Characterization of Recruited Mononuclear Phagocytes following Corneal Chemical Injury.

Mononuclear phagocytes (MP) have central importance in innate immunity, inflammation, and fibrosis. Recruited MPs, such as macrophages, are plastic cells and can switch from an inflammatory to a restorative phenotype during the healing process. However, the role of the MPs in corneal wound healing is not completely understood. The purpose of this study is to characterize the kinetics of recruited MPs and evaluate the role of macrophage metalloelastase (MMP12) in the healing process, using an in vivo corneal chemical injury model. Unwounded and wounded corneas of wild-type (WT) and Mmp12-/- mice were collected at 1, 3, and 6 days after chemical injury and processed for flow cytometry analysis. Corneal MP phenotype significantly changed over time with recruited Ly6Chigh (proinflammatory) cells being most abundant at 1 day post-injury. Ly6Cint cells were highly expressed at 3 days post-injury and Ly6Cneg (patrolling) cells became the predominant cell type at 6 days post-injury. CD11c+ dendritic cells were abundant in corneas from Mmp12-/- mice at 6 days post-injury. These findings show the temporal phenotypic plasticity of recruited MPs and provide valuable insight into the role of the MPs in the corneal repair response, which may help guide the future development of MP-targeted therapies.

Riboflavin and ultraviolet A as adjuvant treatment against Acanthamoeba cysts.

BACKGROUND: Experimental studies have shown that the standard dose of riboflavin (R) or R + ultraviolet-A (UVA) as solo treatment are not able to exterminate Acanthamoeba cysts or even trophozoites. The purpose of this study is to determine whether the application of R + UVA can enhance the cysticidal effects of cationic antiseptic agents in vitro. METHODS: The log of either polyhexamethylene biguanide or chlorhexidine minimal cysticidal concentration in solutions containing riboflavin (concentrations 0.1, 0.05 and 0.025%) plus either Acanthamoeba castellanii cysts or Acanthamoeba polyphaga cysts was determined and compared in groups treated with UVA 30 mW/cm(2) for 30 min and in control groups (with no exposure to UVA). A permutation test was used to determine the P value associated with treatment. RESULTS: Regardless of the riboflavin concentration and UVA treatment condition, no trophozoites were seen in plates where the cysts were previously exposed to cationic antiseptic agent concentrations ≥200 µg/mL for Acanthamoeba castellanii samples and ≥100 µg/mL for A. polyphaga samples. There was no statistical evidence that R + UVA treatment was associated with minimal cysticidal concentration (P = 0.82). CONCLUSION: R + UVA in doses up to 10 times higher than recommended for corneal crosslinking does not enhance the cysticidal effect of either polyhexamethylene biguanide or chlorhexidine in vitro.

Vitreous Biomarkers for Proliferative Vitreoretinopathy Prognostication in Patients Undergoing Primary Retinal Detachment Repair.

Purpose: To compare baseline levels of exploratory biomarkers in the vitreous fluid of patients with primary retinal detachment who subsequently develop proliferative vitreoretinopathy (PVR) versus those who do not. Methods: In this exploratory case-control study, we evaluated the baseline protein biomarker levels from a biobank containing the vitreous fluid of patients who had undergone primary pars plana vitrectomy (PPV) for rhegmatogenous retinal detachment. Undiluted samples were collected at the time of PPV and stored at -80°C. Samples from 13 patients who developed PVR within 6 months (PVR group) and 13 age- and gender-matched controls who did not develop PVR (control group) were included. Protein abundance levels were evaluated using a proximity extension assay, and a confirmatory enzyme-linked immunosorbent assay (ELISA) was used to measure the concentration of vimentin. Results: Baseline vimentin (Normalized Protein eXpression [NPX], 8.6 vs. 6.4, P < 0.0001) and heme oxygenase 1 (NPX 8.9 vs. 7.0, P < 0.001) levels were found to be elevated in vitreous fluid of patients who subsequently developed PVR compared to those who did not. Confirmatory analysis using ELISA demonstrated mean vimentin concentrations of 7254 vs. 2727 ng/mL in the PVR versus control groups (P = 0.0152). The odds ratio for developing PVR was 14 (confidence interval, 1.4-168; P = 0.03), assuming a baseline vimentin threshold of 7500 ng/mL. Conclusions: Vimentin is an intermediate filament protein expressed by retinal glial cells, and our data combined with prior evidence suggest that it may serve as an early vitreous biomarker for subsequent PVR formation and reactive gliosis. Furthermore, we found, for the first time, elevated baseline levels of heme oxygenase 1, a measurable indicator of oxidative stress. Translational Relevance: Our positive findings could impact clinical care for retinal detachment patients by facilitating risk stratification for targeted interventions or closer monitoring in those at the highest risk of developing PVR.

Proximity Extension Assay (PEA) Platform to Detect Vitreous Biomarkers of Diabetic Retinopathy.

Diabetic retinopathy (DR) is one of the leading causes of blindness, affecting more than 100 million people worldwide. Currently, DR prognosis and management are based mainly on biomarkers identified by direct retinal fundus observation or by imaging devices. The use of molecular biology to discover biomarkers of DR has great potential to impact the standard of care, and the vitreous humor can serve as an indirect source for those molecular biomarkers because it is rich in proteins secreted by the retina. Proximity extension assay (PEA) is a technology that combines antibody-based immunoassays with DNA-coupled methodology to obtain information on the abundance of multiple proteins while using minimal sample volume, with high specificity and sensitivity. Matched antibodies labelled with a complementary sequence of oligonucleotides are used to simultaneously bind a target protein in solution, and when in proximity, the complementary sequences on each antibody hybridize, serving as template for DNA polymerase-dependent extension and the generation of a unique double-stranded DNA "barcode." PEA works well with vitreous matrix and has great potential to support the identification of novel predictive and prognostic biomarkers of DR.

Aqueous Fluid Transcriptome Profiling Differentiates Between Non-Neovascular and Neovascular AMD.

Purpose: Early and intermediate non-neovascular AMD (NN-AMD) has the potential to progress to either advanced NN-AMD with geographic atrophy, or to neovascular AMD (N-AMD) with CNV. This exploratory study performed an unbiased analysis of aqueous humor transcriptome in patients with early or intermediate NN-AMD vs. treatment-naïve N-AMD to determine the feasibility of using this method in future studies investigating pathways and triggers for conversion from one form to another. Methods: Aqueous humor samples were obtained from 20 patients with early or intermediate NN-AMD and 20 patients with untreated N-AMD, graded on clinical examination and optical coherence tomography. Transcriptome profiles were generated using next-generation sequencing methods optimized for ocular samples. Top-ranked transcripts were compared between groups, and pathway enrichment analysis was performed. Results: Seventy-eight differentially expressed transcripts were identified. Unsupervised clustering of differentially expressed transcripts was able to successfully differentiate between the two groups based on aqueous transcriptome alone. Pathway analysis highlighted changes in expression of genes associated with mitochondrial respiration, oxidative stress, ubiquitination, and neurogenesis between the two groups. Conclusions: This pilot study compared the aqueous fluid transcriptome of patients with early or intermediate NN-AMD and untreated N-AMD. Differences in transcripts and transcriptome pathways identified in the aqueous of patients with early or intermediate NN-AMD compared with patients with N-AMD are consistent with those previously implicated in the pathogenesis of these distinct AMD subtypes. The findings from this exploratory study warrant further investigation using a larger, prospective study design, with the inclusion of a control group of eyes without AMD.

Longitudinal fundus imaging and its genome-wide association analysis provide evidence for a human retinal aging clock.

Biological age, distinct from an individual's chronological age, has been studied extensively through predictive aging clocks. However, these clocks have limited accuracy in short time-scales. Here we trained deep learning models on fundus images from the EyePACS dataset to predict individuals' chronological age. Our retinal aging clocking, 'eyeAge', predicted chronological age more accurately than other aging clocks (mean absolute error of 2.86 and 3.30 years on quality-filtered data from EyePACS and UK Biobank, respectively). Additionally, eyeAge was independent of blood marker-based measures of biological age, maintaining an all-cause mortality hazard ratio of 1.026 even when adjusted for phenotypic age. The individual-specific nature of eyeAge was reinforced via multiple GWAS hits in the UK Biobank cohort. The top GWAS locus was further validated via knockdown of the fly homolog, Alk, which slowed age-related decline in vision in flies. This study demonstrates the potential utility of a retinal aging clock for studying aging and age-related diseases and quantitatively measuring aging on very short time-scales, opening avenues for quick and actionable evaluation of gero-protective therapeutics.

Comparative Analysis of Multiplex Platforms for Detecting Vitreous Biomarkers in Diabetic Retinopathy.

Purpose: To evaluate the feasibility of using the Proximity Extension Assay (PEA) platform to detect biomarkers in vitreous and to compare the findings with results obtained with an electrochemiluminescent (ECL) sandwich immunoassay. Methods: Vitreous samples from patients with proliferative diabetic retinopathy (PDR) and non-diabetic controls were tested using two different proteomics platforms. Forty-one assays were completed with the ECL platform and 459 with the PEA platform. Spearman's rank correlation coefficient (rs ) was used to determine the direction and strength of the relationship between protein levels detected by both platforms. Results: Three hundred sixty-six PEA assays detected the tested protein in at least 25% of samples, and the difference in protein abundance between PDR and controls was statistically significant for 262 assays. Seventeen ECL assays yielded a detection rate ≥ 25%, and the difference in protein concentration between PDR and controls was statistically significant for 13 proteins. There was a subset of proteins that were detected by both platforms, and for those the Spearman's correlation coefficient was higher than 0.8. Conclusions: PEA is suitable for the analysis of vitreous samples, showing a strong correlation with the ECL platform. The detection rate of PEA panels was higher than the panels tested with ECL. The levels of several proinflammatory and angiogenic cytokines were significantly higher in PDR vitreous compared to controls. Translational Relevance: This study provides new information on the yields of small-volume assays that can detect proteins of interest in ocular specimens, and it identifies patterns of cytokine dysregulation in PDR.

Correlation of Aqueous, Vitreous, and Plasma Cytokine Levels in Patients With Proliferative Diabetic Retinopathy.

Purpose: To investigate the relationship between proangiogenic and inflammatory cytokines in concurrent vitreous, aqueous, and plasma samples from patients with proliferative diabetic retinopathy (PDR). Methods: Vitreous, aqueous, and plasma samples were analyzed using multiplex immunoassay for 10 PDR-related cytokines (IL-6, IL-8, TNF-α, monocyte chemoattractant protein-1 [MCP-1], macrophage inflammatory protein-1ß [MIP-1ß], VEGF receptor 1 [Flt-1], placental growth factor [PlGF], VEGF-A, VEGF-C, VEGF-D). A total of 17 patients with PDR and 7 controls were included. The primary outcome was correlation of cytokines in vitreous, aqueous, and plasma. The secondary outcome was the comparison of cytokine levels in controls and diabetics with and without recent anti-VEGF injection. Results: The following factors were elevated in diabetics compared with controls: vitreous IL-6, IL-8, TNF-α, MCP-1, MIP-1ß, PlGF, and VEGF-A; and aqueous IL-6, IL-8, PlGF, and VEGF-C (all P < 0.05). Vitreous and aqueous IL-8, PlGF, and VEGF-A were significantly correlated in patients with PDR (all P < 0.05). Plasma cytokines were not correlated with those in vitreous and aqueous (all P > 0.05). Vitreous and aqueous IL-6, IL-8, TNF-α, PlGF, and VEGF-A differed among controls and diabetics with and without recent anti-VEGF injection (all P < 0.05). In one-to-one comparisons, aqueous VEGF-A levels were lower in diabetic patients who had recent anti-VEGF injection compared with those who did not (P = 0.01). Conclusions: In this proof-of-concept study, IL-8, VEGF-A, and PlGF demonstrated a strong correlation in vitreous and aqueous of patients with PDR. The aqueous may serve as a proxy for vitreous for some cytokines involved in PDR. Recent anti-VEGF injections decreased VEGF-A levels in aqueous, but did not significantly affect other cytokines, suggesting a role for other targeted therapies in PDR management.

[Anatomical nomenclature in ophthalmology]. / Nomenclatura anatômica em oftalmologia.

The purposes of this article are: to inform ophthalmologists about the differences between the English and Portuguese list of equivalent terms for eye structures, approved by the Federative International Committee on Anatomical Terminology; to present the anatomical terms included in the list of medical subject headings published by the United States National Library of Medicine and translated by the Regional Library of Medicine (BIREME); propose a list of Portuguese terms of common usage by ophthalmologists.

Photochemical crosslinking of caries-affected dentin combined with total- or self-etch systems.

PURPOSE: To evaluate the effects of collagen crosslinking with riboflavin 0.1% and ultraviolet-A (UVA) 5.4 J on bond strength of total-etch or self-etch adhesives on caries-affected dentin. METHODS: Sixty human caries-affected molars were randomly divided into three groups: control (C), riboflavin (R), and riboflavin + 3 minutes of UVA (R+UVA). After each treatment, either total-etch or self-etch adhesives were applied following the manufacturer's instructions, and composite stubs were built up on the treated surfaces. They were de-bonded in tension to measure bond strength. Twelve extra molars were used for scanning electron microscope (SEM) analysis. RESULTS: We observed that R+UVA-treated group yielded significantly higher bond strengths for carious dentin when the total-etch adhesive was applied. For the self-etch adhesive, no statistical differences were observed between the three pretreated-groups. CONCLUSION: Our results, for the first time, are suggesting that etching with phosphoric acid potentialized the benefits of R+UVA crosslinking on carious dentin. R+UVA dentinal collagen crosslinking improves bond strength for caries-affected dentin when using a total-etch adhesive, but did not affect it when using a self-etch adhesive.

880 kHz ultrasound treatment for drug delivery to the vitreous humor.

Clinical management of many chronic ophthalmological disorders requires direct delivery of drugs into the vitreous. There is an important need to investigate novel needle-less alternatives to deliver drugs to the vitreous. The purpose of this study is to assess the effects of a needle-less system using ultrasound to enhance vitreal delivery of small molecules through the sclera in an ex vivo model and to evaluate whether changes in permeability are mainly due to the heat generated by sonication. An eye cup containing 1 mL of sodium fluorescein 0.1% was placed on top of the sclera of cadaveric rabbit eyes. Treated eyes were sonicated for 10 minutes, and left in contact with the fluorescein solution for an additional 50 minutes. Control eyes received the same exposure to fluorescein solution (60 minutes) in the eye cup without ultrasound treatment. Vitreous humor was collected and analyzed using a fluorescence spectrophotometer to calculate the concentration of fluorescein that diffused into the vitreous humor. An additional set of eyes was treated using a heating probe to evaluate whether changes in permeability were mainly due to heat. Vitreous samples from ultrasound-treated eyes showed a 44.6% higher concentration of fluorescein compared to control eyes. The concentration of fluorescein in the vitreous of heat-treated eyes did not show a significant difference when compared to control eyes. Thus, phonophoresis is a promising needle-less method for vitreal drug delivery, and local heating conducted to the surface of the sclera should be mitigated because it does not enhance the efficacy of the method.

Advanced glycation end-product accumulation reduces vitreous permeability.

PURPOSE: To evaluate the effect of nonenzymatic cross-linking (glycation) upon the permeability of the vitreous to small- and large-solute diffusion. METHODS: Vitreous from freshly excised porcine eyes was treated for 30 minutes with control or 0.01%, 0.1%, or 1% methylglyoxal (MG) solution. The efficacy of the glycation regimen was verified by measuring nonenzymatic cross-link density by fluorescence in the vitreous samples. Resistance to collagenase digestion as well as N(ε)-(carboxyethyl) lysine (CEL) content were also measured. The permeability coefficient for fluorescein and fluorescein isothiocyanate (FITC)-IgG diffusion through 3 mL of the vitreous samples was determined by using a custom permeability tester. RESULTS: Vitreous cross-linking with MG treatment was confirmed by increased fluorescence, increased CEL concentration, and increased resistance to collagenase digestion. Vitreous glycation resulted in a statistically significant decrease in the permeability coefficient for fluorescein diffusion when either 0.1% or 1% MG solution was used (5.36 ± 5.24 × 10(-5) cm s(-1), P = 0.04; and 4.03 ± 2.1 × 10(-5) cm s(-1), P = 0.001; respectively, compared with control, 9.77 ± 5.45 × 10(-5) cm s(-1)). The permeability coefficient for diffusion of FITC-IgG between control (9.9 ± 6.37 × 10(-5) cm s(-1)) and treatment groups was statistically significant at all MG concentrations (0.01% MG: 3.95 ± 3.44 × 10(-5) cm s(-1), P = 0.003; 0.1% MG: 4.27 ± 1.32 × 10(-5) cm s(-1), P = 0.004; and 0.1% MG: 3.72 ± 2.49 × 10(-5) cm s(-1), P = 0.001). CONCLUSIONS: Advanced glycation end-product (AGE) accumulation reduces vitreous permeability when glycation is performed in ex vivo porcine vitreous. The permeability change was more pronounced for the larger solute, suggesting a lower threshold for AGE-induced permeability changes to impact the movement of proteins through the vitreous when compared with smaller molecules.

Ultrasound-enhanced penetration of topical riboflavin into the corneal stroma.

PURPOSE: To determine whether ultrasound treatment can promote the permeation of topical riboflavin into the corneal stroma. METHODS: Fresh cadaveric rabbit eyes with intact epithelium were left for 45 minutes in riboflavin 0.1% solution and divided in the following groups: A--untreated, epithelium-on; B--ultrasound-treated (1 W/cm(2) at 880 kHz for 6 minutes) with epithelium-on; and C--epithelium-off (no ultrasound). Eyes were removed from the riboflavin solution, corneas were excised, and group B was divided into B1 (with epithelium maintained) and B2 (epithelium removed for the fluorescence analysis). Confocal microscopy was performed to quantify the fluorescence intensity in the cornea according to the distance from the surface (with epithelium in groups A and B1; without epithelium in groups B2 and C). RESULTS: The average fluorescence intensity of riboflavin at a depth of 100, 150, 200, and 250 µm was 69.97, 58.83, 49.23, and 41.72 arbitrary units (A.U.) in group A, respectively; 255.26, 206.01, 159.81, 124.20 A.U. in group B1; 218.90, 177.90, 141.43, 110.45 A.U. in group B2; and 677.64, 420.10, 250.72 and 145.07 A.U. in group C. The difference in fluorescence was statistically significant between groups A and B1 (P = 0.001) and groups B2 and C (P < 0.0001). CONCLUSIONS: Ultrasound treatment increased the entry of topical riboflavin into the corneal stroma despite the presence of a previously intact epithelial barrier. This approach may offer a means of achieving clinically useful concentrations of riboflavin within the cornea with minimum epithelial damage, thereby improving the risk profile of corneal cross-linking procedures.

Effects of corneal cross-linking on contrast sensitivity, visual acuity, and corneal topography in patients with keratoconus.

PURPOSE: To assess the effects of corneal collagen cross-linking (CXL) on contrast sensitivity (CS), visual acuity, and corneal topography investigating possible predictors of efficacy. METHODS: Sixty-eight eyes of 34 patients with progressive keratoconus were enrolled in this prospective study. CXL was performed in one eye and the other eye was left untreated as a control. CS, best spectacle-corrected visual acuity (BSCVA), simulated keratometry in the steepest meridian (SimK-s), mean power in the central 3-mm zone (C-MP), mean power in the paracentral 3- to 5-mm zone (P-MP), maximum keratometric power in the central zone (C-Kmax), and maximum keratometric power in the paracentral zone (P-Kmax) were evaluated at baseline, 40 days, 3 months, 6 months, 1 year, and after 2 years of follow-up. RESULTS: Treated eyes showed an improvement (P < 0.001) of +0.16 logCS and -0.16 logarithm of the minimum angle of resolution (logMAR) and a reduction in SimK-s of -0.61 diopter (D), C-Kmax -1.11 D, P-Kmax -0.99 D, C-MP -0.39 D, and P-MP -0.30 D. Of the treated eyes, 43.3% had a decrease in C-Kmax greater than 1 D, 50% by 0 to 0.99 D, and 6.7% had an increase of up to +0.89 D. Treated eyes with keratometric apex in the central 3-mm zone (CKA) improved BSCVA -0.19 logMAR and CS +0.19 logCS; whereas in treated eyes with paracentral keratometric apex (PKA), the improvement was -0.13 logMAR and +0.16 logCS. CONCLUSIONS: CXL with riboflavin and UV-A improved CS and inhibited the progression of keratoconus. As a predictor of treatment efficacy, eyes with CKA showed greater improvement in BSCVA after CXL when compared with eyes with PKA.

Cross-linking with ultraviolet-a and riboflavin reduces corneal permeability.

PURPOSE: To investigate the effect of cross-linking treatment on corneal permeability in a live animal model. METHODS: Rabbit eyes were selected at random to be left unoperated or to undergo epithelial debridement with or without treatment consisting of cross-linking (CXL) with riboflavin and ultraviolet-A. Nine eyes received a total dose of 3.6 J/cm² and after epithelial healing the corneas were placed in a two-chamber system for quantification of the diffusion of fluorescein compared with controls. Thirty eyes received a total dose of 5.4 J/cm² and, after epithelial healing, in vivo corneal permeability was quantified as the pupillary response over a 30-minute period to a dose of topical pilocarpine compared with controls. RESULTS: In the ex vivo assay, the mean permeability coefficient in the CXL group (2.42 × 10⁻7) was reduced when compared with the unoperated controls (3.73 × 10⁻7; P = 0.007) and to the eyes that received epithelial debridement alone (3.74 × 10⁻7; P = 0.01). In the in vivo permeability assay, the change in pupillary diameter at 30 minutes after pilocarpine administration was smaller in the CXL group (-1.9 mm), compared with the epithelial debridement group (-2.6 mm; P < 0.001) and with the unoperated controls (-2.7 mm; P = 0.003). CONCLUSIONS: Corneal cross-linking with ultraviolet-A and riboflavin results in a statistically significant reduction in corneal permeability. These findings suggest that dosing of topical medications may need to be increased in eyes with a history of CXL to achieve expected therapeutic effects, and they may have implications for the long-term health of the cornea.

Nomenclatura anatômica em oftalmologia / Anatomical nomenclature in ophthalmology

Os objetivos deste estudo são: informar os oftalmologistas sobre as diferenças existentes entre as listas em língua inglesa e portuguesa de termos equivalentes para as estruturas do olho, ambas aprovadas pela Comissão Federativa Internacional de Terminologia Anatômica; apresentar os termos anatômicos incluídos na lista de descritores publicada pela Biblioteca Nacional de Medicina Norte-Americana e traduzida pela Biblioteca Regional de Medicina (BIREME); para propor uma lista em português de termos de uso comum pelos oftalmologistas.

The purposes of this article are: to inform ophthalmologists about the differences between the English and Portuguese list of equivalent terms for eye structures, approved by the Federative International Committee on Anatomical Terminology; to present the anatomical terms included in the list of medical subject headings published by the United States National Library of Medicine and translated by the Regional Library of Medicine (BIREME); propose a list of Portuguese terms of common usage by ophthalmologists.

Reticulação do colágeno corneano com radiação ultravioleta e riboflavina para tratamento do ceratocone: resultados preliminares de um estudo brasileiro / Corneal collagen crosslinking with riboflavin and ultraviolet radiation for keratoconus treatment: preliminary results of a Brazilian study

OBJETIVO: Avaliar o efeito clínico e topográfico da reticulação do colágeno corneano (crosslinking) em pacientes com ceratocone pertencentes à população brasileira. MÉTODOS: Trinta e sete olhos de 37 pacientes (22 mulheres e 15 homens) com diagnóstico de ceratocone em progressão e com espessura mínima de 395 micra, foram submetidos à técnica de indução da reticulação do colágeno corneano através da aplicação durante 30 minutos de luz ultravioleta (370nm) associada à solução de riboflavina 0,1 por cento (instilada a cada 5 minutos). Foram comparados os valores ceratométricos e a melhor acuidade visual corrigida antes e após o procedimento, com intervalos de 40 e 90 dias. RESULTADOS: Houve redução do poder dióptrico médio (PDM) nos 3mm centrais em 83,8 por cento dos pacientes após três meses. O PDM reduziu em média 0,4D nos 3mm centrais (p<0,01) e 0,33D nos 5mm centrais (p<0,01). O valor ceratométrico máximo reduziu em média 0,6D (p<0,01). A acuidade visual corrigida do olho tratado evoluiu com melhora média de 6,27 letras (p<0,01) após 90 dias. CONCLUSÃO: Observamos uma melhora menos acentuada dos índices topográficos e de acuidade visual em comparação aos resultados encontrados em outras populações. São necessários mais estudos com um maior número de pacientes e maior tempo de seguimento para que esta técnica confirme seu propósito de estabilização da doença com apenas uma aplicação, e possa talvez se tornar, no futuro, o método de escolha para o tratamento do ceratocone.

PURPOSE: Assess the clinical and topographical effects of corneal collagen crosslinking in patients with keratoconus on Brazilian population. METHODS: Thirty seven eyes of 37 patients (22 female and 15 male) with diagnosis of progressive keratoconus and corneal paquimetry higher than 395 micra, were treated with riboflavin and ultraviolet A radiation, over 30 minutes, to induce corneal collagen crosslinking. Keratometric values were compared as well as the best corrected visual acuity, before and after the procedure, with ranges of 40 and 90 days. RESULTS: There was a reduction of mean dioptric power (PDM) in central 3mm in 83.8 percent of patients after three months.The PDM reduced 0.4D on average in central 3mm (p<0,01) and 0.33D in central 5mm (p<0,01). The maximum keratometric value decreased 0.6 D on average (p<0,01). The corrected visual acuity of the treated eye evolved with improvement average of 6,27 letters (p<0,01) after 90 days. CONCLUSION: We could observe a less pronounced improvement of the topographical values and visual acuity in comparison of the findings in other populations. Further studies with a larger number of patients and longer follow-up are necessary to confirm this technique's purpose of stabilizing the disease with only one application, and allow that to become the method of choice for keratoconus treatment.