Contact Lens Assessment
Contact lenses are thin, flexible pieces of plastic that mould to the front window of the eye called the cornea. They allow flexibility for people with shortsightedness, longsightedness and astigmatism. A persons prescription is the exact amount of shortsightedness, longsightedness and or astigmatism that each individual has. This is calculated by the optometrist and is then used to decide the power of the contact lens needed.
Contact lenses are available in hard or soft varieties. The hard lenses (rigid gas permeable lenses) are excellent for patients with high prescriptions, astigmatism and keratoconus. The soft variety, are also suitable for astigmatism and larger prescriptions but may not provide the ultimate visual clarity depending on how large the individual prescription is.
We must always remember that the cornea is living tissue like our skin. It needs oxygen and nutrients to survive. Other parts of the body have blood vessels to channel oxygen and nutrients to the living cells. The cornea however, has intricately structured layers which allow it to be “see through” allowing us to “see”. It does not have blood vessels to provide it with oxygen. It relies solely on oxygen from the air. When we place a contact lens on the eye, this piece of plastic reduces the oxygen going through to the eye. If contact lenses are over-worn or we sleep in lenses that are not suitable for this, the cornea can become starved of oxygen. This can lead to contact lens intolerance or even worse an eye infection. New technology has allowed companies to produce contact lenses that channel more oxygen to the cornea, thus allowing 30 days of continuous wear, day and night. This continuous wear is only suitable for certain patients and does require consultations to assess the reaction and stability of the cornea following wear. Some people wear these lenses as a general day wear lens for better comfort and reduced redness.
No matter what your needs are we can go through the list of contact lenses available and assess you for contact lens wear. We will find the contact lens that fits your cornea for optimal wear. The optometrist will ensure the lens is not too loose as a loose lens will be inclined to move too much and be irritating or even fall off. If the lens doesn’t move enough (too tight), tear exchange behind the lens is minimal and the fluid can become stagnant leading to discomfort and possibly increased risk of infection.
In the case of disposable lenses, patients are given a free trial of the contact lenses. This gives the patient an opportunity to get used to contact lens wear (or a new type of lens if an existing wearer) and the optometrist can review the fit of the lenses after several hours wear. Once you are successfully fitted with a particular type of contact lens by the optometrist, you can happily wear these lenses as advised like billions of others all around the world!
