People with Stargardt disease, age related macular degeneration (AMD) and diabetic retinopathy (DR) have decrease in central vision from damage to photoreceptors. One of the mechanisms causing damage is high levels of oxygen in the eye. This damage produces specific biomarkers that can be measured in eye fluid (aqueous humor). In this study, these biomarkers will be assessed in people with Stargardt disease, age related macular degeneration and diabetic retinopathy, compared to controls.