Relationship Between Symptoms, Retinal Morphology, and the Nigrostriatal Dopamine System in Parkinson's Disease

Inclusion criteria

• Willing and able to give informed consent.
• Between the ages of 50-80 years old.
• Male or female with idiopathic PD who fulfill UK PD Society brain bank criteria for diagnosis of Parkinson's disease.
• Early stage subjects will need to have Unified Parkinson's Disease Rating Scale (UPDRS) motor scores of < 10, be within 3 years of diagnosis, and not requiring dopaminergic therapy
• Later stage subjects will need to have Unified Parkinson's Disease Rating Scale motor scores of > 20 and be > 5 years from diagnosis
• If female, one of the following three scenarios must apply:

• at least two years post-menopausal
• surgically sterile
• negative urine pregnancy test, and following a reliable method of birth control (oral contraceptive, intrauterine device, contraceptive implant, barrier, or abstinence) for at least two months prior to entry, and agreeing both to follow a reliable method of birth control, and (if relevant) to desist from breast feeding during, and for two weeks following tracer administration.

Exclusion criteria

• Abrupt onset of Parkinsonism
• 'Other Parkinson-like syndromes (e.g. progressive supranuclear palsy, multiple system atrophy)
• Any condition that would preclude successful completion of SPECT scanning
• Use of anti-coagulant therapy
• Any clinically significant eye disease that would complicate interpretation of OCT data
• Use of any drugs that would alter or interfere with tracer binding for SPECT imaging studies (ex., cocaine, amphetamines, methylphenidate, ephedrine, phentermine, bupropion, fentanyl, selective serotonin reuptake inhibitors).
• Known sensitivity to the imaging agent or to Lugol's solution or to potassium perchlorate.
• History or presence of severe renal disease.