The primary analysis will involve comparing the retinal thickness measurements between subjects undergoing PRP with and without Trientine use. Secondary analyses will involve evaluations of visual acuity and fluorescein angiography. As well, changes in visual acuity, angiographic leakage, and retinal thickness will be regressed against serum copper levels. Sample size calculations suggest 15 subjects per arm should be adequate to demonstrate a 40% reduction in retinal thickness with a power of 80% comparing subjects receiving Trientine to controls.