Posted on the OSN SuperSite June 20, 2008
Technique good for detecting, classifying glaucomatous optic neuropathy vision loss
Evaluating retinal asymmetry using pupillometry can rapidly detect and classify visual field defects caused by glaucomatous optic neuropathy, a small study suggests.
"In this patient population, classification agreed with perimetry in 70% of eyes," the study authors said.
Yanjun Chen, PhD, and colleagues investigated the efficacy of a technique using pupillometry and functionally shaped stimuli for evaluating vision loss in 40 glaucomatous patients and compared results with testing data obtained from 40 normal controls. During the pupil-based assessment, the investigators alternately displayed pairs of large stimuli, mirror images about the horizontal meridian in the upper and lower visual field. Relative sensitivity to the upper and lower stimuli (contrast balance) and pupil constriction to upper and lower stimuli (response amplitude) were analyzed separately at baseline and between 1 and 3 weeks later.
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"Results for the normal subjects indicated functional symmetry in upper/lower retina, on average," the authors said.
Half of the patients in the control group had a contrast balance within 0.06 log units of equality and 80% had a contrast balance within 0.1 log units.
Conversely, half of the patients in the glaucoma group had a contrast balance more than 0.1 log units from equality.
The investigators found that contrast balances for patients in the glaucoma group were moderately associated with predictions from perimetric data (P < .00001).
Contrast balance analysis correctly classified visual field damage in 28 patients (70%), and response amplitudes correctly classified 24 patients (60%), the authors noted.
When contrast balance and response amplitude were combined, receiver operating characteristic area for discriminating glaucoma from normal was 0.83, according to the study, published in the June issue of Optometry and Vision Science.
