Selective Breeding for Susceptibility to Myopia Reveals a Gene–Environment Interaction

Abstract

Purpose. To test whether the interanimal variability in susceptibility to visually induced myopia is genetically determined. Methods. Monocular deprivation of sharp vision (DSV) was induced in outbred White Leghorn chicks aged 4 days. After 4 days' DSV, myopia susceptibility was quantified by the relative changes in axial length and refraction. Chicks in the extreme tails of the distribution of susceptibility to DSV were kept and paired for breeding (high- and low-susceptibility lines). A second round of selection was then performed. The third generation of chicks, derived from the selected parents, was assessed after either monocular DSV (4 or 10 days) or lens wear. Results. After two rounds of selective breeding, the chicks from the high-susceptibility line developed approximately twice as much myopia in response to 4 days' DSV as did those from the low-susceptibility line (P < 0.001). All ocular component dimensions differed significantly (P < 0.001) between the two selected lines, both before treatment and in the responses of the treated eye. When DSV was conducted for 10 days, the relative changes in axial length and refractive error were still significantly different between the high and low lines (P < 0.001). The chicks bred for high or low susceptibility to DSV also showed significantly different responses to minus lens wear, but not to plus lens wear. Additive genetic effects explained ∼50% of the interanimal variability in response to DSV. Conclusions. Genes and environment interact to shape refractive development in chicks.

Body Stature Growth Trajectories during Childhood and the Development of Myopia

“…However, despite the appeal of this line of reasoning, and the attraction of axial length as an endophenotype for refractive error 60 , recent results in an animal model of myopia suggest that the genetic variants that influence overall body size and eye size might be distinct from those that confer susceptibility to myopia 26,61 . Moreover, cross-sectional studies in both children and adults demonstrate that the relationship between axial length and refractive error is not "one-toone" in nature, as exemplified by the large range of axial lengths observed in emmetropes, and the observed correlations between refractive error and both crystalline lens and corneal growth trajectories 10,37,[61][62][63] . The findings here also suggest that -at the level of the individual -the genetic variants found to influence height in adulthood might not be predictive of myopia development to any useful extent.…”

Worldwide prevalence and risk factors for myopia

“…Selective breeding for susceptibility to myopia reveals a geneenvironment interaction on refractive development. 93 However, questions remain on the applicability of animal models of myopia to physiological human myopia. 94 …”

Association of Insulin-Like Growth Factor-1 Gene Polymorphisms with Different Types of Myopia in Egyptian Patients

“…Myopia is a complex disease caused by multiple genetic and environmental factors and potentially the interaction of those two factors (Chen et al, 2011). Feldkaemper et al (2009 stated that recent studies have provided evidence that IGF-1 plays a role in ocular growth, even axial myopia.…”