effect of head and gaze position on soft toric contact lens performance

Conditions: Astigmatism; Myopia

Summary: primary hypotheses: senofilcon a will provide significantly less rotation with subjects in a recumbent position than filcon ii 3 monthly . etafilcon a will provide significantly less rotation with subjects in a recumbent position than filcon ii 3 1 1 day . etafilcon a will provide rotation with subjects a recumbent position non-inferior to nelfilcon a. a margin of 5 degrees will be used. secondary hypotheses: senofilcon a will have significantly better monocular visual performance with subjects in a recumbent position than filcon ii 3 monthly. etafilcon a for astigmatism will have significantly better monocular visual performance with subjects in a recumbent position than filcon ii 3 1 day. etafilcon a will have monocular visual performance with subjects in a recumbent position non-inferior nelfilcon a. a margin of 0.05 logmar will be used.


Eligibility criteria:
inclusion criteria: * age range 18-60 years. * read, understand, and sign written statement of informed consent. * appear able and willing to adhere to the instructions set forth in the clinical protocol. * be existing soft contact lens wearers (no extended wear in the last 3 months, but silicone hydrogels in daily wear are allowed). * require a visual correction in both eyes (monovision allowed but no monofit). * have a spherical contact lens requirement in the range -1.00 to -6.00d. * have astigmatism of between -0.75 and -2.00dc in both eyes. * have axes of astigmatism within +/-10° of the following available lens axes: 70°, 90°, 110°, 20°, 180° \& 160°, i.e. 60-120, 10-30 and 150-180. * monocular distance visual acuity correctable to 6/9 or better in each eye with best sphero-cylindrical refraction. * have normal eyes with no evidence of any ocular abnormality or disease. for the purposes of this study a normal eye is defined as one having: i) clear cornea ii) no anterior segment disorder iii) no clinically significant slit lamp findings (i.e. edema, staining, scarring, vascularization, infiltrates or abnormal opacities) iv) no other active ocular disease or recent surgery exclusion criteria: * having worn rigid gas permeable (rgp) contact lenses within the last 30 days or polymethyl methacrylate (pmma) contact lenses within the last 3 months. * clinically significant corneal edema, corneal vascularization, corneal staining, tarsal abnormalities, bulbar injection or any other abnormality of the cornea that would contraindicate contact lens wear. * extended lens wear in last 3 months. * any systemic or topical medications that will in the investigator's opinion affect ocular physiology or contact lens performance. * any systemic disease affecting ocular health. * abnormal lacrimal secretions. * keratoconus or other corneal irregularity. * pregnancy, lactating or planning a pregnancy at the time of enrolment. * participation in any concurrent clinical trial. * any previous anterior ocular surgery. * subjects who are known to have an infectious systemic disease (e.g.,hepatitis, tuberculosis). * subjects who are known to have an immunosuppressive disease (e.g., hiv positive). * subjects who are known to have diabetes. * employees or family members of the research site, principal investigator or study team.