Papers by Renato Ambrósio
Acta Ophthalmologica, Oct 16, 2021
Purpose: This retrospective cross-sectional study evaluated the potential of an additional biomec... more Purpose: This retrospective cross-sectional study evaluated the potential of an additional biomechanical parameter 'E' as an addition to the tomographic ABCD ectasia/keratoconus (KC) staging. The Corvis Biomechanical Factor (CBiF) represents the modified linear term of the Corvis Biomechanical Index (CBI) developed based on 448 KC corneas from the Homburg Keratoconus Center (HKC). The CBiF range was divided into five stages (E0 to E4) to create a grading system according to the ABCD stages. Stage E0 was characterized by values smaller than the 2.5 percentile. The thresholds were created by dividing the CBiF range between the 2.5 and 97.5 percentiles into four groups of equal values (E1-E4). The frequency distribution of 'E' was analysed and independently validated based on another 860 KC corneas dataset from Milano and Rio de Janeiro (MR). The relationship between 'E' and the ABCD staging was analysed by crosstabulation. The specificity of 'E' was assessed based on healthy controls (112|851) from both datasets (HKC|MR). Results: 'E' was normally distributed with E0 = 37|30, E1 = 86|200, E2 = 155|354, E3 = 101|206, E4 = 69| 70 in the KC group and 96.4%|90.5% of the controls classified E0 in the HKC|MR dataset, respectively. Crosstabulation revealed that 'E' was most comparable to posterior corneal curvature ('B') in both datasets, while showing a trend towards more advanced stages in comparison to anterior corneal curvature ('A') and thinnest corneal thickness ('C'). The novel Corvis-derived parameter 'E' provides a biomechanical staging for ectasia/KC potentially enhancing the ABCD staging and may detect abnormalities before tomographic changes, which requires further studies.
Recebido para publicação em 01/08/2015 -Aceito para publicação em 25/08/2015 Os autores declaram ... more Recebido para publicação em 01/08/2015 -Aceito para publicação em 25/08/2015 Os autores declaram não haver conflitos de interesse. Objetivo: Avaliar a capacidade de dados de perfil paquimétrico horizontal, a fim de distinguir o ceratocone de córneas normais, e comparar a precisão de índices com outros tomográficos mais complexos. Métodos: Em um estudo retrospectivo, um olho selecionado aleatoriamente de 225 pacientes com ceratocone bilateral e de 335 pacientes com córneas normais foram incluídos. Todos os pacientes foram examinados por um especialista em córnea e foram submetidos ao exame de tomografia de córnea, Pentacam HR (Oculus, Wetzlar, Alemanha). Os dados de perfil paquimétrico horizontal em 6 milímetros passando pelo ápice foi avaliado. Com esses dados, a espessura no ápice corneano (P.ápice), a espessura no ponto mais fino do perfil horizontal (P.min.H), a progressão paquimétrica do ponto mais fino para o mais espesso (PPmin-máx), a progressão paquimétrica média no meridiano temos como referencial a média normal (PPméd) e a adequação a uma linha de tendência polinomial do segundo grau (R 2 ). Um modelo de inteligência artificial foi construído para combinar esses dados. O desempenho para distinguir ceratocone do normal foi avaliada por curvas ROC. Resultados: Todos os índices avaliados foram estatisticamente diferentes entre os dois grupos (p <0,001). A área sob a curva ROC (AUC) de paquimetria no ápice e no TP foram de 0,904 e 0,938, respectivamente. O índice tomográfico com maior AUC foi o BAD-D (0,997). Em relação ao perfil horizontal, a AUC do P.min.H e PPmin-max foram 0,915 e 0,927, respectivamente. A adequação à linha de tendência para o gráfico de espessura no ápice apresentou AUC 0,896. O melhor desempenho foi obtido com o PPméd (AUC 0,932 Sensibilidade = 84,4% e especificidade de 92,5%). O modelo de inteligência artificial combinando todos os itens derivados do perfil horizontal melhorou o desempenho (AUC 0,991 Sens. = 96% e espec. = 98%). Conclusão: O perfil de espessura horizontal permite detectar o ceratocone, com capacidade comparável aos índices mais complexos. Esse tipo de análise pode fornecer o básico para novas abordagens, que utilizem dados presentes em aparelhos mais simples que o tomógrafo, reduzindo o custo para os pacientes. Descritores: Ceratocone/diagnóstico; Doenças da córnea; Córnea/anatomia & histologia; Tomografia/normas Purpose: To evaluate the ability of horizontal thickness profile to distinguish keratoconus from normal corneas, and compare the accuracy of these indices with more complex tomographic indices. Methods: In a retrospective study, one eye randomly selected from 225 patients with bilateral keratoconus and 335 patients with normal corneas were included. All patients were examined by a corneal specialist and underwent the examination of corneal tomography, Pentacam HR (Oculus, Wetzlar, Germany). Data of horizontal pachymetric profile passing through the apex of 6 mm was evaluated. With these data, the thickness at the corneal apex (P.ápice), the thickness of the thinnest point of the horizontal profile (P.min.H), the pachymetric progression from the thinnest point to the thickest (PPmin-max), the average pachymetric progression in the meridian as reference the average from the normal population (PPméd) and the fitness with a second degree polynomial trendline (R2). An artificial intelligence model was built to combine this data. The performance for distinguishing normal keratoconus was evaluated by ROC curves. Results: All of these indices were statistically different between the two groups (p <0.001). The area under the ROC curve (AUC) thickness at the apex and TP were 0.904 and 0.938, respectively. The tomographic index with higher AUC was BAD-D (0.997). Regarding the horizontal profile, the AUC of PP.min.H and PPmin-max were 0.915 and 0.927, respectively. The fitness to the trendline to the horizontal thickness graph AUC was 0.896. The best performance was obtained with the PPméd (AUC 0.932 sensitivity = 84.4% and specificity of 92.5%). The artificial intelligence model combining all items derived from horizontal profile improved performance (AUC 0.991 Sensitivity = 96% and specificity of 98%). Conclusion: The horizontal thickness profile can detect keratoconus, with a capacity comparable to more complex indices. This type of analysis can provide the basics for new approaches, using data present in simpler devices than the tomographer reducing the cost for the patients.
PLOS ONE, Sep 13, 2018
To evaluate variability of central corneal thickness measurement (CCT) devices using a hitherto u... more To evaluate variability of central corneal thickness measurement (CCT) devices using a hitherto unprecedented number of CCT devices. CCT was measured consecutively in 122 normal corneas of 61 subjects with seven different devices using three distinct measurement technologies: Scheimpflug, Ultrasound, and Optical Coherence Tomography (OCT). Per device deviation from the mean CCT value per eye was used to determine which of the devices performed best, compared to the mean value. Cirrus OCT yielded the lowest deviation. Deviations of the individual devices from the mean CCT of each eye were (OS/OD) 12.8±5.0/14.9±9.4 μm for Topcon noncontact specular microscopy (NCSM), 11.3±5.9/10.6±7.3 μm for Pentacam, 10.7±5.2/10.4±4.8 μm for Spectralis OCT, 6.0±3.9/6.2±4.9 μm for Topcon DRI OCT, 5.1±3.4/5.9±10.3 μm for AngioVue OCT, 4.8±4.1/5.7±4.6 μm for US pachymetry, and 4.2±3.2/5.7±4.6 μm for Cirrus OCT. The maximum differences between US pachymetry and the other devices were very high (up to 120 μm). Central corneal thickness may be under-or overestimated due to high interdevice variations. Measuring CCT with one device only may lead to inappropriate clinical and surgical recommendations. OCT showed superior results.
Arquivos Brasileiros De Oftalmologia, Dec 1, 2010
Nota Editorial: Depois de concluída a análise do artigo sob sigilo editorial e com a anuência do ... more Nota Editorial: Depois de concluída a análise do artigo sob sigilo editorial e com a anuência do Dr. Ítalo Mundialino Marcon sobre a divulgação de seu nome como revisor, agradecemos sua participação neste processo.
International journal of keratoconus and ectatic corneal diseases, Apr 13, 2022
Background: Although classically described as a noninflammatory disease, recent evidence suggests... more Background: Although classically described as a noninflammatory disease, recent evidence suggests that chronic inflammation may play a role in keratoconus pathophysiology. Continued eye rubbing is well established on ectasia development, taking part in the "two-hit" hypothesis, which combines the concept of intrinsic biomechanical susceptibility and external stimuli decompensating the structural integrity of the cornea. Aim and objective: To describe a case of very asymmetric bilateral keratoconus requiring different approaches on both eyes. Case description: A 14-year-old patient with a history of atopy and intense eye rubbing was referred for a cornea consultation because of low vision accompanied with pruritus on both eyes and pain on the left eye. Corneal hydrops was present on the left eye. A diagnosis of grade II keratoconus was established for the right eye. Distance-corrected visual acuity (DCVA) was 20/70 in the right eye and count fingers at 1 meter in the left eye. After 1 month of avoiding eye rubbing, topical mild steroids, and anti-allergic prescription, the patient referred significant improvement in both eyes. DCVA was 20/30, and flattening of 2.5D in the anterior curvature was noted in the right eye. Three months later, ectasia progression was detected in the right eye, and transepithelial cross-linking was performed. More than 6 years after the procedure, the right eye maintained visual and tomographic stability and the left eye had resolution of edema with residual stromal scar. DCVA was 20/30 in the right eye and 20/40 in the left eye. Anterior corneal curvature maintained stable, with a overall decrease of 2.1D in the right eye and 40.9D in the left eye. In the presented clinical case, avoidance of eye rubbing and topical anti-inflammatory drugs were followed by spontaneous partial regression of the ectasia, delaying the necessity for a more invasive treatment. When progression was documented, transepithelial corneal cross-linking was effective in halting disease progression, with topographic stability for more than 6.5 years follow-up period. Clinical significance: Avoidance of deleterious factors like eye rubbing in keratoconic eyes is crucial for clinical stabilization or even improvement. Anti-inflammatory therapy may play a role in ectasia stability.
Revista Brasileira De Oftalmologia, 2015
Objetivo: Avaliar a capacidade de dados de perfil paquimétrico horizontal para distinguir o cerat... more Objetivo: Avaliar a capacidade de dados de perfil paquimétrico horizontal para distinguir o ceratocone de córneas normais, e comparar a precisão desses índices com índices tomográficos mais complexos. Métodos: Em um estudo retrospectivo, um olho selecionados aleatoriamente de 225 pacientes com ceratocone bilateral e de 335 pacientes com córneas normais foram incluídos. Todos os pacientes foram examinados por um especialista em córnea e foram submetidos ao exame de tomografia de córnea, Pentacam HR (Oculus, Wetzlar, Alemanha). Os dados de perfil paquimétrico horizontal em 6 milímetros passando pelo ápice foi avaliado. Com esses dados, a espessura no ápice corneano (P.ápice), a espessura no ponto mais fino do perfil horizontal (P.min.H), a progressão paquimétrica do ponto mais fino para o mais espesso (PPmin-máx), a progressão paquimétrica média no meridiano tendo como referencial a média normal (PPméd) e a adequação a uma linha de tendência polinomial do segundo grau (R 2 ). Um modelo de inteligência artificial foi construído para combinar esses dados. O desempenho para distinguir ceratocone do normal foi avaliada por curvas ROC. Resultados: Todos os índices avaliados foram estatisticamente diferentes entre os dois grupos (p <0,001). A área sob a curva ROC (AUC) de paquimetria no ápice e no TP foram de 0,904 e 0,938, respectivamente. O índice tomográfica com maior AUC foi o BAD-D (0,997).Em relação ao perfil horizontal, a AUC do P.min.H e PPmin-max foram 0,915 e 0,927, respectivamente. A adequação à linha de tendência para o gráfico de espessura no ápice apresentou AUC 0,896. O melhor desempenho foi obtido com o PPméd (AUC 0,932 Sensibilidade = 84,4% e especificidade de 92,5%). O modelo de inteligência artificial combinando todos os itens derivados do perfil horizontal melhorou o desempenho (AUC 0,991 Sens. = 96% e espec. = 98%). Conclusão: O perfil de espessura horizontal permite detectar ceratocone, com capacidade comparável aos índices mais complexos. Esse tipo de análise pode fornecer o básico para novas abordagens, que utilizem dados presentes em aparelhos mais simples que o tomógrafo reduzindo o custo para os pacientes. Descritores: Ceratocone/diagnóstico; Doenças da córnea; Córnea/anatomia & histologia;Tomografia/normas Purpose: To evaluate the ability of horizontal thickness profile to distinguish keratoconus from normal corneas, and compare the accuracy of these indices with more complex tomographic indices. Methods: In a retrospective study, one eye randomly selected from 225 patients with bilateral keratoconus and 335 patients with normal corneas were included. All patients were examined by a corneal specialist and underwent the examination of corneal tomography, Pentacam HR (Oculus, Wetzlar, Germany). Data of horizontal pachymetric profile passing through the apex of 6 mm was evaluated. With these data, the thickness at the corneal apex (P.ápice), the thickness of the thinnest point of the horizontal profile (P.min.H), the pachymetric progression from the thinnest point to the thickest (PPmin-max), the average pachymetric progression in the meridian as reference the average from the normal population (PPméd) and the fitness with a second degree polynomial trendline ( ). An artificial intelligence model was built to combine this data. The performance for distinguishing normal keratoconus was evaluated by ROC curves. Results: All of these indices were statistically different between the two groups (p <0.001). The area under the ROC curve (AUC) thickness at the apex and TP were 0.904 and 0.938, respectively. The tomographic index with higher AUC was BAD-D (0.997). Regarding the horizontal profile, the AUC of PP.min.H and PPmin-max were 0.915 and 0.927, respectively. The fitness to the trendline to the horizontal thickness graph AUC was 0.896. The best performance was obtained with the PPméd (AUC 0.932 sensitivity = 84.4% and specificity of 92.5%). The artificial intelligence model combining all items derived from horizontal profile improved performance (AUC 0.991 Sensitivity = 96% and specificity of 98%). Conclusion: The horizontal thickness profile can detect keratoconus, with a capacity comparable to more complex indices. This type of analysis can provide the basics for new approaches, using data present in simpler devices than the tomographer reducing the cost for the patients.
Ophthalmology, Feb 1, 2019
International journal of keratoconus and ectatic corneal diseases, 2012
Purpose: To evaluate the correlations of Pentacam keratometric, topometric (derived from front su... more Purpose: To evaluate the correlations of Pentacam keratometric, topometric (derived from front surface curvature) and tomographic (derived from 3D corneal shape analysis) indices with best corrected visual acuity in patients with keratoconus. Materials and methods: One eye randomly selected of 123 patients with bilateral keratoconus was retrospectively enrolled. All patients underwent a comprehensive ophthalmic examination including subjective refraction, distance best-spectacle corrected visual acuity (DCVA) measurement, and rotating Scheimpflug corneal tomography (Pentacam HR; Oculus, Wetzlar, Germany) at the same office visit. The correlations between the logarithm of the minimum angle of resolution (LogMAR) of DCVA and keratometric indices, topometric indices and tomographic indices were tested with nonparametric Spearman correlation coefficients (). The mean LogMAR DCVA was 0.32 (~20/42) ±0.27 [range: -0.10 (20/15) to 1.30 (20/400)]. There were strong correlations between DCVA and many keratometric, topometric and tomographic indices. A strong positive correlation was found between DCVA and BAD-Df ( = 0.648, p < 0.001), BAD-Db ( = 0.633, p < 0.001), K2 ( = 0.643, p < 0.001), K max ( = 0.608, p < 0.001), TKC ( = 0.558, p < 0.001), BAD-D ( = 0.577, p < 0.001), ISV ( = 0.573, p < 0.001), CKI ( = 0.530, p < 0.001), KI ( = 0.531, p < 0.001). A strong negative correlation was seen between DCVA and Asph Q front 30° ( = -0.521, p < 0.001). There are significant correlations between visual acuity and Pentacam parameters. Such parameters may be considered for improving staging of the disease, as well as for monitoring progression or treatment as outcome measures. There is a potential for combining parameters to enhance the correlations.
Current Ophthalmology Reports, Jul 9, 2019
Purpose of Review In this paper, we prospectively review some artificial intelligence (AI) techni... more Purpose of Review In this paper, we prospectively review some artificial intelligence (AI) techniques and models used to enhance clinical decisions for patients with corneal diseases and conditions. Recent Findings Cornea subspeciality was a pioneer in aggregating technology to clinical practice. It provided the ability to early diagnose diseases and improve treatments. Currently, we face the challenge of dealing with a tremendous amount of information from complementary multimodal imaging devices. The analysis of such data for enhancing clinical decisions is perfectly suitable for AI. While AI models are rapidly growing in various fields, some are already available and in use by clinicians, for instance to help in refractive surgery screening. Summary AI models represent a boundless method for helping to deal with and avoid the overload of an extraordinary amount of information provided by advances in complementary diagnosis. It is currently ready to use in refractive surgery screening. The challenge is to coordinate multicentre collaborations in order to build good quality and large data collection to train and improve AI models. AI is an instrument to upturn clinical decision power with many possible applications for ophthalmologists.
Journal of Cataract and Refractive Surgery, Mar 1, 2016
To test correlations between Scheimpflug optical densitometry and ocular higher-order aberrations... more To test correlations between Scheimpflug optical densitometry and ocular higher-order aberrations (HOAs) in patients with mild nuclear cataract.
Journal of Refractive Surgery, Feb 1, 2014
Background/Aims-To develop parameters using a combination of optical coherence tomography (OCT) a... more Background/Aims-To develop parameters using a combination of optical coherence tomography (OCT) and videokeratography to 'early' detect keratoconus. Methods-We performed videokeratography, wavefront analysis and measured OCT indices on 180 normal, 46 moderate keratoconus, 54 early keratoconus, 7 'forme fruste' keratoconus and 16 keratoconus 'suspect" eyes, to determine the most sensitive parameters for separating these groups. Results-A combination of videokeratography and OCT indices (I-S value and Minimum pachymetry) was statistically the most significant in separating the keratoconus groups from normals (P<.001). Using a newly derived index, the Minimum pachymetry divided by the I-S value (PA/I-S index) with a cut off of 100, we could identify 100% of "early" and 'forme fruste' keratoconus as being abnormal with 7 normals misclassified (misclassification rate of 2.7%). By adding keratoconus 'suspects' to the analysis and an I-S value of 1.2 as a cut of point, we classified 5 'suspects' as normal and 11 normals as abnormal (misclassification rate 7.8%). The PA/I-S index, with a cut of point of 100, reduced this misclassification rate to 4.4%.
Acta Scientific Ophthalmology, Feb 8, 2021
Purpose: To describe the preliminary clinical experience, including corneal structural response t... more Purpose: To describe the preliminary clinical experience, including corneal structural response to Ripasudil hydrochloride hydrate (Glanatec ® ophthalmic solution 0.4 %, Kowa Company, Ltd, Japan) in cases of corneal endothelial dysfunction. : Retrospective observational study based on patients' clinical records treated with Ripasudil hydrochloride hydrate three times a day for different conditions of corneal endothelial dysfunction. Outcome measures included clinical data with subjective response, uncorrected distance visual acuity (UDVA, Snellen), central corneal thickness (CCT, µm) measured with rotating Scheimpflug tomography (Pentacam HR, Oculus ® , Wetzlar, Germany), intraocular pressure (IOP, mmHg) measured with dynamic Scheimpflug imaging (Corvis ST, Oculus ® , Wetzlar, Germany) and endothelial cell density (ECD, cells/mm 2 ) measured with EM-4000 Specular Microscope (Tomey ® ,
International journal of keratoconus and ectatic corneal diseases, 2018
Aim: This article reports the case of a patient with severe symptoms related to bad quality of vi... more Aim: This article reports the case of a patient with severe symptoms related to bad quality of vision after toric multifocal intraocular lens (IOL) that was diagnosed with mild keratoconus. To present a case report and prospectively review of the literature, considering the relevance of screening ectaticconreal disease prior to refractive cataract (or lens) surgery. The patient was dissatisfied, seeking a second opinion after the implantation of a toric multifocal IOL in the left eye. The IOL was properly centered and surgery had no complications. The preoperative refraction was -4.00 -1.50 × 160, giving 20/40. Patient denied any history of keratoconus or transplant in his family. After cataract surgery, uncorrected distance vision acuity (UDVA) was 20/60, and J4 for near. Manifest refraction was + 2.00 -0.50 × 130, giving 20/30. Corneal topography, tomography, and biomechanical assessments indicated the diagnosis of mild keratoconus. The patient was advised for IOL exchange, which was successfully done for a monofocal aspheric IOL. The patient was satisfied with the final result, presenting a final UDVA of 20/25, J3, and manifest refraction of +0.75 -0.50 × 105, giving 20/20. Screening for corneal abnormalities including ectatic corneal disease is fundamental prior to the indication of a premium lens. Advanced corneal imaging plays a fundamental role to help select candidates for multifocal IOLs, as for individualized planning of refractive cataract surgery.
Revista Brasileira De Oftalmologia, Feb 1, 2012
Purpose: To assess the repeatability of central corneal thickness measurement at the geometrical ... more Purpose: To assess the repeatability of central corneal thickness measurement at the geometrical center (Central Corneal Thickness -CCT) given by the Pentacam High Resolution (HR) Comprehensive Eye Scanner (Oculus, Wetzlar, Germany) over time. Methods: Prospective, single center, observational study. Two separate CCT measurements were taken by the Pentacam corneal tomography exam (CTm) 3 to 12 months apart, and compared. Results: One hundred and sixteen eyes (n=116) of 62 health patients were included in this study. Average CCT in first and last visits was 541.6±37 µm and 543.6±36.9 µm respectively. Mean difference between both measurements was 9.2±6.4 µm, and there was no statistically significant difference in CCT measurement between visits, with good correlation between them (P = 0.057, r 2 = 0,9209). Conclusion: Pentacam (HR) CTm gives repeatable CCT measurements over time.
International Journal of Environmental Research and Public Health, Mar 23, 2020
Purpose: To review the role of corneal biomechanics for the clinical evaluation of patients with ... more Purpose: To review the role of corneal biomechanics for the clinical evaluation of patients with ectatic corneal diseases. Methods: A total of 1295 eyes were included for analysis in this study. The normal healthy group (group N) included one eye randomly selected from 736 patients with healthy corneas, the keratoconus group (group KC) included one eye randomly selected from 321 patients with keratoconus. The 113 nonoperated ectatic eyes from 125 patients with very asymmetric ectasia (group VAE-E), whose fellow eyes presented relatively normal topography (group VAE-NT), were also included. The parameters from corneal tomography and biomechanics were obtained using the Pentacam HR and Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany). The accuracies of the tested variables for distinguishing all cases (KC, VAE-E, and VAE-NT), for detecting clinical ectasia (KC + VAE-E) and for identifying abnormalities among the VAE-NT, were investigated. A comparison was performed considering the areas under the receiver operating characteristic curve (AUC; DeLong's method). Results: Considering all cases (KC, VAE-E, and VAE-NT), the AUC of the tomographic-biomechanical parameter (TBI) was 0.992, which was statistically higher than all individual parameters (DeLong's; p < 0.05): PRFI-Pentacam Random Forest Index (0.982), BAD-D-Belin -Ambrosio D value (0.959), CBI -corneal biomechanical index (0.91), and IS Abs-Inferior-superior value (0.91). The AUC of the TBI for detecting clinical ectasia (KC + VAE-E) was 0.999, and this was again statistically higher than all parameters (DeLong's; p < 0.05): PRFI (0.996), BAD-D (0.995), CBI (0.949), and IS Abs (0.977). Considering the VAE-NT group, the AUC of the TBI was 0.966, which was also statistically higher than all parameters (DeLong's; p < 0.05): PRFI (0.934), BAD-D (0.834), CBI (0.774), and IS Abs (0.677). Conclusions: Corneal biomechanical data enhances the evaluation of patients with corneal ectasia and meaningfully adds to the multimodal diagnostic armamentarium. The integration of biomechanical data and corneal tomography with artificial
Journal of Refractive Surgery, Apr 1, 2013
Journal of Cataract and Refractive Surgery, Oct 1, 2009
Purpose-To compare the incidence of laser in situ keratomileusis (LASIK)-associated dry eye and t... more Purpose-To compare the incidence of laser in situ keratomileusis (LASIK)-associated dry eye and the need for postoperative cyclosporine A treatment after flap creation with a femtosecond laser or a mechanical microkeratome.
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Papers by Renato Ambrósio