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  • 1
    ISSN: 1573-2622
    Keywords: luminance electroretinogram ; pattern electroretinogram ; point-spread function ; straylight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It is generally accepted that the pattern electroretinogram for very large spatial elements is the result of local luminance stimulation. Responses due to the luminance differences between elements may be assumed to be relatively unimportant because in the case of large elements only few retinal units are stimulated by gradients. With decreasing pattern element size one wonders to what extent the electroretinogram continues to be based on the local luminance stimulation. We investigated this question using 8 Hz checkerboard reversal and compared the pattern recordings with the recordings resulting from the same stimulus field modulated homogeneously (focal electroretinogram). A 100% modulated checkerboard at retinal level may be considerably less modulated because of imperfect optics of the eye. So the pattern electroretinogram should be compared with homogeneous field stimulation of correspondingly lower modulation depth. On the basis of the optical transfer properties of the eye we compared by subtracting the proper focal electroretinogram from the pattern electroretinogram. The difference response was virtually zero for check sizes larger than 120′. For checks from 60′ down the difference response was of the same order of magnitude as the adjusted focal recording. This difference response for eyes with normal optics is largest around 30′; its wave form was found to be rather invariant with check size.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-2622
    Keywords: Competer ; automatic perimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We evaluated the perimetric concept and the technical construction of the Competer. The testprocedures of the Competer are well conceived. The screening-strategy may fail in cases of central islands or large central defects. The interpretation of the visual field results is not easy, due to the use of a numerical print-out which, in addition, is different for screening and threshold examinations. The mechanical and electrical construction of the instrument could be improved. In the accompanying paper (Graniewski et al., 1982) results are presented of a comparative clinical evaluation.
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  • 3
    ISSN: 1573-2622
    Keywords: Fieldmaster 101 PR ; automatic perimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The perimetric concept and the technical construction of the Fieldmaster 101 PR were evaluated. 64 eyes of patients and 10 normal subjects were examined. We conclude that the Fieldmaster is a well-engineered instrument, using an inefficient test strategy. The presentation of visual field results could be impoved. Clinical results of the patient examinations are presented.
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  • 4
    ISSN: 1573-2622
    Keywords: Ocuplot ; automatic perimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The perimetric concept and the technical construction of the Ocuplot were evaluated. The mechanical and electrical construction of the instrument we tested was poor. The manufacturer claims improvements in newer specimens. We examined 87 eyes of patients and normal subjects with the Ocuplot and learned that the test-strategy is not efficient and yields a high proportion of false positive results. Clinical results of the patient-examinations are presented.
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  • 5
    ISSN: 1573-2622
    Keywords: Friedmann Visual Field Analyser Mark II ; perimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The perimetric concept and the technical construction of the Friedmann Visual Field Analyser Mark II (VFA Mk II) were evaluated. This instrument for multiple stimulus static campimetry of the central 25° is the successor of the Friedmann VFA Mk I. The number of stimuli is increased (99 vs. 47) and the console is improved. The positions of the presented stimuli are indicated on a LED-monitor. The mechanical and electrical construction of the VFA Mk II appeared to be good. 106 eyes of patients and normal subjects were tested and we conclude that the larger number of stimuli, though improving the chance of detecting small defects, complicates the manual registration and the interpretation of clinical results and prolongs the test, especially in the case of visual fields with substantial defects.
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  • 6
    ISSN: 1573-2622
    Keywords: Filtering surgery ; cataract extraction ; central visual island ; visual field defect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Fifty advanced glaucoma patients with central visual field islands were evaluated before and after intra-ocular surgery with respect to visual acuity and visual field behavior. Thirteen patients underwent a cataract extraction, and 37 a filtering procedure. Visual acuity generally improved to a certain extent after lens extraction, and deteriorated after filtering surgery. For both groups the visual field island became somewhat larger with respect to the surface area, but the foveal value was usually lower after the operation. There was no clear relationship between visual acuity and foveal values or the surface area of the central island. One patient suffered unexplained loss of central vision.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Documenta ophthalmologica 73 (1989), S. 255-274 
    ISSN: 1573-2622
    Keywords: red glasses ; retinitis pigmentosa ; visual function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract As a consequence of animal studies reduction of the light regimes have been tried on patients with retinitis pigmentosa. The trials have been very limited and have not given reason for hope that such reduced light therapy may be beneficial. However, RP patients trying red glasses have reported acute subjective improvement of their visual function. It was the purpose of this study to try to document the reports more objectively. Five visual functions were tested with and without red glasses with the following results: 1. Visual acuity and contrast sensitivity. For one volunteer a small reproducible improvement was found. 2. Color vision. In most cases deterioration was found of already deficient color vision. 3. Visual fields. For volunteers with relatively preserved vision no difference or slight deterioration was found. For the other volunteers slight improvements were found. 4. Intraocular light scatter. No differences were found. 5. Dark adaptation. Improvements were found when the glasses were used as adaptation aid according to the method of Trendelenburg (rod function). For cone function no difference was found upon continuous wearing of red glasses. In conclusion: use of red glasses does not seem to be of great benefit as a rule. On the other hand, apart from the reduction in color discrimination no serious disadvantages seem to be inherent in their wear by RP patients.
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  • 8
    ISSN: 1573-2622
    Keywords: Corneal dystrophy ; Glare ; Straylight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The direct compensation method allows for an accurate determination of intraocular light scattering between 3.5 and 25 degrees of scattering angle and is suitable for untrained subjects. The method was used to study light scattering in four forms of hereditary corneal dystrophies. Light scattering is the basis of glare complaints and was compared with visual acuity loss. The findings corresponded to the complaint patterns: in central crystalline dystrophy light scattering can be much increased with relatively well preserved visual acuity. In posterior polymorphous dystrophy the reverse is true. In macular dystrophy (Groenouw II) and lattice dystrophy the situation is more or less intermediate between these two extremes.
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  • 9
    ISSN: 1573-2622
    Keywords: Peripheral iridectomy ; Angle closure glaucoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In 67 eyes of 46 patients with chronic primary angle closure glaucoma, the effect of peripheral iridectomy in lowering the intraocular pressure was investigated retrospectively. In the majority of cases the pressure was reduced. For the whole population the mean reduction was 3.9 mmHg (SD 6.7 mmHg). The presence or extent of peripheral anterior synechiae showed no significant correlation with the amount of pressure reduction. A peripheral iridectomy is still recommended as first step in the treatment of primary angle closure glaucoma.
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  • 10
    ISSN: 1573-2622
    Keywords: Multiple stimulus ; Peritest perimeter ; Single stimulus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In a total of 24 randomly selected eyes of glaucoma patients, tested with the automated (single stimulus) and the manual (multiple stimulus) modes of the semi-automated Peritest perimeter, the numbers and depths of defects were compared as estimated with these two different measurement strategies. It was found that with the manual technique considerably less defects were detected than with the automated strategy.
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