Relative peripheral hyperopic defocus alters central refractive development in infant monkeys

Abstract

Understanding the role of peripheral defocus on central refractive development is critical because refractive errors can vary significantly with eccentricity and peripheral refractions have been implicated in the genesis of central refractive errors in humans. Two rearing strategies were used to determine whether peripheral hyperopia alters central refractive development in rhesus monkeys. In intact eyes, lens-induced relative peripheral hyperopia produced central axial myopia. Moreover, eliminating the fovea by laser photoablation did not prevent compensating myopic changes in response to optically imposed hyperopia. These results show that peripheral refractive errors can have a substantial impact on central refractive development in primates.

Visual regulation of refractive development: insights from animal studies

“…Moreover, optical manipulations of peripheral vision, which do not alter central vision, may be effective in controlling central refractive development. [51][52][53] Figure 1 Interocular differences in refractive error (treated eye correction À fellow eye correction) plotted as a function of age for individual monkeys reared with À 3D (left panel) or þ 3D lenses over one eye (middle panel). 22,46 The fellow eyes viewed through zero-powered lenses.…”

“…The time course and efficiency of emmetropization is also not altered by foveal ablation. In addition, laser ablation of the fovea does not prevent the eye from becoming myopic in response to either optically induced hyperopic defocus (left) 53 or form deprivation (right). 55 Nor does foveal laser ablation interfere with the ability of the eye to recover from either induced myopia or hyperopia.…”

“…Although there is still much to learn about these factors, when there are conflicting visual signals between the central retina and the periphery, the peripheral signals can dominate central refractive development. For example, as illustrated in the left and middle panels of Figure 4, infant monkeys, which are reared with treatment lenses with central apertures that provide unrestricted central vision and produce either form deprivation 53 or hyperopic defocus 51,53 in the periphery, develop central myopia, although the central retina received visual signals that should have supported normal emmetropization. Similarly, the right panel in Figure 4 shows that myopic defocus imposed in the periphery is very effective in slowing axial growth and in producing central hyperopia in chickens, 51,52 which specifically provides support for peripheral optical treatment strategies for myopia.…”

Identification of myopia-associated WNT7B polymorphisms provides insights into the mechanism underlying the development of myopia

“…For example, it is well known that central hyperopic defocus can cause myopia in chicks 15 and mice models 16 . In addition, experiments conducted by Smith et al [17][18][19] have shown that peripheral hyperopic defocus can cause myopic shift in monkeys. This is a herald of 'peripheral defocus theory' that implicates defocus at the peripheral retina as the trigger for myopia.…”

Is the peripheral retina an important site for myopic development? [Liu Y, Wildsoet C (2011) The effectof two-zone concentric bifocal spectacle lenses on refractive error development and eye growth in young chicks. Invest Ophthalmol Vis Sci 52(2):1078–1086]

“…Although Liu and Wildsoet used the chick as their model for myopia development, they demonstrated that the effective visual field which starts to alter refractive changes was about 12°or more from the visual axis. Smith and co-workers found that an image with hyperopic defocus at the location of 10.3°from the visual axis would also induce myopic development in monkey eyes [5]. It is very interesting to show that the sensitive zone in the eye for refractive development is the paracentral to peripheral retina, and the most impaired retinal region in myopia is also the same retinal region.…”