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How Do Contact Lenses Work?

Genetic factors, disease of the cornea and retina , and old age are just a few of the factors that lead to deterioration of good eyesight .Fortunately, most eye problems can be corrected using contact lenses which can be used in place of glasses.

Contact Lenses - What Are They?

Contact lenses are thin, clear, plastic films that are placed on the eye surface to enhance vision. Though they may also be worn for aesthetic purposes, they are primarily meant to act as medical tools. When placed in the eye, the lenses become nearly indistinguishable from the real eye surface. Because of this, they are often given a tint, or a visible edge to make them easier to handle. Contact lenses can be used to correct a number of eye problems including hyperopia, myopia, presbyopia, and astigmatism which respectively refer to farsightedness, nearsightedness, blurred vision and the inability to see things up-close.

How Contact Lenses Work

Most people understand the function of contact of lenses; however, not many know how the devices actually function –the process is quite simple yet intriguing. Given that the films have no adhesive, one may wonder why the lenses do not fall off once inserted. What makes this possible is the flexible material that the lenses are made of. When placed in the eye, the film gets into direct contact with the cornea and gently folds over it and once this happens, the wearer's tears help to hold it in place. In addition, the moisture in the eye helps to keep dust and other foreign particles away from the lens. This implies that contact lenses function in a manner very similar to the natural eyes. When the eyes move, the lenses simultaneously move in the same direction, eliminating any refractive errors. This presents the wearer with more natural vision.

However, it is important to note that contact lenses will only work as required if obtained through proper prescription – the base curve and the diameter of the lens have to be just right. Otherwise, the films may lift off the eye surface and create blurry images. To ascertain acquisition of the right lenses, eye specialists apply different tools in an eye exam to measure the cornea and determine whether or not it is too curved. With such measurements and the patient’s personal information, it then becomes possible to prescribe suitable lenses. Worth noting also is that a contact lens cannot function properly without adequate hydration. Thus, even where one has to focus on one thing (such as a computer) up-close for an extended period, it is important to constantly blink to keep the lenses moistened.

The Various Types of Contact Lenses

Contact lenses can generally be classified into two categories: soft lenses, and Gas Permeable (GP) lenses. As implied by the name, the soft lenses are made from soft material and they allow the user to quickly adjust to the film after insertion. This is unlike the GP options which may require some time before maximum comfort is attained by the wearer. On the contrary however, GP lenses provide good clarity, and are easier to clean. Some types of GP lenses allow the user to keep them on without removal for periods of up to 30 days. Such options are suitable for people who may not like the idea of having to remove and put back the lenses every day.

Due to the material they are made of, soft lenses do not last as long as the gas permeable alternatives. In this regard, there are options which can be used for just a day and disposed off. What’s more, there are others which can last up to a year before a new pair is required. The daily disposable selections are however chiefly worn by those who need to change their eye colour for beauty purposes. Soft contact lenses are the most commonly prescribed type of lens. To keep them from drying, however, soft lenses have to be retained in the lens solution when not in use.

Advantages of Contact Lenses over Glasses

Wearing contact lenses presents several benefits over glasses. First, they allow the wearer to have a more natural vision—in other words, the entire field of vision remains unobstructed. Besides, unlike glasses, contacts have no frames, and no weight; thus, they are more comfortable to wear and can be easily used in sporting and other rigorous outdoor activities. In addition, such devices do not gather moisture; hence, even where they are worn in bad weather conditions (such as rain or snow), vision remains unaffected. In addition, it takes only between a day and two weeks for one to adjust to the devices, with some options such as the extended wear contact lenses even being suited for overnight wear. Cleaning of the lenses doesn’t require much time or effort either. Still, contact lenses will oblige the user to go for a longer examination at the start, and many follow up visits.

Risks of Wearing Contact Lenses

Like any other medical devices, contact lenses also have their risks. First off, the lenses can cause allergies such as giant papillary conjunctivitis which mainly arises when the eye gets into contact with particular components of the lens solution. Such reactions are normally experienced at the start when the wearer begins to use the lenses. In such instances, it is usually helpful to try other types of lenses, or different lens solutions as prescribed by an optometrist.

A wearer can also be affected by corneal warpage whereby the shape of the cornea may get distorted. This may arise when a person uses rigid lenses that are poorly fit. When the lens is removed, the persons’ cornea remains flattened and in such a case, clear vision may be impossible even where glasses are opted for. However, the distorted cornea can regain its shape if the lenses are detached and kept out of the eye for several weeks. Proper fitting should be done thereafter to avoid recurrence of the problem.

Corneal ulcer is yet another risk that contact lens wearers face. This infection affects the cornea and is said to arise when disposable lenses are worn for a period longer than that which they were meant. In this instance, the cornea is abrased, and this causes significant discomfort regardless of the size of the abrasion. If not dealt with on time, the infection may make the user’s cornea lose sensitivity. In the event of such an infection, therefore, it is very important to first remove the lens, and then schedule an appointment with an eye specialist through whom the required treatment can be administered. Taking this into consideration, however, lenses which need to be discarded after single use must be disposed after the time elapses –their usage should never be extended. Other eye problems that may come about due to the use of contact lenses include eye redness, and corneal swelling whose risk is increased by sleeping with contacts.

Given the above, the following are the symptoms you need to look out for when using lenses:

  • pain in the eye
  • blurry vision
  • itchiness in the eye
  • excessive redness
  • Discharge
  • sensitivity to light

Inasmuch as lenses will give you great benefits with regards to your vision, you need to watch out so that the health of your eyes is not put at risk. In line with this, there are a number of steps one can take to reduce the risk of getting an infection from wearing contact lenses.

These include:

  • Cleaning and disinfecting the lenses frequently- this should be done every time they are removed to eliminate germs
  • Avoiding reuse of the contact lens solution-the solution should be discarded following each use and should not be mixed with a fresh solution
  • Avoiding to keep lenses in the same solution for an extended period
  • Avoiding home-produced cleaning solution
  • Avoiding the use of water to clean the case or lenses -lenses should also be removed while swimming
  • Cleaning and drying the lens case on a daily basis- the case should ideally be replaced every 3 months
  • Sticking to prescribed eye drops- non prescribed brands of eye drops can interact with the lenses and cause harmful reactions
  • Additionally, it is important to wash your hands each time you need to handle the lenses and once you insert them, you shouldn’t touch them with dirty hands. Furthermore, even where you need to obtain non-prescription lenses, you should get them fitted by a qualified eye specialist.
In Summary

Contact lenses are great; however, they are not suitable for everyone. People who have a dry eye and severe allergies are advised not to use contact lenses. The same applies to those who have recurrent eye infections and those who work in excessively dusty environments. Besides, anyone who is unable to handle and clean the lenses as needed is advised against obtaining them.

Contact lenses present an ideal solution for individuals who require vision correction but prefer not to use glasses. While they come with a few complications, they are generally safe provided they are used in the right way, and cleaned and disinfected as required. Accordingly, anyone looking to make use of contact lenses should strictly adhere to the directions on handling given by their doctor as this is the only sure way to limit infections and maximise on clear vision.


• How Stuff Works - Vision Problems and Contact Solutions - Contact Lenses
• Contact Lenses - types, risks, care, handling, proper wearing of : University of Michigan Kellogg Eye Center
• Contact lens safety - Live Well - NHS Choices
• 10 risks for contact lens wearers - Family and Child Health - Body & Health
• Contact Lenses - WebMD
• Edel-Optics – supplier of glasses and contact lenses
• Dangers of Contact Lenses: Amoeba Eye Infection Blinds Woman - Live Science
• Contact lenses: What to know before you buy - Mayo Clinic
• How Could Contact Lens Wearers Be at Risk of Acanthamoeba Infection; A Review | Journal of Optometry
• Disease and risks associated with contact lenses - US National library of medicine national institutes of health
• Types of contact lenses - BCLA British Contact Lens Association
• Advantages and Disadvantages of Various Types of Contact Lenses - American Optometric Association
• Contact Lens Risks - U.S. Food and Drug Administration