Bertil E. Damato

The detection of glaucomatous visual field defects by oculo-kinetic perimetry: Which points are best for screening?

Oculo-kinetic perimetry (OKP) uses the patients ocular movements to position a test stimulus in the visual field. By virtue of its simplicity and low cost, this test could be useful in the screening of glaucoma. The general purpose OKP chart, however, which tests 100 points in the central 25° field, is too time-consuming for this purpose, taking approximately 4-7 minutes per eye. Accordingly, this study was performed to identify the points most likely to detect patients with glaucoma. Fifty-one eyes with glaucomatous visual field defects and 51 non-glaucomatous eyes of age matched individuals were tested by conventional and oculo-kinetic perimetry. At least one of only six points were missed by 82.4% of glaucomatous eyes and by 9.8% of non- glaucomatous eyes. These results, although falling short of the ideal efficiency, are comparable with data published by other research groups using computerised equipment and suggest that, with further development, a specialised OKP chart testing only a small number of points might be valuable in screening for glaucoma.

Visual evoked cortical potentials from transient dark and bright stimuli

The superior hemifields of five normal left eyes were stimulated by novel equal and opposite contrast pattern onset stimuli which were generated on a cathode ray tube. Patterns consisted of 144 discs, each subtending 60 min arc at the viewing distance of 40 cm and were separated by a distance equal to their diameter. Equal and opposite light changes were created by presenting the disc patterns with different luminance values on a uniform constant background (20 cd/m2). Transient visual evoked cortical potentials to the appearance and disappearance of the patterns were recorded separately and analysed. Significant amplitude differences between the responses to bright and dark stimuli were observed with light increment responses being 36–53% larger than the light decrement responses for pattern on-set and 54–80% larger for pattern off-set respectively. This finding is attributed to the difference in the input to the ON and OFF Parallel Pathways which are known to carry light increment and decrement information respectively, as well as differences in the metabolic and discharge rates of these pathways.

Oculo-kinetic perimetry: A visual field test for neuro-ophthalmic patients

Conventional perimetry is not always convenient or readily available. A new method, entitled oculo-kinetic perimetry has recently been described which greatly simplifies visual field examination by moving the subjects eye instead of the stimulus. This test is inexpensive, fully portable and simple to perform and can therefore supplement conventional perimetry in non-ophthalmic clinics, by the bedside and in the patients home. In the present study 14 patients with visual field defects caused by intracranial or optic nerve disease were tested by oculo-kinetic perimetry and the results were compared to visual fields plotted using conventional techniques. In 22 eyes the results with the two methods were identical. In five eyes the plotted field defects showed slight differences. Oculo-kinetic perimetry appears to be a useful tool for the measurement of visual field defects in neuro-ophthalmic practice.

B-Lymphocytes from melanoma patients and normal individuals react with melanoma cells but also with irrelevant antigens

Peripheral B-lymphocytes of 13 patients with uveal melanoma and of 5 healthy individuals were transformed with Epstein-Barr virus (EBV). The reactivity of these transformed cells with autologous or allogeneic melanoma cells and lymphocytes was measured by the enzyme-linked immunosorbent assay (ELISA). Antigens which are neither self nor common environmental antigens (i.e., plant protoplasts, schistosome antigen and keyhole limpet haemocyanin) were used for controls. Lymphocyte reactivity with all types of antigen was apparent both in patients with uveal melanoma and in normal controls. The response detected by the techniques available is likely to reflect antibody multispecificity leading to mis-identification of irrelevant antigens.

Monoclonal Antibodies to Uveal Melanoma

Rat monoclonal antibodies were prepared against antigens expressed by uveal melanomas. Uncultured cells from primary human uveal melanomas were used for the rat inoculations and for the screening of hybridomas by enzyme-linked immunosorbent assay (ELISA). One of the monoclonal antibodies, designated 4A3, recognised a cytoplasmic antigen which was relatively specific for melanoma cells and which could be detected by immunohistochemistry in formalin-fixed, paraffin embedded tumour tissue. Western blotting showed the antigen to have a molecular weight of approximately 55–60 kD, with a doublet configuration which showed inter-tumour variation. The antigen was also detected by Western Blotting in the subretinal fluid of patients with uveal melanoma.