Effect of a Fresnel Prism on Visual Function
Research type
Research Study
Full title
The effect of a temporary unilateral Fresnel prism, used to correct diplopia, on visual function tested both eyes open.
IRAS ID
191526
Contact name
Helen Griffiths
Contact email
Sponsor organisation
The University of Sheffield
Duration of Study in the UK
0 years, 2 months, 29 days
Research summary
Prisms are routinely used by Orthoptists and Ophthalmologists to measure and assess the control of misalignment of the eyes and as a conservative treatment of double vision. In the UK the standard prism used as a form of treatment is a 3M plastic Press-on(TM)Fresnel prism, which is usually fitted to one lens of a pair of glasses. Fresnel prisms can be used as a temporary form of treatment whilst awaiting recovery or stability prior to surgery; otherwise as a permanent treatment option for patients where alternative treatments are unsuitable. Although these plastic prisms do correct double vision they also cause distortion and reduction in vision. Previous studies have assessed their effect, in visually normal individuals, on vision in the eye viewing through the Fresnel prism and have shown considerable reduction in eye sight. However a Fresnel prism fitted on one lens is prescribed for binocular viewing. The effects of a prism when both eyes are open cannot be tested in participants with normally aligned eyes because it would induce double vision in a normal visual system. This study aims to evaluate the effects on vision of a single prism used to correct double vision in a clinical population when viewing and tested with both eyes open. Results will determine if a significant decline in vision is induced with the use of a Fresnel prism placed over one lens. A qualitative measure of the patient's experience wearing the prism will also be taken using a questionnaire. This will help clinicians to gain a better understanding of the overall benefits and possible detriment induced with this type of treatment.
REC name
East Midlands - Leicester South Research Ethics Committee
REC reference
16/EM/0049
Date of REC Opinion
26 Jan 2016
REC opinion
Further Information Favourable Opinion