Spectacles for correcting irregular astigmatism
Research type
Research Study
Full title
Spectacles for correcting irregular astigmatism
IRAS ID
282471
Contact name
Neil French
Contact email
Sponsor organisation
University of Liverpool
Duration of Study in the UK
0 years, 11 months, 30 days
Research summary
Summary of Research
This project aims to create spectacle lenses that correct irregular astigmatism for keratoconic patients. The idea is based on a proof of concept study that now requires clinical validation, which will be carried out with the Fight for Sight funding sought.As advanced keratoconic patients find difficulty in their daily life during the times when they cannot wear their contact lenses, this project will be a step towards the development of spectacles that can maintain a reasonable visual acuity.
The project addresses the visual side effects of the resultant distortion with the development of spectacle lenses that can correct non-orthogonal astigmatism. This is not possible with current spectacle lens manufacturing techniques, leaving patients with this condition entirely dependent on contact lenses, or in serious cases, corneal transplants, in order to achieve reasonable visual acuity.
The outcome of this project will form the basis of a larger funding application to take the technology from concept to a clinical product, potentially leading to a major step forward in the current prescription system for keratoconic patients.Summary of Results
A ratio of 70% (14 eyes) achieved an improvement in LogMAR Visual Acuity, with 10 of those eyes also reporting a reduction in ghosting and all 14 reporting some improvement in letter clarity.
A ratio of 25% (5 eyes) achieved the same LogMAR Visual Acuity, with all of these reporting a slight to moderate reduction in ghosting and 4 also reporting moderate to significant improvement in clarity.
A ratio of 5% (1 eye) reported a slightly reduced LogMAR VA but did experience an improvement in letter clarity.
All of the 15 subjects had at least one eye eligible for the study, and all found some improvement in visual acuity, letter clarity, reduction in ghosting or a combination of the three. (See Table 1 in the supporting material for details) In the questionnaire, subjects were asked if they would wear non-orthogonal spectacles if they had the opportunity. This was a little difficult for some to assess if they only had one keratoconic eye, but 13 of the subjects (72%) said they would definitely wear them, whereas one said they would not. The remainder did not answer the question, even if they responded positively in terms of improved clarity and reduced ghosting. We feel this was partly due to some subjects reporting they felt a little “strange” when wearing the trial lenses.
Therefore, the objective of determining whether the visual experience of keratoconics improves VA, increases the clarity of images and reduces ghosting using non-orthogonal cylindrical lenses has been achieved.REC name
London - Bromley Research Ethics Committee
REC reference
21/PR/0561
Date of REC Opinion
9 Jul 2021
REC opinion
Further Information Favourable Opinion