Focus on contact lenses

By Abigail Sevigny

SOFTLY, SOFTLY
• Soft lenses are made of soft plastic called hydrogel. These lenses allow the eye to breathe and permit a steady flow of oxygen to the cornea. The material is quite porous, which can increase the risk of infection and irritation due to bacteria, dust and protein.

• Extended-wear lenses are soft lenses that have been licensed for continuous wear for up to 30 days and nights without being removed. Extended-wear lenses are made from new super-permeable silicone hydrogel materials, which provide much more oxygen to the eye than most conventional extended-wear contact lenses.

• Cosmetic contact lenses are non-corrective contact lenses that change the eye colour or look of the iris (cat-eye looks are popular). They are sold by retail drugstores or optometrists. The Canadian Ophthalmological Society recently raised concerns about the safety of these unregulated lenses and is asking doctors to submit reports of any eye injuries or adverse reactions they've come across (fax: 613-729-7209).

HARD SELL
• Hard lenses are made of firm polymer plastic. These lenses restrict the flow of oxygen to the cornea, but they're easier to clean and are less likely to absorb dust and bacteria.

• Rigid gas permeable (RGP) lenses are hybrid lenses of sorts, combining the best of both worlds. RGPs contain silicone that allows oxygen to pass through the lens to the cornea. In many cases RGP lenses transmit more oxygen than regular soft lenses.

RESHAPE UP
• Corneal reshaping lenses are gas permeable lenses that reshape the surface of the eye to correct minor degrees of nearsightedness and astigmatism while the patient sleeps. The effect is temporary and lasts about the duration of the day. Health Canada recently changed regulations regarding the licensing of these lenses, demanding that manufacturers show proof that their product is safe before they get licensed. The new licensing procedure comes after reports that the lenses used in Ortho-K could cause eye and sight damage.