Cooper Vision released the Biofinity contact lens recently in a toric version. This will increase the number of peoeple who can be helped by the aquaform technology by providing options for astigmatism. The original Biofinity lens for nearsighted patients was releases in 2008. It has been referred to as the beginning of the third generation silicone hydrogel contact lens.
Hydrogel has been the primary material soft contact lenses have been manufactured from for the last 30+ years. The first soft contact lens approved by the FDA was the original Bausch & Lomb Soflens. Hydrogels are gel like substances that are formed by polymer chains.Polymers are large molecules composed of repeating units connected together. This structure allows a matrix for water to reside in, giving the contact lens its soft nature and allowing air to permeate the through the lens. Various additives and manipulations have been used over the years to improve the handling and percentage of water the lenses retain. The amount of oxygen transmitted through the lenses is restricted by the water content, and their is a maximum amount of air that can pass through traditional hydrogel lenses.
The levels of oxygen flow in hydrogel materials have never been adequate to keep the corneal eye tissue from significant swelling when worn overnight. Silicone lenses were developed a number of years ago to increase the air flow through contact lenses but were plagued by poor wettablity with discomfort and never bacame popular.
Silicon is an very common element found in nature. Silicones are mostly man made polymers. Silicon alternating with oxygen forms the backbone of the backbone of silicone with branches coming off the Silicon. Silicione is also referred to as siloxane.
Cooper Vision developed the Aquaform Technolgy to manipulate this process and enhance the lens properties. By making the backbone chains longer and reducing the cross links the lens material is softer. Two different lengths of polymers are also used to enhance the lenses properties.
The secondary result of these changes are an increase in the inherent wettabiltiy without utilizing a coating or weeting agent. The lens edges have been rounded or softened according to Cooper Vision to increase the comfort. The front surface is aspheric, flattening out towards the edge to enhance vision by correcting some of the aspherical shape the cornea tissue has. The end result is a new material with new properties-comfilcon A. The Biofinity lens is 48 percent water, and in the units we use to measure air flow through the lens it is 600% or more permeable than the normal hydrogel lenses that had been the main stay of soft contact lenses for 30 years (Dk = 128, and Dk/t = 160).
For our patients in the low humidity dry eye climate of Fort Collins this has been a very comfortable healthy lens, and we use it as a daily removal lens and as a 30 day extended wear lens. The lens is approved for a one month replacement cycle which is much easier to remember than the traditional two weeks. Overall, it is a great addition to contact lens technology and now we look forward to fitting more of our patients with astigmatism into a healthier, more comfortable lens.