Marta Gonzalez-Hernandez

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 (ru200a=u200a0.182, ru200a=u200a0.185 respectively; pu200a=u200a0.950). For SAP-MS <22.42 dB, the logarithmic and linear relationships between SAP-MS and mean RNFL thickness were not different (ru200a=u200a0.353, ru200a=u200a0.344 respectively; pu200a=u200a0.884). 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.

Combined spatial, contrast, and temporal functions perimetry in mild glaucoma and ocular hypertension

PURPOSEnTo evaluate the diagnostic ability of a new perimetric procedure in glaucoma.nnnMETHODSnPulsar perimeter shows white circular sinusoidal grating patterns with decreasing amplitude, 5 in diameter, 500 msec in duration in 66 locations. The stimuli scale combines spatial resolution and contrast. The stimuli were shown with centrifugal wave motion at 8 cyl/deg (K6W) or pulse at 30 Hz (T30W). Fifty-six normal eyes and 82 eyes with ocular hypertension and mild glaucoma were included. These 82 cases were classified into four levels of diagnostic certainty, from 0 (ocular hypertension) to 3 (mild glaucoma).nnnRESULTSnMean examination time was 3:49 min. Specificity was 96.4% (T30W) and 94.6% (K6W). Sensitivities for levels 0 and 3 were 34.5% to 100% (T30W) and 24.1% to 75% (K6W). The receiver operating characteristic (ROC) curve areas for T30W at levels 1, 2, and 3 were 0.88, 0.94, and 0.99. The ROC areas for K6W were 0.83, 0.91, and 0.97. There was good correlation between both Pulsar perimetries (r=0.88), but it was lower with conventional perimetry (r=0.58 for T30W and r=0.59 for K6W).nnnCONCLUSIONSnThe novel Pulsar T30W perimetry may be helpful for the study of mild glaucoma and ocular hypertension. (Eur J Ophthalmol 2004; 14: 514-22).

Quantification of interpoint topographic correlations of threshold values in glaucomatous visual fields

PurposeThe authors sought to quantify neighboring and distant interpoint correlations of threshold values within the visual field in patients with glaucoma. MethodsVisual fields of patients with confirmed or suspected glaucoma were analyzed (n = 255). One eye per patient was included. Patients were examined using the 32 program of the Octopus 1-2-3. Linear regression analysis among each of the locations and the rest of the points of the visual field was performed, and the correlation coefficient was calculated. The degree of correlation was categorized as high (r2 > 0.66), moderate (0.66 ≧r2 > 0.33), or low (r2 ≦ 0.33). The standard error of threshold estimation was calculated. ResultsMost locations of the visual field had high and moderate correlations with neighboring points and with distant locations corresponding to the same nerve fiber bundle. Locations of the visual field had low correlations with those of the opposite hemifield, with the exception of locations temporal to the blind spot. The standard error of threshold estimation increased from 0.6 to 0.9 dB with an r2 reduction of 0.1. ConclusionLocations of the visual field have highest interpoint correlation with neighboring points and with distant points in areas corresponding to the distribution of the retinal nerve fiber layer. The quantification of interpoint correlations may be useful in the design and interpretation of visual field tests in patients with glaucoma.

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.

Stabilization and comparison of TOP and Bracketing perimetric strategies using a threshold spatial filter

BackgroundTo evaluate a new perimetric spatial filter that takes into account relations of dependence between regions of the glaucomatous visual field.Methods51 glaucoma patients and 30 controls were examined using the Octopus 1-2-3 on four occasions using program 32; two with TOP and two with Bracketing (BRA) strategy. Each threshold was replaced by a filtered threshold, calculated as the mean of its own value and the four points best correlated with it, weighted with the correlation coefficient (r) that relates them.ResultsApplication of the filter had minimal effect on the absolute mean defect (MD) but reduced the square root of loss variance (sLV) by 17.6% in TOP and 28.8% in BRA, increasing the similarity between their results. Filtered TOP and BRA thresholds were more similar than those obtained in the two unfiltered BRA examinations. Filtering reduced the value of short fluctuation by 28.6% in TOP and 45.4% in BRA and reduced sLV fluctuation by 14.3% in TOP and 24.2% in BRA, thus harmonizing the two strategies for these two parameters (pu2009>u20090.05). The influence of filtering on MD fluctuation was minimal (pu2009>u20090.05). In normal subjects the number of points beyond 5xa0dB of normality (not reproducible false scotomas) reduced from 1.5% to 0.2% in TOP and from 4.9% to 1.6% in BRA, while in glaucoma patients changes were minimal.ConclusionsThe proposed spatial filter stabilized perimetric results, acting with greater effect on BRA than on TOP, making their results more similar.

A strategy for averaged estimates of visual field threshold: spark.

Purpose:The purpose of this work is to design a rapid perimetric strategy to provide averaged results. Methods:We designed a simulation examination model using the distribution frequency of local deviations or defects, based on a retrospective study of 90,335 examinations performed in a glaucoma department. Results:Threshold deviation from normal age-adjusted values of 6 points representative of the main areas of glaucomatous visual field allowed estimating the real mean deviation (MD) with a correlation coefficient r=0.995 (SE=0.71 dB) when original values were used, and r=0.984 (SE=1.26 dB) when values from a rapid simulated test model were used. SE of the local deviations (average=3.06 dB) was close to usual mean threshold fluctuation in patients with different degrees of defect. In patients with early glaucoma (MD<6 dB) the SE of the estimated MD was <0.9 dB and the SE in estimating the local point-to-point deviations was 1.8 dB. We included 3 additional phases to obtain 3 additional results and a final averaged result. For the average and median of the 4 phases, the SE of MD ranged from 0.4 to 0.5 dB for the whole sample and from 0.3 to 0.4 in early glaucoma. Local deviation SE was close to 2 dB in the whole sample and between 1.2 and 1.5 dB in early glaucoma. Conclusions:Bearing in mind threshold fluctuation, the strategy allows for several possible outcomes, and provides averaged and theoretically more stable results.

Measuring Hemoglobin Levels in the Optic Disc of Parkinson's Disease Patients Using New Colorimetric Analysis Software

Objective. To evaluate a new method of measuring hemoglobin (Hb) levels and quantifying the color changes in the optic nerve head of Parkinsons disease (PD) patients. We also compared differences in retinal nerve fiber layer (RNFL) thicknesses obtained using spectral domain optical coherence tomography (OCT) device between PD group and healthy group. Methods. One hundred and fifty-five PD patients and 91 sex- and age-matched healthy subjects were included in this cross-sectional study. OCT examinations and one photograph of the optic disc were performed. The Laguna ONhE (“optic nerve hemoglobin”; Insoft SL, Tenerife, Spain) software was used to analyze the Hb level on the acquired optic disc photographs. Results. PD patients exhibited significantly reduced mean optic disc Hb percentages (57.56% in PD, 67.63% in healthy subjects; P = 0.001) as well as reduced Hb in almost all analyzed sectors, with the largest differences detected in the inferior and nasal sectors. RNFL parameters were significantly reduced in PD patients compared with healthy subjects, especially in the inferior quadrant. Conclusions. Measurements of optic disc Hb levels obtained with the Laguna ONhE software had good ability to detect optic nerve color changes (more papillary paleness and consequently this could suggest optic atrophy and axonal loss) in PD patients.

Monitoring visual field progression.

We recently published a prospective study analysing the possibility of detecting progression in the early stages of glaucoma.1 The paper outlines certain advantages of functional procedures with respect to morphological procedures. However, it does not signal the end of the journey, but simply the state of the problem when the study was performed. Morphological methods of analysis are continuously progressing, as are functional methods. The ‘state of the art’ will change as new diagnostic and analytical procedures are developed.nnOur experience lies in the design of algorithms and methods related to function. Studies such as the one published in the British Journal of Ophthalmology earlier this year1 have led to new ideas on how currently available methods may be improved. In this article we attempt to summarise these new ideas.nnOne of the conclusions drawn from the results of our work is that the progression of functional defects can easily be masked by false improvement brought about by training. It is customary to discount the first two tests of the patient to reduce the ‘learning effect’ and this we have done, but, disconcertingly, the patients improvement in sensitivity may continue until the fifth test or even beyond.2 In our opinion it would be interesting to have a specific training method that should be applied before starting patient monitoring.nnTo this end we are designing a program that provides a quick and accurate estimate of the mean deviation (MD) of the patient, in line with another idea that we published 20u2005years ago.3 This preliminary step will constitute the first phase of a new perimetric strategy, called Spark, designed for use in Oculus perimeters (Oculus Optikgerate GmbH, Wetzlar, Germany). The duration of this training phase is about 36u2005s and can be applied repeatedly to verify that sufficient stability …

New visual field indices of disharmony for early diagnosis of glaucoma, alone or associated with conventional parameters

Purpose: To evaluate the specificity of new perimetric indices based on harmony, alone and in combination with structural data, for glaucoma detection. Methods: In this prospective observational cross-sectional study, one eye of 105 healthy subjects and 97 early and suspect glaucomas were sequentially included and examined with Cirrus optical coherence tomography, twice with OCULUS Smartfield perimeter (SPARK strategy) and twice with Humphrey Analyzer (24-2 SITA-Fast) at the Ophthalmology Department from the University Hospital La Candelaria. Disharmony in the visual field was evaluated including vertical threshold symmetry, threshold rank), and homogeneity (threshold standard deviation from its maximum) using the patient himself/herself as a reference. We also evaluated disharmony in combination with the mean deviation and the pattern standard deviation in a single index (mismatch) and various combinations of morphological and functional indices. Combinations used a new score based on values above certain critical cut-off levels of each index. Results: For 95% specificity, the highest sensitivities were as follows: vertical cup/disc ratio: 28.9%; SPARK threshold rank: 29.9%; and SITA-Fast threshold standard deviation: 28.9%. For the combined indices and 100% specificity, they were 5 SPARK indices mismatch: 10.3%; 5 SITA-Fast indices mismatch: 11.3%; 8 optical coherence tomography indices: 21.9%; 13 SPARK and optical coherence tomography indices: 27.8%; and 13 SITA-Fast and optical coherence tomography indices: 32.0%. Conclusion: Disharmony combined with normative value-based indices and/or optical coherence tomography indices is useful for very specific early diagnosis of glaucoma.