An Introduction to Contact Lenses

Often the main motivation to wear contact lenses is cosmetic, to avoid the need for spectacles. However many spectacle wearers are choosing to wear disposable contact lenses for sport or a special occasion. Contact lenses may even be worn with no prescription (Plano) simply to change eye colour. Nevertheless, they are still a prescription device that sits on a healthy eye and must only be fitted by a qualified eye care professional. Nothing is more precious than your sight and you should never put it at risk.

Although all eyes look pretty much the same, in reality everybody's eyes are slightly different. Eyes come in a variety of shapes and sizes and it is essential that anyone wanting to try contact lenses should visit an optometrist for a contact lens consultation and fitting.  After being fitted for contact lenses you will be given instructions on how to properly insert and remove your contact lenses without causing any damage to your eye, you will also be given advice on lens handling, which will help you get the most out of your lenses without damaging them.  If you wear a damaged contact lens it can irritate your eye and cause a nasty eye infection.

All contact lenses have a different wearing schedule according to the lens and the patient, so it is very important that you follow recommendations made by your optometrist.  If you are experiencing any discomfort or eye redness, remove the contact lens immediately and consult your optometrist.

Borrowing contact lenses, or obtaining them without a prescription, could lead to serious vision problems due to incorrect fit. Even if you've been wearing contacts for years, it's a good idea to have your optometrist check your prescription to make sure that your lenses offer the best possible fit for your unique eyes.

Contact Lens types available

Soft Contact Lenses are hydrophilic or "water loving". Their water content ranges from 24% to 80% for different applications. Usually the higher the water content the higher the oxygen transmission, except for silicone hydrogel lenses.  Soft lenses are divided into two main groups – Conventional and Disposable.

Conventional Soft Contact Lenses or non-disposable contact lenses are expected to last for 12 to 18 months of normal wear.  They are sold individually, and are often custom made for each person.  They require more lens care than disposable contact lenses – there are usually separate solutions for cleaning, rinsing, disinfection and storage.

Disposable Soft Contact Lenses offer better eye health through regular lens replacement before lens aging and protein deposits on the lens surface can develop.  Always comply with the replacement schedule advised by your optometrist.  Disposable contact lenses are available in daily wear, 2 weekly replacement, monthly replacement or 30 day continuous wear.   If you are wearing a monthly lens it will be good for 30 wears, but needs to be discarded after 3 months even if you have not worn it 30 times.  These are sold in multi- packs for each eye.  They have simple one step lens care cleaning and storage solutions.

Rigid Contact Lenses
Rigid contact lenses (Rigid Gas Permeable) have zero water content, however because of the chemicals in the new gas-permeable materials they do allow oxygen to pass through for the eye’s health.  Rigid contact lenses are often called hard lenses. 

Spheres
Standard contact lenses are “spheres” - they do not correct astigmatism.

Toric
Toric contact lenses correct astigmatism.  These have a cylinder and axis (like a spectacle lens) and a special feature to keep the contact lens stable without rotating it out of position.  These lenses are more complicated in design and are specific to the individual patient and often need to be custom made.

Bi-focal/Multi-focal Contact Lenses
These have and add (like a spectacle lens) which is an extra adjustment which will allow you to see near and far.

Clear or Tinted
There are different tint options with different lenses.
 
A Visibility Tint
Makes is easier to see and handle the contact lens, it is often pale blue or green and is usually included in lenses at no extra charge. 

Transparent Tints
These are also known as enhancer colours, they are designed to enhance/brighten the natural eye colour.

Cosmetic Tints
These are used to change eye colour e.g. make brown eyes blue, and for matching eye colour for those with 2 different coloured eyes.  They are also available in fun lenses such as Wild Eyes or Crazy Lenses.

Common Diseases of the Eye

Glaucoma is a disease where the pressure within the eye is increased, and can damage parts of the eye and if left untreated can cause blindness.  There are not always symptoms for glaucoma, so it is advisable to have your eyes checked at least every 24 months.  Your optometrist will measure the pressure of your eye during your regular eye examination.  Treatment usually consists of special drops to control pressure, however in advanced cases laser surgery may be necessary.

A Cataract is a clouding of the lens inside the eye giving you misty vision (try looking through white tissue-paper to give you an idea). Symptoms are a gradual painless decrease in vision/vision clarity and increased sensitivity to glare and sometimes double vision.  Treatment is removal of the lens and insertion of an artificial lens (also known as - an intra-ocular lens).

Macular Degeneration is a disease which causes permanent damage to the macula (the central part of the retina).  Regular eye exams will allow early detection and treatment.  Macular degeneration can be age or toxin related.  Treatment is vitamin supplements.  Good sunglasses (ultra-violet protection) can help slow / prevent this condition.

Pterygium is a growth of degenerative tissue on the sclera (white of the eye) sometimes it can grow onto the cornea, it is usually on the nasal side of the eyeball.  It is caused by irritation and long term exposure to UV light, wind glare or dust.  Treatment is removal by surgery – eye drops – protective eye wear (sunglasses).

Floaters are semi-transparent specks of natural materials which float in your visual field.  They can look like you have worms or spiders floating in your eye (best seen when looking at a bright plain background).  They can be caused by remnants of an artery (the hyaloid) which is present in your eye before birth, injury or eye disease.  A sudden onset of floaters can indicate a serious retinal condition.  Your optometrist will determine what steps if any need to be taken.

Blepharitis is an inflammation around the edges of the eyelids.  Symptoms are sore, red irritated eye lids, crusted eye lashes and foreign body discomfort.  Treatment is improved lid hygiene.  Lid Care is used to clean the lids and lashes and ocular lubricants for dryness and sometimes antibiotic eye-drops.  This infection is associated with conjunctivitis which is an inflammation of the conjunctiva also known as ‘pink eye’

Diabetic Retinopathy is a condition of the retina which occurs when diabetes damages retinal blood vessels causing haemorrhages on the retina.  30% of all diabetics already have retinal damage.  Treatment is laser coagulation of the damaged blood vessels and works well if detected early.  Again, have your eyes examined at least every 2 years.

Nothing is more precious than your sight, you should never put it at risk.