Biomedical subjects
Publications and source records attributed to A Hobley.
Disturbances in colour vision are a well-reported adverse ocular effect to toxic levels of digoxin. We present a case history of a patient with both colour vision changes and transient visual field defects to therapeutic serum levels of digoxin.
The visual field results from 104 eyes with early glaucomatous loss and 1860 normal eyes have been used to derive the relationship between sensitivity, specificity and the number of test locations in a visual field screening test. A logarithmic relationship was found between sensitivity and the number of test locations and a linear relationship between specificity and the number of test locations. The results indicate that large numbers of test locations are not required to reach high levels of sensitivity and that clinically it might be better to screen all patients with a few stimuli quickly than to examine carefully those patients who meet a precondition such as raised intraocular pressure or abnormal disc appearance.
The visual fields and intraocular pressures (IOP's) of 115 normal volunteers and 107 suspect/diagnosed early glaucoma subjects were recorded by Friedmann static perimetry and noncontact tonometry or applanation tonometry. The visual field data were analyzed statistically and quantified numerically by a microcomputer. The readings obtained from the suspect/diagnosed early glaucoma subjects were compared to those from an age-matched control group according to four criteria: highest field score; field score asymmetry; highest IOP; and IOP asymmetry. A combined field score and asymmetry analysis was found to be more sensitive, 86%, than a combined IOP and IOP asymmetry analysis, 56%. The combined field score and field score asymmetry analysis also gave a clear bimodal separation of subjects with early visual field defects from those with normal visual function.