Evaluación de la perfusión del nervio óptico en las neuropatías ópticas y las enfermedades neurodegenerativas / Evaluation of optic nerve perfusion in optic neuropathies and neurodegenerative diseases

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Variabilidad interindividual y reproducibilidad de tres métodos de medida del espesor de la capa de fibras nerviosas / Variability and reproducibility of 3 methods for measuring the thickness of the nerve fiber layer

Objetivos: Calcular la variabilidad interindividual y reproducibilidad de la tomografía confocal (HRT), polarimetría láser (GDx) y tomografía de coherencia óptica (OCT Cirrus) para determinar el espesor de la capa de fibras ganglionares. Método: Se examinaron 2 veces 75 ojos normales. La variabilidad interindividual se analizó previa normalización de los resultados. Para medir la variabilidad entre exámenes se utilizó el coeficiente de variación y para analizar la correlación entre variables, el coeficiente de Pearson. Resultados: La variabilidad interindividual fue similar en GDx (8,9%) y en OCT (11,1%) pero muy elevada en HRT (30,0%). Ningún instrumento detectó cambios significativos con la edad. El coeficiente de variación del espesor total, entre 2 exámenes del mismo sujeto, fue significativamente inferior (p < 0,05) en GDx (1,4) que en OCT (2,0) y muy elevado en HRT (6,4). Lo mismo ocurrió al analizar las fibras superiores (GDx = 1,8; OCT = 2,9; HT = 6,6), pero no las inferiores, donde solo se observaron diferencias significativas con HRT (GDx = 2,2, OCT = 2,7, HRT = 7,0).Entre los resultados de OCT y GDx existió una correlación significativa al comparar los primeros (r = 0,46; p < 0,0001) y los segundos exámenes (r = 0,52; p < 0,0001). Sin embargo, no se observó ninguna correlación significativa entre los datos aportados por HRT respecto a los 2 instrumentos restantes (p > 0,05). Conclusiones: HRT presenta un exceso de dispersión interindividual y de variabilidad intertest en la estimación del espesor del haz de fibras nerviosas. GDx presenta, en este aspecto, ligeras ventajas respecto a OCT (AU)

Objective: To estimate the variability and reproducibility of confocal tomography (HRT), scanning laser polarimetry (GDx) and optical coherence tomography (OCT-Cirrus) to determine the thickness of the layer of ganglion fibers. Method: A total of 75 normal eyes were examined twice. Inter-individual variability was analyzed after standardizing the results. The coefficient of variation was used to measure the variability between tests, and the Pearson coefficient was used to analyze the correlation between variables. Results: The inter-individual variability was similar in GDx (8.9%) and OCT (11.1%), but very high in HRT (30.0%). No instrument detected significant changes with age. The coefficient of variation of the total thickness between the examinations of the same subject was significantly lower (P < 0.05) in GDx (1.4) than in OCT (2.0), but very high in HRT (6.4). The same was true when analyzing the upper fibers (GDx = 1.8, OCT = 2.9, HRT = 6.6), but not with the lower ones, where the only significant differences were observed with HRT (GDx = 2.2, OCT = 2.7, HRT = 7.0). Among the results of OCT and GDx, there was a significant correlation when comparing the first (r = 0.46, P < 0.0001) and second examinations (r = 0.52, P < 0.0001). However there was no significant relationship between the data provided by HRT for the two remaining instruments (P > 0.05). Conclusions: There is a wide variation in the inter-individual and inter-test measurement of the thickness of the of nerve fibers layers using HRT. GDx has, in this respect, slight advantages over OCT (AU)

[Variability and reproducibility of 3 methods for measuring the thickness of the nerve fiber layer]. / Variabilidad interindividual y reproducibilidad de tres métodos de medida del espesor de la capa de fibras nerviosas.

OBJECTIVE: To estimate the variability and reproducibility of confocal tomography (HRT), scanning laser polarimetry (GDx) and optical coherence tomography (OCT-Cirrus) to determine the thickness of the layer of ganglion fibers. METHOD: A total of 75 normal eyes were examined twice. Inter-individual variability was analyzed after standardizing the results. The coefficient of variation was used to measure the variability between tests, and the Pearson coefficient was used to analyze the correlation between variables. RESULTS: The inter-individual variability was similar in GDx (8.9%) and OCT (11.1%), but very high in HRT (30.0%). No instrument detected significant changes with age. The coefficient of variation of the total thickness between the examinations of the same subject was significantly lower (P<.05) in GDx (1.4) than in OCT (2.0), but very high in HRT (6.4). The same was true when analyzing the upper fibers (GDx=1.8, OCT=2.9, HRT = 6.6), but not with the lower ones, where the only significant differences were observed with HRT (GDx = 2.2, OCT = 2.7, HRT = 7.0). Among the results of OCT and GDx, there was a significant correlation when comparing the first (r=0.46, P<.0001) and second examinations (r=0.52, P<.0001). However there was no significant relationship between the data provided by HRT for the two remaining instruments (P>.05). CONCLUSIONS: There is a wide variation in the inter-individual and inter-test measurement of the thickness of the of nerve fibers layers using HRT. GDx has, in this respect, slight advantages over OCT.

Variabilidad entre expertos al delimitar el borde y área papilar / Variability between experts in defining the edge and area of the optic nerve head

Objetivo: Estimar el grado de error en la determinación subjetiva del límite papilar.Método1) Fueron evaluadas 169 imágenes papilares por cinco expertos para delimitar los bordes papilares en 8 posiciones (cada 45°). 2) Las áreas estimadas en 26 casos se compararon con las medidas mediante tomógrafo de coherencia óptica (OCT-Cirrus). Resultados: 1) La variación media del radio papilar estimado fue de ± 5,2%, sin diferencias significativas entre sectores. Entre los cinco expertos existieron diferencias específicas (p<0,001) de cada uno respecto a los restantes. 2) El área papilar medida por OCT-Cirrus fue de 1,78 mm2 (DE=0,27). Los resultados de los expertos que informaron de áreas menores estuvieron mejor correlacionados con el área de OCT-Cirrus (r = 0,77-0,88) que los que informaron de áreas mayores (r=0,61-0,69) (p<0,05 en casos extremos). Conclusiones: Existen patrones específicos de cada experto para definir los límites papilares que pueden significar variaciones del 20% en la estimación de su área. Aquellos expertos que realizan delimitaciones menores tuvieron una mayor coincidencia con el método objetivo utilizado. Proponemos una herramienta web de autoevaluación y entrenamiento en esta tarea (AU)

Objective: Estimation of the error rate in the subjective determination of the optic nerve head edge and area.Method1) 169 images of optic nerve disc were evaluated by five experts for the defining of the edges in 8 positions (every 45°). 2) The estimated areas of 26 cases were compared with the measurements of the Cirrus Optical Coherence Tomography (OCT-Cirrus). Results: 1) The mean variation of the estimated radius was ±5.2%, with no significant differences between sectors. Specific differences were found between the 5 experts (P <.001), each one compared with the others. 2) The disc area measured by the OCT-Cirros was 1.78 mm2 (SD =0.27). The results corresponding to the experts who detected smaller areas were better correlated to the area detected by the OCT-Cirrus (r=0.77-0.88) than the results corresponding to larger areas (r =0.61-0.69) (P <.05 in extreme cases). Conclusions: There are specific patterns in each expert for defining the disc edges and involve 20% variation in the estimation of the optic nerve area. The experts who detected smaller areas have a higher agreement with the objective method used. A web tool is proposed for self-assessment and training in this task (AU)

Variability between experts in defining the edge and area of the optic nerve head.

OBJECTIVE: Estimation of the error rate in the subjective determination of the optic nerve head edge and area. METHOD: 1) 169 images of optic nerve disc were evaluated by five experts for the defining of the edges in 8 positions (every 45°). 2) The estimated areas of 26 cases were compared with the measurements of the Cirrus Optical Coherence Tomography (OCT-Cirrus). RESULTS: 1) The mean variation of the estimated radius was ±5.2%, with no significant differences between sectors. Specific differences were found between the 5 experts (P <.001), each one compared with the others. 2) The disc area measured by the OCT-Cirros was 1.78 mm² (SD =0.27). The results corresponding to the experts who detected smaller areas were better correlated to the area detected by the OCT-Cirrus (r=0.77-0.88) than the results corresponding to larger areas (r =0.61-0.69) (P <.05 in extreme cases). CONCLUSIONS: There are specific patterns in each expert for defining the disc edges and involve 20% variation in the estimation of the optic nerve area. The experts who detected smaller areas have a higher agreement with the objective method used. A web tool is proposed for self-assessment and training in this task.

[Pulsar perimetry. A review and new results]. / Pulsarperimetrie. Überblick und neue Ergebnisse.

We present a review and update on Pulsar perimetry, which combines temporal frequency, contrast and spatial frequency stimuli. The effects of age, visual acuity, and learning on results are described. Data on threshold fluctuation, signal-to-noise ratio, and the possibility of reducing noise with filtering techniques are provided. We describe its dynamic range and the possibility of compensating for profound defects. Finally, we show the results obtained in normal patients and in those with ocular hypertension or initial glaucoma, as well as an analysis of glaucoma progression.

[Comparing the ranges of defect measured with standard white on white and Pulsar perimetries]. / Comparación del rango de medida de defectos entre la perimetría estándar blanco/blanco y la perimetría Pulsar.

OBJECTIVES: Normal thresholds on Pulsar perimetry fall faster than those of standard perimetry in the peripheral visual field. Two related studies were performed. Firstly, the frequency distributions of glaucoma defects on standard automated perimetry (SAP) and the relationship of the centre and periphery (Study A) were studied first, followed by an attempt to establish the limits of pulsar perimetry (Study B). MATERIAL AND METHOD: A: frequency of defects was calculated in 78.663 SAP perimetries (G1-TOP, Octopus 1-2-3, Haag-Streit). Study B: 204 eyes with mean defect (MD-SAP) lower than 9 dB were examined 8.92 ± 4.19 times with SAP (TOP-32, Octopus 311) and temporal modulation perimetry (T30W, Pulsar Perimeter, Haag-Streit). RESULTS: Study A: 50.7% of the SAP examinations showed MD values lower than 9 dB and 32.7% bellow 6 dB. The MD correlation of the central 20° with the MD of the most peripheral points was r=0.933. Study B: in cases with MD-TOP-32 lower than 6 dB, SAP had the maximum possibility of detecting defect in 0.02% of points and Pulsar in 0.29%. In subjects with MD-TOP-32 between 6 and 9 dB frequencies were 0.38% in SAP and 3.5% in Pulsar (5.1% for eccentricities higher than 20°). CONCLUSIONS: Pulsar allows detecting defects, without range limitations, in the initial half of SAP frequencies expected on glaucoma patients. In order to study the progression of deeper defects the examination should focus on the central points, where the dynamic range of both systems is more equivalent.

Comparación del rango de medida de defectos entre la perimetría estándar blanco/blanco y la perimetría Pulsar / Comparing the ranges of defect measured with standard white on white and Pulsar perimetries

Objetivo: Los umbrales normales de la perimetría Pulsar caen más rápidamente en el campoperiférico que los estándar. Se han realizado dos estudios relacionados, en primer lugar seha investigado la distribución de frecuencias de los defectos glaucomatosos en perimetríaautomática estándar (SAP), y la relación de los periféricos con los centrales (estudio A). Acontinuación se han tratado de definir los límites de examen Pulsar (estudio B).Material y métodos: Estudio A: las frecuencias se calcularon en 78.663 perimetrías SAP (G1-TOP, Octopus 1-2-3, Haag-Streit). Estudio B: 204 ojos con defecto medio (MD-SAP) inferiora 9 dB se examinaron 8,92±4,19 veces con SAP (TOP-32, Octopus 311) y con perimetría demodulación temporal (T30W, Perímetro Pulsar, Haag-Streit).Resultados: Estudio A: el 50,7% de los estudios SAP presentaron valores de MD inferiores a9 dB y el 32,7% inferiores a 6 dB. La correlación delMDde los 20◦ centrales con respecto alMDde los más periféricos fue de r = 0,933. Estudio B: en los casos con valores de MD-TOP-32 inferioresa 6 dB, SAP alcanzó sus posibilidades máximas de detección de defecto en el 0,02% delos puntos y Pulsar en el 0,29%. En los sujetos con MD-TOP-32 situado entre 6 y 9dB las frecuenciasfueron 0,38% en SAP y 3,5% en Pulsar (5,1% para excentricidades superiores a 20◦).Conclusiones: Pulsar permite detectar defectos, sin limitación de rango, en la mitad inicialde las frecuencias de defecto SAP esperables en el paciente glaucomatoso. Para estudiar laprogresión de defectos más profundos el análisis deberá centrarse en los puntos centrales,donde el rango dinámico de ambos sistemas es más equivalente(AU)

Objectives: Normal thresholds on Pulsar perimetry fall faster than those of standard perimetryin the peripheral visual field. Two related studies were performed. Firstly, the frequencydistributions of glaucoma defects on standard automated perimetry (SAP) and the relationshipof the centre and periphery (Study A) were studied first, followed by an attempt toestablish the limits of pulsar perimetry (Study B).Material and method: A: frequency of defects was calculated in 78.663 SAP perimetries (G1-TOP, Octopus 1-2-3, Haag-Streit). Study B: 204 eyes with mean defect (MD-SAP) lower than9 dB were examined 8.92±4.19 times with SAP (TOP-32, Octopus 311) and temporal modulationperimetry (T30W, Pulsar Perimeter, Haag-Streit).Results: StudyA: 50.7% of the SAP examinations showedMDvalues lower than 9 dB and 32.7%bellow 6 dB. The MD correlation of the central 20◦ with the MD of the most peripheral pointswas r = 0.933. Study B: in cases with MD-TOP-32 lower than 6 dB, SAP had the maximumpossibility of detecting defect in 0.02% of points and Pulsar in 0.29%. In subjects with MDTOP-32 between 6 and 9 dB frequencies were 0.38% in SAP and 3.5% in Pulsar (5.1% foreccentricities higher than 20◦).Conclusions: Pulsar allows detecting defects, without range limitations, in the initial half ofSAP frequencies expected on glaucoma patients. In order to study the progression of deeperdefects the examination should focus on the central points, where the dynamic range ofboth systems is more equivalent(AU)

Detection of morphological and functional progression in initial glaucoma.

BACKGROUND: To observe the prospective follow-up results of functional and morphological data in patients with early, moderate and suspected glaucoma. METHODS: Eyes (n=156; average mean defect (MD)=2.2 dB) were examined every 3 months for an average of 3.6 years. Progression was estimated using regression analysis of the indices rim area and Glaucoma Probability Score of the Heidelberg retinal tomograph, mean thickness of the fibre layer using laser polarimetry with corneal compensation, MDs of standard, Pulsar and frequency doubling technology perimetries, and the threshold noiseless trend (TNT) program for the standard and Pulsar perimetries. RESULTS: TNT showed more than twice the diagnostic capacity of other methods. The maximum diagnostic sensitivity was obtained with TNT Pulsar. This procedure indicated progression in 40% of cases after seven examinations, and presented the lowest number of cases of progression not confirmed in two consecutive examinations. Most of the progressions of initial glaucoma were diffuse, without changes in the lens or loss of visual acuity. Heidelberg retinal tomograph and laser polarimetry made few diagnoses of progression. The diagnostic agreement between different methods was low, but higher between functional than morphological procedures. CONCLUSION: Functional indices, especially Pulsar, showed better detection of progression than morphological indices.

Topographical spatial summation in glaucoma.

PURPOSE: Stimulus luminance (L) and area (A) are related by the equation L x A(k)=constant. The authors evaluated the k value at 66 positions of the central visual field in patients with glaucoma, to modify L and A simultaneously in order to examine advanced glaucomas with a bigger dynamic range. METHODS: The luminance limitation of a computer screen with automatic photometric control was compensated for by increasing the stimulus area in the range between 0 and 17 dB, using the k topographic values previously calculated on normal subjects. Four initial series of 21, 12, 10, and 10 glaucomas were sequentially examined with the Octopus 311 in which the stimulus size cannot be freely changed during the examination, and with the experimental method (Pulsar-SAP) modifying stimulus sizes to equal the results. k Final estimation was verified in 60 new cases. RESULTS: k values increase progressively with defect deepness. Values higher than those of the normal population with equivalent topographic differences were obtained. Correlation between indices was as follows: MD: r=0.94 (p<0.0001); square root of the loss of variance (sLV): r=0.93 (p<0.0001). Frequency of local defects was similar in both procedures. Average topographic differences between thresholds were usually less than 1 dB. The average threshold difference favored Pulsar-SAP by 0.45 dB at those points where the average threshold of both examinations was less than 18 dB and 0.37 dB where such average was higher than or equal to 18 dB. CONCLUSIONS: k value is higher in patients with glaucoma than in normal subjects, although the topographic features are similar. It is feasible to design a scale combining stimulus luminance and sizes to use screens with relative low brightness as surfaces for visual field examination.

[Diagnostic capability of PULSAR, FDT y HRT-II in glaucoma suspects]. / Capacidad diagnóstica del HRT-II y de las perimetrías TOP, PULSAR y FDT en pacientes sospechosos de sufrir glaucoma.

PURPOSE: To determine the diagnostic capability of PULSAR-T30W, FDT-Threshold-N30 and HRT-II in glaucoma suspects. METHODS: Forty-seven eyes from 47 referred glaucoma suspects (GS) were examined twice with each technique. Cases with TOP-WW-MD>6dB were excluded. Results were compared with those of 70 eyes from 70 normal controls (C). RESULTS: Mean MD value using TOP-WW in the GS group (0.96dB. sd=1.7) was not significantly different from C (0.8dB. sd=1.77) (p>0.05). Disc area in GS group (2.12 mm(2). sd=0.34) was significantly greater than in C (1.97 mm2. sd=0.45) (p<0.01). For 95.7% specificity, PULSAR-sLV showed the highest sensitivity of 30.9% in individual examinations. The highest reproducible sensitivity in the two examinations was obtained using HRT-II maximum contour elevation (23.4%) and reference height (23.4%), and was 14.9% for various indices after correcting for the influence of disc area (cup area, cup/disc area ratio, maximum contour depression and mean RNFL thickness). Reproducible sensitivity of the perimetric indices was: PULSAR-MD=8.5%, PULSAR-sLV=17%, FDT-MD=6.4%, FDT-PSD=4.3%. The association of perimetric and HRT-II indices achieved high sensitivity but low diagnostic reproducibility. CONCLUSIONS: The most effective indices were maximum contour elevation, reference height and PULSAR-sLV, although the inclusion of the optic nerve head assessment in the selection of the GS sample may have favored the HRT-II results.

Capacidad diagnóstica del HRT-II y de las perimetrías TOP, PULSAR y FDT en pacientes sospechosos de sufrir glaucoma / Diagnostic capability of pulsar, FDT y HRT-II in glaucoma suspects

Objetivos: Determinar la capacidad diagnóstica de TOP-32, PULSAR-T30W, FDT-Umbral-N30 y HRT-II en glaucoma de sospecha. Métodos: 47 ojos de 47 sujetos remitidos por sospecha de glaucoma (SG) se examinaron dos veces. Se excluyeron los casos con defecto medio (MD) superior a 6dB en TOP-32. Los resultados se compararon con los obtenidos en 70 sujetos normales control (C). Resultados: No se observaron diferencias significativas entre los valores de MD obtenidos en TOP- 32, en los grupos SG (0,96dB. DE=1,7) y C (0,8dB. DE=1,77) (p>0.05). El área papilar de SG (2,12 mm2. DE=0.34) fue significativamente superior que en C (1,97 mm2. DE=0,45) (p<0,01). Para una especificidad del 95%, la raíz cuadrada de la varianza de pérdida (sLV) de PULSAR presentó la mayor sensibilidad (30,9%) en exámenes individuales. La mayor reproducibilidad diagnóstica se obtuvo con la máxima elevación del contorno de HRT-II (23%) y con el Plano de referencia (23,4%), siendo del 14,9% para varios índices, después de corregir la influencia del tamaño papilar (área de la excavación, cocientes de área excavación/papila, máxima depresión del contorno y espesor de la capa de fibras). La reproducibilidad de los índices perimétricos fue: PULSAR-MD=8,5%, PULSARsLV= 17%, FDT-MD=6,4%, FDT-PDT=4,3%. La asociación entre índices perimétricos y HRT-II elevó la sensibilidad pero redujo la reproducibilidad diagnóstica. Conclusiones: Los índices de mayor eficacia fueron la máxima elevación del contorno, el plano de referencia y PULSAR-sLV, aunque la inclusión del aspecto papilar en la selección del grupo SG favoreció los resultados de HRT-II

Purpose: To determine the diagnostic capability of PULSAR-T30W, FDT-Threshold-N30 and HRT-II in glaucoma suspects. Methods: Forty-seven eyes from 47 referred glaucoma suspects (GS) were examined twice with each technique. Cases with TOP-WW-MD>6dB were excluded. Results were compared with those of 70 eyes from 70 normal controls (C). Results: Mean MD value using TOP-WW in the GS group (0.96dB. sd=1.7) was not significantly different from C (0.8dB. sd=1.77) (p>0.05). Disc area in GS group (2.12 mm2. sd=0.34) was significantly greater than in C (1.97 mm2. sd=0.45) (p<0.01). For 95.7% specificity, PULSAR-sLV showed the highest sensitivity of 30.9% in individual examinations. The highest reproducible sensitivity in the two examinations was obtained using HRT-II maximum contour elevation (23.4%) and reference height (23.4%), and was 14.9% for various indices after correcting for the influence of disc area (cup area, cup/disc area ratio, maximum contour depression and mean RNFL thickness). Reproducible sensitivity of the perimetric indices was: PULSARMD= 8.5%, PULSAR-sLV=17%, FDT-MD=6.4%, FDT-PSD=4.3%. The association of perimetric and HRT-II indices achieved high sensitivity but low diagnostic reproducibility. Conclusions: The most effective indices were maximum contour elevation, reference height and PULSAR-sLV, although the inclusion of the optic nerve head assessment in the selection of the GS sample may have favored the HRT-II results (AU)

Progresión del glaucoma y de la catarata. Una ecuación y dos incógnitas / Glaucoma and cataract progression. One equation containing two variables

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Diagnostic accuracy and reproducibility of tendency oriented perimetry in glaucoma.

PURPOSE: To evaluate the diagnostic capability of tendency oriented perimetry (TOP) in glaucoma. METHODS: A): The diagnostic accuracy of mean defect (MD), square-root of the loss variance (s LV), and number of pathologic points (NPP) was calculated in 295 normal and 414 glaucoma eyes (179 early, 112 moderate, and 123 advanced) examined with TOP. B): Threshold fluctuation (F) and its relationship with the loss variance (LV) was measured in 34 normal and 33 glaucoma eyes (mean MD=3 dB; SD=3.9) for TOP and for full-threshold perimetry (FT). C): Twenty-eight eyes with stable glaucoma (mean MD=9.5 dB; SD=7.2) were examined six times to quantify LV error. D): TOP and FT were tested with the simulation program PeriSim using different behavior models. RESULTS: A): The best diagnostic index in early glaucoma (MD<6dB) was sLV (specificity=90.2%, sensitivity=84.9). The three indices had similar precision in moderate and severe glaucoma. B): Threshold fluctuation and sLV were better correlated in TOP (r=0.72, p<0.01) than in FT (r=0.62, p<0.01). For normal subjects, in FT the incidence of F<2 dB was 8.82% and s LV<1.5 dB 5.88%. The same frequencies in TOP were 67.65% and 55.88%. C): Averaging six examinations reduced the sLV val ue by 22%. D): The threshold estimation error increased 1 dB in TOP in relation to FT for the same patient's behavior, but the error in TOP was lower than i n FT when the worst behavior was modeled. CONCLUSIONS: TOP is a good discriminator between glaucoma and normality. Perimetry results overestimate the real sLV value. TOP's high diagnostic ability is probably associated to the algorithm design and to less contaminating influences during the examination.