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Raymond Luval Warner, David H Brainard, Jessica Ijams Wolfing Morgan; Reliability and Reciprocity of the Population Cone Optoretinogram. Invest. Ophthalmol. Vis. Sci. 2022;63(7):2687.
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© ARVO (1962-2015); The Authors (2016-present)
Optoretinography assesses photoreceptor function. To develop optoretinography as a biomarker for disease affecting cones, we characterize the reliability of the cone optoretinogram in healthy subjects, as well as its dependence on stimulus duration.
Healthy subjects (N=5, 28-41 years) were imaged with an adaptive optics scanning laser ophthalmoscope (AOSLO). In each session, 270 AOSLO videos were acquired (785 nm, 1° x 1° imaging field, 1.5° temporal retina). A visible light stimulus (545Δ10 nm) was presented 1 s after the start of each video. The confocal reflecances of identified cones were extracted for each video frame, and the optoretinogram reflectance response for that frame was taken as the pooled standard deviation of the reflectances across cones (Cooper et al., 2017). We analyzed the peak response after stimulus initiation, taken from the fit of a smooth curve to the frame-by-frame response. We studied four intensity/exposure duration conditions, each with stimulus energy of 153 nJ/deg2: 1) 153nW/1s, 2) 306nW/0.5s, 3) 917nW/0.167s, 4) 2.75µW/0.056s. To measure intra-session variation, condition 4 was measured twice per session. For each subject, the full set of measurements was repeated in two sessions separated by at least a week.
Stimulus condition effects were not significant [F(3,39) = 7.69, p = 0.355]. Peak response varied significantly with subject [three-way ANOVA; subject, session, stimulus condition; F(4,39) = 9.42, p = .025]. Individual subject mean responses ranged from 2.4 to 4.5 on our response scale (arbiturary units). There was no main effect of session, but there was a significant subject by session interaction [F(4,39) = 15.75, p < .001]. This size of the session effect was small (mean absolute value 0.63) relative to intersubject differences. Within session variation for condition 4 was not significant in session 1 [one-way ANOVA; F(1,49) = 0, p =0.975] nor session 2 [F(1,49) = 0.06, p= 0.810].
The population cone optoretinogram is reliable for individual subjects, with a single session and a short duration stimulus sufficient for characterizing a subject’s response. Though the magnitude of the response varied across subjects, reciprocity between stimulus irradiance and duration held. Future work to establish optoretinography norms in larger numbers of healthy subjects is needed to apply optoretinography in studies of disease.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.
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