Biomedical subjects

A Junghardt

Publications and source records attributed to A Junghardt.

5 recordsLinked to original sources

PubMed1998

[Critical (foveal) flicker fusion frequency (CFF) is helpful in differential diagnosis of organic lesions from orthoptic amblyopias].

PURPOSE: To measure critical (foveal) flicker fusion frequencies (CFF) in normal eyes, unilateral maculopathies and neuropathies and in orthoptic amblyopias. METHODS: A newly developed apparatus (4F) with LED's measured subjective foveal CFF by ascending and descending mode in a group of normals and patients. RESULTS: The apparatus (4F) measures temporal resolution. Foveal CFF ist more reduced in neuropathies than in maculopathies. In contrast, CFF in amblyopic eyes is hardly reduced, in most cases equal or better than in the dominant fellow eye. This is independent from the visual acuity of the amblyopic eye. CONCLUSION: CFF testing is useful in the evaluation of unexplained (unilateral) reduction of visual acuity. A dissociation between visual acuity and CFF (within normal range) is present in cases of amblyopia.

Amblyopia↗

PubMed1996

Reproducibility of the data determined by scanning laser polarimetry.

BACKGROUND: Scanning laser polarimetry is a tool for measuring the retinal nerve fiber layer: both its cross-sectional surface (polarimetric data analysis) and its thickness (mean sector values). METHODS: Two observers examined 56 normal volunteers twice by means of scanning laser polarimetry (Nerve Fiber Analyzer type 1, software version 1.6). Measurements of the retinal nerve fiber layer were carried out in four equal sectors of a circle around the optic nerve head. The measured values of the sectors and the calculated ratios among them were used for statistical analysis. Interobserver and intraobserver reproducibility were analyzed following a balanced random three-way cross classification with interactions. Interobserver reproducibility was defined as the part of variance not influenced by the observers. Intraobserver reproducibility was defined as the part of variance not influenced by the time. RESULTS: For repeated measurements of the retinal nerve fiber layer, better intraobserver than interobserver reproducibility was found (0.57-0.79 vs 0.11-0.44). The interobserver reproducibility was improved (0.24-0.65) in comparison to the intraobserver reproducibility (0.32-0.68) by calculating the ratios of the measured values. CONCLUSION: The instrument is clinically useful only if used by the same observer. If measurements are performed by different observers the ratios of the measurements must be used. Further development in the apparatus is needed to improve interobserver reproducibility.

Adolescent↗

PubMed1995

Pattern electroretinogram, visual evoked potential and psychophysical functions in maculopathy.

To compare pattern electroretinograms and visual evoked potentials with psychophysical examinations, such as visual acuity, static (automated) perimetry and color vision in unilateral maculopathies of various origins, 20 patients with unilateral retinal diseases within the macula and the posterior pole were tested. Pattern electroretinography, visual evoked potential testing and static perimetry (Octopus program M1) were performed with three different test field sizes (20 degrees x 20 degrees, 10 degrees x 10 degrees and 6 degrees x 6 degrees). The best correlation in all three test field sizes was found between visual acuity, static perimetry and visual evoked potential. This result is surprising, since central area defined functions (visual evoked potentials, visual acuity) correlated well with a total area integrating function (mean defect in static perimetry. The pattern electroretinogram, which seems to reflect an area-related function as well, showed a correlation to static perimetry only in the smaller 10 degrees x 10 degrees and 6 degrees x 6 degrees fields and not a significant correlation in the 20 degrees x 20 degrees field. Smaller stimulation fields may therefore produce sharper results in pattern electroretinographic testing. There was no correlation between pattern electroretinograms and visual evoked potentials or visual acuity. The pattern electroretinogram was recorded under monocular and binocular viewing conditions. In 60% of the patients, the amplitude of the affected eye was more reduced in the monocular than the binocular viewing condition; the healthy fellow eye controlled stable fixation of the affected eye more readily during binocular pattern electroretinogram registration. The degree of the color vision disturbance (C-index, desaturated panel D-15 test) did not correlate to any of the other examinations.

Adolescent↗

PubMed1993

Pattern electroretinogram and visual evoked potential amplitudes are influenced by different stimulus field sizes and scotomata.

The pattern electroretinogram and the visual evoked potential were recorded simultaneously with various stimulus fields and artificial scotomata of increasing sizes. In contrast to an earlier study, a smaller check size (20') and two stimulus field sizes (20 degrees x 20 degrees and 10 degrees x 10 degrees) for the scotomata were used. With a concentric decreasing stimulus field, a reduction of both the pattern electroretinogram and visual evoked potential was found. Both showed a simultaneous reduction of amplitudes, but, compared with the amplitude in the full field, the reduction was more extensive for the pattern electroretinogram at each test field size. This implies a greater contribution to the pattern electroretinogram from more eccentric retinal parts. An artificial central scotoma of increasing size in the 20 degrees x 20 degrees field had less influence on the pattern electroretinogram than on the visual evoked potential. The percentage amplitude loss of the visual evoked potential was more pronounced. The visual evoked potential was eventually abolished by a scotoma size from 10 degrees x 10 degrees upward, while the pattern electroretinogram was still registrable. When scotomata of similar size were introduced in a smaller (10 degrees x 10 degrees) field, percentage pattern electroretinogram and visual evoked potential amplitude losses were less separated than in a larger (20 degrees x 20 degrees) test field.

Adult↗

PubMed1991

[Is there an ideal surgical time for retinitis pigmentosa patients with cataract?].

According to the literature, a fully developed cataract should be removed generally when the macula is intact. However, patients with a slowly progressing retinal disease find themselves in a particularly difficult situation. In this clinical, retrospective study, 24 retinitis-pigmentosa (RP) patients after cataract surgery were asked whether they recommend cataract surgery early or late in the course of the development of the retinal disease. A correlation was found between the answers to this question and the time elapsed between each patient's own operation and his interview. Three preference groups resulted through statistical evaluation: 1) those who recommend an early operation (n = 8), 2) those who recommend a late operation (n = 8), and 3) those who were undecided (n = 8). All patients had been operated at the same time following the RP onset and cataract diagnosis. Those patients who preferred a late operation had been questioned in this regard considerably later after their own operation than those who preferred an early operation. In other words, the preference for an early or late operation depended on how much prior to the questioning the patient's own operation had been conducted. The RP patient, quite disease conscious, has an exact conception of the ideal time of cataract operation in RP patients in general, but this does not always coincide with the opinion of his physician. It is considerably more necessary to consider the individual situation of the RP-patient than that of normal cataract patients.

Cataract Extraction↗