Proclear Toric lenses by Coopervision are designed to provide the astigmatic patient with comfort, maintenance of ocular health, and clear, crisp vision. Astigmatism is the most common refractive error found among patients. Astigmatism is caused when the irregular shape of the cornea diverts light into two different meridians as it passes through the refractive medium of the cornea causing it to focus at two different points on the retina. Depending on the degree of astigmatism, a compound lens correcting errors in each meridian must be prescribed. When prescribing contacts a very minor degree of astigmatism is generally left uncorrected since it poses no real distortion of visual acuity. As a result, most patients with very minor degrees of astigmatism are wearing spherical lenses.
Spherical lenses differ from toric lenses in that the power is the same in any meridian of the lens. This lens will rotate constantly throughout the day as the patient blinks or feels a need to rub their eye. Visual acuities are not compromised due to their spherical nature. Toric lenses are designed differently to correct for refractive errors in two different planes — sagittal and tangential, or spherical and cylindrical oriented at an axis of 90⁰ from one another. This requires a high degree of stability in toric lenses since they correct in different meridians. If the lens is allowed to rotate, the patient’s visual acuity will suffer. Proclear Toric lenses are prism ballasted and available in a wide range of powers, diameter and base curve. In fact, more than 45,000 different parameters are available to the eyecare professional when fitting this lens. This translates to a better fit, more comfort and better visual acuity.
In addition to providing stable vision for astigmatic patients, Proclear Toric lenses are made with a combination of phosphorylcholine technology as well as hydrogel polymers. Phosphorylcholine is a unique substance harvested from human cellular membranes that surround themselves with water. This provides the contact with two important features: maintenance of moisture and biocompatibility. Maintaining the fluid environment of the corneal tear film is vitally important to overall ocular health. Proclear Toric lenses have a water content of 38%. If the corneal tear film is disrupted, the cornea becomes more susceptible to allergies and infections as both bacteria and allergens are allowed to infiltrate the surface of the cornea causing discomfort or visual complaints. Hyrdogel materials are hydrophilic meaning they absorb and retain moisture. This provides the patient with comfortable wear throughout the course of the day as natural tears, rewetting drops and contact solutions all work together to maintain the fluidity of the corneal tear film.
The biocompatibility of a contact lens is important since the cornea has an autoimmune mechanism triggered if an area is deprived of nutrients and oxygen. This response is called cornea neovascularization. The eye will begin growing new blood vessels to combat the lack of oxygen caused by either dirty or ill-fitting contact lenses. In advanced cases, this ingrowth of new blood vessels may encroach on the visual axis causing irregular astigmatism and diminishing visual acuities. Using phosphorylcholine and the hydrogel polymer omafilcon A, Proclear Toric lenses provide nearly six times the amount of oxygen as traditional planned replacement soft toric lenses.