title: Community-based trial of a peripheral prism visual field expansion device for hemianopia.
abstract: OBJECTIVE
  To determine the functional utility for general mobility of peripheral prism glasses, a novel visual field expansion device for hemianopia, in a large-scale, community-based, multicenter study with long-term follow-up.
  
  
  METHODS
  Forty-three participants with homonymous hemianopia were fitted with temporary press-on Fresnel peripheral prism segments of 40 prism diopters. Follow-up questionnaires evaluating functional benefits for mobility were administered in the office at week 6. Participants who continued wearing the prisms were interviewed again by telephone after a median of 12 months. Primary outcome measures included clinical success (a clinical decision to continue wear) and 5-point ratings of prism helpfulness for obstacle avoidance when walking.
  
  
  RESULTS
  Thirty-two participants (74%) continued prism wear at week 6, and 20 (47%) were still wearing the prisms after 12 months (median time, 8 hours per day). These participants rated the prism glasses as very helpful for obstacle avoidance and reported significant benefits for obstacle avoidance in a variety of mobility situations. Success rates varied among clinic groups (27%-81%), with higher rates at the clinics that fitted more patients.
  
  
  CONCLUSIONS
  Our results demonstrate the functional utility of peripheral prism glasses as a general mobility aid for patients with hemianopia.
authors.affiliation: Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114, USA. alex.bowers@schepens.harvard.edu
authors.forename: Alex R
authors.initials: AR
authors.lastname: Bowers
authors.forename: Karen
authors.initials: K
authors.lastname: Keeney
authors.forename: Eli
authors.initials: E
authors.lastname: Peli
mesh_terms: D000203:Activities of Daily Living; D005139:Eyeglasses; D005500:Follow-Up Studies; D006423:Hemianopsia / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D017060:Patient Satisfaction; D017755:Prosthesis Fitting; D011795:Surveys and Questionnaires; D014794:Visual Fields / Q000502:physiology*