Facts about contact lenses, visual defects and caring instructions

General information

A contact lens is a thin lens, which is placed on the cornea of the eye. Contact lenses improve vision by refracting light to the retina of the eye. In Ireland the most common kind of contact lenses are of the soft kind. Contact lenses are made of fluidous plastic. The latest kinds of contact lenses are made of a mixture of silicone and plastics called Silicone Hydrogel. Silicone is the best material for letting oxygen pass to the eye. Many different kinds of visual defects that can be corrected with contact lenses including nearsightedness, farsightedness and errors of refraction, but not every kind of visual defect can be corrected with contact lenses. The thickness and shape of the contact lens depends on the power and kind of visual defect.

Contact lenses have beside the comfort improvements the following obvious benefits over glasses:

• Suitable for an active lifestyle.
• Unimpaired field of vision, which is impossible with glasses and is an advantage in sports and while driving.
• Women don't have to be extremely close to the mirror (to be able to see) while putting on makeup.
• You can use all kinds of sunglasses.
• Practical while wearing protection-grade glasses.
• Good alternative to laser surgery.
• Never gets fogged-over.
• You can change the colour of your eyes.

Contact lenses can also be stylish - so called cosmetic/coloured lenses - are common with actors, models and artists who use these kinds of lenses for their looks. Contact lenses can in certain cases also be used to correct visual defects that can't be corrected with regular glasses.

The history of the contact lens

The idea of using a lens on the surface of the eye to correct visual defects has been discussed as early as the 16th century by Leonardo da Vinci, although it took a couple of hundred years for the first contact lens to become a reality. In 1887 the Swizz doctor, A.E. Fick, created the first contact lens. It covered the whole eye and was very uncomfortable and hard to fit. The first plastic lens arrived in 1938 and was made of Plexiglass®. The greatest drawback of the first lenses was that tears couldn't circulate between the lens and the eye and the wearer had to change the lens after just a few hours of use. The year 1950 saw the dawn of a lens that could be worn the whole day, it was the cornea-lens, that unlike its predecessors only covered the cornea of the eye and floated on the wearer's tears.

Bausch & Lomb introduced the soft contact lenses in the 1970's.

Contact lenses have improved drastically during the last decades and they now only take a short while to get used to.

Kinds of contact lenses

Soft & hard contact lenses

• Soft contact lenses

Contact lenses can be divided into either hard or soft. Most common today is the soft kind. The soft contact lenses are manufactured from a gelatinous plastic material, with a high fluid content. The latest soft lenses are made of a new material called Silicone Hydrogel (a mixture of silicone and plastics) and allows for oxygen to pass to the cornea. These contact lenses are considered by most to be more comfortable to use and can in most cases be used as continuous wear lenses.

• Hard contact lenses

Rigid (Rigid Gas Permeable, RGP) contact lenses, so-called "hard" lenses have recently been developed to also transport oxygen and have thus become easier on the eye. Hard contact lenses give dry eyes a better tear-exchange and are used to correct severe errors of refraction. Although they are known as "hard" this kind of contact lenses has some flexibility.

Monthly contact lenses

Monthly contact lenses should be removed in the evening, cleaned and put back in the following morning. They should be replaced with a fresh pair after a month. Unlike the daily contact lenses you need lens solution to clean them and a lens case to store them.

Daily contact lenses

Daily contact lenses are designed to be removed in the evening before going to bed and replaced with a fresh pair in the morning. Unlike monthly contact lenses they do not require a maintenance scheme i.e. lens solution and lens case. Daily contact lenses are the perfect choice for you if you want a simple and safe contact lens experience. Many daily contact lens users switch between contact lenses and glasses or only use contact lenses during sports etc.

Continuous wear lenses

The latest in contact lens technology are the so-called silicone lenses (Silicone Hyrdrogel lenses). They let a great amount of oxygen pass to the eye letting them "breathe". This kind of contact lens can be used continuously (24 hours) for up to 30 days straight. Please note that the length of wear might vary depending on the kind of lens and individual condition of the user. Continuous wear lenses let up to five times more oxygen pass to the cornea than conventional contact lenses, even while you sleep. Lensstore offers among other things the soft continuous wear lenses PureVision from Bausch & Lomb and Night & Day from CIBA Vision.

Progressive contact lenses

With progressive contact lenses you will be able to see equally well at close, medium and long range. Progressive lenses have had a special kind of grinding to make the shift as comfortable as possible and to remove the need to make unnatural movements with the head. These kinds of contact lenses are a good alternative for you if you are using progressive glasses and/or reading glasses. Progressive contact lenses can be of both daily and monthly use.

Bifocal contact lenses

With age comes the risk of needing reading glasses. There now exist bifocal lenses that correct this kind of age-related visual defect. Bifocal contact lenses work more or less the same way as bifocal glasses. the bifocal lens ordinarily comes in two powers - one for short and one for long range. Not everyone can use bifocal contact lenses. Who can, depends on what kind of refractive error the person has and if he/she can adapt to using two powers in the same contact lens.

Toric contact lenses

Toric contact lenses corrects astigmatism, they come as daily, monthly and continuous wear lenses. A toric lens's power varies from meridian to meridian. If you have an astigmatic defect on both nearsightedness and farsightedness and have been told you can't wear contact lenses you can probably wear toric contact lenses. Toric contact lenses are made of the same materials as regular lenses but they come in two powers, one for spherical correction and one for cylindrical correction. Toric lenses are designed to keep a steady position regardless of the movements of the eye. In a lot of cases the lenses are heavier at the bottom and also got a small marking to help the wearer apply them correctly. Toric contact lenses can also be designed to align themselves correctly again with the blink of an eye if they happen to come askew.

Coloured & cosmetic contact lenses

The first cosmetic contact lens was designed for a playboy-model and cost $5000. She needed "Halloween-eyes" for a photo shoot in which she was going to sit entwined with a snake - since then the range of application has widened significantly! Cosmetic contact lenses are seldom worn daily but are rather for special occasions like a masquerade. Cosmetic lenses are worn regularly by actors in Hollywood, for example Ray Park in the role as Darth Maul in Star Wars Episode I: The Phantom Menace. It's also possible to use cosmetic contact lenses to mask or hide eye visible eye defects e.g. damage to, or lack of iris.

Coloured contact lenses are, unlike cosmetic lenses, used by a lot of people at a daily basis. They are used instead of non-coloured contact lenses. The coloured lenses can be used to either enhance the natural colour of the eye or to change the colour completely. Both cosmetic and colour contact lenses need the same care and adjustment as regular contact lenses.

Lens solution, cleaning & disinfection

During the day a coating of proteins and refuse from the tear fluids accumulates on your contact lenses and needs to be removed. It is necessary to clean and disinfect your contact lenses after each period of use. It is also important to make sure your lens case is cleaned regularly and replaced frequently to avoid contamination. All lens solution bottles must be kept properly closed when they are not used and should be disposed of at the date of expiration stated on the bottle. There are a number of products that can be used for regular cleaning and disinfection, to preserve both clarity and to prevent infections.

• "Multipurpose solution bag" is the most popular cleaning kit for contact lenses. It's used for rinsing, disinfecting, cleaning and storage of the contact lenses. This is the easiest way to clean the lenses since you don't need any other fluids. Lensstore offers one of the latest multipurpose solutions on the market, Optifree Express NoRub from Alcon, which unlike regular lens solutions removes protein build-ups with out the need for an extra protein removal solution.
• Saline solution - A fluid used to rinse the lens after cleaning it and to prepare it for fitting.
• Cleaner - Used for daily cleaning of the contact lenses. Usually a few drops of the solution is used to scrub the lens for 20 seconds on each side (used if you have a high amount of build-up on your lenses). If you have long nails you should be extra careful at this stage. Always follow the manufacturers instructions!
• Disinfectant (hydrogen peroxide) - Used for the disinfection of contact lenses, can be either a one- or two-step system. A two-step product requires the lens to be neutralized before it's fitted to the eye again, or the result might be excruciatingly painful. Never use a saline solution to rinse the disinfectant of the lens! If you let the contact lens soak in the solution with the tab for at least six hours the active ingredients of the disinfectant dissolves and what remains is a saline solution that do not harm the eye. This solution is well suited for contact lens wearers with extra sensitive eyes. Always follow the manufacturers instructions!
• Protein removal solution - Can be found as both tablet and solution. Used if cleaning solution is not enough. This solution is used to remove proteins from the surface of the lens, either daily or (usually) once a week. Protein build-up makes the contact lens uncomfortable and could lead to a number of eye related issues. Always follow the manufacturers instructions!

Lens case

It is easy to forget that it is equally important to be as careful in cleaning your lens case, as it is to clean your contact lenses. The lens case should be replaced with a new one after two months of use. An old and dirty lens case can be the cause of dangerous eye issues such as cuts on the cornea. Contact lens users who suffer from discomfort from wearing their lenses should take a look inside their lens case. You should always dispose of the fluid remaining in the case when you have fitted your lenses and wash it with either a saline solution or disinfectant. Let the lens case air-dry. Never use tap water! The faucet and water can contain numerous harmful microorganisms.

Practical advice on care & use

• Have your eyes examined regularly (at least once a year) by your optician.
• Never use "old" contact lenses.
• Always use fresh solution for storing your contact lenses.
• Always wash your hands before handling your contact lenses. To avoid small fibers sticking to the lens surface, shake your hands instead of wiping them on a towel before handling the lenses.
• Carefully follow the advice and instructions of your optician.
• Keep your lens case clean and replace it regularly (for more info see: "Lens case").
• Remove your contact lenses if you experience discomfort and consult with your optician if the problem remains.
• Don't use makeup on the inner part of your eyelid or drip anything in your eyes before consulting with your optician.
• Make sure your contact lenses don't come into contact with hairspray and other cosmetic sprays.
• Never dilute or overfill the amount o fluid in your lens case.
• Don't wear your contact lenses for a longer period of time than what is recommended by your optician and always remove them before going to bed unless you're using continuous wear lenses.
• Don't use contact lenses in environments containing hazardous smoke.

Eye exams & checkups

Your sight and condition for wearing contact lenses change over time. It is important to see a licensed optician/doctor continuously to avoid complications that might result due to a bad fit or insufficient oxygen transfer to the eye.

You have the right to get your prescription from your optician at any time. Be careful to make sure you get all the information from your prescription or old lensbox when you order contact lenses at Lensstore. We save all your information for you so you get easy and fast access next time you want to order the same kind of lenses.

To order contact lenses from Lensstore you are required to have a valid prescription from a licensed optician or doctor regarding the contact lens you are ordering. Eyes are sensitive and the usage of contact lenses without an optician's prescription could cause damage to the eye. It is important that you use the right kind of contact lenses since your eyes are always changing. We recommend that you see a licensed optician/doctor at least once a year to have an eye exam and make sure you use the right kind of contact lenses.

Common visual defects

Refractive errors

• Nearsightedness and farsightedness

Simple so called spherical refractive errors, can be corrected with spherically ground lenses. These lenses are of the same power in different directions from their optical center. Both nearsightedness (myopia) and farsightedness (hypermetropia) are counted among the simple visual defects.

In the case of far- or longsightedness the retina is to close to the lens of the eye and the eye becomes slightly pressed together compared to a normal eye. In the case of near- or shortsightedness the eye is stretched horizontally and the retina is too far from the lens of the eye. Corrective glasses (eyeglasses) are convex (+) to correct farsightedness and concave (-) to correct nearsightedness.

Astigmatism

It's not uncommon for a spherical correction to still provide blurred images in some respects, commonly the user experience this as a round dot becomes oval and blurred in only one direction. These kinds of defects are known as astigmatic defects and can be corrected with toric (cylindrical) corrective glasses. Astigmatism occurs when the light in the horizontal and vertical planes refracts through the lens to different points in the eye and thus the image created on the retina becomes blurred.

It's common for people with astigmatism to also suffer from either near- or farsightedness; the lens of the glasses must then be ground with different powers in different directions. Toric lenses can be used to correct astigmatism. Toric lenses come in two powers one for spherical correction and one for cylindrical.

In case there are no refractive errors present in the eye it's referred to as emmetropia.

Impaired power of accommodation

When a person reaches about 50 years of age, the lens of the eye has started to change and stiffen; it has more difficulty to accommodate (adjust) quickly or at all. This makes it difficult for older people in general to focus on things up close even though their eyesight might have been spotless during younger years. This age-related vision impairment (Presbyopia) should not be confused with nearsightedness.

To correct age-related vision impairment glasses with different power in different parts of the lens are used. This allows the wearer to raise or lower his/her head to use the different powers depending on what he/she is looking at. These kinds of glasses are called progressive glasses and the transitions between the different powers are nowadays smooth. Before the technique of progressively grinded glasses was good enough; bifocal or trifocal glasses was common, these kinds of glasses had lenses divided into different areas with different grindings, this could feel uncomfortable and be annoying to the wearer. Another alternative that is popular is to have different kinds of glasses, one pair for reading and one pair for looking at things farther away. Today you can get both bifocal contact lenses and progressive contact lenses to correct age-related vision impairment.

A disturbance of the eyes ability to accommodate can happen even during younger years and can make the person see worse at close range than is considered normal. This impairment can have physiological causes or be the result of pharmaceuticals.

Visual defects not caused by errors of refraction

In addition to errors of refractions there are numerous causes of vision impairment, e.g. glaucoma, cataract, loiasis and other diseases of the eye, which can cause, even with correctional glasses, among other things: field of vision decline and declining night vision etc.