Information throughput characteristics--a new method for evaluation of visual efficiency.

A method based on information theory for computer-aided assessment of visual capacity has been elaborated. In this method, the rate of recognition of visual targets is considered along with the accuracy of perception. Measurements are performed in a wide range of optical stimulus intensities (the Landolt ring size ranging from 0.125 to 1.57, in 10 logarithmic steps). For each step the information throughput (IT) is calculated and the results are displayed as a function of stimulus intensity. Thus, the IT characteristics of the visual system, with regard to motor response, are obtained. Within the reported range, they reveal low-pass properties of the system. Preliminary experiments show that these curves are useful in the evaluation of visual performance, especially in ergophthalmology. A recently developed IBM PC-based system for automatic measurements of the IT characteristics is described. Some aspects of application of the method are also discussed.

[The UTAS-E1000 System in electrophysiological studies of the visual system. I. Characteristics of the system and its possibilities and equipment]. / System UTAS-E1000 w badaniach elektrofizjologicznych ukladu wzrokowego. I. Charakterystyka systemu, mozliwosci, rozwiazania sprzetowe.

The paper presents the technical and medical characteristics of the computerized system UTAS-E1000 (made by LKC, USA) destined for the electrodiagnostics of the visual system. Discussed are the properties of the construction which decide on the possibility of automatization of electrodiagnostic tests and also personal experience on the development of the system in order to increase its scope of application.

[The UTAS-E1000 System in electrophysiological studies of the visual system. II. Programming and clinical use]. / System UTAS-E1000 w badaniach elektrofizjologicznych ukladu wzrokowego. II. Oprogramowanie, praktyka kliniczna.

The authors discuss a set of electrodiagnostic tests of the UTAS-E1000 system and their personal work on new tests. They present the scope of applications of the equipment in examinations of some pathological conditions of the visual system and--on the basis of their personal experience--the possibilities of introduction of new electrodiagnostic tests.

[Value of the ERG in the "pattern" type (PERG) in the diagnosis of glaucoma]. / Znaczenie ERG typu "pattern" (PERG) w diagnostyce jaskry.

The authors examined 14 persons (20 eyes) aged 51-77 years with open angle glaucoma and 3 persons (5 eyes) aged 37-59 years who were suspected for this condition. The control group consisted of 23 healthy persons (30 eyes) aged 14-40 years. The PERG results were statistically worked up using the t-Student test. Full clinical examinations and PERG were performed by means of the UTAS E-1000 system of LKC (USA) production according to modified by the authors method of May and coworkers. In the observed glaucoma group the authors revealed a statistically significant reduction of the interpeak values of the PERG in comparison with the control group; this points to a lesion of the ganglion cells in the course of this disease. The modified and adapted for the UTAS E-1000 method of May and coworkers and the applied system of conductors ensured the optimal reception of the PERG signals i.e. the maximal amplitude with minimal disturbances.

[Electrophysiologic tests for diagnosis of congenital night blindness]. / Badania elektrofizjologiczne w diagnostyce wrodzonej slepoty nocnej.

UNLABELLED: Electrophysiological study in diagnosis of congenital stationary night blindness. MATERIAL AND METHODS: The goal of this study was to describe a family with X-linked congenital stationary night blindness (CSNB) in which 3 brothers had similar symptoms: night blindness, reduced visual acuity and "negative" type of Flash ERG. RESULTS: Electrophysiological study permitted to differentiate CSNB from generalized progressive retinal degeneration, what has a prognostic value for these patients.

[Foveal electroretinogram: its application in the diagnosis of macular diseases. Preliminary report]. / Elektroretinogram dolkowy--zastosowanie w diagnostyce chorób plamki. Doniesienie wstepne.

PURPOSE: To present difficult method of recording and analysis of the Foveal Cone Electroretinogram (FCERG, a type of focal ERG) for evaluation of foveal cone function in healthy subjects and patients with different macular diseases. The FCERG signal is of great importance in diagnosis of these diseases because the full-field ERG is dominated by the extrafoveal cones activity. MATERIAL AND METHODS: In this study FCERGs were obtained in 90 healthy subjects (90 normal eyes), several with known macular diseases and subjects with optic neuritis and suspected maculopathy. The fovea was stimulated with a 5-degree flickering light spot surrounded by a 20-degree annulus of steady retinal illuminace. The stimulus was applied to the eye with the use of a hand-held stimulator-ophthalmoscope. FCERG signals were analysed by means of Fast Fourier Transformation method. RESULTS: Mean FCERG amplitudes, phase and standard deviation (SD) values were established in 3 control groups of different age. There was in decrease in amplitude of FCERGs with age, which is a agreement with literature data. In this study significant abnormalities of the FCERG recordings are illustrated in some cases of known macular diseases. CONCLUSION: Our preliminary clinical investigations manifest the value of the FCERGs in objective evaluations of macular diseases undetectable with conventional electroretinography.

[Modification of Bagolini's registration method of normal macular and perimacular electroretinography in normal and selected cases of central retinal diseases]. / Modyfikacja metody Bagoliniego rejestracji elektroretinogramu plamkowego i przyplamkowego w normie i w wybranych przypadkach schorzen centralnej czesci siatkówki.

The authors applied the modified method of Bagolini's et al., who were the first to make use of the technique based on standard stimulation of "pattern" type for simultaneous macular and perimacular ERG registration. UTAS E-1000 system was applied for stimulation and registration of bioelectrical signals. 26 eyes in 16 healthy patients, aged 18 to 41 years (mean 29.5), have been examined. The anterior and posterior segment of all examined eyes was not changed, function of both eyes was normal. The mean values of macular and perimacular potentials and M/P value, that is proportion of macular and perimacular potential and standard deviations have been determined. The examples of pathologically changed macular and perimacular potentials in some diseases of central retina have been presented.

[The significance and interpretation of the electrophysiological and psychophysiological analyses in the diagnosis of glaucoma]. / Znaczenie i interpretacja badan elektrofizjologicznych i psychologicznych w diagnostyce jaskry.

The goal of this paper is to discuss and indicate which electrophysiological and psychophysical tests are useful for diagnosis and monitoring of glaucoma patients. In diagnosis of glaucoma, among electrophysiological methods, the authors perform mainly transient and steady-state pattern electroretinogram (PERG). Steady-state as well as transient PERG have the best sensitivity and specificity in diagnosis of this disease even in its early stages. Pattern visual evoked potentials (PVEPs) are less sensitive and specific, that is why this examination is rare in practical use. The authors describe the method of PERG, discuss most frequent mistakes in the method and interpretation of the obtained results. Among psychophysical tests the authors emphasize the significance of short-wave-length perimetry (blue-on-yellow) and standard static perimetry in early diagnosis of glaucoma. On the basis of literature, the authors present also other psychophysical methods, which can be applied in diagnosis of glaucoma.

[Assessment of foveal function in eyes of patients with exudative age-related macular degeneration before and after argon laser treatment]. / Ocena funkcji dolka w oczach z wysiekowa postacia zwyrodnienia plamki zwiazanego z wiekiem pacjentów przed i po leczeniu laserem argonowym.

PURPOSE: 1. Can foveal cone electroretinogram (FCERG) be a useful diagnostic test in evaluation of efficacy of argon laser treatment in eyes with exudative (wet) age-related macular degeneration (AMD)? 2. Comparison of FCERG with visual acuity, static perimetry and fluorescein angiography results. MATERIAL AND METHODS: FCERGs were recorded from 30 eyes with mean visual acuity 0.6 (Snellen Table) of 20 patients (mean age: 61 years) with wet AMD. The fovea was stimulated with 5-degree flickering light spot (f = 31.25 Hz), surrounded by a 20-degree annulus of intensive steady retinali illuminance. FCERGs were recorded and analysed in amplitude according to the computer-aided method recently put in practice in our laboratory. FCERGs were obtained twice for each AMD patients: before and 3 months after argon laser treatment. Electrophysiological data were also compared with the results of fluorescein angiography, visual acuity and static perimetry. RESULTS: In the group of patients with wet AMD, significant increase of FCERG amplitude (p < 0.001) after laser treatment was obtained in group I (33% of analysed eyes) and there were mainly patients with extrafoveal choroidal neovascularisation (CNV). Significant decrease of FCERG amplitude (p < 0.01) was obtained in group II (67% of analysed eyes). These were mainly patients with subfoveal CNV and also with extrafoveal CNV. In both groups after laser treatment we did not receive significant changes in visual acuity and macular perimetric mean sensitivity. CONCLUSIONS: These findings suggest that foveal cone ERG can be a useful, independent from fluorescein angiography, test for objective evaluation of efficacy of argon laser treatment in patients with wet AMD, opposite to visual acuity and static perimetry (macula threshold) examinations. FCERG probably indicates patients with better or worse prognosis.

[Oscillatory potentials in electroretinographic evaluation of retinal function in insulin-dependent diabetics without retinopathy]. / Potencjaly oscylacyjne w elektroretinograficznej ocenie funkcji siatkówki u pacjentów z cukrzyca insulinozalezna bez objawów retinopatii.

PURPOSE: Can oscillatory potentials be a useful method for detection of retinal dysfunction in insulin-dependent diabetics without retinopathy? MATERIAL AND METHODS: In this study scotopic oscillatory potentials (OPs) were obtained in 35 subjects (70 eyes) with insulin-dependent diabetes without retinopathy (mean disease duration--5 years) and in 15 healthy subjects (30 eyes). This examination was performed according to the recommendations of the International Society of Clinical Electrophysiology of Vision (ISCEV). The oscillatory potentials were extracted from the maximal combined response by high-pass filtering. We analysed amplitude and peak-latencies of the first three electroretinographic oscillatory potentials O1, O2, O3, index of wavelets [sum of amplitudes (O1 + O2 + O3)] and compared with the results of the control group. RESULTS: In group of patients with insulin-dependent diabetes without retinopathy, we received statistically significant reduction of amplitude O1 (p < 0.003) and index of wavelets (p < 0.04). Reduced amplitude O1 was obtained in 10%, index of wavelets in 31.4% of analysed eyes. We didn't observe statistically significant changes in amplitudes O2, O3 and latencies O1, O2, O3. CONCLUSIONS: Our results suggest that retinal dysfunction is present in insulin-dependent diabetics without retinopathy 5 years after onset of the disease. The sum of amplitudes (O1 + O2 + O3) was the most sensitive parameter of retinal abnormalities. It seems reasonable to have more frequent ophthalmological examination of the diabetics with abnormal oscillatory potentials.

Electro-oculogram in patients with neurofibromatosis type 1.

PURPOSE: The electro-oculogram (EOG) is a powerful test to evaluate the functional status of the retinal pigment epithelium (RPE). Clinically detectable changes of the RPE desribed in neurofibromatosis type 1 (NF-1) patients include combined hamartoma of the retina/RPE and congenital hypertrophy of the RPE. The goal of this study was to determine whether the function of RPE as measured by EOG is also changed in individuals with NF-1. PATIENTS: Studies were undertaken in 20 patients with clinically diagnosed NF-1 and compared to 16 normal healthy controls. METHODS: Standard EOG and flash ERG recordings were performed in accordance with International Society for Clinical Electrophysiology of Vision (ISCEV) standards. RESULTS: In NF-1 patients the Arden indexes of the EOG test were significantly higher primarily due to the lower values of dark troughs. Supernormal EOGs were present in 60% of NF-1 patients in comparison to the control group mean +2 SD. No one patient showed so high abnormalities during flash ERG examination. CONCLUSIONS: Dysfunction of the RPE may be characteristic feature of individuals with NF- 1.