Abstract
Purpose :
Although much is known is about the ultrastructural, physiological, and genomic changes associated with development of optically induced refractive errors, little research exists about concurrent early changes in biometrics, proteins and ion distribution patterns across the retina/RPE.
Methods :
Chicks were fitted with +10D lenses, -10D lenses or No Lens on post-hatch day 5. Biometrics were performed on 5 chicks per lens group following a further 6 or 48hrs. After anesthesia, eyes were enucleated and the posterior retina/RPE was divided and concurrently prepared for elemental microanalysis on a scanning electron microscope and for proteomics by LC-ESI-MS/MS on a LTQ-orbitrap Elite (Thermo-Scientific). Proteomic raw data was processed using MaxQuant. Differentially abundant proteins were identified using t-test (FDR<0.05) in Perseus and pathway expression changes were identified using Gene Set Enrichment Analysis (GSEA).
Results :
Biometrics showed 3.9D and 7.7D of refractive compensation (RC) to +10D defocus after 6 and 48 hours respectively, while RC to -10D was -2.6D and -9.7D at the same times. X-Ray microanalysis demonstrated that 6hrs of RC to optical defocus is accompanied by increased hyperosmolarity for K+, Na+ and Cl- ions across the retina/RPE compared to No Lens eye. This hyperosmolarity persisted through to 48hrs of defocus. In line with this, expression of proteins in the Solute-Carrier (SLC) mediated transmembrane transport pathway for ions and water was significantly down-regulated following 6hrs of myopia induction.
Conclusions :
Chicks show substantial refractive compensation and associated hyperosmotic shifts and protein expression changes after just 6 hours of refractive compensation to defocusing lenses. These findings highlight the importance of the acute period post-lensing for understanding the aetiology of optically-induced growth changes.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.