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Lenses for nearsighted people are thin in the center but get thicker at the edge of that center zone. To correct farsightedness, lenses have a thick center that tapers down at the edge of the optical zone. Because standard Lenses are free to rotate as they sit on the eye''s surface, they can''t correct for astigmatism, a condition in which the cornea doesn''t have a spherical shape. Astigmatic eyes require toric lenses, which have different lens powers along different axes of vision. Recently, lens designers have produced contacts for astigmatism. discount By making the outer part of the lens, called the carrier portion, thicker on one side than the other, the manufacturer can ensure that the correction stays in line with the axis of irregular vision. As the wearer blinks and the lens moves, the thicker, heavier part stays at the bottom, ensuring that the lens is oriented correctly. These contacts have become widely available within the past 2 years.

The cornea consumes oxygen and produces carbon dioxide at rates proportionate with free diffusion of gases in air. The corneal epithelium requires a minimum p02 of 15 mmHg for proper aerobic glucose metabolism. Since available atmospheric oxygen is carried in the precorneal tear film, any lens material incapable of transmitting oxygen may lead to corneal haziness and corneal necrosis. Keeping the eyes closed or wearing Lenses lowers the p02 from normal to 32 mmHg to 9 mmHg. The availability of oxygen to the cornea can be determined by monitoring the lactate concentration in the cornea. For the cornea to maintain its functional integrity, the lens must be able to slide and move over the corneal surface with each blink so as to allow oxygen permeation. This oxygenation process in hard contact lens wearers is often referred to as "tear pump phenomenon" whereby the corneal epithelium is provided with oxygen-coated tears.

Typical teen curiosity has some eye doctors concerned about infections that could spread from one youngster to another when they trade cosmetic Lenses. The lenses often worn to change eye color or add designs, contacts but not necessarily to correct vision. And with this Halloween sparking the highest-ever interest in novelty lenses -- the kind imprinted with images -- consumer groups are warning users about the dangers of lens swapping. Fortunately, cases have been rare, but some have been serious. Kids are unaware that these are optical devices, and they''re using them as toys. Soft Lenses are like sponges, and they can hold onto bacteria. Doctors also warn that an ill-fitted lens can cause damage to the eye''s surface. Even if a lens does not correct vision, it is considered a medical device and can be sold only by prescription. Wearers must have eye exams; lenses must be fitted properly.

Are you in the market for some new contacts? Are you looking for quality contacts by Biomedics? Check us out. We have a comprehensive selection of contacts by all the major manufacturers including Biomedics.