Experimental study reveals positive defocus impairs retinal ON-responses and thins ciliary muscle in myopes, suggesting altered optical blur processing.
Key Points
To investigate the acute physiological effects of sustained positive lens defocus on retinal ON- and OFF-pathway activity and ciliary muscle morphology in myopes compared to near-emmetropes.
Assessed ciliary muscle morphology using optical coherence tomography in myopes and near-emmetropes aged 18–30 years after 30 minutes of movie viewing in focus and with +3.00 D lenses.
Recorded long-flash electroretinogram b- and d-waves following clear and defocused viewing to evaluate retinal ON- and OFF-responses, with an exploratory red-light restriction subgroup.
Defocus significantly reduced electroretinogram b-wave amplitudes by −4.74 µV and delayed timing by +0.30 ms in both groups (both p < 0.001).
Ciliary muscle thickness decreased significantly following defocus exposure only in myopic participants (−19.43 µm, p = 0.007).
Red-filter conditions produced smaller b-wave amplitudes with defocus (Δ = −6.44 µV, p = 0.003) and delayed b-waves (Δ = 1.03 ms without defocus, Δ = 0.67 ms with defocus; both p < 0.001), with myopes showing reduced i-waves.