In vitro effects of insulin and RPE on choroidal and scleral components of eye growth in chicks.

In chick eyes, exogenous insulin prevents the choroidal thickening caused by wearing positive lenses and increases ocular elongation and scleral glycosaminoglycan (GAG) synthesis, an indicator of eye growth. Using in vitro eye-cups, a novel experimental system, we examined the role of the retinal pigment epithelium (RPE) and insulin on choroidal thickness and scleral GAG synthesis. Specifically, we asked whether insulin causes the release of diffusible factors from the RPE that affect the choroid.