A contact lens is a corrective, cosmetic or therapeutic lens usually placed onto the front surface of the eye.

Contact lenses are predominately used to correct vision and offer many advantages over glasses. People choose to wear contact lenses for some or all of the following reasons:

• Cosmetic – virtually invisible to the observer
• No steaming or fogging in rainy weather
• Wider field of view
• Safer for sport
• To obtain the best vision possible in certain conditions where spectacles cannot do so e.g. keratoconus
• To temporarily correct short sightedness without spectacles – orthokeratology

Contact lenses are used to correct the same conditions that spectacles correct:

• Myopia (nearsightedness)
• Hyperopia (farsightedness)
• Astigmatism (distorted vision)
• Presbyopia (need for reading glasses)

Special tinted contacts can be used to change the colour of the eyes to various degrees.

Types of Contact Lenses:

• PMMA lenses made from a rigid plastic material were the original contact lens. They are pretty much obsolete now due to their poor ability to allow oxygen to pass through to the cornea.

• Gas-permeable lenses:These lenses are also known as “RGPs.” They are newer rigid or “hard” lenses made of plastics combined with other materials, which allow oxygen in the air to pass directly through the lens. Different RGP materials allow varying amounts of oxygen through to the eye.Replacement Schedule: RGP lenses are usually replaced on an annual basis. However if they are well cared for and maintained they can last for longer periods.

• Soft contact lenses: These lenses are made of plastic materials that incorporate water and in some cases silicone. The addition of silicone to contact lens materials allows more oxygen to reach the cornea.

• Soft Contact Lens Replacement : Soft contact lenses are available in the following replacement designs depending on the brand.

• Daily
• Two weekly
• Monthly
• Three monthly
• Annual

Extended wear contact lenses are made of material that is so permeable to oxygen that they are safe to wear even with the eyes close i.e. while asleep.
Replacement schedules for extended wear lenses are usually on a weekly, two weekly or monthly basis depending on the material and manufacturer guidelines.

N.B. Sleeping in contact lenses should only ever be done with approval from your eye care practitioner

Caring For Your Contact Lenses:

Contact lenses that aren’t being disposed of on a daily basis need to be cared for appropriately. Deposits from tears and general debris can build up on all types of contact lenses and cause irritation or infection if not cleaned properly. There are many types of cleaning systems including:

All In One / Multipurpose Solutions: The one bottle of solution allows cleaning, soaking, disinfection, storing and rinsing of the lenses. With modern multipurpose solutions no other products should be required.

Hydrogen Peroxide Systems (1 or 2 step solutions): Hydrogen peroxide systems allow cleaning, disinfecting, rinsing and storing your contact lenses. With this system, you usually place your lenses in the provided basket / holder , then place the basket in its cup and fill the cup with solution to clean and disinfect your lenses. Some lens holders for hydrogen peroxide systems have a built-in neutralizer (to convert the hydrogen peroxide to a mild solution, so it doesn’t sting your eyes), but with others you need to add a neutralizing tablet.

With most hydrogen peroxide systems you must leave your lenses so soak for a least six hours, but often over night before putting them back into your eyes. It is often recommended that the lenses be rinsed in saline (purified water) before putting them into the eyes.

Separate cleaning and storing system: This involves a daily cleaner and a separate solution for rinsing and storing.

Protein remover tablets: Depending on what kind of contact lenses you wear and how much protein your eyes deposit on your contacts, your optometrist may recommend you use a product for protein removal. While cleaning them does remove some protein, it can still build up on your lenses causing discomfort. The longer you use your lenses for before replacing them, the more likely it is that you will need a protein removing product e.g. lenses replaced on an annual or biannual basis are very likely to need a protein removing treatment.

Saline solution: This is a solution of purified water often used to in conjunction with different lens care routine and to rinse lenses before they are inserted in the eye. Contact lenses should never be rinsed in tap water as it contains microbes that can cause serious eye infections.

It is vital that you adhere to the specific lens care routine advised by your optometrist or contact lens fitter. While some routines are cheaper / quicker / more convenient than others, there are reasons why a specific routine has been advised. DO NOT change your lens care routine without consulting your eye care practitioner first.

Contact lens wearers can have mild allergic reactions to certain solutions as many contain preservative to which the eye can be sensitive. Preservative free solutions are available and your optometrist can discuss options with you should you be have problems.

Wearing Schedule

There is no universal maximum wearing time for contact lens wear. Many factors influence how long someone can wear their lenses. The following factors will influence wearing times:

• Contact Lens Material – Lenses with lower oxygen permeability levels can mean reduced wearing times are necessary to ensure the eye is breathing properly. Newer silicone hydrogel lenses are very permeably to oxygen and therefore should allow long wearing times without risk of oxygen deprivation.
• Tear quality – those with dry eyes may need to wear lenses for shorter periods even if using re-wetting drops on a regular basis.
• Wearer environment – air conditioning and central heating can influence wearing comfort and influence wearing times.
• Activities – VDU work for long periods may not be compatible with contact lens wear for some people.

Oxygen supply is the main factor influencing wearing schedules. Poor oxygen supply can cause a number of adverse effects in the eye and if ignored can ultimately lead to having to stop contact lens wear altogether. Your optometrist will advise you if they notice signs of over-wear in your eyes and discuss available options to help improve oxygen supply.

Contact Lens Check Ups

Regular contact lens check ups are vital for all contact lens wearers. Although your lenses may feel great and your vision is sharp, you still need to have your lenses checked. Lack of oxygen from over-wear of contact lenses often has no symptoms but can have severe consequences for your eyes and may result in a wearer having to cease lens wear altogether.

In Ireland you are required by law to have your lenses checked at least once a year and more regularly if your contact lens practitioner advises. In order to purchase contact lenses, either from an optical practice or from an internet source you must have an up to date contact lens prescription.
If purchasing contact lenses on the internet you should ensure that the lenses you receive match exactly the brand and all the parameters indicated on your prescription.

For the majority of people, contact lens wear provides freedom from glasses without problems. Adhering to wearing times, replacement schedules and lens care routines as recommended by your eye-care practitioner reduces the likelihood of contact lens related problems.

Remember if you experience any of the following symptoms while wearing your lenses ;

• Blurred vision
• Pain
• Red eye
• Discharge
• Discomfort

Remove your lenses and contact your eye-care practitioner immediately.

FREQUENTLY ASKED QUESTIONS:

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