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Naheed W Khan, Husam Alghanem, Thiran Jayasundera; Post-Illumination Pupil Response in Argus II Prosthesis Users . Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):753.
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© ARVO (1962-2015); The Authors (2016-present)
To use chromatic pupillometry to assess function of intrinsic photosensitive (melanopsin) retinal ganglion cells (ipRGCs) in patients using the ArgusII retinal prosthesis and to associate the sustained post-illumination pupil response (PIPR) with measures of visual outcome.
Subjects were 3 Argus patients (56 y/o male, 65 y/o female, 75 y/o female) fitted 3 to 6 months prior with the Argus II 60 electrode epiretinal implant (Second Sight Medical Products, Sylmar, CA) in their left eye. Control subjects were advanced RP patients that also met criteria for implantation, and 9 healthy normal subjects. Monocular PIPR was measured after 10 minutes of dark adaptation on both eyes using a Ganzfled system which was equipped with an eye tracking camera/software and emitted 1 second flashes at 2.6 log cd-s/m2 and 625 nm (red) or 470 nm (blue) wavelengths ( Roland Consult, Germany). Constriction as a percent of baseline at 6 seconds for red stimulus was subtracted from blue stimulus PIPR to yield an estimate of melanopsin response (Park et al., 2011). Visual function was quantified by having the subject localize a high contrast square shaped target on a touch screen.
Argus patients and RP subjects had bare light perception acuity. Rod- and cone-mediated pupil response was significantly diminished in the Argus patients and in the RP control subjects. The ipRGC PIPR for the Argus patients was of comparable amplitude to the normal control and RP subjects: AR1: 70% OS and 72% OD; AR2: 77.1% OD and 69.9% OS; AR3: 60.1% OD, 52.5% OS. Mean percent PIPR was 71.5% ± 6.7% SD for RP subjects, and 70.4% ± 7.96% SD for normal controls. Difference in PIPR amplitude between the implanted and non-implanted eye was minimal for the Argus patients. For the square localization visual function test, 40 trials were presented in two subsequent sessions, once with the device on and once with the device off. Number of correct responses were - AR1: 15%, AR2: 30%, and AR3: 20% with the device on, and AR1: 12.5%, AR2: 17.5%, with the device off. AR3 did not take the test in the device off condition.
The ipRGC pupillary response in Argus patients and RP control subjects is comparable to normal mean indicating normal ipRGC function. There was no association between PIPR amplitude and visual function tests at least at 6 months after implantation.<br /> Park et al., Invest Ophthalmol Vis Sci. 2011, 52: 6624-6635.
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