Contact lenses are worn on the eye primarily to improve vision or protect the anterior ocular surface. Soft contact lenses are slightly larger than the cornea and are manufactured from hydrogel or silicone hydrogel plastics that allow oxygen to pass through the lens to reach the cornea. Rigid contact lenses are typically smaller than the cornea and as the name suggests are produced from stiffer plastics than soft lenses. They can correct the simple refractive errors including myopia, astigmatism, hyperopia and presbyopia, along with more complex optical problems resulting from an irregular cornea (eg. keratoconus).
Scleral Contact Lenses
Scleral contact lenses are large diameter rigid lenses often used in the refractive correction of corneal ectasia or therapeutic treatment of severe dry eye. A number of studies conducted within the Contact Lens and Visual Optics Laboratory have investigated the physiological response of the eye to short-term scleral contact lens wear including; ocular tissue compression, changes in intraocular pressure and corneal optics, and corneal swelling and recovery.
Optics of Contact Lenses
The optical properties of contact lenses on the eye can be measured by using a wavefront sensor to acquire the eye’s wavefront without a contact lens (“bare eye”) and with a contact lens on the eye. The difference in wavefront between these two conditions is the optical effect of the contact lens on the eye.
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