Animal models have demonstrated a link between dysregulation of the
retinal dopamine system and the excessive ocular growth associated with the development of
myopia. Here we show that intravitreal or topical application of
levodopa, which is widely used in the treatment of
neurological disorders involving dysregulation of the dopaminergic system, inhibits the development of experimental
myopia in chickens.
Levodopa slows ocular growth in a dose dependent manner in chicks with a similar potency to
atropine, a common inhibitor of ocular growth in humans. Topical
levodopa remains effective over chronic treatment periods, with its effectiveness enhanced by coadministration with
carbidopa to prevent its premature metabolism. No changes in normal ocular development (biometry and refraction),
retinal health (histology), or intraocular pressure were observed in response to chronic treatment (4 weeks). With a focus on possible clinical use in humans, translation of these avian safety findings to a mammalian model (mouse) illustrate that chronic
levodopa treatment (9 months) does not induce any observable changes in visual function (electroretinogram recordings), ocular development, and
retinal health, suggesting that
levodopa may have potential as a therapeutic intervention for human
myopia.