Quantification of the Visual Benefits of Soft Toric Contact Lenses Compared to Soft Spherical Contact Lenses

Quantification of the Visual Benefits of Soft Toric Contact Lenses Compared to Soft Spherical Contact Lenses Over a Range of Refractive Astigmatism

The aim of this work is to undertake a range of vision-related measures with soft toric contact lenses soft spherical contact lenses and spectacle lens correction across a range of levels of astigmatism.

This will be a randomised, crossover, partially subject-masked (for contact lenses only), non-dispensing study, controlled by cross-comparison.

Inclusion Criteria:

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Subjects will only be eligible for the study if:

1. They are of legal age between 18 and 40 years.
2. They understand their rights as a research subject and are willing and able to sign a Statement of Informed Consent.
3. They are willing and able to follow the protocol.
4. They are current wearers of any soft contact lens (i.e. have worn lenses in the last six months).
5. They have refractive ocular astigmatism between 0.00DC and -1.50DC in one or both eyes.
6. They have a spherical component to their ocular refractive error between 0.00 and - 6.00 DS.
7. They could attain at least 0.10 logMAR distance high contrast visual acuity in one eye with the study lenses within the available power range.
8. They can be fitted satisfactorily with both lens types.
9. They own an acceptable pair of spectacles.
10. They agree not to participate in other clinical research for the duration of this study.

Exclusion Criteria:

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Subjects will not be eligible to take part in the study if:

1. They have an ocular disorder which would normally contra-indicate contact lens wear.
2. They have a systemic disorder which would normally contra-indicate contact lens wear.
3. They are using any topical medication such as eye drops or ointment.
4. They have had corneal refractive surgery.
5. They have any corneal distortion resulting from previous hard or rigid lens wear or have keratoconus.
6. They are pregnant or breastfeeding.
7. They have any ocular abnormality which would, in the opinion of the investigator, normally contraindicate contact lens wear.
8. They have an amblyopic eye, in which case only dominant eye will be assessed for that subject.
9. They have an infectious disease (e.g. hepatitis), any immunosuppressive disease (e.g. HIV) or diabetes.
10. They have a history of severe allergic reaction or anaphylaxis.
11. They have taken part in any other contact lens clinical trial or research, within two weeks prior to starting this study.