Ma González de la Rosa

Structure-function relationship depends on glaucoma severity

Background/aims: To determine the structure–function relationship throughout the different stages of glaucoma. Methods: Subjects: 228 controls and 1007 suspected, early, moderate, or advanced glaucomas. In controls, Pearson coefficient of variation (PCV) of standard automated perimetry mean sensitivity (SAP-MS) and global mean retinal nerve fibre layer thickness (RNFL, Heidelberg Retina Tomograph) were calculated. Piecewise linear regression was used to evaluate if the data were related better to two separate regression lines in all population. Results: PCV for SAP-MS and RNFL was 6.19% and 29.27%, respectively. For SAP-MS >22.42 dB (piecewise linear regression-obtained breakpoint, p<0.05), the logarithmic and linear relationships between SAP-MS and mean RNFL thickness were not different (r = 0.182, r = 0.185 respectively; p = 0.950). For SAP-MS <22.42 dB, the logarithmic and linear relationships between SAP-MS and mean RNFL thickness were not different (r = 0.353, r = 0.344 respectively; p = 0.884). Conclusion: The logarithmic and linear relationships between SAP-MS and mean RNFL thickness did not differ when individuals were stratified using the piecewise linear regression-obtained cut-off point. The curvilinear relationship between the morphological and perimetric results may be due to the wide variability in normal morphology and limitations in the dynamic range of the morphological tests in cases with moderate and severe defects.

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 (sLV), 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 sLV<1.5 dB 5.88%. The same frequencies in TOP were 67.65% and 55.88%. C): Averaging six examinations reduced the sLV value by 22%. D): The threshold estimation error increased 1 dB in TOP in relation to FT for the same patients behavior, but the error in TOP was lower than in FT when the worst behavior was modeled. Conclusions TOP is a good discriminator between glaucoma and normality. Perimetry results overestimate the real sLV value. TOPs high diagnostic ability is probably associated to the algorithm design and to less contaminating influences during the examination.

Comparison of diagnostic ability between a fast strategy, tendency-oriented perimetry, and the standard bracketing strategy

Purpose: To compare the diagnostic abilities of the standard bracketing strategy (BR) and a fast strategy, the tendency-oriented perimetry (TOP). Methods: Seventy-seven controls and 91 eyes from patients with glaucoma were analyzed with the strategies TOP and BR. Sensitivity (Se), specificity (Sp), the area under the receiver operating characteristic (ROC) curve (AC) and the optimum cutoff value (CO) were calculated for the visual field indices mean defect (MD), the square root of the loss variance (sLV) and the number of pathological points (NPP). Results: In the glaucoma group, the mean MD value using TOP and BR was 7.5 and 8.3 dB, respectively. The mean sLV value using TOP and BR was 5.0 and 5.3 dB, respectively. Indices provided by TOP had higher ROC values than the ones provided by BR. Using TOP, the index with the best diagnostic ability was sLV (Sp = 94.8, Se = 90.1, AC = 0.966, CO = 2.5 dB), followed by NPP and MD. Using BR, the best results were obtained for MD (Sp = 92.2, Se = 81.3, AC = 0.900, CO = 2.5 dB) followed by sLV and NPP. Conclusions: A fast strategy, TOP, had superior diagnostic ability than the standard BR. Although TOP provided lower LV values than BR, the diagnostic ability of this index was higher than that of the conventional strategy.

Nomograma de riesgo de progreso de hipertensión ocular basado en el Ocular Hypertension Treatment Study

Introduccion: Se ha construido un nomograma practico para representar los resultados del Ocular Hipertension Study (Gordon et al. Arch Ophthalmol 2002;120: 714-720) que relacionan la presion intraocular y el espesor corneal con el riesgo de evolucionar de hipertension ocular a glaucoma en un plazo de 6 anos. Material y Metodos: Se ha aplicado una regresion logaritmica multiple a los 9 datos mostrados en la figura 1 del trabajo senalado anteriormente. Resultados: Un coeficiente de correlacion de 0,91 (p<0,001) permite definir la siguiente ecuacion: Probabilidad de evolucion (%) = 13539,5 x (1,1385PIO) x (0,9818ESPESOR CORPORAL) Esto significa que una variacion de 10 micras en el espesor corneal equivale a una variacion de 1,5 mmHg en el mismo sentido de la presion intraocular. Con estos datos se ha construido un nomograma que se incluye en el trabajo. Conclusiones: La PIO y la paquimetria permiten estimar el riesgo de evolucion de hipertension ocular a glaucoma de una manera grafica practica. Estimada de esta manera indirecta, la influencia del espesor corneal sobre la medida de la presion intraocular parece muy superior a la que se habia estimado hasta el momento.

Estado actual del diagnóstico y control evolutivo del glaucoma

espanolObjetivo: Comparar los diversos metodos propuestos para el diagnostico y control evolutivo del glaucoma. Metodo: Revision de los trabajos que han publicado cifras de sensibilidad y especificidad de los diferentes procedimientos, asi como los estudios comparativos simultaneos de varios de ellos, especialmente los que han utilizado pacientes en fases iniciales. Resultados: Analizado globalmente las cifras de sensibilidad y especificidad de las diferentes tecnicas que se han propuesto, no hemos encontrado evidencia de que la perimetria azul-amarillo (SWAP), la fotografia de las fibras nerviosas, la polarimetria laser (GDx), las pruebas electrofisiologicas o la topografia papilar superen en capacidad diagnostica a la perimetria blanco blanco. Esta ultima evoluciona con las otras tecnicas proporcionando nuevos criterios y estrategias de mayor precision. Los diversos resultados comparativos de los procedimientos anatomicos y funcionales no son coincidentes y no permiten establecer conclusiones definitivas. Conclusiones: Las mejores expectativas se encuentran actualmente en los fenomenos temporales (FDT, Flicker, PULSAR), en nuevos metodos de analisis de los resultados de la topografia papilar y en el valor de la varianza (LV) en la perimetria TOP. Los peores resultados corresponden a la perimetria azul-amarillo y a GDX. EnglishPurpose: To compare the different methods proposed for glaucoma diagnosis and follow-up. Methods: Review of those papers that have published the sensitivity and specificity of the different methods, as well as simultaneous comparative studies of several of these methods, especially those that used patients in the initial stages of the disease. Results: After analyzing the sensitivity and specificity results of the proposed techniques, we have found no evidence that blue-yellow perimetry (SWAP), nerve fibers photography, laser polarimetry (GDx), electrophysiological techniques or optic nerve head topography have better diagnosis abilities than white-white perimetry. This last technique evolves with the others, giving new criteria and strategies with higher precision. The different comparative results of the anatomical and functional procedures do not coincide and do not allow one to establish definite conclusions. Conclusions: The most promising expectations are nowadays on temporal phenomena (FDT, Flicker, PULSAR), new methods for analyzing optic nerve topography results and the value of the loss variance (LV) on TOP perimetry. The worst results correspond to blue-yellow perimetry and GDx.

Perimetrías blanco-blanco, azul-amarillo y azul-azul en sujetos normales

espanolObjetivo: Comparar la perimetria de contraste diferencial azul sobre azul (AZ-AZ) acorde con la teoria «Retinex» de E. Land, con las perimetrias blanco-blanco (BL-BL) y azul-amarillo (AZ-AM) en sujetos normales. Metodo: Un perimetro Octopus 101 fue modificado para perimetria AZ-AZ, usando fondo de 4 cd/m² y estimulo V de Goldmann. 50 sujetos sanos (10 por decada entre 20 y 70 anos) fueron examinados dos veces con los tres tipos de perimetria, usando estrategia TOP. Resultados: Para BL-BL, AZ-AM y AZ-AZ se obtuvo respectivamente: perdida de sensibilidad por ano: 0,13, 0,27 y 0,13 dB; coeficiente de correlacion (r) del umbral con la edad (y error de estimacion de Y sobre X): -0,63 (2,24 dB), -0,70 (3,77 dB) y -0,80 (1,32 dB); fluctuacion del umbral: 2,21, 3,03 y 2,03 dB; porcentaje de puntos desviados a mas de 5 dB del valor previsto para la edad: 8,1, 16,0 y 4,2%. Conclusiones: La perimetria AZ-AZ produce resultados mas estables que los otros dos tipos de perimetria. La perimetria AZ-AM produce los peores resultados: la reduccion del umbral con la edad es dos veces superior, la fluctuacion individual un 50% superior y mucho mas frecuentes los puntos alejados del valor medio. En el perimetro Octopus el solapamiento entre los filtros azul y amarillo es minimo. Por lo tanto se examina un umbral absoluto, mucho mas inestable que el umbral diferencial BL-BL o AZ-AZ. EnglishPurpose: To compare blue-on-blue differential contrast perimetry (BB), in accordance with E. Land «Retinex» theory, with white-on-white (WW) and blue-on-yellow (BY) perimetries on normal subjects. Methods: An Octopus 101 perimeter was modified for BB perimetry, using a 4cd/m² background and stimulus Goldmann size V. Fifty healthy subjects (10 per decade, from 20 to 70 years) were examined twice with each type of perimetry (WW, BB, BY) using the TOP strategy. Results: The results obtained with WW, BY and BB perimetry were respectively: Reduction of sensitivity per year: 0.13, 0.27 and 0.13 dB; correlation coefficient (r) of threshold with age (and error of estimation of Y over X): -0.63 (2.24 dB), -0.70 (3.77 dB) and -.80 (1.32 dB); threshold fluctuation: 2.21, 3.03 and 2.03 dB; percentage of points deviated more than 5dB from the expected value for the patient age: 8.1, 16.0 and 4.2%. Conclusions: Perimetric results are more stable with BB strategy than with the other two types of perimetry. BY perimetry gives the worst results: threshold reduction with age is twice higher, individual fluctuation is 50% higher and points away from the mean value are much more frequent. Overlapping between blue and yellow filters is minimal in Octopus. Therefore, an absolute threshold is examined, which is much more unstable than WW or BB differential thresholds.