Ocular Coherence Tomography (OCT) is a non-invasive ophthalmologic test that uses reflected, unheated, non-concentrated visible light in order to scan and provide a 2-dimensional topographic analysis of the retina and optic nerve. It has wide diagnostic utility especially in patients with clinically significant macular edema, glaucoma, and other retinal eye diseases. At the University of Chicago, we have utilized the Stratus brand OCT (Carl Zeiss Inc) for the past 5 years. Recently we have acquired a beta version of the company's new model, the Cirrus HD-OCT (Carl Zeiss Inc.) which features improved resolution, shorter scanning time and a more user-friendly interface. The purpose of this study is to compare findings between the two models in patients with different common and uncommon eye diseases, including diabetic macular edema, glaucoma and age-related macular degeneration. We hypothesis that the Cirrus OCT is able to accurately quantify eye pathology compared to Stratus OCT.