Repeatability and Reproducibility of Cirrus HD-OCT Measurements of Illumination Areas Under the Retinal Pigment Epithelium

Inclusion Criteria: * Males or females 50 years of age and older diagnosed to have advanced dry AMD with geographic atrophy. * Geographic atrophy lesions should: * Not be greater than 5 mm at the widest diameter. The entire lesion(s) should fit into the 6x6 mm scan area of the Cirrus HD-OCT. * Not be smaller than 1.25 mm2. * Not be confluent with peri-papillary atrophy. * Not be combined with other lesions such as CNV. * Able and willing to make the required study visits. * Able and willing to give consent and follow study instructions. Exclusion Criteria: * History of retinal surgery, laser photocoagulation, and/or radiation therapy to the eye. * Evidence of other retinal diseases of the eye, including wet AMD, diabetic retinopathy, diabetic macular edema, or significant vitreomacular traction. * Thick media opacity or inability to fixate that precludes obtaining acceptable scans. * Concomitant use of hydrochloroquine or chloroquine. * Unable to make the required study visits. * Unable to give consent or follow study instructions.