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  • 1
    ISSN: 1573-2622
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Documenta ophthalmologica 85 (1993), S. 115-124 
    ISSN: 1573-2622
    Keywords: Electro-oculogram ; Electrophysiology ; Retina ; Retinal pigment epithelium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The electro-oculogram is a widely used electrophysiologic test, but recording techniques vary among different laboratories. This Standard, approved by the International Society for Clinical Electrophysiology of Vision (ISCEV), describes simple technical procedures that will allow reproducible and comparable electro-oculograms to be recorded under a few defined conditions. The document is intended to improve the comparability of electrooculogram data obtained throughout the world by guiding both clinicians and manufacturers, and ISCEV recommends that future published reports indicate whether the recording technique meets the international Standard.
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  • 3
    ISSN: 1573-2622
    Keywords: Electroretinogram ; Intensity-response function ; International Standard for Clinical Electroretinography ; Normative values
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The internationalStandard for Clinical Electroretinography requires a minimum of 5 standard response types. In a sample of 20 healthy subjects, the normative values according to this standard were established. Since the distribution of amplitude and implicit time does not follow a Gaussian distribution, we have found the median value and the 1st to 99th percentile or the 5th to 95th percentile useful for determination of abnormality, presented here separately for intraindividual and interindividual variation. To improve quality and reliability, we propose that individual laboratories extend the minimum standard and record the standard responses as parts of a stimulus series of increasing intensity. The normal value of the b/a ratio can easily be established from the maximum response to the Standard for Clinical Electrophysiology standard flash, pointing to abnormalities especially in circulatory disturbances and in degenerative diseases of the retina. The b/a ratio is between 1.5 and 1.7. If flicker responses are recorded at the 1st and 10th minutes after the onset of the rod saturating adaptation light (25 cd/m2), an increase in amplitude can be observed, which in our sample has a relative value of 1.3. A reduced increase in cone response amplitudes during light adaptation might point to abnormality within the rod/cone interaction. Responses from the cone system can be further differentiated by the use of chromatic stimuli. With appropriate filters, short-wavelength cone-sensitive and long-wavelength cone-sensitive responses can be differentiated also in clinical daily practice, which might be helpful for further differentiation of cone disorders. Regular measurements of intraindividual variability can help to improve the quality of electroretinogram recordings. Medians and ranges between the 1st and 99th and the 5th and the 95th percentiles were determined for all recordings for interindividual, as well as for intraindividual variations.
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  • 4
    ISSN: 1573-2622
    Keywords: Clinical electrophysiology ; Electroretinogram ; Pattern electroretinogram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The pattern electroretinogram is a retinal response that can be evoked by viewing an alternating grating or checkerboard. It is receiving increasing clinical and research attention because it can provide information about inner retinal cells and the macula. However, clinicians may have trouble choosing between different techniques for recording the Pattern electroretinogram that have been described in the literature. The International Society for Clinical Electrophysiology of Vision has prepared guidelines for a basic pattern electroretinogram recording procedure to aid new users in obtaining reliable responses and to encourage more uniformity among existing users.
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  • 5
    ISSN: 1573-2622
    Keywords: diabetes ; electroretinography ; maculopathy ; multifocal ERG ; optic nerve atrophy ; retinal dystrophy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The multifocal ERG using the m-sequence stimulation technique allows the derivation of 61 – 241 local ERG signals in a central visual field of about 60 degree diameter in a short time between 4 and 16 min. A recording in a light adapted state offers local information comparable to cone responses in the full-field ERG. Retinal functional losses due to regional disorders in outer retinal layers can be described in detail with this technique. In maculopathies decreased or absent central ERGs are found surrounded by normal ERG. The extent of the central lesion can be estimated. In diseases of the outer retina the pattern of distribution of multifocal ERG activity is similar to the the pattern of the visual field defect. In addition to decreased ERG amplitudes a delay of implicit time may be an important sign of pathology, i.e. the pronounced delay of implicit times in the periphery in retinitis pigmentosa and the implicit time delays in regions associated with retinal edema like CRVO and cystoid macula edema in intermediate uveitis. No simple correlation of the first order kernel multifocal ERG and field defects could be found in disorders of the ganglion cell layer. The multifocal ERG is therefore useful in the differential diagnosis of retinal and optic nerve diseases.
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  • 6
    ISSN: 1573-2622
    Keywords: animal model hereditary retinal degeneration ; clinical electrophysiology ; multifocal ERG ; scanning-laser ophthalmoscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Introduction: Multifocal electroretinography (MF-ERG) is widely used in the detection of local retinal dysfunction. However, the position of the stimulus on the retina and the stability of fixation are usually not directly accessible. Thus, devices have been designed for a continuous fundus visualization during recording. Methods: MF-ERGs were recorded with a RetiScanTM system connected to two different Scanning-laser ophthalmoscopes (SLOs) that use either a red (633 nm) or green (415 nm) laser for stimulation, and a VERISTM 4 system connected to a piggyback stimulator prototype that added the stimulus to the optical pathway of the SLO by means of a wavelength-sensitive mirror. Fundus visualization was achieved with the infrared lasers of the SLOs (780 and 835 nm). Results: The most extensive study so far with a green laser stimulus in a cat model of retinal degeneration demonstrated the capability of the device to detect retinal landmarks and the different stages of degeneration. Also, the advantages of exactly reproducible stimulus positioning for averaging within and comparison between disease groups became apparent. The results with the same setup in transgenic mice suggest a pure cone origin of the responses. In humans, recordings show that fixation is sufficiently good in most subjects. It is not clear yet whether red or green laser stimulation (or both) is preferable. The results with the prototype were very similar to the MF-ERGs obtained with a standard CRT screen. Conclusions: All three devices allowed us to record MF-ERGs with continuous fundus monitoring. Although further refinements are necessary, it is obvious that fundus controlled methods will improve the reliability of MF-ERG in future research on glaucoma, transplantation studies, and evaluation of gene therapy.
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  • 7
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  · Purpose: The aim of the present study was to test the influence of smoking on colour perception. · Subjects and methods: At the University Eye Hospital Tübingen, 76 generally healthy smokers with inconspicuous ophthalmological findings (visual acuity, refraction, intraocular pressure, morphology) were examined by the cap-sorting test, Roth 28-hue desaturated. Group 1 was comprised of smokers (n=20; M 9, F 11; mean age 28.1±10.3 years) with a smoking consumption of less than one packet of cigarettes per day (8.4±5.3 cigarettes/day) for 9.1±8.3 years. Group 2 consisted of smokers (n=32; M 22, F 10; mean age 28.6±9.7 years) with a smoking consumption of one or more than one packet per day (30±8.4 cigarettes/day) for 9.5±8.3 years. Generally healthy and ophthalmologically normal non-smokers served as a control group (n=76; M 41, F 35; mean age 30±9 years). · Results: The average error score of the control group was (median±mean absolute deviation) 42±18. Group 1 showed no difference to the control group (51±27; P=0.42). On the other hand, group 2 had a significantly higher error score than the control group (102±45; P〈0.0001). · Conclusion: Otherwise healthy smokers with a cigarette consumption of less than 20 cigarettes per day do not show any disturbances in colour vision. Smokers who consume more than 20 cigarettes per day may suffer colour vision defects as a result.
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  • 8
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  · Background: Tumors compressing the optic pathway may lead to irreversible loss of vision which may be detected by the pattern electroretinogram (PERG) because of its relation to ganglion cell function. · Methods: Eyes of 19 patients were tested shortly before and 5–10 days after tumor surgery. Visual acuity, the 30-deg visual field and the transient and steady-state pattern reversal ERG were measured. · Results: Using patterns of 1.5×1.2 deg there was a good correlation between the change of pre- and post-surgical visual performance and most of the pattern ERG amplitudes. For all variables tested – P50, N95 and steady-state amplitude – there was a critical value beyond which the visual outcome could be bad or favorable, whereas patients showing higher amplitudes always remained stable or improved after surgery. · Conclusion: The positive correlation between pattern ERG amplitudes and the post-surgical outcome in the case of tumors affecting the optic pathway may be helpful in predicting the outcome for these patients.
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  • 9
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  · Background: The Night Vision Spectacles (NiViS) were developed by a consortium of European companies to assist individuals who suffer from impaired night vision. They consist of a head-mounted video camera (input) and binocular displays (output) connected to a portable computer processor, which uses an algorithm to enhance the luminance and contrast of the video image. · Methods: Eighteen patients with impaired night vision were tested, including those with retinitis pigmentosa (7), Usher syndrome (2), fundus albipunctatus (1) and complete (4) and incomplete (4) congenital stationary night blindness. Normal trichromats (3) and typical, complete achromats (2) acted as controls. A battery of tests assessed: visual acuity at 5 m (projection unit) and 1 m (chart) and at high and low contrasts; contrast sensitivity; absolute and increment threshold; the influence of glare; contrast motion detection; and hand-eye performance. The tests were performed, with and without the NiViS, at three adaptation levels: low scotopic (10–3 cd/m2), high scotopic (10–2 cd/m2) and mesopic (10–1 cd/m2). · Results: At the low and high scotopic levels, the majority of patients showed improved performance on the visual acuity, contrast sensitivity and motion contrast tests with the NiViS. At the mesopic level, the advantage with the NiViS was greatly reduced, but still present for contrast sensitivity. · Conclusion: Patients with impaired night vision can benefit from the NiViS when performing tasks involving contrast and motion perception. Those with normal visual fields and retaining good photopic vision will benefit more than those with constricted visual fields and impaired cone vision. Recommendations regarding desirable improvements of the NiViS and suitability for the individual patient are given.
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  • 10
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  · Background: Usher syndrome is a genotypically and phenotypically heterogeneous group of autosomal recessive diseases featuring retinitis pigmentosa (RP) and sensorineural hearing loss. A general ciliary dysfunction has been suspected following reports of a mutated cytoskeletal protein (myosin VIIA) in type IB, and preliminary data has suggested an olfactory deficit. The purpose of this study was to quantitatively assess olfactory function in Usher syndrome patients and to search for a correlation between the degree of impairment of the three sensory systems as indication of an underlying ciliary defect. · Methods: 39 patients with Usher syndrome (8 type I, 31 type II) were examined. The ophthalmologic protocol included patient history, visual acuity, eye morphology, Goldmann perimetry, and electroretinography. The ENT protocol included a thorough examination, speech-recognition test, pure-tone audiometry and an olfactory function test. · Results: In both groups, visual acuity was typically 20/40, the remaining visual field area was small, and the ERG responses were low to non-detectable. Average hearing loss was 100% in type I and 40% in type II. Olfactory thresholds were normal [median 9.7 (I) and 8.5 (II) vs 8.5 in the control group]. There were multiple significant correlations between parameters of the same organ, but no relationship between parameters of different sensory systems. · Conclusion: Almost all Usher syndrome patients in this study had an advanced form of RP. In contrast, auditory function differed considerably between type I and type II. An impairment of the olfactory system could not be detected, and there was no correlation between parameters representing visual function, hearing ability, and olfactory sense.
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