Abstract
Purpose: To test whether the melanopsin-containing, intrinsically photosensitive retinal ganglion cells (ipRGCs), as evaluated by examination of the pupillary light reflex (PLR), are preserved in genetically confirmed autosomal dominant optic atrophy (ADOA).Method: Twenty-nine patients with either the c.983A > G (n = 14) or the c.2708_ 2711delTTAG mutation (n = 15) were examined with monochromatic pupillometry, using isoluminant (300 cd/m2), red (660 nm) or blue (470 nm) light, optical coherence tomography, automated visual field analysis, and with determination of best corrected visual acuity (BCVA). Since we examined two different mutations, initially we compared all outcome variables between the two, and finding no statistically significant difference, pooled them.Results: Despite a poor BCVA (56 letters, ETDRS) in the ADOA patients, their post-illuminatory pupil responses did not differ significantly from those of healthy controls (blue, p = 0.45, red, p = 0.49, t-test), and no statistically significant effect was noted of peripapillary retinal nerve fiber layer thickness, ganglion cell-inner plexiform layer thickness, or age.Conclusion: The PLR to blue light of high luminance (300 cd/m2) was preserved in both c.983A > G and c.2708_2711delTTAG ADOA despite severe visual loss and optic nerve atrophy. The study confirms, in a large sample of two genetically homogenous groups, that the ipRGCs are spared in ADOA.
Highlights
The intrinsically photosensitive retinal ganglion cells play a key role in the physiology of the pupillary light reflex (PLR), as well as in other non-image-forming (NIF) light responses, including entrainment of circadian rhythms and regulation of secretion of the hormone melatonin [1,2,3,4]
The study confirms, in a large sample of two genetically homogenous groups, that the intrinsically photosensitive retinal ganglion cells (ipRGCs) are spared in autosomal dominant optic atrophy (ADOA)
The contribution of melanopsin to the PLR is best evaluated by monochromatic pupillometry, measuring the sustained post-illumination pupillary response, after blue light stimulation [8], while the synaptic contribution from cones is measured during stimulation with red light (660 nm) of high luminance (300 cd/m2)
Summary
The intrinsically photosensitive retinal ganglion cells (ipRGC) play a key role in the physiology of the pupillary light reflex (PLR), as well as in other non-image-forming (NIF) light responses, including entrainment of circadian rhythms and regulation of secretion of the hormone melatonin [1,2,3,4]. The contribution of melanopsin (the intrinsic response) to the PLR is best evaluated by monochromatic pupillometry, measuring the sustained post-illumination pupillary response, after blue light stimulation [8], while the synaptic contribution from cones is measured during stimulation with red light (660 nm) of high luminance (300 cd/m2). Earlier pupillometric studies in humans [23] and in animals [24] have indicated that the pupillary light reactions are preserved in ADOA. While studies on genetically confirmed ADOA have been performed on animal models, to the best of our knowledge, such studies on humans are lacking
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