Manuel González de la Rosa

Rapid assessment of the visual field in glaucoma using an analysis based on multiple correlations

We wished to determine which areas of the visual field contribute most strongly and most frequently to the deterioration of the visual fields in patients with high ocular pressure. The computerized analysis, using linear and multiple regressions of the findings in 382 visual fields, allowed us to select four test points sensitive enough to estimate the actual global sensitivity of the central visual field (correlation coefficient, 0.98). This system also allowed us to estimate the number of pathological points and even to classify accurately over 75% of the cases in terms of their normal or pathological condition, as well as to determine the depth of the defect. The remaining cases show that the deterioration, if it exists, is not significant. Requiring less than 1 min a threshold examination at these four test points enables us to acquire greater insight into the glaucomatous defect.

Linear regression analysis of the cumulative defect curve by sectors and other criteria of glaucomatous visual field progression.

Purpose To analyze the progression of visual field loss using sector analysis of the cumulative defect curve and other procedures. Methods Visual fields of 260 glaucomatous eyes were analyzed over 2.8 years (SD = 1.2) with at least five examinations (mean 6.9; SD = 2.0) using Octopus 311 perimeter and TOP strategy. The authors applied Threshold Noiseless Trend (TNT) program, which performs local filtering of threshold to reduce fluctuation, and analyzed five criteria: 1) a score based on significant progression of eight sectors of the cumulative defect curve (CD); 2) a score based on the presence of points (PO) with significant progression; 3) global progression (GL) of all local deviations; 4) progression of mean defect (MD); 5) progression of the square root of loss variance (sLV). The authors estimated false diagnoses (FD), randomly reordering examinations of each patient. An index of focality of progression (FI) was obtained. Results sLV presented low sensitivity and GL low specificity. CD and PO presented twice the sensitivity of MD, often proving earlier indicators. The authors observed significant progression of some of the three criteria in 17.5% of the cases when MD <6 dB and in 20.7% when MD >6 dB (FD=5.7%). Agreement between two criteria occurred in 6.8% of cases with MD <6 dB and in 11.6% when MD >6 dB (FD=1.9%). Result reproducibility in successive examinations was observed in 9.9% of cases (FD=1.3%). Focality of progression increased with MD. Conclusions PO and CD indicate suspected progression earlier than MD. Reproduction of results in successive examinations or agreement between criteria allows confirmation of progression.

Diagnostic ability of a new method for measuring haemoglobin levels in the optic nerve head in multiple sclerosis patients

Aims To evaluate a new method for measuring haemoglobin (Hb) levels and quantifying the colour changes in the optic nerve head of multiple sclerosis (MS) patients to detect axonal loss and consequently optic disc atrophy. Material and methods 40 MS patients and 40 age and sex-matched healthy subjects were included in this prospective cross-sectional study and underwent a full ophthalmological examination, including three photographs of the optic disc. The Laguna ONhE (‘optic nerve hemoglobin’; Insoft SL, Tenerife, Spain) software was used to obtain the Hb analysis in each of the 24 sectors and average Hb of optic disc photographs acquired. Reproducibility of measurements provided by Laguna ONhE program was analysed. Results MS patients showed significant reduction of optic disc Hb percentages in average Hb (58.99% in MS, 65.39% in healthy subjects; p<0.001) and in almost all analysed sectors with the largest differences in temporal sectors. Laguna ONhE program showed good reproducibility measuring Hb percentages in MS patients and healthy subjects. Conclusions Measurements of optic disc Hb levels obtained with Laguna ONhE software had good ability detecting optic atrophy and axonal loss in MS patients. This method had good reliability and is easy to implement in routine clinical practice.

Chronic pseudophakic endophthalmitis versus saccular endophthalmitis.

Abstract A retrospective survey of 1456 cataract operations done at one hospital from 1991 to 1994 found three cases of chronic pseudophakic endophthalmitis. In two of these cases and one referred from another center, microbiological studies from aqueous humor, capsular bag, and vitreous humor were performed using an identical technique. The histopathology in the three cases showed the presence of microorganisms in the capsular wall, although the cultures were only positive in one case (for corynebacterium species).

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.

Neuro-Fuzzy Nets in Medical Diagnosis: The DIAGEN Case Study of Glaucoma

This work presents an approach to the automatic interpretation of the visual field to enable ophthalmology patients to be classified as glaucomatous and normal. The approach is based on a neuro-fuzzy system (NEFCLASS) that enables a set of rules to be learnt, with no a priori knowledge, and the fuzzy sets that form the rule antecedents to be tuned, on the basis of a set of training data. Another alternative is to insert knowledge (fuzzy rules) and let the system tune its antecedents, as in the previous case. Three trials are shown which demonstrate the useful application of this approach in this medical discipline, enabling a set of rule bases to be obtained which produce high sensitivity and specificity values in the classification process.

The spectrophtal: An instrument for ocular spectrophotometry and fluorophotometry

We describe the technical characteristic of a new instrument, which is controlled by a microcomputer and is aimed at ocular spectrophotometric and fluorophotometric studies. We also discuss some practical applications.

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. Our 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. One 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. To 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 20 years 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 36 s and can be applied repeatedly to verify that sufficient stability …

Detecting Optic Atrophy in Multiple Sclerosis Patients Using New Colorimetric Analysis Software: From Idea to Application.

Abstract Neuro-ophthalmologists typically observe a temporal pallor of the optic disc in patients with multiple sclerosis. Here, we describe the emergence of an idea to quantify these optic disc color changes in multiple sclerosis patients. We recruited 12 multiple sclerosis patients with previous optic neuritis attack and obtained photographs of their optic discs. The Laguna ONhE, a new colorimetric software using hemoglobin as the reference pigment in the papilla, was used for the analysis. The papilla of these multiple sclerosis patients showed greater pallor, especially in the temporal sector. The software detected the pallor and assigned hemoglobin percentages below normal reference values. Measurements of optic disc hemoglobin levels obtained with the Laguna ONhE software program had good ability to detect optic atrophy and, consequently, axonal loss in multiple sclerosis patients. This new technology is easy to implement in routine clinical practice.