Background: Retinal diseases cause the loss of rod and cone photoreceptors. Symptoms include vision loss and night blindness. Researchers want to learn about rod and cone function in healthy people and people with retinal disease. They want to know if how well a person sees in the dark can test the severity of retinal disease.

Objectives: To find out if how well a person sees in the dark can test the severity of retinal disease. To find out if this can help detect retinal disease and track its changes.

Eligibility: People ages 5 and older with: Retinal disease OR 20/20 vision or better with or without correction in at least one eye

Design: Participants will be screened with medical and eye history and eye exam. Those with retinal disease will also have: Eye imaging: Drops dilate the eye and pictures are taken of it. Visual field testing: Participants look into a bowl and press a button when they see light. Electroretinogram (ERG): An electrode is taped to the forehead. Participants sit in the dark with their eyes patched for 30 minutes. Then they get numbing drops and contact lenses. Participants watch lights while retina signals are recorded. Visit 1 will be 3-8 hours. Participants will have up to 6 more visits over 6-12 months. Visits include: Eye exam and imaging Time course of dark adaptation: Participants view a background light for 5 minutes then push a button when they see colored light. Dark adapted sensitivity: Participants sit in the dark for 45 minutes. They push a button when they see colored light. For participants with retinal disease, ERG and visual field testing