Acuvue Oasys for Astigmatism are toric contacts designed to not only correct astigmatism, but also provide better comfort than other toric lenses due to an innovative technology called “Hydraclear.” These lenses are specifically designed to combat the problem associated with dry eyes and discomfort from toric contact lens wear. Since they are designed to be replaced on a bi-weekly basis, they also combat the problem of diminished visual acuity planned replacement contacts often present at the end of their wearing time. They require less time spent instilling rewetting drops making them providing convenience to the patient and assisting in maintain the fluid environment necessary for corneal health.
There are two types of astigmatism: regular and irregular. Regular astigmatism occurs as a result of the cornea having a less round, or spherical shape like that of a football. This causes light to focus at two different radii, not allowing a sharp clear ray of light to focus on the retina. This type of astigmatism can be corrected using glasses or contacts.
Toric contacts correct this refractive error by correcting each radii independently allowing light to refocus at one point rather than two. These contacts are weighted, known as prism ballasting, to allow the spherical and cylinder (both radii) prescriptions to be correctly oriented. Acuvue Oasys for Astigmatism has an accelerated stabilization design that minimizes the effect of rotational recovery.
Instead of having only one area of prism ballasting to weight the lens in the 6 o’clock position, as most conventional toric lenses, Acuvue Oasys for Astigmatism has four areas of prism ballasting residing at intervals of 90 degrees allowing for greater stability and shorter rotational recovery time. Rotational recovery is the amount of time required for a contact to return to its original position after an interruption such as blinking or eye rubbing. The less time the contact spends returning to its original orientation, the better the patient can maintain clear vision.
Acuvue Oasys for Astigmatism contacts also combine a wetting agent with an oxygen-permeating hydrogel polymer. Hydraclear technology contains a material called galyfilcon A. This creates an extremely smooth surface on both sides preventing the buildup of protein deposits, allowing 98% of available oxygen to reach the cornea, and maintaining moisture. Maintaining a healthy cornea requires the proper amount of oxygenation. If deprived of oxygen, the cornea will initiate an autoimmune response in the form of growing new blood vessels that will carry oxygen and nutrients to the affected areas. This ingrowth of new blood vessels is known as corneal neovascularization.
If neovascularization becomes a significant problem, it will disrupt this pathway and not allow light to properly reach the retina resulting in distorted vision. The hydrogel polymer galyfilcon A allows for more absorption of water in the form of contact solutions, rewetting drops and naturally produced tears that allow the contact to retain moisture. These absorption and retention properties assist in prevention of dry eye complications which may eventually lead to infections or compromise of visual clarity.