Biomedical subjects

A Jenni

Publications and source records attributed to A Jenni.

5 recordsLinked to original sources

PubMed1990

Evaluating a perimetric expert system: experience with Octosmart.

When evaluating expert systems to be used in clinical perimetry, various aspects of their performance as compared with that of human interpreters must be considered. In this investigation, the results produced by the new Octosmart diagnostic program have been compared with the performance of three interpreters with various amounts of experience in visual field analysis. The evaluations were based on 27 visual fields with glaucomatous damage, which had been examined with the Octopus program G1. It is shown that in borderline cases (i.e., neither clearly normal nor clearly pathological) where strict statistical criteria must be employed in order to distinguish between possible pathology and artifacts, the "personal styles" of human interpreters, more than standardized decision criteria, implicitly guide the decision process, resulting in unpredictable, non-standardized interindividual differences. A standardized expert system, based on constant, explicit, and logical criteria is therefore considered to be superior to unaided human interpretation. It is pointed out that the influence of the implicit decision criteria of human interpreters must be controlled carefully if expert systems are to be evaluated with reference to human interpreters.

Analysis of Variance↗

PubMed1990

A comparison of cupola-free perimetry with conventional perimetry: preliminary results.

In the comparison of ten normal and two pathological visual fields, excellent agreement was found between examinations made with Octopus perimeters (types 201 and 500) and a prototype version of a new cupola-free perimeter (CFPP). The examination of a single glaucomatous visual field, however, exhibited an elevated mean defect value with the prototype instrument in comparison with Octopus 201 examinations of the same visual field. Although this difference may be easily explained by long-term fluctuation effects, further investigations based on a broader empirical basis will be required. Based on the results of this preliminary work the following remarks can be made with respect to the cupola-free perimeter: provided that the zero point of the dB scale is chosen appropriately, ie, with a stimulus luminance of about 4,000 asb used as the 0 dB level, the same differential light sensitivity (DLS) values for normal visual fields can be obtained with the CFPP as with all Octopus models (201, 500, 2000). Within the limits of measurement error, the same decrease of DLS was found with the CFPP as obtained using the other perimeters for test locations (of the G1 program), ranging from the center out to an eccentricity of 30 degrees. Thus it appears that the normal values as used in the other Octopus perimeters can also be utilized in this cupola-free instrument within this range.

Adult↗

PubMed1990

Evaluating human and automated interpretation of visual field data in perimetry.

The complexity of visual field result evaluation has increased with the advent of automated perimetry. This in turn makes software assistance such as provided by the new Octosmart program interesting and desirable. Its accuracy and reliability in visual field evaluation must be tested, though, and the testing methodology itself must be developed. For this purpose, 27 visual fields were evaluated by three human interpreters and the Octosmart program. Based on a newly developed compound index, the performance of the three interpreters and Octosmart is described and a high degree of consistency is demonstrated.

Diagnosis, Computer-Assisted↗

PubMed1988

Extrapolating global visual field indices from local parameters in the nasal region.

The local mean and the average difference of four pairs of test locations within the 26 degrees visual field, situated above and below the horizontal nasal meridian, were used to predict the global field indices MD and CLV of the Gl glaucoma program. Out of 539 examinations (194 eyes suspected of having glaucoma), the local indices NDIFF (describing asymmetrical behavior around the nasal horizontal meridian), ND0 (the mean defect in the nasal region), and the global indices MD and CLV were calculated. Seven hundred fifty-five examinations (446 normal eyes) served as a control group. First and second examinations of 146 glaucoma suspect eyes were used to calculate the retest reliability scores for the indices in question. When analyzing the glaucoma suspects, the local index NDIFF, together with the local mean defect, ND0, yielded highly reliable estimates of the global indices MD and CLV, with a retest correlation r = 0.86 for NDIFF, and r = 0.96 for ND0. The covariance of NDIFF with CLV was r = 0.67, while the co-variance of MD with ND0 was r = 0.95. The ranges of the local indices ND0 and NDIFF were each classified into 'normal range' and 'range of suspected pathology', in analogy to the normal and pathological ranges of the global field indices. Equivalence of the local indices with the corresponding ranges of MD and CLV was investigated and the results are shown. The establishment of local indices may prove to be a powerful tool in early detection of glaucomatous damage.

Glaucoma↗

PubMed1978

[Practical experiences with the Octopus automatic perimeter (author's transl)].

A statistical analysis comparing the results of more than 1000 visual field examinations carried out with the automatic perimeter Octopus and with a conventional Goldman-perimeter, clearly demonstrates the superiority of the automatic instrument in many respects: Apart from a higher precision of the perimetric measurements (smaller fluctuations), a better reproducibility of the results (larger correlation coefficients) is noticed. Due to great ease of operation of the automatic perimeter, the ophthalmologist is discharged from the time-consuming task of perimetric examinations.

Computers↗