Purchase this article with an account.
William Hogue, Christopher Patrick Taylor; Axial length is associated with individual differences in ON- and OFF- pattern detection. Invest. Ophthalmol. Vis. Sci. 2021;62(8):2894.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The ON and OFF visual pathways have different spatial tuning and cortical connectivity. The ON and OFF pathways may play a role in emmetropization. Currently, the literature on the mechanisms that control choroidal thickness and emmetropization is, at best, immature. We measured individual differences in two detection tasks to explore the role contrast polarity plays in emmetropization.
39 observers completed four one-hour sessions of psychophysical testing. We screened for a history of ocular disease, refractive surgery, or the use of ortho-k lenses. Refractive error was measured with a wavefront aberrometer and axial-length with an ocular biometer. Psychophysical detection and identification thresholds for two tasks were measured. The stimuli were Sloan Letters and Difference of Gaussians (DoG). The contrast polarity of the stimuli was either positive (ON) or negative (OFF). In the identification task, contrast sensitivity for the ten Sloan letters was measured. The detection task measured contrast sensitivity via a two-interval forced-choice task with a DoG stimulus as the target and a blank foil interval. Sessions consisted of either positive ON- or negative OFF- contrast on a grey background and never both. The two tasks were interleaved randomly during a single session of sub-blocks of 150 trials.
We found the ratio of OFF/ON sensitivities defined as ONOFFindex = (con - coff) / (con + coff) increased as axial-length increased with a Difference of Gaussian (DoG) target (r=0.41, P<0.01). The lack of effect for letters is curious because we did not replicate a previous study that found an effect in an ON/OFF letter identification task (r=-0.017, P=0.92). Sensitivity decreased with axial length for all conditions. DoG ON (r=0.33, P<0.05), DoG OFF (r=0.48, P<0.001), Letters ON (r=0.47, P<0.01), Letters OFF (r=0.41, P<0.01).
Natural scenes contain more information in the OFF than ON visual channels. The altered balance of OFF/ON thresholds for DoG provides a conceptual link between altered retinal ganglion cell sensitivity and the evidence that time spent outdoors slows the progression or onset of myopia.
This is a 2021 ARVO Annual Meeting abstract.
This PDF is available to Subscribers Only