Photic Blink Reflex in People With Blepharospasm and Increased Blinking

Study Summary

Background: Some people who have increased blinking may later develop blepharospasm. Blepharospasm is a neurological disorder that causes involuntary closing of the eyes. Researchers want to learn more about how eyes close in response to different stimuli. They want to study this in healthy people, people with increased blinking, and people with blepharospasm. Objective: To learn how light exposure affects people with blepharospasm. Eligibility: People ages 18 and older with blepharospasm or increased blinking, and healthy volunteers Design: Participants will be screened with: Medical history Physical exam Neurological exam Participants will have up to 5 visits. The number of visits will depend on the number of tests they opt to have. They can opt to have up to 4 tests. Visits last 60-90 minutes. They cannot drink alcohol or caffeinated drinks for at least 12 hours before visits. Visits could include the following tests: Evaluation of eyelid movements. This will be video recorded. Electromyography: Small sticky electrodes are placed on the lower eyelid skin. These are attached to wires. Muscle activity is recorded during blink reflex procedures. Electrical stimulation: An electrode is placed close to the eyebrow. It will deliver small electrical shocks. The strength of the shocks will be enough to provoke a blink. Photic stimulation: A lamp is placed in front of the face. It will deliver single or paired flashes. The flashes will be at various intervals and intensities. Participants will wear a patch over one eye during this test. Combination of electrical and photic stimulation ...