Abstract
Purpose: :
To investigate 4 variants of multifocal pupillographic perimetry in glaucoma.
Methods: :
We tested 87 normal and 82 glaucoma subjects. All subjects were examined with HFA achromatic, SWAP and Matrix 24-2 perimetry, Stratus OCT, slit lamp and tonometry. Informed written consent was obtained from all subjects under ANU ethics approval 238/04. Multifocal stimuli were presented concurrently to both eyes with a dartboard layout, having 24 independent test regions/eye extending to 30 deg eccentricity. Each subject was tested with 4 stimulus sets which adopted either 2 or 4/s/region, and a flicker rate on each presentation of 15, or 30Hz. Recording duration was 4 minutes, divided into 8 segments of 30s. Pupil diameter was monitored by video cameras under infrared illumination. Data from fixation losses and blinks was automatically excluded. Up to 15% data loss from blinks, fixation losses were permitted by our regressive analysis method, which produced error estimates for each region. Measures of field loss examined the N worst amplitudes, response areas, delays or pairwise linear combinations of those.
Results: :
Since some blinks and fixation losses were permitted only 1 in 45 of the 30s test segments had to be repeated. The simple N-worst region method, based upon the area of the pupillary responses and delay for the 4/s, 30Hz test, produced the best areas under ROC curves, which ranged from 0.74 for moderate fields to 0.81 for more severe fields. The largest age effect was -0.10 um×s per decade (p<0.0001). Whichever of the direct or consensual responses gave the lowest error was used, hence only one pupil need function.
Conclusions: :
The results suggest that this form of objective test for glaucoma may be practical for test durations equivalent to 2 min/eye. The method eliminates problems associated with false positive and negative errors, and fixation losses found in conventional perimetry, all of which effectively lower sensitivity and specificity. Consideration of clusters of damage or between eye comparisons, and or using more regions may improve sensitivity and specificity.
Keywords: perimetry • pupil • visual fields