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J Jason McAnany, Jason C Park, Norman P Blair, Felix Yan-Fay Chau, Jennifer I Lim, Yannek Isaac Leiderman, Mahnaz Shahidi; Pupillary light reflexes in non-proliferative diabetic retinopathy.. Invest. Ophthalmol. Vis. Sci. 2016;57(12):No Pagination Specified.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate rod-, cone-, and melanopsin-mediated pupillary light reflexes (PLRs) as indices of neural dysfunction in diabetic patients who have different stages of non-proliferative diabetic retinopathy (NPDR).
PLRs elicited by full-field, brief-flash stimuli were recorded from 50 diabetic patients (no NPDR [N = 17], mild NPDR [N = 16], moderate-severe NPDR [N = 17]) and in 25 age-equivalent, visually-normal controls. Subjects were dark-adapted for 10 minutes and the PLR was recorded in response to short-wavelength flashes (0.001 cd/m2: rod condition; 450 cd/m2: melanopsin condition). Subjects were then exposed to a short-wavelength, rod-suppressing luminance field and 10 cd/m2 long-wavelength flashes were presented (cone condition). PLRs were quantified as the maximum transient constriction (rod and cone conditions) and the post-illumination pupil constriction (melanopsin condition), relative to the baseline pupil size.
The mean baseline (pre-stimulus) pupil diameter was significantly smaller for the NPDR patients, both in the dark (p < 0.001) and in the light (p = 0.002), consistent with previous literature. A two-way ANOVA indicated significant effects of subject group (control, no NPDR, mild NPDR, moderate-severe NPDR; p < 0.001) and condition (rod, melanopsin, cone; p < 0.001) on the PLR. There was also a significant group by condition interaction (p < 0.001). Pairwise comparisons indicated that: 1) the mean melanopsin-mediated PLR was significantly reduced in all diabetic groups; 2) the mean rod-mediated PLR was reduced significantly only in the moderate-severe NPDR group; 3) the mean cone-mediated PLR was reduced significantly in the mild and moderate-severe NPDR groups. Approximately 1/4 of the patients in the mild and moderate-severe groups had normal baseline pupil diameters and reduced melanopsin- and cone-mediated PLRs, emphasizing the value of recording the PLR in addition to baseline pupil size.
The observed PLR reductions in NPDR patients indicate compromised neural function. PLR measurement, particularly under the melanopsin-mediated condition, may provide a useful functional measure in patients who have NPDR, possibly capable of quantifying sub-clinical neural abnormalities in these patients.
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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