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Nabin Joshi, Suresh Viswanathan, Mitchell W Dul; Pupillary response to blue light correlates with severity of glaucomatous neural damage. Invest. Ophthalmol. Vis. Sci. 2016;57(12):388.
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© ARVO (1962-2015); The Authors (2016-present)
To determine whether aspects of the pupil response to red and blue light were altered in glaucoma patients and how any changes relate to clinical measures of optic nerve structure and visual function.
Pupil responses from 15 patients with open angle glaucoma (mean age 63±8 years) were compared to that of 32 normal healthy subjects (mean age 62±10 years) using a RAPDx infrared pupillometer (Konan Medical Inc.). Baseline pupil diameter was measured over 300 ms following 10 minutes of dark-adaptation. Subsequently, pupil diameter was measured to a 20 photopic cd/m2 red (x=0.645, y=0.341) test flash of 1 second duration delivered on a LCD monitor and the sequence was repeated for a 20 photopic cd/m2 blue (x=0.153, y=0.53) flash. The diameters at baseline, peak constriction, sustained constriction at 6 seconds after stimulus offset, peak and sustained constrictions over baseline, response latency, time to peak and maximum velocity of constriction and re-dilation were compared between glaucoma patients and control subjects using unpaired t-test after applying Hochberg correction to p-values for multiple comparisons. We also studied the correlation of the significant parameters with Retinal Nerve Fiber Layer (RNFL) thickness obtained with Spectralis OCT (Heidelberg Engineering Inc.) and mean deviation (MD) of visual field sensitivity obtained with Humphrey Field Analyzer (Zeiss International) 24-2 strategy.
The sustained constriction over baseline (SCOB) for the glaucoma (100.78+2.45%) and control (97.78+2.6%) groups were significantly different (p<0.0099) for the blue test flash as was the difference between peak velocity of re-dilation (p<0.0114) for the glaucoma (1.86+0.44 mm/sec) and control (2.3+0.24 mm/sec) groups. Other parameters for the blue and all of the parameters for the red test flash were similar for the two groups. The re-dilation velocity for the blue test flash but not SCOB showed significant correlations with RNFL thickness (r=0.6, p<0.0005) and MD of visual field sensitivity (r=0.62, p<0.0001). Pupil re-dilation velocity of 2.05 mm/sec (least sum of false positives and negatives) had sensitivity and specificity of 80% and 72% respectively for glaucoma detection.
Velocity of pupillary re-dilation to blue test flashes can potentially serve as an objective indicator of the severity of glaucomatous neural damage.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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