Abstract
Purpose: :
We have previously reported altered expression of many genes in chick retinal pigment epithelium (RPE) after short-term exposure (2 and 48 hours) to myopia-inducing stimuli.1 Here we report on changes in vascular endothelial growth factor (VEGF) expression with short and long-term exposure to the same stimuli.
Methods: :
White-Leghorn chicks were fitted with monocular negative defocusing lenses or diffusers to induce high myopia; fellow eyes were left untreated. Lenses were worn for either 48 hr, two weeks or three months from 3 weeks of age. Refractions and eye growth were monitored using retinoscopy and high frequency A-scan ultrasonography. RPE cells were isolated and total RNA extracted for analysis by real-time quantitative PCR. Changes in treated and fellow eyes were compared using paired t-tests.
Results: :
Statistically significant upregulation of mRNA expression of VEGF in RPE from lens wearing eyes was observed after 48 hr (41% increase, p=0.01), and increases, albeit more variable, were also observed after treatment periods of both two weeks (29% with -20 D lenses; 13.5% for diffusers), and three months (12, 41 & 67% for -7.5 or -10D lenses, -20D lenses and diffuser treatments respectively). The larger changes in eyes fitted with -20D lenses and diffusers compared with those treated with lower-powered lenses is consistent with changes in refractive error and axial lengths (means of axial length dimensions of treated and fellow eyes after 3 months: 15.728 vs. 13.765 mm (lenses), 16.717 vs. 14.235 (diffusers)).
Keywords: myopia • retinal pigment epithelium • vascular endothelial growth factor