Prism Adaptation Treatment of Parkinson's Disease

Subjects diagnosed with Idiopathic Parkinson's Disease, between ages of 40-85 inclusive, who have been referred for gait training. Since there can be subtle differences in the brain organization of left- and right-handed people that may influence some of the measurements, right handed participants are preferred. However, a left handed participant may be considered. Participants will be randomly assigned to one of two groups to undergo two weeks of twice-daily sessions. Group A receiving goggles fitted with lenses that distort vision and Group B patients receiving sham goggles

The participants will be trained to undergo two daily sessions of visual adaptation at home for 14 consecutive days. For each adaptation session, subject will sit in a chair within reaching distance of a wall or cabinet upon which two dime-sized targets will be placed (one above the other, approximately ten inches apart). While wearing goggles, you will point rapidly to one target then the next, bringing the hand back to his/her torso between each pointing movement. They will be instructed to perform these movements "as quickly as possible" for a total of 50 pointing movements in each treatment session. After performing the 50 pointing movements, they will remove their goggles. Throughout the treatment period they will be asked to keep a diary in which they will log the time and duration of each prism adaptation session. At the first and second site visits, participants will be assessed for posture, gait and activities of daily living which will include some questionnaires. Questionnaires will be sent via mail after post-treatment at one week,1 month and 3 months.

Eligibility Criteria:
Inclusion Criteria:

* Diagnosis of idiopathic Parkinson's Disease
* Referral for gait training
* Aged 40 -85
* If the subject is taking CNS-acting medications (benzodiazepines, hypnotics, antidepressants), regimen must be stable for 30 days prior to baseline visit
* Subjects with Stage 11.5 - Stage IV (Hoehn and Yahr scale) where stage II.5 is bilateral involvement with axial involvements, but without balance difficulty, to Stage IV where one has severe disability but is still able to walk or stand unassisted
* Subjects with any of the following abnormal scores (greater than 0) in the MDS-UPDRS Part III; a) Part III.10 Gait; b) Part III.11 Freezing of gait c) Part III.12 Postural Stability; subjects with Timed up and go test \>12 seconds
* Right handed participants are preferred due to the cortical lateralization of functions related to sensorimotor adaptation and postural control.
* However, we will recruit left-handed participants if there are insufficient right-handed volunteers.

Exclusion Criteria:

* Subjects with a known psychiatric comorbidity that in the investigator's opinion would compromise participation in the study; subjects with a neurologic diagnosis, other than Parkinson's disease that can cause imbalance and gait impairment (e.g., multiple sclerosis, stroke, subdural hematoma, peripheral neuropathy)
* Injury or impairment to the right arm (other than that which is due to Parkinson's disease) that would affect pointing movements; subjects with normal score on UPDRS part III
* Classified as legally blind or lacking sufficient visual acuity to view the target and pointing hand during prism adaptation
* Lacking sufficient understanding of verbal and written information in English to complete any of the consent screening forms.