LAUSR

Myopia (shortor near-sightedness) is a widespread and costly eye disorder, affecting as many as 80 90% of young adults in some Asian cities [1,2]. It is a condition in which vision at a distance is blurred, so that myopic individuals (myopes) have to bring objects closer to see them clearly. Myopic vision can be corrected with prescription lenses or corneal refractive surgery, making vision clear at any distance; but this does not correct the underlying problem, excessive elongation of the eye along the visual axis, which increases the risk of more severe consequences including retinal detachment and visual impairment. Simple, safe, and effective therapies are needed, to prevent the onset and progression of unrestrained axial elongation [1,2]. Such therapies are available as eye drops containing the drug atropine [3], multifocal contact lenses [4], and overnight orthokeratology [5] but none of them is completely satisfactory. Drugs might seem to be the treatment of choice, because of convenience for administering, and low risk of ocular infection or trauma. Low-dose atropine (0.01 0.05%) [3] is available and used rather widely; but for myopia treatment it is strictly off-label, it is not 100% effective, and it produces undesirable side-effects. These side effects are due mainly to atropine’s well-known and generally assumed action as antagonist at muscarinic cholinergic receptors; they might be eliminated by switching to non-muscarinic agents such as alpha-adrenergic agonists [6]. However, discovery of such an alternative by the usual methods of drug development has largely failed. Ideally, one could select candidate drugs by testing those that are expected to target the underlying pathogenetic mechanisms. Mechanisms responsible for myopia have been investigated in animal models: form-deprivation myopia (FDM), in which viewing through a translucent diffuser causes blurred vision, and lens-induced myopia (LIM), in which defocus by a negative lens causes hyperopic defocus and compensatory axial elongation [7]. Studies using these models in