking following conventional versus customized corneal epithelial debridement

Aim of the Study: Using anterior segment optical coherence tomography (AS-OCT) to compare the depth of corneal demarcation line (DL) after corneal collagen cross-linking (CXL) with subtotal versus customized corneal epithelium debridement. Design: Prospective multi centric case-control study. Materials and Methods: The study enrolled 18 patients with bilateral progressive keratoconus. Both eyes treated by CXL using 3 mW/cm2 / 30 minutes setting. One eye with subtotal epithelial debridement ( about 9 mm diameter) and the contralateral eye with customized debridement ( approximately 1 mm single horizontal scratch ). One month postoperatively, patients had AS-OCT imaging to detect and measure the depth of DL. Results: Patients’ age mean was 25.17 years +/- 4.81 SD . Epithelial healing completed with in 3-7 days in conventional treatment group and demarcation line was evident in 16 eyes ( 89% ) with a mean depth of 290.31 micro m while in customized epi-off treatment group, the epithelial healing lasted less than 24 hours and DL was detectable in 10 patients ( 55.5 % ) with a mean DL depth of 221 micro m with a statistically significant difference ( p < 0.05 ) Subjective postoperative pain graded as “moderate to severe” in about 77% of eyes underwent 9 mm epi-off CXL compared with 55% of those with customized treatment. Conclusions: Although the DL if found in majority cases, but the shallow location in customized corneal debridement cases questioned the efficacy of this technique despite the quick re-epithelialization and less postoperative pain that accompanied it.

Visual improvement after corneal collagen cross-linking in keratoconus

This study was carried out to evaluate the effect of corneal collagen cross-linking on visual acuity, astigmatism and topographic readings (K1, K2, Kapex). : A nonrandomized noncontrolled clinical study was conducted in two tertiary eye centres in Bangladesh from July 2017 to June 2019. All attending patients diagnosed with Keratoconus were included in this study according to selection criteria. Patients with a corneal thickness of fewer than 400 microns, previous viral infection, cornea scarring, corneal opacification, severe ocular surface disease, history of immune disorders, pregnancy, and breastfeeding were excluded from the study. All selected patients underwent collagen cross-linking with Riboflavin and Ultraviolet A, followed up five days, one and six months following the procedure. Visual acuity, topographic readings (K1, K2, Kapex) and cylindrical values were assessed on every visit. The mean value of visual acuity was compared statistically with the baseline value.: A total of 30 eyes of 30 patients were studied in this study. The male-to-female ratio was 2:1. The Mean age (± SD) of the study subjects was 22.7±7.10. Before CXL, the Mean uncorrected visual acuity (UCVA) ±SD was 0.86±.35. In post-CXL follow-up time, the mean UCVA±SD was 0.46±.23 after six months of CXL. Before CXL, the Mean BCVA±SD was 0.35±.22. In post CXL era, the Mean ± SD BCVA was 0.14±.13 after six months of CXL. The Mean K1±SD was 45.66±3.43 before CXL, and the result changed after CXL. The Mean K1±SD was 43.29±3.29 after six months of CXL. The Mean K2±SD was 50.22±5.93 before CXL, and the result differed after six months of CXL. The Mean Kapex ±SD was 54.50±7.38 before CXL, and that was 51.32±6.93 after six months of CXL. Keratoconus is a bilateral non-inflammatory disorder progressively leading to vision-threatening ocular morbidity. Collagen cross-linking improves visual and topographic findings– K1, K2, and Kapex and reduces astigmatism. Early diagnosis of Keratoconus and prompt treatment will help achieve better vision.

Tear film mediators after corneal cross‐linking

AbstractBackground and Purpose: Currently, the gold‐standard treatment of progressive keratoconus (KC) is corneal collagen cross‐linking (CXL), in which riboflavin and ultraviolet‐A radiation increase the corneal biomechanical rigidity, arresting progression. However, post‐operatory results vary significantly among patients. Although it has been suggested that corneal thickness, cone location and patient's age are important factors, their contribution is controversial. The reason for this variability remains obscure. This project aims to find biomarkers that could explain the variability within surgical results after corneal CXL by investigating the correlation between the local corneal inflammatory environment and these results. We hypothesize that better post‐operatory results are related to a reduction in the inflammatory cytokine levels in the patients' tear film. Ultimately, we aim to optimize the patients' surgical outcomes according to their corneal inflammatory environment.Materials and Methods: The research protocol was established after testing different sample collection methods. Patients are interviewed to assess their medical history and relevant habits. Their corneal tomographic and best corrected visual acuity data are registered before and 6 months after surgery. The patient's tear film is sampled twice 6 months apart using Schirmer strips, as the volume yield is larger compared with direct methods (microcapillary tubes or micropipettes), which are more difficult to perform and require stimulation or the instillation of saline into the cul‐de‐sac, originating reflex tearing. The samples are analysed for their total protein content (BCA Protein Assay Kit) and cytokine concentration using Multiplex technology (Th1/Th2/Th9/Th17 Cytokine 18‐Plex Human ProcartaPlex™ Panel) and not ELISA, as we tried before. Statistical analysis to assess sample differences and the correlation between cytokine concentration and tomographic indexes and visual acuity values for each group and subgroup is performed at 6 months.Preliminary results and Discussion: Thirty‐five patients and fifteen control subjects have been enrolled in the study and the first collection of tears has been carried out, as well as some second collections. CXL surgeries for the twenty patients is being performed since October 2020. Two samples were lost due to excessively length of dry Schirmer strip, which we improved by cutting the dry portion. Additionally, the tear fluid from the first eight samples from patients and from control participants was successfully processed for their total protein content.Conclusion: Tear film analysis poses several challenges concerning the small amount of material available without reflex production. This fact precludes the use of conventional ELISA, requiring multiplex modified technology. When dealing with tears it is also important to avoid contamination by using sterilized material, to avoid dilution and to establish an efficient flow of samples from the clinic to the laboratory. This pilot study enabled to identify several methodological frailties and to establish a solid research protocol that can be replicated by other researchers. Understanding the correlation between inflammatory cytokines and surgical outcomes of CXL may allow for the optimization and personalization of CXL. In addition, the results of this research protocol are expected to establish prognostic factors for CXL‐related surgical outcomes, ultimately improving the quality of life of KC patients.

Role of AS‐OCT in DALK and PKP for KC

AbstractOCT has been a diagnostic device in corneal diseases for many years. Non‐contact examination enables obtaining morphological and morphometric data useful in clinical practice. For example, a patient with keratoconus is a diagnostic tool in surgical procedures such as keratoplasty, intracorneal ring implants, and corneal collagen cross‐linking (CXL). The presentation will show the practical aspects of using AS OCT diagnostics in patients with a cone qualified for deep lamellar keratoplasty and penetrating keratoplasty. The use of intraoperative OCT in surgical treatment supported by excimer and femtosecond lasers will also be presented.

Tear proteome profile in eyes with keratoconus after intracorneal ring segment implantation or corneal crosslinking

AbstractPurpose: Intracorneal Ring Segment (ICRS) and Corneal collagen Crosslinking (CXL) are widely used treatments in keratoconus (KC) disease, but the alterations they cause in biomechanical mediators in the cornea, are still poorly understood. The aim of this study was to analyse the tear proteome profile before and after treatments to identify biomarkers altered by surgery.Methods: An observational, prospective, case–control pilot study was conducted, analysing tear samples from KC patients by nano‐liquid chromatography‐mass spectrometry (nLC‐MS/MS). Patients with KC who underwent ICRS surgery (n = 4), CXL (n = 4), and healthy subjects (CT, n = 4) were included in this study. Clinical parameters were measured and tear samples were collected before and 18 months after surgery. Proteins with ≥2 expression change and p‐value &lt;0.05 between groups and times were selected to study their role in postoperative corneal changes.Results: These analyses led to the identification of 447 tear proteins. In comparisons between the two surgical groups and CTs, the biological processes that were altered in KC patients at baseline were those that were dysregulated as a consequence of the disease. Among the biological processes seen to be altered were: immune responses, cytoskeleton components, protein synthesis, and metabolic reactions. When comparing the two treatment groups, A‐kinase anchor protein 13 (AKAP‐13) was the most overexpressed protein before and after surgery in CXL group.Conclusions: The changes observed in tears after 18 months postoperatively could be due to the treatments performed and the pathology. Among the deregulated proteins detected, AKAP‐13 deserves special attention for its involvement in corneal thinning, and for its strong overexpression in the tears of patients with more active KC and faster disease progression. However, it should be kept in mind that this is a pilot study conducted on a small number of patients.