Contact lenses have been around for over 70 years. Snipers were issued with glass contact lenses in WWII; initially all lenses were rigid, however with the improvement of polymers, soft contact lenses were introduced and latterly silicone hydrogel lenses have become available. About 5% of the population wears lenses, of which 90% are the soft variety. There are 1 billion lens wearers worldwide.
Contact lens wear is generally very safe; as attested to by the numbers of wearers. There is, however, a lack of awareness regarding the potential risks associated with contact lens wear. I feel that you should know about these risks.
The safest lenses to wear are still the rigid variety, but unfortunately they are generally less comfortable to begin with, and are less popular these days; accounting for around 10% of all wearers.
The most serious complication that can occur with contact lenses is keratitis, an infection of the cornea (which is the clear window at the front of the eye). This infection can be devastating to vision. It is more common in soft lens wearers, and in particular those who wear lenses for extended periods, including night-time wear. Many authorities claim that these lenses have better oxygen permeability, which is perfectly true. This does not however, alter the fact that these lenses have a much higher infection rate. I would only recommend night-time wear where there are handling difficulties such as the very young (where lens wear is medically required) or the elderly.
The reasons for infection are generally related to a lack of oxygen getting to the cornea, biofilm material coating the lenses and accumulating with time (biofilm is like the slime that collects on a ship’s hull), and contamination of lens containers with bacteria and other organisms.
Tips for safe contact lens wear
- Always have your eyes reviewed by the optometrist annually – it is particularly tempting to omit this if you order lenses online
- Replace lenses according the manufacturer’s schedule. This is important since different lens materials have different usable durations. Do not wear daily disposables for more than a day
- Always wash and dry your hands before handling lenses
- If you store lenses at night, always change the fluid solution each day. Leave the container to air dry during the day. This way bugs will not collect in the solutions
- Change the containers every few months
- Never lubricate your lenses with saliva
- Smoking increases the risk of infection
- Always remove your lenses when swimming
- Remember that in lenses you should “Look Good, Feel Good and See Good”.
What to do if you get a red eye?
ALWAYS REMOVE THE LENS UNTIL THE EYE SETTLES
From time to time you may get irritation, watering and redness associated with a minor foreign body. If, however, the redness and pain persists for more than a day you should seek the advice of an ophthalmologist as a matter or urgency. This referral can be made by your GP, your optometrist or local casualty department. Do not “push on” with wearing the lens.
The picture on the left shows a nasty sight threatening bacterial infection
and the picture on the right show contact lens overwear with new vessels growing onto the cornea.
Most serious bacterial corneal infections can be arrested with intensive fortified antibiotics; however, an ophthalmologist should manage this.
See under keratitis
Other problems associated with contact lens wear:
Dry Eye – This is quite common after many years of lens wear, particularly in women of middle age and onwards. A preservative free lubricating drop every now and again may help.
Giant Papillary Conjunctivitis GPC
This is a hypersensitivity reaction (allergic) to the contact lens material. Treatment includes abstinence from wear for several weeks. Sometimes changing the lens material helps, as does reducing wearing time. Unfortunately in some cases continued wear is not possible.
Contact lens intolerance
Contact lens intolerance may occur, often after many years of successful wear. There are many causes, including: allergic problems, dry eye, blepharitis, and poor oxygen transfer leading to new vessel formation. Your optometrist will be able to monitor and manage many of these problems.
Sometimes reducing wearing times, or changing the lens material may solve the problem. Another trick is to wait an hour or two in the morning before putting the lenses in.
If there are concerns you may be referred to your ophthalmologist.
If you truly become contact lens intolerant, refractive surgery may be an appropriate option.
More contact lens related information can be found at:
www.cclsa.org.au
http://www.bcla.org.uk/en/consumers/index.cfm
