Detection of glaucomatous visual field loss with the DAMATO Multifixation Campimeter
Fenerty CH., Damato BE.
The DAMATO Multifixation Campimeter (DMFC) is a white, hand-held tangent screen with a series of numbered fixation targets around a central window, in which a grey or black stimulus is presented briefly by dialling a disc inside the campimeter. Purpose. To devise an abbreviated test strategy for glaucoma detection and predict its sensitivity and specificity. Methods. DMFC examinations were performed with a chart testing 60 points in the central 24° with 3mm stimuli having contrasts of 2.5%, 5%, 10%, 25% and 100% and with a 6mm 100% contrast stimulus. Normal values were determined in 130 normal eyes from individuals of different age groups. Retinal sensitivity curves for each stimulus were derived from 3000 point-for-point comparisons with the Humphrey Visual Field Analyser (HVFA), using a customised thresholding program in 50 glaucomatous eyes. Sector-by-sector comparisons were performed in 50 eyes with raised intraocular pressure with or without visual field loss according to the HVFA Glaucoma Hemifield Test. Results. Approximately 1% of normal eyes less than 60 years old and no older eyes missed the 10% and 25% contrast stimuli in Bjerrum areas 12-20° from fixation. The 50% thresholds of the 2.5%-, 5%-, 10%-, 25%-, and 100%- 3mm stimuli and the 100%-6mm stimulus were 29.0dB, 26.9dB, 24.0dB, 21.1dB, 15.4dB and 2.2dB respectively. An abnormal DMFC result was obtained in 77% of 74 abnormal visual field sectors and in 4% of 456 normal sectors. Conclusions. An abbreviated test examining Bjerrum areas in about 100 seconds per eye should detect defects <10dB in these areas with a specificity greater than 95%.