Spatial tuning loss of pattern reversal visual evoked response in optic nerve disease.

We compared the pattern reversal visual evoked response (PVER) amplitude-check size functions from 25 eyes (25 normal subjects; visual acuities > or = 20/20) with those from 32 eyes (22 patients; visual acuities 20/15 to 20/50; mean, 20/25.5) with mild optic nerve disease to determine if spatial tuning loss of the PVER occurs in the presence of optic nerve dysfunction. The steady-state PVER was recorded with five check sizes (range, 160 to 10 minutes of arc). To analyze the PVER amplitude-check size function, we calculated the difference between the maximum and minimum PVER amplitudes and then calculated the area of spatial tuning (the area under the function). Values were significantly smaller in patients than in normal subjects (1.81 +/- 1.27 microV versus 5.73 +/- 3.27 microV; F = 41.24, p = 0.0001; 3.87 +/- 2.70 area units versus 12.57 +/- 7.60 area units; F = 38.62, p = 0.0001). There was no shift in the distribution of peak check sizes. Results suggest that a spatial tuning loss occurs in optic nerve disease. The shape of the function, including the area of spatial tuning, appears to be a sensitive indicator of early or mild optic nerve dysfunction.

Pattern-reversal visual-evoked response in bull's eye maculopathy associated with Stargardt's disease.

Using steady-state pattern-reversal visual-evoked response (PVER), we studied the macular function in patients with bull's eye maculopathy. The results were correlated with fluorescein angiography. Study patients with an established (25 eyes of 14 patients) and a suspected (8 eyes of 4 patients) diagnosis of Stargardt's disease with bull's eye maculopathy were divided into group G (good vision group: 15 eyes with visual acuity of 20/40 or better) and group P (poor vision group: 18 eyes with visual acuity of 20/50 or worse). The diameters of the atrophic area and the normal or less affected central area of the bull's eye were measured form the fluorescein angiograms. The mean diameter of the central area in group G (2.0 degrees) was significantly larger than that in group P (0.6 degrees; d.f. = 17, p = 0.0227). The PVER amplitudes were reduced in the patient groups with all check sizes and the amplitude-check size functions were flat. Amplitude differences were observed between the patient groups with the 20' checks (d.f. = 17, p = 0.0638), probably due to the difference in the mean central diameters (2.0 degrees vs. 0.6 degrees). Patients with a perifoveal abnormality can have an abnormal PVER despite relatively good visual acuity. We also recorded the PVER in 7 normal controls tested with simulated ring-shaped scotomas, the sizes of which matched the mean diameters of the scotomas in the patient groups (7.0 degrees x 0.6 degrees and 7.0 degrees x 2.0 degrees). The controls also showed markedly reduced responses with all check sizes.(ABSTRACT TRUNCATED AT 250 WORDS)

Stargardt's disease/fundus flavimaculatus: psychophysical and electrophysiologic results.

Retinal functions were analyzed psychophysically and electrophysiologically in 73 patients (146 eyes) with Stargardt's disease/fundus flavimaculatus. Patients were classified into types 1, 2, 3, and 4; patients with type 3 were subdivided into 3E and 3L (early and late onset of initial symptoms). Most had visual acuity (VA) of 20/200 or greater at initial testing. VA declined 0.25 octave/year during follow-up (mean, 6.1 years). Four of 16 patients (25%) older than 40 years had VA of 20/200 or less in the stronger eye. Psychophysical tests (flicker profile, central scotoma, dark adaptation) showed variable degrees of abnormalities. Electrophysiological tests showed significant photopic b-wave amplitude decreases, particularly in type 3E (42.2% of normal). The electro-oculogram light peak/dark trough ratio was abnormal in 60 of 132 eyes (45.5%), especially in type 3E (25 of 34 eyes, 73.5%). Visual prognosis and overall visual function varied depending upon disease type, location of retinal lesions, and age of onset. In Type 3E, overall retinal function was poorest and accompanied by the most severe decline of central vision and function in the surrounding macula.

[Development of image processing system for fundus video-angiography with non-stroboscopic illumination].

A new recording system for fluorescein video-angiography using a highly sensitive color charge coupled device (CCD) camera was developed. An image processing unit installed in a personal computer made it possible to process video signals from the camera and/or a video tape recorder. Functions of the unit are on-line and/or off-line operations on image data such as smoothing, digital subtraction, differentiation etc. Application of the unit improved the quality of images observed on a monitor screen. This system enabled observation of the ocular fundus with illumination of low intensity, which reduced physical and psychological suffering of patients. In addition continuous and whole sequences of fundus fluorographs were recorded, without using strong stroboscopic lights. Extraction of a clear image from ambiguous records at any moment was possible through off-line processing on the stored data. Furthermore quantification of the blood flow in any blood vessels was possible by subtracting two successive images. With this system, quantitative expression of a slight difference in the color of the fundus could be made through calculation of the ratios among R-, G-, and B-components of signals at any place. Finally, comparative study of images of the fundus with natural color could be made with those of fluorography. These features may provide further information on the physiology and pathology of the fundus.

Cone activation delaying recovery time of rod sensitivity after flash exposure.

The recovery time of rods to the fully dark adapted state after flash exposure was psychophysically and electrophysiologically measured. The recovery time increased abruptly once cones were activated. This abrupt increment was not found for the receptor component (P III) of the frog electroretinogram. It was suggested that the cone activation results in inhibitory influence upon the recovery process of the rod sensitivity.