Both the central and peripheral retina contribute to myopia development in chicks

PurposeThis study examined the contribution of the central and peripheral retina to the development of form deprivation myopia in chicks. MethodsChicks were treated for 7days either with centrally form-deprived (CFD) lenses of 2/4/6/8mm diameter central diffuse zone, or a full size diffuser lens on their right eyes. The left eyes wore a full field plano lens. Axial dimensions and refractions were measured before and after 4 and 7days of lens wear. ResultsAll eyes that had worn CFD lenses of 2/4/6/8mm had significant changes in refractive errors (from -2.690.40D to -6.13 +/- 0.76D, p<0.05), vitreous chamber depth (from 0.19 +/- 0.04mm to 0.56 +/- 0.04mm, p<0.05) and axial length (from 0.42 +/- 0.03mm to 0.96 +/- 0.04mm, p<0.05) during the experiment, except for the changes in refractive error (-2.81 +/- 0.33D, p=0.053) and axial length (0.77 +/- 0.04mm, p=0.050) in the 2mm lens group after 7days of lens wear. The myopic shift in the CFD lens wearing eyes was due primarily to an increase in vitreous chamber depth. Linear regression analysis showed that the changes of refractive error, vitreous chamber depth and axial length were positively correlated with the size of central form-deprived retina. Form depriving the central retina produced axial myopia even in the presence of clear peripheral vision. ConclusionsThe current study showed that both the central and peripheral retina contributes to myopia development in chicks. The amount of myopia induced increased linearly with the area of retina being form-deprived. It suggests that in terms of decoding optical input for growth, the area of retina being exposed to optical signals may be critical in determining eye growth.