Spherical vs Toric in a Low Astigmatic Population
Research type
Research Study
Full title
Performance and Acceptance of Spherical vs. Toric Multifocal Contact Lenses in a Low Astigmatic Population - Proof of Concept Study
IRAS ID
294068
Contact name
Michel Guillon
Contact email
Sponsor organisation
CooperVision International Limited
ISRCTN Number
ISRCTN92830937
Duration of Study in the UK
0 years, 9 months, 12 days
Research summary
Presbyopia is a condition associated with aging in which the eye exhibits a progressively diminished ability to focus on near objects. When correcting presbyopia with contact lenses, multifocal designs are used to correct vision at far, intermediate and near distances. This differs from the correction of younger wearers, for whom a single focal (single vision) corrects at all three distances.
Single vision spherical soft contact lenses are fitted to patients with low level of astigmatism within their CE markings, an approach that has been followed since contact lenses became a modality of vision correction. The approach, which was shown to give good vision, has been successfully adapted for presbyopia correction with spherical multifocal contact lenses.
Multifocal contact lenses decreases the intensity of the retinal image for any distance of interest (e.g. distance or near vision) which leads to a decrease in vision quality. Astigmatism, which is not corrected also produces a decrease in vison, as the two effects are additive this may lead to decreased acceptance by patients.
The rationale for the current proof of concept study is therefore to investigate the potential benefits of correcting low levels of astigmatism in multifocal wearing presbyopes.
Up to 45 participants will be screened with a view to achieve a per protocol population (PPP) of up to 24 participants divided into three near addition groups from emergent to established presbyopes. The study includes four study visits. Participants will wear both contact lens types (test: Spherical clariti multifocal, control: Toric clariti multifocal )in a randomised sequence. Both contact lenses are CE marked and each lens type will be worn for a week on a daily wear, daily disposable basis. Both participants and investigators will be masked.
REC name
East of England - Essex Research Ethics Committee
REC reference
21/EE/0034
Date of REC Opinion
4 Mar 2021
REC opinion
Further Information Favourable Opinion