Contact Lenses

About Contact Lenses

 Contact lenses are a popular alternative to spectacles for correcting short-sightedness, long-sightedness and astigmatism. Properly prescribed contact lenses provide excellent vision and comfort. In some cases contact lenses provide better vision than spectacles, while their advantages for athletes and other people with active lifestyles are obvious. Contact lenses can also provide a better cosmetic effect, and can often be tinted to change the colour of the wearer’s eyes.

Although contact lenses have many advantages, they do have some disadvantages. They must be individually prescribed to ensure that they fit the eyes correctly, as well as focusing light properly. Poorly fitting lenses can lead to severe eye problems including infections. Because contact lenses are placed in direct contact with the eyes they must be cleaned and disinfected regularly, and contact lens wearers need more frequent eye examinations in order to prevent any problems developing.

Eye Examinations for Contact Lens Wearers

Contact Lens Prescriptions

There are many steps involved in arriving at a prescription for contact lenses. After assessing the health of the eyes and measuring any refractive error that is present, the optometrist will discuss the various types of contact lenses with the patient, as well as the patient’s visual needs, lifestyle and other factors that may influence the decision on what type of lenses to prescribe. Some additional measurements will need to be taken, including measuring the curvature of the front surface of the eye.

A trial lens will then be placed on the eye, so that the optometrist can assess the fit of the lens.

These preliminary lenses are then placed on the eyes, and the patient is instructed on how to put the lenses in and out of their eyes, as well as how to clean and maintain the lenses. The optometrist will usually reassess the lenses after they have been worn for a week or two, in order to make sure that the lenses are fitting and performing properly, and that the patient is not having any difficulties. It is sometimes necessary to alter the lens prescription at this point to solve any problems which may have arisen.

After-care

Regular eye examinations allow any problems to be detected and corrected early, before they have had time to cause permanent damage.

 

Types of Contact Lenses

Soft Lenses

 Soft contact lenses/most commonly used lenses are made from soft, flexible plastics, known as hydrogels, which contain water. The water allows oxygen to pass through the lens to the eye. This is important, as the cornea (the clear front surface of the eye) obtains its oxygen supply directly from the air.

Most soft contact lens wearers find that they adapt to the lenses quickly and they are comfortable straight away (unlike rigid lenses, which require some adaptation). This makes soft lenses suitable for people who do not want to wear their lenses every day, such as a footballer or netballer who only wears their lenses when they are playing.

Soft lenses are particularly suitable for sports, as they are difficult to accidentally dislodge. Soft lenses are suitable for correcting most refractive errors. Special “toric” lenses can be used to correct astigmatism.

Hard Lenses

Hard lenses are made from plastics that are less flexible than those used for soft lenses.  Materials today allow almost as much oxygen to reach the eye as if no lens was being worn.

Rigid lenses provide better vision than soft lenses, as the optics can be better controlled, and are suitable for a wider range of refractive errors. In some conditions in which the front surface of the eye becomes distorted, such as keratoconus, hard lenses are the only way of satisfactorily correcting vision.

Hard lenses require some adaptation on the part of the wearer. Typically they are less comfortable than soft lenses for the first week or two of wear, but after that they do not cause any discomfort. Adapting to hard lenses is a bit like breaking in a new pair of shoes.

Rigid lenses are more durable than soft lenses, so they do not need to be replaced as often.

Daily wear Only Lens

The most common wearing schedule is “daily wear”, where the lenses are inserted in the morning, worn through the day, and taken out at night. The lenses are then cleaned and disinfected before being worn again.

24 hour x 30 Day/Extended wear Lens

Some newer lens types allow wearers to sleep in their contact lenses, either occasionally, or for up to 30 days. You should NEVER sleep in your contact lenses unless your optometrist has specifically advised you that you can do so. Sleeping in the wrong type of lenses can cut off your corneas’ oxygen supply while you are asleep, causing severe inflammation and possibly permanent damage.

Hard lenses

Rigid lenses are typically replaced every one to two years. Often the replacement is necessary because the wearer’s prescription has changed or the lenses are scratched.

“Disposable” Soft lenses

Most soft contact lenses these days are intended to be replaced at shorter intervals, typically from one day to 4 weeks. This ensures that the lenses are always clean, as they are replaced before any deposits can build up on them. The frequent replacement of lenses especially One Day/Use lenses have reduced infection Rates.

 

Ortho 'K' Lenses

What is Ortho‘K’eratology

Orthokeratology, or OrthoK, involves use of specially designed hard gas-permeable (RGP) contact lenses to alter the shape of the cornea in order to reduce or correct myopia (short-sight). It can also be effective with low degrees of certain types of astigmatism (when the front of the eye is rugby ball shaped). In the past 10 years new technology has become available to accurately scan the cornea and manufacture lenses that will achieve a controlled and precise reduction in the eye’s optical imperfection. The technique of OrthoK is now a safe, viable and reversible alternative to refractive surgery. The cornea, whilst being moldable, always returns to its original shape if lens wear is stopped. For this reason lenses are worn nightly.

Why have OrthoK done?

The main purpose of OrthoK is to be free of both contact lenses and spectacles for all waking hours. The freedom from any artificial aid appeals to myopic spectacle and contact lens wearers and is ideal for sportsmen, those who work in dusty or dirty environments or people who find spectacles and conventional contact lenses inconvenient.

Possibly one of the ideal situations for using OrthoK is for the children with early myopia. Not only does it have all the advantages already given above, but the procedure appears to retard the progression of the myopia.

What does the visit involve?

The initial assessment appointment includes computerized corneal topographical scanning. This gives the practitioner a chance to assess both the general condition and health of the eyes and also determine the likely effect of the procedure in that individual.

What does the treatment involve?

Once they will start to wear lenses on a regular basis, typically overnight excellent vision will develop. Occasionally more than one set of lenses are required to effect the desired change.

As most of the visual changes occur rapidly in the first few weeks, fairly frequent examinations and possible lens changes may need to take place. Stabilization procedures then follow at a slower pace over the next few weeks. The program length varies between one and two months depending upon the degree of visual error. The fees for OrthoK treatment include all visits in the first year.

OrthoK Cost?

The procedure is time consuming and may involve several lens changes. For this reason the initial costs are greater than conventional contact lens correction but less than refractive surgery

Advantages of OrthoK

Good vision without spectacles or contact lenses all day. This is not a surgical procedure.It is reversible.It is modifiable.Early research suggests it will slow down the progression of myopia in children. Using well established contact lens fitting techniques means that there are very few risks.

Disadvantages of OrthoK?

  • You must be prepared to allow for four to six visits over three to six months.
  • Continued lens wear is essential or the cornea will revert to its original shape.
  • The degree of success is high but cannot always be guaranteed.
  • The speed of reduction in the myopia varies from one person to the next.
  • You must follow the instructions implicitly for the best results.

Contact Lens Care

All contact lenses have to be cleaned and disinfected after every time they are worn. Poor lens hygiene is one of the common causes of problems with contact lenses, particularly eye infections.

Cleaning

Contact lenses have to be cleaned each time they are removed from the eye in order to prevent the buildup of deposits. The deposits are composed of proteins and lipids from the tears, and if they are not removed they can make the lenses uncomfortable, as well as making it easier for microorganisms to adhere to the lenses.

There are special lens cleaning solutions provided for different types of lenses. The lenses are usually rubbed between the palm of one hand and a finger, using an appropriate cleaning solution, then rinsed with a sterile saline solution, not water

Disinfection

After cleaning, contact lenses need to be disinfected to kill any bacteria or other microorganisms which may still adhere to the lenses. If lenses are not disinfected, the microorganisms can reproduce, and when the lens is worn again the microorganisms will be introduced into the eye.

Wearing Times

Over-wearing lenses is a common cause of problems with contact lenses. Your Optometrist will help you with the best advice.

When to replace your lenses

No contact lens lasts forever, but different types of lenses need to be replaced at different intervals, both because the lenses wear out and to maintain good eye health.

 

Monovision

In about their early 40's many people start to encounter problems with reading unaided. For many years the answer to this problem has been reading glasses or multifocals. 

However, monovision can be a great solution for some people. Monovision involves having your dominant eye focussed for distance vision and your non-dominant eye focussed for near to intermediate vision through the use of contact lenses. This alleviates the need for glasses and so is ideal for people with an active lifestyle or those who find glasses a "nuisance".  

Monovision will involve a period of adaption as your brain has to learn which eye to use to see specific distances. 

Monovision is not for everyone as it does involve some compromise in the quality of vision. If you would like to "try" monovision talk to the Stepehen about a trial period to see if it will work for you!