World Glaucoma Congress 2009, Boston MA, 8-11 July 2009
Authors
T. Maddess(1), M. Kolic(1), RW Essex(2), A.C. James(1).
(1) ARC Centre of Excellence in Vision Science, Australian National University, Canberra, Australia.
(2) Dept. Ophthalmology, Australian National University, Canberra, Australia.
Purpose
To investigate the diagnostic power and repeatability of 8 variants of multifocal pupillographic perimetry in open angle glaucoma.
Design
Experimental design.
Participants
Eight stimulus protocols were examined in two blocks of experiments. Block 1 contained 40 normal and 39 glaucoma subjects; block two: 41 normal and 47 glaucoma subjects. Diagnosis was confirmed by examining all subjects with HFA achromatic, 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.
Methods
Independent multifocal stimuli were presented concurrently to both eyes with a dartboard layout, having 44 independent test regions/eye extending to 30 deg eccentricity. The recording duration for 5 protocols was 4 min., divided into 8 segments of 30 s each, and for the other 3 was 6 min. divided into 9 segments of 40 s. Stimuli in each protocol could differ in the presentation rate per stimulus region (0.25, 1, presentations/s), or luminosity (150, 180, 290 or 340 cd/m²). Background luminance was 10 cd/m². Since both pupils responded to stimuli from both eyes, 88 responses/eye were obtained giving 176 contraction amplitudes and 176 delays per protocol, with SE for all 352 measures. Retest was done within 4 weeks. Visual fields were classified by HFA mean defects: moderate: 6 to 12 dB, severe: >12 dB.
Main outcome measures
The relative diagnostic power of the 8 protocols was examined using areas under receiver operator plots (AUC). The signal qualities were quantified as the median t-static across regions and subjects for peak (relative) constriction amplitude. Test-rest quality was quantified by the width of the 25th to 75th and 5th to 95th percentiles on plots of visit 1 versus visit 2 defects.
Results
In Block 1 for severe fields the mean of the 20 regional amplitudes that most deviated from the normative data gave an AUC of 0.98 ± 0.01 (mean ± SE), and for combined moderate and severe fields 0.86 ± 0.04. The median t-stat for that protocol was 2.79 ± 0.29. That protocol had a mean presentation rate of 0.25/s and luminance of 150 cd/m2. These results were reproduced in Block 2 and a 6 min. version of the best protocol of Block 1 had a median t-stat of 3.26 ± 0.45, with a concomitant improvement in test-test variability.
Conclusions
This study indicates that multifocal pupil perimetry can yield acceptable diagnostic power, excellent median signal quality and test-retest variability comparable to the Matrix perimeter using a test duration equivalent to 3 min/eye. Data on efferent and afferent defects is obtained for all regions and data from blinks and fixation losses are automatically discarded. That protocol had a mean presentation rate of 0.25/region/s and luminance of 150 cd/m2. These results were reproduced in Block 2 and a 6 min. version of the best protocol of Block 1 had a median t-stat of 3.26 ± 0.45, with a concomitant improvement in test-test variability.
Downloads
Download the full paper hereTags: WGC
