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Citation: Haj Yahia S, Hamburg A, Sher I, et al. Effect of stimulus intensity and visual field location on rod-and conemediated pupil response to focal light stimuli. Invest Ophthalmol Vis Sci. 2018;59:6027-6035. https://doi.org/ 10.1167/iovs.18-23767 PURPOSE.To assess the effect of stimulus intensity on rod-and cone-mediated pupil light reflex (PLR) to small stimuli presented at central and peripheral visual field (VF) locations.METHODS. The PLR to small (0.438) chromatic stimuli was tested in the right eye of healthy subjects. Blue (485 6 20 nm) and red (625 6 15 nm) stimuli were presented at incremental light intensities (0.5-3.75 log cd/m 2 ) at peripheral (21.218) and central (4.248) VF locations using a chromatic pupilloperimeter under mesopic or blue light adaptation conditions. The percentage of pupil contraction (PPC), maximal pupil contraction velocity (MCV), latency of MCV (LMCV) and the ratio of central to peripheral responses for PPC (Q PPC value) were determined.RESULTS. Under mesopic light adaptation conditions, the mean PPC recorded in response to red stimuli was lower than blue stimuli in all VF locations and light intensities, and the Q PPC values were higher in response to red compared with blue light stimuli across the light intensity range tested. With blue background light, the pupil responses for red and blue light stimuli were approximately the same in the peripheral VF. LMCV was nearly constant in all VF locations for blue and red stimuli, respectively.CONCLUSIONS. The chromatic pupilloperimeter enables the assessment of rod-and conecontribution to the PLR in different VF locations. The optimal light intensities determined here for the assessment of focal activation of the two photoreceptor systems may be used for clinical evaluation of photoreceptor health.

Purpose To determine the pupil response of Best vitelliform macular dystrophy (BVMD) patients for focal blue and red light stimuli presented at 76 test points in a 16.2° visual field (VF) using a chromatic pupilloperimeter. Methods An observational study was conducted in 16 participants: 7 BVMD patients with a heterozygous BEST1 mutation and 9 similar-aged controls. All participants were tested for best-corrected visual acuity, chromatic pupilloperimetry and Humphrey perimetry. Percentage of pupil contraction (PPC), maximal pupil contraction velocity (MCV) and latency of MCV (LMCV) were determined. Results The mean PPC and MCV recorded in BVMD patients in response to red stimuli were lower by >2 standard errors (SEs) from the mean of controls in 47% and 43% of VF test points, respectively. The mean PPC and MCV recorded in the patients in response to blue stimuli were lower by >2 SEs from the mean of controls in 36% and 24% of VF test points, respectively. The patients’ mean and median MCV recorded in response to red light correlated with their Humphrey mean deviation score ( r =−0.714, P =0.071 and r =−0.821, P =0.023, respectively) and visual acuity ( r =0.709, P =0.074 and r =0.655, P =0.111, respectively). A substantially shorter mean LMCV was recorded in BVMD patients compared to controls in 54% and 93% of VF test points in response to red and blue light, respectively. Receiver operating characteristic analysis for LMCV in response to red light identified a test point at the center of the VF with high diagnostic accuracy (area under the curve of 0.94). Conclusion Chromatic pupilloperimetry may potentially be used for objective noninvasive assessment of rod and cone cell function in different locations of the retina in BVMD patients.