Optical coherence tomography angiography findings in patients with ocular and non-ocular Behcet disease / Achados de angiografia por tomografia de coerência óptica em pacientes com doença de Behçet com e sem acometimento ocular

ABSTRACT Purposes: To evaluate the optical coherence tomography angiography findings in patients with Behçet disease with and without ocular involvement. Methods: A total of 40 patients with Behçet disease and 30 healthy controls were enrolled in the study. Retinal vessel density in the superficial capillary plexus and deep capillary plexus, foveal avascular zone area and perimeter, acirculatory index, foveal density, and nonflow area in the superficial retina were automatically measured using the optical coherence tomography angiography software AngioVue and compared between the groups. Results: The mean parafoveal and perifoveal vessel densities in the superficial capillary plexus and deep capillary plexus and foveal density were significantly lower in the eyes with Behçet uveitis compared to the eyes without Behçet uveitis and eyes of the healthy controls. In the eyes with Behçet uveitis, logMAR visual acuity showed a moderate correlation with parafoveal and perifoveal vessel densities and foveal density (r=-0.43, p=0.006; r=-0.62, p<0.001; r=-0.42, p=0.008; respectively). Conclusion: Behçet disease with posterior uveitis was associated with significant perifoveal and parafoveal vascular decrements in the superficial and deep retina.(AU)

RESUMO Objetivo: Avaliar achados de angiografia por tomografia de coerência óptica em pacientes com doença de Behçet com e sem acometimento ocular. Métodos: Foram incluídos 40 pacientes com doença de Behçet e 30 controles saudáveis. A densidade vascular retiniana nos plexos capilares superficial e profundo, a zona avascular foveal, o índice de circularidade, a densidade foveal e a área sem fluxo da retina superficial foram medidos automaticamente, através do software AngioVue para angiografia por tomografia de coerência óptica, e comparados entre os grupos. Resultados: A densidade vascular parafoveal e perifoveal média nos plexos capilares superficial e profundo, bem como a densidade foveal, foram significativamente menores nos olhos com uveíte de Behçet em comparação com os olhos sem uveíte de Behçet e os olhos dos controles saudáveis. Nos olhos com uveíte de Behçet, a acuidade visual logMAR mostrou correlação moderada com a densidade vascular parafoveal e perifoveal e com a densidade foveal (respectivamente, r=-0,43, p=0,006; r=-0,62, p<0,001; e r=-0,42, p = 0,008). Conclusão: A doença de Behçet com uveíte posterior foi associada a decréscimos significativos da vascularização perifoveal e parafoveal na retina superficial e profunda.(AU)

Punctate inner choroidopathy with atypical presentation / Coroidopatia interna ponteada de apresentação atípica

ABSTRACT We report a case of a young Caucasian female presenting with sudden decrease of vision in the left eye, metamorphopsia, and nasal scotoma. Past medical history revealed a diagnosis of myasthenia gravis, which was currently treated with azathioprine, pyridostigmine, and prednisone. Ophthalmological examination showed fundus with clear vitreous and yellow-white lesions that were isolated and perimacular in the right eye, multiple and confluent in the macula, and punctate in periphery in the left eye. Laboratory workup ruled out the presence of infectious and inflammatory diseases. Fundus autofluorescence disclosed hypoautoflurescence with hyperfluorescent margins corresponding to the lesions observed in both eyes and the angiogram revealed hyperfluorescence since early phases without late leakage. Spectral-domain optical coherence tomography showed areas of intermittent retinal pigment epithelium elevations and disruption of the ellipsoid zone. She was diagnosed with punctate inner choroidopathy and then treated with an increased dose of daily prednisone, which resulted in progressive improvement of her visual acuity and anatomical status.(AU)

RESUMO Relato de caso de mulher jovem, caucasiana, com súbita diminuição de acuidade visual de olho esquerdo, metamorfopsia e escotoma nasal. Apresentava diagnóstico de Miastenia gravis, em tratamento com Azatioprina, Piridostigmina e Prednisona. Fundo de olho demonstrava vítreo límpido e lesões amarelo-esbranquiçadas, perimaculares e isoladas em olho direito, múltiplas e confluentes em mácula e pontilhadas em periferia no olho esquerdo. Exames laboratoriais descartaram doenças infecciosas e inflamatórias. Auto-fluorescência revelou lesões hipoautofluorescentes com margens hiperfluorescentes correspondentes às observadas em ambos os olhos, enquanto angiofluoresceinografia mostrou hiperfluorescência desde as fases iniciais sem vazamento tardio. Tomografia de coerência óptica de domínio espectral revelou áreas de elevações intermitentes do epitélio pigmentar da retina e interrupção da zona elipsóide correspondente. Definiu-se como diagnóstico a coroidopatia interna ponteada, sendo instituído aumento na dose diária de Prednisona, com melhoria progressiva da acuidade visual e do aspecto de fundo de olho da paciente.(AU)

Caracterización de indicadores de detección de glaucoma con los equipos OCT Spectralis y campímetro Humphrey II en pacientes altos miopes y altos miopes glaucomatosos del Hospital Clínico Universidad de Chile / Characterization of glaucoma detection indicators with OCT Spectralis equipment and Humphrey II campimeter in patients with high myopia and high myopia glaucomatous at the Hospital Clínico Universidad de Chile

Purpose: Characterize and describe glaucoma index parameters of the results of visual exams, Optical Coherence Tomography and Visual Field, in high myopic subjects with and without the pathology. Method: Cross sectional and observational study of 39 eyes, 15 high myopic with glaucoma y 24 high myopic without it. Visual Field (VF) were performed, where the global index between both groups were analyzed; Mean Deviation (MD), Model Standard Deviation (MSD) and Visual Field Index (VFI), beside Optical Coherence Tomography (OCT), in which the thickness of the ganglion cells layer (GCL) inside 3 central mm was compared. Results: The results were satisfactory, demonstrating different characteristics between the high myopic group with glaucoma and without it, both in VF and OCT exams. It was obtained in the VF analysis difference in average MD of -4,92 dB + 3,71 (p<0,05); difference in average DSM of 2,01 dB + 2,85 (p>0,05) and VFI with Friedman Test 10,29 (p>0,05). The statistical OCT analysis, when comparing GCL, observed that the Temporary sector (T) had a statistically significant decrease (p<0,05). Conclusions: To continue studies in this investigative line, can expand the knowledge in this area, mainly in the study of the GCL. (AU)

Coriorretinopatia central serosa tratado con bevacizumab a propósito de un caso / Treatment bevacizumab of central serous chorioretinopathy disease in a case report

La inyección intravitrea de Bevacizumab se ha difundido ampliamente debido a sus resultados prometedores, como una alternativa de tratamiento que ha permitido tener nuevas esperanzas en ciertas patologías incluyendo la Coriorretinopatia Central Serosa (CCS) recidivante y crónica. Presentamos el caso de una paciente mujer de 37 años de edad con CCS crónica en ojo derecho, que fue sometida a inyección intravitrea de Bevacizumab, con resultados espectaculares confirmada con la Tomografía de Coherencia Óptica (TOC).

Intravitreal injection of Bevacizumab has been widely diffused because of its promising results, as an alternative treatment that has allowed having new hopes in certain pathologies including recurrentand chronic Choroidal Serous Choroidopathy (CCS). We present the case of a 37-year-old female patient with chronic CCS in the right eye, who underwent intravitreal injection of Bevacizumab, with spectacular results confirmed with the Optic Coherence Tomography (TOC).

Optical Coherence Tomography; A Modern Technique to Detect Oral Mucosal Lesion: A Review.

Early detection and management of potentially malignant oral lesions can significantly reduce progression of these lesions into invasive cancer, and would thus reduce morbidity and fatality rate. Cancerous and potentially malignant lesions show dysplastic feature which is mostly detected by biopsy. However, biopsy has a certain constraints like (i) biopsy can cause delay in the result, (ii) experienced pathologist must expound the biopsy sample (iii) sometimes can cause spread of cancer cells, (iv) cannot be done repeatedly. Therefore, in potentially malignant lesions and cancer optical coherence tomography (OCT) is utilized to detect early dysplastic changes. Therefore, we are presenting a review on the applications of OCT in oral mucosal lesions.

Optical Coherence Tomography for the Diagnosis and Evaluation of Human Otitis Media

We report the application of optical coherence tomography (OCT) to the diagnosis and evaluation of otitis media (OM). Whereas conventional diagnostic modalities for OM, including standard and pneumatic otoscopy, are limited to visualizing the surface of the tympanic membrane (TM), OCT effectively reveals the depth-resolved microstructure below the TM with very high spatial resolution, with the potential advantage of its use for diagnosing different types of OM. We examined the use of 840-nm spectral domain-OCT (SD-OCT) clinically, using normal ears and ears with the adhesive and effusion types of OM. Specific features were identified in two-dimensional OCT images of abnormal TMs, compared to images of healthy TMs. Analysis of the A-scan (axial depth scan) identified unique patterns of constituents within the effusions. The OCT images could not only be used to construct a database for the diagnosis and classification of OM but OCT might also represent an upgrade over current otoscopy techniques.

Optical Coherence Tomography for the Diagnosis and Evaluation of Human Otitis Media

We report the application of optical coherence tomography (OCT) to the diagnosis and evaluation of otitis media (OM). Whereas conventional diagnostic modalities for OM, including standard and pneumatic otoscopy, are limited to visualizing the surface of the tympanic membrane (TM), OCT effectively reveals the depth-resolved microstructure below the TM with very high spatial resolution, with the potential advantage of its use for diagnosing different types of OM. We examined the use of 840-nm spectral domain-OCT (SD-OCT) clinically, using normal ears and ears with the adhesive and effusion types of OM. Specific features were identified in two-dimensional OCT images of abnormal TMs, compared to images of healthy TMs. Analysis of the A-scan (axial depth scan) identified unique patterns of constituents within the effusions. The OCT images could not only be used to construct a database for the diagnosis and classification of OM but OCT might also represent an upgrade over current otoscopy techniques.

Changes in anterior chamber eye during accommodation as assessed using a Dual Scheimpflug system / Mudanças na câmara anterior do olho durante a acomodação avaliadas por meio de sistema de Scheimpflug duplo

Purpose: To study the changes in anterior chamber depth (ACD), anterior chamber angle (ACA), and pupil diameter (PD) during accommodation. Methods: Eighty eyes of 80 subjects, aged 22 to 40 years, were included. The rotating Dual Scheimpflug and a Placido disc system (Galilei G4, Ziemer Ophthalmic Systems AG, Switzerland) was used to measure the changes in ACD, ACA, and PD during accommodation. ACD measurement was taken for the central zone and for 4 more positions, each in different orientation (nasal, superior, temporal and inferior), 4 mm away from the centre. ACA was measured for the whole eye as well for the nasal, superior, temporal, and inferior quadrants. These metrics were obtained for various accommodation stimuli, ranging from +1 D to -4 D in 1-D steps. Results: For a given position, the ACD did not vary significantly with accommodation. For the central ACD, the percentage of relative change between far and near vision was -4.11%. The ACA was significantly lower at the inferior, temporal, and superior positions. There was no change in the ACA of the whole eye and that of the nasal orientation. These two eye metrics were significantly lower in the superior-nasal than in the inferior-temporal region. At each vergence studied, the PD decreased significantly with accommodation. The relative change after the -4 D stimulus was -8.13%. Conclusion: ACA and PD varied significantly with accommodation, whereas no such variation of ACD was observed. Further, the anterior chamber was found to be asymmetrical, with the nasal-superior area becoming significantly shallower than the inferior temporal region. .

Objetivo: Estudar as mudanças na profundidade da câmara anterior (ACD), ângulo da câmara anterior (ACA) e diâmetro da pupila (PD) durante a acomodação. Métodos: Foram incluídos 80 olhos de 80 indivíduos com idades entre 22 e 40 anos. Um sistema rotacional de Scheimpflug duplo acoplado a um sistema de disco de Placido (Galilei G4, Ziemer Ophthalmic Systems AG, Suíça) foi usado para medir as mudanças na ACD, ACA e PD, durante a acomodação. As medidas da ACD foram consideradas na zona central e em mais 4 posições, cada uma em orientação diferente (nasal, superior, temporal e inferior), a 4 milímetros de distância do centro. O ACA do olho inteiro, assim como nos quadrantes nasal, superior, temporal e inferior foram medidos. Todos estes indicadores foram obtidos por vários estímulos acomodativos, que variaram de +1 D a -4 D em intervalos de 1 D. Resultados: A ACD não variou significativamente com acomodação para qualquer determinada orientação, sendo a percentagem de variação relativa entre longe e visão de perto -4,11% para a ACD central (onde sinal negativo representa uma diminuição na ACD). Em relação ao ACA, este diminuiu significativamente em posições inferiores, temporais e superiores. O ACA total de olho e o ACA nasal não se alterou. Estas duas métricas oculares foram significativamente menores no par nasal-superior do que no temporal-inferior. Finalmente, PD diminuiu significativamente com a acomodação em cada vergência estudada, a mudança relativa após o estímulo de -4 D foi -8,13%. Conclusão: ACA e PD variaram significativamente com a acomodação, enquanto ACD não. Além disso, a câmara anterior se mostrou alterar assimetricamente, com a área nasal-superior se tornando ...

Sensitivity and specificity of machine learning classifiers for glaucoma diagnosis using Spectral Domain OCT and standard automated perimetry / Sensibilidade e especificidade dos classificadores de aprendizagem de máquina para o diagnóstico de glaucoma usando Spectral Domain OCT e perimetria automatizada acromática

PURPOSE: To evaluate the sensitivity and specificity of machine learning classifiers (MLCs) for glaucoma diagnosis using Spectral Domain OCT (SD-OCT) and standard automated perimetry (SAP). METHODS: Observational cross-sectional study. Sixty two glaucoma patients and 48 healthy individuals were included. All patients underwent a complete ophthalmologic examination, achromatic standard automated perimetry (SAP) and retinal nerve fiber layer (RNFL) imaging with SD-OCT (Cirrus HD-OCT; Carl Zeiss Meditec Inc., Dublin, California). Receiver operating characteristic (ROC) curves were obtained for all SD-OCT parameters and global indices of SAP. Subsequently, the following MLCs were tested using parameters from the SD-OCT and SAP: Bagging (BAG), Naive-Bayes (NB), Multilayer Perceptron (MLP), Radial Basis Function (RBF), Random Forest (RAN), Ensemble Selection (ENS), Classification Tree (CTREE), Ada Boost M1(ADA),Support Vector Machine Linear (SVML) and Support Vector Machine Gaussian (SVMG). Areas under the receiver operating characteristic curves (aROC) obtained for isolated SAP and OCT parameters were compared with MLCs using OCT+SAP data. RESULTS: Combining OCT and SAP data, MLCs' aROCs varied from 0.777(CTREE) to 0.946 (RAN).The best OCT+SAP aROC obtained with RAN (0.946) was significantly larger the best single OCT parameter (p<0.05), but was not significantly different from the aROC obtained with the best single SAP parameter (p=0.19). CONCLUSION: Machine learning classifiers trained on OCT and SAP data can successfully discriminate between healthy and glaucomatous eyes. The combination of OCT and SAP measurements improved the diagnostic accuracy compared with OCT data alone.

OBJETIVO: Avaliar a sensibilidade e especificidade dos classificadores de aprendizagem de máquina no diagnóstico de glaucoma usando Spectral Domain OCT (SD-OCT) e perimetria automatizada acromática (PAA). MÉTODOS: Estudo transversal observacional. Sessenta e dois pacientes com glaucoma e 48 indivíduos normais foram incluídos. Todos os pacientes foram submetidos a exame oftalmológico completo, e perimetria automatizada acromática (24-2 SITA; Humphrey Field Analyzer II, Carl Zeiss Meditec, Inc., Dublin, CA) e exame de imagem da camada de fibras nervosas utilizando SD-OCT (Cirrus HD-OCT; Carl Zeiss Meditec Inc., Dublin, California). Curvas ROC (Receiver operator characteristic) foram obtidas para todos os parâmetros do SD-OCT e índices globais do campo visual (MD, PSD, GHT). Subsequentemente, os seguintes classificadores de aprendizagem de máquina (CAMs) foram testados usando parâmetros do OCT e CV: Bagging (BAG), Naive-Bayes (NB), Multilayer Perceptron (MLP), Radial Basis Function (RBF), Random Forest (RAN), Ensemble Selection (ENS), Classification Tree (CTREE), Ada Boost M1(ADA), Support Vector Machine Linear (SVML) e Support Vector Machine Gaussian (SVMG). Áreas abaixo da curva ROC (aROC) obtidas com os parâmetros isolados do campo visual (CV) e OCT foram comparados com os CAMs usando dados associados do OCT e CV. RESULTADOS: Combinando os dados do OCT e do CV, aROCs dos CAMs variaram entre 0,777(CTREE) e 0,946 (RAN). A maior aROC dos CAMs OCT+CV obtida com RAN (0,946) foi significativamente maior que o melhor parâmetro do OCT (p<0,05), mas não houve diferença estatística significativa com o melhor parâmetro do CV (p=0,19). CONCLUSÃO: Os classificadores de aprendizagem de máquina treinados com dados do OCT e CV podem discriminar entre olhos normais e glaucomatosos com sucesso. A combinação das medidas do OCT e CV melhoraram a acurácia diagnóstica comparados aos parâmetros do OCT.

Reproducibility of peripapillary retinal nerve fiber layer thickness measurements using Spectral Domain OCT in Brazilian patients / Reprodutibilidade da espessura da camada de fibras nervosas da retina utilizando-se o Spectral Domain OCT em pacientes brasileiros

PURPOSE: To evaluate the reproducibility of peripapillary retinal nerve fiber layer (RNFL) thickness measurements in normal eyes and eyes with glaucoma using spectral domain optical coherence tomography (SDOCT). METHODS: One eye of 79 normal and 72 glaucoma patients was analyzed. All patients underwent a complete ophthalmological examination, including visual acuity testing; intraocular pressure, slit-lamp examination, indirect ophthalmoscopy; and the glaucoma group underwent achromatic perimetry with the 24-2 SITA Fast Humphrey Field Analyzer. All patients' eyes were scanned using the spectral domain optical coherence tomography - Spectralis® and one of them was chosen randomly. Three consecutive circular B-scan centered at the optic disc were performed in one visit. RESULTS: The intraclass correlation coefficient (ICC), coefficient of variation and test-retest variability for the mean retinal nerve fiber layer thickness were respectively: 0.94, 2.56% and 4.85 µm for the normal group and 0.93, 4.65% and 6.61 µm for the glaucomatous group. The intraclass correlation coefficient for retinal nerve fiber layer thickness in all quadrants were all excellent in both groups, with the superior quadrant having the highest ICCs (0.964) in glaucomatous eyes and nasal quadrant measurements having the lowest (0.800), but still excellent in eyes without glaucoma. The coefficient of variation was between 2.56% - 8.74% and between 4.65% - 11.44% in normal and glaucomatous group respectively. The test-retest variability was between 4.85 µm and 11.51 µm in the normal group and between 6.61 µm and 14.24 µm in the glaucomatous group. The measurements in glaucomatous eyes were more variable than normal eyes. CONCLUSIONS: Spectral domain optical coherence tomography showed excellent reproducibility with regard to retinal nerve fiber layer thickness measurements in normal and glaucomatous eyes.

OBJETIVO: Avaliar a reprodutibilidade da medida da espessura da camada de fibras nervosas da retina (CFNR) em olhos sem e com glaucoma utilizando-se tomografia de coerência óptica de domínio espectral (spectral domain OCT - SDOCT). MÉTODOS: Foram analisados apenas um olho de 79 pacientes normais e 72 com glaucoma. Todos os pacientes realizaram um exame oftalmológico completo, incluindo acuidade visual, pressão intraocular, biomicroscopia, oftalmoscopia indireta e, para o grupo com glaucoma, perimetria acromática 24-2 SITA Fast Humphrey Field Analyzer. Foram realizados em todos os olhos e em apenas uma visita, três B-scans circulares centrados no disco óptico utilizando-se o SDOCT - Spectralis® RESULTADOS: O coeficiente de correlação intraclasse (ICC), coeficiente de variação e variabilidade teste-reteste para a média de espessura da camada de fibras nervosas da retina foram respectivamente: 0,94, 2,56% e 4,85 µm para o grupo sem glaucoma e 0,93, 4,65% e 6,61 µm para o grupo glaucomatoso. O coeficiente de correlação intraclasse foi excelente em ambos os grupos em todos os quadrantes, com o quadrante superior sendo o maior (0,964) no grupo glaucomatoso e o nasal sendo o menor (0,800), mas ainda excelente, em olhos sem glaucoma. O coeficiente de variação foi entre 2,56% - 8,74% e entre 4,65% - 11,44%, nos grupos sem e com glaucoma, respectivamente. A variabilidade teste-reteste variou de 4,85 µm e 11,51 µm no grupo sem glaucoma; e entre 6,61 µm e 14.24 µm no com glaucoma. Olhos com glaucoma apresentaram-se mais variáveis que os sem glaucoma. CONCLUSÃO: A tomografia de coerência óptica "spectral domain" apresentou excelente reprodutibilidade da espessura da camada de fibras nervosas da retina em pacientes sem e com glaucoma.

In vivo sectional imaging of the retinal periphery using conventional optical coherence tomography systems.

Optical coherence tomography (OCT) has transformed macular disease practices. This report describes the use of conventional OCT systems for peripheral retinal imaging. Thirty-six eyes with peripheral retinal pathology underwent imaging with conventional OCT systems. In vivo sectional imaging of lattice degeneration, snail-track degeneration, and paving-stone degeneration was performed. Differences were noted between phenotypes of lattice degeneration. Several findings previously unreported in histopathology studies were encountered. Certain anatomic features were seen that could conceivably explain clinical and intraoperative behavior of peripheral lesions. Peripheral OCT imaging helped elucidate clinically ambiguous situations such as retinal breaks, subclinical retinal detachment, retinoschisis, choroidal nevus, and metastasis. Limitations of such scanning included end-gaze nystagmus and far peripheral lesions. This first of its kind study demonstrates the feasibility of peripheral retinal OCT imaging and expands the spectrum of indications for which OCT scanning may be clinically useful.

The use of high resolution optical coherence tomography to evaluate robotic radical prostatectomy specimens

OBJECTIVE: Optical coherence tomography (OCT) is a unique technology, developed to provide high resolution, cross sectional images of human tissue. The objective of this study was to explore the feasibility of OCT for the evaluation of positive surgical margins and extra capsular extension in robotic prostatectomy specimens and compare it to histopathology. MATERIAL AND METHODS: Radical prostatectomy was performed in 100 patients. Twenty OCT images of each specimen were taken from the base of the seminal vesicles (SV), apical and vesicle margins, peripheral and posterolateral area and any palpable nodule. Predictions were made regarding positive surgical margin, SV involvement, capsular invasion and compared with the final histopathology. RESULTS: A total of 2000 OCT images were taken and analyzed. Out of 100 specimens, 85 had T2 disease, 15 had T3 disease with a median Gleason's score of 7 (range 6 to 9) and 10 had positive surgical margins. We predicted 21 specimens to have positive margins based on OCT images out of which 7 were truly positive and 14 were falsely positive. Based on OCT images, 79 specimens were predicted to have negative margins out of which 76 were truly negative and 3 were falsely negative. We found the sensitivity, specificity, positive predictive value and negative predictive value to be 70 percent, 84 percent, 33 percent and 96 percent respectively. CONCLUSION: Our initial feasibility study established the template for the visual OCT characteristics of the prostate, SV and cancerous tissue. The negative predictive value of evaluating surgical margins was high.

Normative data of optic nerve head in Thai population by laser scanning tomography: Siriraj study.

OBJECTIVE: To study the normative values of topographic optic disc parameters in a Thai population. MATERIAL AND METHOD: Two hundred and six eyes of 103 normal subjects aging from 30-80 years were studied Thirteen topographic disc parameters were analyzed by confocal scanning laser ophthalmoscope using Heidelburg retina tomography (HRT II). The average value of two eyes in the same subject was used as the unit of statistical analysis, and then the normal values and means were statistically calculated at 95% reference interval (95% RI). Ethnic differences of the calculated optic nerve topography were compared with previous studies. The relationship of age, intraocular pressure (IOP), central corneal thickness (CCT), and optic disc parameters were assessed by Pearson correlation. RESULTS: Mean values with 95% RI of all 13 parameters were analyzed Whole parameters except cup volume demonstrated normal distribution. Mean value (95% RI) of disc area in normal Thai people was 2.67 mm2 (1.96, 3.71) which was larger than Caucasian people. Ethnic differences in topographic optic disc parameters were found among Thai and other races including Asians, Caucasians, African-Americans, and Hispanics. The results also revealed that age, IOP, and CCT had no significant relation to all optic disc parameters. CONCLUSION: Thai people had a larger optic disc area than Caucasians. There are marked differences of topographic optic nerve parameters among different ethnic groups. These differences need to be taken into account when evaluating glaucomatous optic neuropathy and when comparing results of studies completed among population of different ethnic and racial origins.