Is Contact Lens Safe?
Since contact lens made its first appearance more than half a century ago, the number of contact lens wearers today has grown to around 150 million people worldwide. In Hong Kong, there are about 750,000 on different types of contact lenses. Contact lens has become a very popular vision correction modality largely because of its great comfort.
Is it safe? What can go wrong?
Studies have shown the incidence of serious sight threatening complications such as corneal ulceration is around 4 in 10,000, a very safe figure for medical devices.
The major causes of contact lens complications are:
1. Poor fitting
2. Overuse and infrequent replacement
3. Noncompliance to care regimen
5. Lack of follow up
Most of the contact lens problems can either be avoided or treated if detected early enough. A regular visit to your contact lens practitioner is therefore essential.
Common contact lens complications are:
1. Hypoxia (Lack of oxygen)
When lenses are fit too tight, worn overtime and in a poor oxygen permeable material, hypoxia will occur leading to corneal swelling, redness of the eye, blurred vision, corneal cell damage, discomfort and growth of new vessels into the cornea.
Loosely fitted lens may lead to damage to the corneal and conjunctival surface causing discomfort and possibly infection.
Wearers of insufficient tear quantity or quality should not consider wearing contact lenses as a dry lens may cause damage to the cornea and the eye lid resulting in abrasions and discomfort. An assessment by an optometrist for the suitability of contact lenses is highly recommended.
Inappropriate or incorrect use of contact lens care system may lead to allergic or toxic response. Deposits, particularly protein, on the lens may also trigger allergic conditions such as Giant Papillary Conjunctivitis and cause itchiness, discharge, excessive lens movement, blurred vision and reduced tolerance to the lenses.
When there is a break in the corneal surface, it increases the chance of an infection especially when the lenses are not properly disinfected. A poorly fitted lens, low oxygen permeable material and sensitivity reaction to the care solutions are major causes of corneal damage. If not handled appropriately and timely, it may lead to ulceration and even blindness.
Prevention is better than cure
Most contact lens problems are not symptomatic in the early stage, regular eye examination is the best preventive measure. When you choose to have contact lenses, remember:
1. Look for a professional optometrist
2. Keep proper lens care procedures and wearing time
3. Replace your lenses regularly (conventional lenses should be replaced at least every 6-8 months)
4. Visit your practitioner as scheduled (e.g. every 6 months)
5. Remove your contacts immediately when your eyes do not feel or look good and see your optometrist as soon as possible