Abstract
Purpose :
Both near work and retinal OFF pathway activation have been implicated in the development of myopia. This study examined the interaction between accommodation and retinal ON and OFF pathway activation, and their association with changes in choroidal thickness in healthy young adults.
Methods :
Nineteen subjects with a mean age of 25 ± 5 years and refractive error of -1.6 ± 2.2 D (range -5.5 to +0.75 D) participated. The left eye’s sub-foveal choroidal thickness (SFCT) was assessed with Spectralis optical coherence tomography before and after a series of 30-min long binocular viewing tasks, including reading a passage of bright text on a dark background (ON pathway activation) and dark text on a bright background (OFF activation), and a control condition of viewing a movie with no bias towards ON or OFF pathways. Each task was preceded by a 20-min adaptation period of watching a movie at distance. The tasks were performed with 0 D and 5 D (induced by soft contact lenses) accommodation demands. Repeated measures ANOVA was conducted to examine the change in SFCT associated with contrast polarity (3 levels) and accommodation (2 levels).
Results :
Significant main effects of accommodation and polarity were observed (both p < 0.001), with the SFCT reducing significantly by -7 ± 1 µm with 5 D accommodation compared to 0 D accommodation (-3 ± 1 µm, p < 0.001), and by -9 ± 1 µm with OFF pathway compared to ON pathway activation (-4 ± 1 µm, p = 0.002) and the control condition (-2 ± 1 µm, p < 0.001). The change in SFCT with ON pathway activation was not significantly different from that observed with the control condition, both at 0 D (-2 ± 2 µm vs +1 ± 1 µm, p = 0.52) and 5 D (-6 ± 1 µm vs -5 ± 1 µm, p = 0.99) accommodation. However, selective activation of the retinal OFF pathway resulted in a significantly greater thinning of the choroid compared to the control condition, both at 0 D (-7 ± 1 µm, p = 0.003) and 5 D (-11 ± 1 µm, p = 0.005) accommodation demands.
Conclusions :
The choroidal thinning associated with accommodation was approximately doubled with selective activation of the retinal OFF pathway through reading standard dark on light background text, providing a potential mechanism that involves accommodation and the OFF signalling pathway, linking near work and myopia.
This is a 2021 ARVO Annual Meeting abstract.