Purchase this article with an account.
A. R. Bowers, K. Keeney, D. Apfelbaum, E. Peli; Randomised Controlled Multi-Center Trial of High-Power Peripheral Prism Glasses for Hemianopia - Final Results. Invest. Ophthalmol. Vis. Sci. 2010;51(13):6006.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
We have completed a community-based, multi-center clinical trial to evaluate the functional utility for general mobility (walking) of new, high-power (57Δ, ~30°) peripheral prism (PP) glasses for patients with hemianopia.
A randomized, placebo-controlled, masked, crossover design was used in which real (57Δ) PP glasses were compared to sham (5Δ) PP glasses. Two PP designs were used, the previously evaluated horizontal design and a new oblique design that provides field expansion more centrally.
Patients (with homonymous hemianopia with neither neglect nor cognitive decline) were randomly allocated to two treatment groups: (1) real horizontal and sham oblique, (2) real oblique and sham horizontal. Order of sham and real glasses were counterbalanced. The PMMA Fresnel PP segments were fitted unilaterally on the side of the field loss. With the exception of the allocator (DA) and optical lab (Chadwick), patients and data collectors were masked (as far as possible) to the treatment allocation. Clinicians at each site recruited and screened patients, fitted prism glasses, trained patients in their use, while data collectors conducted questionnaires evaluating functional benefits for mobility after each pair of glasses had been worn for 4 weeks. Patients with a clinical decision to continue wear at the end of the crossover were interviewed by telephone 6 months later.
97 patients were screened at 14 clinics: 73 met the criteria, of which 61 completed the crossover. In a comparison questionnaire before debriefing, real glasses were rated as significantly better than the sham for obstacle detection (p < 0.001). Subsequently 37 (61%) selected real glasses, 16 (26%) sham glasses and 8 (13%) neither. Those who received real glasses second were more likely to select the real glasses than those who received real glasses first (75% and 49%, p < 0.01). Those who selected sham glasses were more likely to report difficulties with the real prism glasses than those who selected real glasses (p = 0.06). After debriefing, 36 (59%) continued to wear real glasses, with no difference (p = 0.87) in continuation rates for the two designs. To date, 27 have completed 6 months, with 19 continuing wear, reporting lower levels of perceived difficulty with mobility than at baseline (p < 0.01).
The majority of patients found that the real PP glasses assisted with obstacle detection when walking while the sham PP glasses did not. Long-term follow up results are promising.
Clinical Trial: :
This PDF is available to Subscribers Only