Biomedical subjects

D Birkner-Binder

Publications and source records attributed to D Birkner-Binder.

3 recordsLinked to original sources

PubMed1993

[In incipient glaucoma the pattern electroretinogram displays diffuse, retinal damage].

The pattern electroretinogram (PERG), a noninvasive tool to measure the activity of retinal ganglion cells, shows changes in early glaucoma. We wanted to investigate whether or not the PERG is preferentially affected when the Bjerrum area is stimulated. We recorded the PERG from 17 eyes in 17 patients with initial stages of visual field defects due to open-angle glaucoma and from 10 eyes in 10 normal subjects. Counter-phasing checkerboard patterns were used as visual stimuli with a check size of 0.8 degrees at 16 reversals/s and 98% contrast. Three visual field extents were stimulated: (1) full screen (31 degrees x 27 degrees), (2) central stimulation with a diameter of 14 degrees, (3) peripheral stimulation = full screen with central mask of 14 degrees in diameter. The latter stimulus covers the regions where traditionally glaucomatous defects are expected early. In glaucoma patients, there was a significant decrease in the PERG amplitude compared to normals. This reduction was very similar for all three stimuli (42%, 52% and 47%, respectively). Thus, the PERG amplitude is reduced to a similar degree both in regions of the visual field where early damage is found (Bjerrum area) and in the central area. This result suggests that in early glaucoma there is focal as well as diffuse retinal damage.

Adult↗

PubMed1991

[Pattern ERG in ocular hypertension and glaucoma. Effect of pattern size, contrast and retinal eccentricity].

We have previously shown that check-size-specific changes of the Pattern-Electroretinogram (PERG) can be used to detect early glaucoma. This time we conducted a study to determine whether different check sizes, contrasts and eccentricities can improve the diagnostic yield. We examined 15 normal eyes (15 subjects), 32 eyes (24 patients) in stage I or II glaucoma and 36 eyes (25 patients) with ocular hypertension (OHT). Visual acuity was always better than 0.8. The stimuli were checkerboards, phase-reversing at 16 rev/s. The check sizes were 0.8 degrees or 15 degrees with contrast at 60% or 98%. The stimulation area was either "full-field" (27 degrees x 30 degrees), "central" (less than or equal to 7 degrees) or "paracentral" (greater than 7 degrees). In the glaucoma group, all PERG amplitudes were significantly reduced compared to normals: maximally for stimuli of 0.8 degrees, 98% contrast, full-field to 51% +/- 18%, and least for stimuli of 15 degrees, 98% contrast, central (to 70% +/- 20%). Under paracentral stimulation, the amplitude was reduced to 55% and in the central condition to 64%. The single-most-sensitive stimulus to separate normal and glaucoma patients was 0.8 degrees, 60% contrast and full-field, as the variance was low for this condition. Only 4 patients (8.5%) were incorrectly classified using these parameters; when 8 different stimuli were entered into the discriminant analysis, the rate was marginally reduced to 3 patients (6.4%). Seventy-five percent of the OHT eyes were classified as pathological. These results confirm previous findings that in early glaucoma, PERG amplitudes are more reduced using check sizes of 0.8 degrees compared to 15 degrees.(ABSTRACT TRUNCATED AT 250 WORDS)

Electroretinography↗

PubMed1990

[The pattern electroretinogram in early glaucoma and ocular hypertension].

The pattern electroretinogram (PERG) reflects the activity of the retinal ganglion cells. To assess its value to detect early glaucoma damage, we recorded the PERG in 44 normal eyes, in 52 eyes with early stages of glaucoma, and in 34 eyes with elevated intraocular pressure but normal visual fields (ocular hypertension, OHT). All eyes had a decimal acuity of greater than or equal to 0.8. We used checkerboard patterns for the stimulation with check sizes of 0.8 degrees and 15 degrees, a contrast of 98% and a reversal rate of 16/s. Compared to the controls, in eyes with early glaucoma PERG amplitude was reduced to 50% using 0.8 degrees (p less than or equal to 0.0001) and to 74% using a check size of 15 degrees (p less than or equal to 0.001). However, due to the high interindividual variability, confidence limits overlapped to a large extent. Based on the preferential reduction at 0.8 degrees vs 15 degrees, a sensitivity of 74% and a specificity of 92% were achieved using a two-dimensional logistic regression; 50% of the OHT eyes were thus classified as pathological. These results suggest that the PERG can detect retinal ganglion cell damage before measurable changes in the visual field occur if responses to two check sizes are evaluated.

Adult↗