Localized Nerve Fiber Layer Defects Research Articles

Trend-Based Analysis of Retinal Nerve Fiber Layer Thickness Measured by Optical Coherence Tomography in Eyes with Localized Nerve Fiber Layer Defects

To evaluate the rate of change in retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) in eyes with stable and progressive localized RNFL defects and to investigate, in a trend-based approach, the diagnostic capability of OCT in the detection of progressive RNFL thinning. The study included 153 glaucomatous eyes with localized RNFL defects. The patients were divided into nonprogressors (n = 77) and progressors (n = 76) on the basis of an evaluation of serial red-free photographs. The rates of progressive thinning in global, quadrant, and clock-hour OCT RNFL thicknesses were determined, by linear regression, and were compared between groups. Areas under receiver operating characteristic curves and sensitivities at fixed specificities were calculated for each parameter. The rate of progressive RNFL thinning was significantly faster in progressors than in nonprogressors globally; in the inferior quadrant; in the 10, 11, 6, and 7 o'clock sectors; and in the affected quadrant and clock-hour sector thicknesses (all P ≤ 0.001). The rate of RNFL thinning in affected clock-hour sectors had the highest ability to discriminate between stable and progressive RNFL thinning with a sensitivity of 62% (95% confidence interval, 50%-73%) at a specificity ≥80%. Agreement between OCT and red-free photography was strongest when the criterion of -3.6 μm/year with P < 0.1 was used for each clock hour. The rate of OCT RNFL thinning was significantly greater in patients with progressive localized RNFL defects than in those with stable localized defects. The data suggest that trend-based analysis of OCT RNFL thickness may be useful in glaucoma progression analysis and may complement other diagnostic tests.

False Negative Findings of Optical Coherence Tomography in Eyes with Localized Nerve Fiber Layer Defects

False Negative Findings of Optical Coherence Tomography in Eyes with Localized Nerve Fiber Layer Defects

Análise de Fourier para detecção de defeitos localizados na camada de fibras nervosas da retina com a polarimetria a laser

OBJETIVO: Avaliar a utilidade da análise de Fourier como método para detecção de defeitos localizados na camada de fibras nervosas da retina (CFN), utilizando as medidas obtidas com a polarimetria de varredura a laser. MÉTODOS: O estudo incluiu 40 olhos de 40 pacientes com glaucoma apresentando defeitos localizados na CFN detectados à oftalmoscopia e/ou em fotografias da camada de fibras nervosas. O grupo controle foi constituído por 43 olhos de 43 pacientes normais, sem antecedente de pressão intra-ocular elevada ou glaucoma, e com exame normal da CFN e disco óptico. Todos os pacientes foram submetidos a exame da CFN utilizando o aparelho GDx® - Nerve Fiber Analyzer. Para comparação entre os grupos, foram utilizados os parâmetros fornecidos pelo software do aparelho e medidas provenientes dos coeficientes obtidos pela análise de Fourier da curva de distribuição dos valores de espessura da CFN. As várias medidas dos coeficientes de Fourier foram combinadas numa função linear discriminante de maneira a encontrar a combinação que resultasse na melhor separação entre pacientes glaucomatosos com defeitos localizados e os sujeitos normais. Curvas ROC foram construídas para cada medida e valores de sensibilidade para especificidades fixas foram calculados. RESULTADOS: Os parâmetros fornecidos pelo software do GDx mostraram baixo poder de diferenciação entre os pacientes normais e com defeitos localizados na CFN, com sensibilidades variando de 15 a 48% (com especificidade a 91%). Para a mesma especificidade de 91%, a combinação dos coeficientes de Fourier teve sensibilidade de 80%. A área sob a curva ROC para a combinação dos coeficientes de Fourier (0,90) foi significativamente superior à obtida para o parâmetro The Number (0,76). CONCLUSÃO: A análise de Fourier resultou em melhora na capacidade do GDx de detectar defeitos localizados na CFN em relação aos parâmetros fornecidos pelo software do aparelho.

Laser scanning tomography of localised nerve fibre layer defects

AIMSRetinal nerve fibre layer photography is a well established method to qualitatively document early structural changes which might be induced by primary open angle glaucoma. The aim was to analyse...

Optic Disk Appearance in Ocular Hypertensive Eyes

We examined the optic disk appearance in ocular hypertensive eyes that had a normal result of conventional computed perimetry. Color stereo-optic disk photographs of 104 ocular hypertensive subjects and of 216 normal individuals were morphometrically evaluated. In the ocular hypertensive eyes as compared to the normal eyes, significant differences (P < .0001) were detected for a smaller area and an abnormal shape of the neuroretinal rim, larger zones alpha and beta of the parapapillary chorioretinal atrophy, a decreased visibility of the retinal nerve fiber layer, and a higher frequency of localized nerve fiber layer defects. The variables most useful to indicate optic nerve damage were an abnormal shape of the neuroretinal rim and a decreased visibility of the nerve fiber layer. The most specific variable was the presence of localized retinal nerve fiber layer defects. Evaluation of these variables may be helpful for the early diagnosis of glaucoma.