Is central vision (and a fovea) needed for emmetropisation?

Investigations into the neural circuits underlying emmetropisation have identified key components responsible for converting visual input into molecular signals that regulate eye growth. Studies in chicks and primates have shown that isolating the eye from higher brain centres through surgical transection of the optic nerve does not prevent form-deprivation myopia or lens-induced myopia in chicks. In addition, eliminating the autonomic neural input to the eye's accommodative system does not affect the visual regulation of ocular growth in chicks. Furthermore, in both chicks and primates, partial diffusers applied to only half of the visual field resulted in localised ocular elongation and myopia in the corresponding half of the eye. Research conducted across multiple laboratories and species has consistently demonstrated that the eye' ability to respond to optical manipulations is linked to a local, regionally selective retinal mechanism within the eye.