Figure 1. Effects of intravitreal saline, insulin, mitogen-activated protein kinase kinase inhibitor U0126, and phosphatidylinositol 3-kinase inhibitor Ly294002 injections on the development of the refractive state in chicks without any lenses, and after bilateral treatment with +7 D: lenses and −7 D: lenses. The large squares represent the means of the changes in refractive state±SEM from the beginning of the experiment and four days later. The small squares denote data from individual eyes. Six animals per group were used. Insulin and insulin + PI3K inhibitor prevented hyperopia development in positive lens–wearing animals, whereas the MEK inhibitor blocked the insulin effect. Animals wearing negative lenses and injected with insulin and insulin+ MEK inhibitor overcompensated the imposed defocus. In contrast, with the same lens treatment, the PI3K inhibitor plus insulin–injected eyes had similar refractions as insulin-injected eyes. Statistically significant differences, as determined by one-way ANOVA, are denoted in the graph (* p<0.05, ** p<0.01).