Medical Marijuana is used widely, and its effects on the visual system and the function of the retina have not been investigated thoroughly. Some evidence suggests that cannabinoids may be beneficial in certain degenerative diseases of the retina.

The purpose of the study is

1. To determine whether cannabis derivatives affect the visual functions in healthy adults
2. To examine the effect of cannabis derivatives on the retina of retinitis pigmentosa patients

Twenty five healthy subjects and 25 retinitis pigmentosa patients will be recruited and will sign an informed consent form. An initial eye exam will include visual acuity and stereo vision, eye movements and eye movement recording, a full slit lamp eye exam, intra-ocular pressure measurement, visual field, OCT and electrophysiology. The subjects will receive a single sublingual dose of cannabis (THC:CBD 1:1, THC 5 mg, or THE:CBD 1:40, THC 5 mg), and will undergo the above examination again. Subjects will be monitored for 5 hours after the administration of cannabis.

Inclusion Criteria:

• consenting adults
• generally healthy with or without retinitis pigmentosa

Exclusion Criteria:

• chronic or acute disease other than retinitis pigmentosa
• use of medication
• congestive heart failure
• recent use of illicit drugs (past month)
• history of drug dependency
• history of psychiatric disorder in subject or immediate relatives
• pregnancy

Electrophysiology will be analyzed by a blinded investigator.