Effect of Astigmatism Axis Location on MF CL Visual Performance
Research type
Research Study
Full title
The Effect of Astigmatism Axis Location on Multifocal Contact Lens Visual Performance
IRAS ID
281917
Contact name
Michel Guillon
Contact email
Sponsor organisation
CooperVision, Inc.
ISRCTN Number
ISRCTN14840896
Duration of Study in the UK
0 years, 6 months, 30 days
Research summary
When correcting astigmatism with soft contact lenses, two factors are important; the magnitude or power of the correction needed and the alignment of the astigmatism axis. One study has shown that correcting astigmatism power to the nearest 0.25DC up to 1.00DC of astigmatism using a 0.75DC astigmatic correction achieves better overall visual acuity than not correcting the astigmatism. In terms of the axis alignment, the precision with which the contact lens correction is aligned with the axis of the patient refractive astigmatism availability vary from every 5 to 20 degrees. The question, therefore, is whether there is a need for the multifocal correction of astigmatism to be exactly on axis (within ± 5degree) or if a 10 or 20 degree misalignment would be acceptable and comparable to the visual performance achieved by correcting the 0.75DC of astigmatism with perfect axis alignment. Therefore, the rationale of the study is to carry out the initial non-dispensing measurement of visual performance in order to identify the astigmatism axis misalignment acceptability before initiating a more complex dispensing study to assess acceptance.
REC name
London - City & East Research Ethics Committee
REC reference
20/LO/0633
Date of REC Opinion
18 May 2020
REC opinion
Further Information Favourable Opinion