Silicone vs. Non-silicone Lenses - Student Health & Wellness

Optometry TidbitSally WuSilicone Soft Lenses vs. Non-silicone SoftLensesThere are a dozen choices when determiningwhich soft lenses are the best and the bestcan vary among each patient. To furtherunderstand and narrow down the search, thisarticle will explain the differences betweensilicone soft lenses and non-silicone softlenses.What is silicone and non-silicone softlenses made of?To start off, silicone lenses are made of twospecific monomers: PHEMA (hydrophilic)and silicone (hydrophobic). Thesemonomers are combined to form acopolymer. When a bunch of thesecopolymers are cross-linked together, theyform the lens material.In a similar process, non-silicone lens aremade of other monomers which arecombined to make polymer chains thatwoven together by cross-linking thosepolymers together to make the lens material.Unlike, silicone lenses, non-silicone lensescan be made with many types of monomerswhich include: methacrylic acid, isobutylmethacrylate and more.Pros and Cons of Silicone Soft LensesAside from the obvious benefits ofappearance and practicalities, the mainbenefit of silicone lenses is its high oxygenpermeability, which is crucial formaintaining the health of the cornea.ReferencesSilicone lenses may actually allow fivetimes more oxygen through the cornea thannon-silicone lenses. These lenses may alsoreduce hypoxia-related symptoms whichinclude: corneal swelling, blurred vision,and red eyes. However, high oxygenpermeability does not directly correlate tohow comfortable the lenses may be,especially because it can lead to highsensitivity in the cornea. Such support canbe found in two studies, conducted in 2005,that compared Proclear Compatible lens(non-silicone) to Acuvue Advance (silicone)and O 2 Optix (silicone). Both studies hadsimilar results where the participants had agreater preference toward the Proclear lensthan silicone lens that were given.Pros and Cons of Non-silicone Soft LensesMany of the same benefits from usingsilicone soft lenses can still be applied fornon-silicone lenses, such as comfort, easyadaptation and durability. However, asmentioned previously, non-silicone lensesdo not allow as much oxygen to permeate tothe cornea as compared to silicone lenses.On the other hand, because non-siliconelenses are less oxygen permeable, patientsmay feel more comfortable with nonsiliconelenses because there is lesssensitivity in the cornea.What is better for you?Almost all of the newest contact lenses aremade of silicone contact lenses. Therisks/benefits ratio leans towards siliconelenses though your optometrist can help youdecide what lens is best for you.

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