Declaration of interest
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.
Funding
This work was supported by National Eye Institute grant NEI 09052 and the Eye Defects Research Foundation Inc. (to Y.S.R.); NCRR grant M01-RR00425 and Southern California Diabetes Endocrinology Research Center grant DK063491 (to K.D.T).