How Fresnel prisms effect binocular visual functions in patients
Research type
Research Study
Full title
The effect of Fresnel prisms on the binocular visual functions in a clinical population
IRAS ID
193045
Contact name
Sonia Toor
Contact email
Sponsor organisation
University of Sheffield
Duration of Study in the UK
0 years, 3 months, 27 days
Research summary
If a patient attends the eye clinic with symptoms of double vision they can be given a Fresnel prism, a thin plastic membrane that can be stuck onto one lens of their glasses, to alleviate their symptoms. One of the disadvantages of the prism is that it reduces the vision in the eye viewing through the prism, in particular how small a letter can be correctly identified (visual acuity) and how pale a letter can be on a white background and still be identified (contrast sensitivity). This study will investigate how vision (visual acuity and contrast sensitivity) is affected when viewing with both eyes open in the clinical population when a Fresnel prism is fitted to one lens of their glasses. Forty four participants will be recruited from a cohort of patients experiencing double vision who attend the Royal Gwent Hospital Orthoptic Department. Participants will have their visual acuity and contrast sensitivity tested with either eye without the prism, and again with both eyes open with the prism. These additional tests will take approximately 10-15 minutes in addition to the normal clinic appointment. This study hopes to be able to advise patients wearing a Fresnel prism about their eligibility to drive based on the reduction of vision.
REC name
North West - Haydock Research Ethics Committee
REC reference
16/NW/0109
Date of REC Opinion
18 Feb 2016
REC opinion
Favourable Opinion