What are contact lenses?

Contact lenses are small polymer bowls, which float on the corneal tears. They correct the existing visual deficiencies similarly to glasses.

What are the advantages of contact lenses?

The enormous advantage compared to spectacles is the mostly natural image formation. As you already know, glasses diminish - like in myopia - or enlarge - like in hyperopia - the image. The reason is the distance of the glasses from the eye, mostly about 14 mm.

Thus, the advantages are:

  • hardly any diminution or enlargement of the image
  • no peripheral blurr: glasses distort or deform the periphery
  • better visual performance, especially in complicated refractive conditions
  • lenses are invisible, your natural appearance is not changed
  • no steaming up or getting dusty
  • ideal for persons with different refractive power
  • often the only successful means to treat children with diminished visual acuity

Which types of contact lenses are available?

There are two large groups of contact lenses: hard lenses and soft lenses.

Today, most of the hard lenses are manufactured from polymers and are somewhat flexible, i.e. deformable. Therefore, they are no longer called "hard" but "inherently stable", instead. Due to their elasticity especially at the lens margin, this type of lenses is tolerated very well. Another advantage is that today almost all contact lenses are permeable to oxygen or gas. This means that the long-term tolerance is improved considerably.

Tell me more about hard lenses. Which types are available and which ones do you recommend?

Without any doubt, soft contact lenses are better in the beginning regarding tolerance. However, for long-term application inherently stable contact lenses are preferrable, the reasons will be explained in detail below.

Certainly, a very high advantage of the inherently stable, gas permeable contact lenses is that also more complicated refractive errors, such as astigmatism = corneal deformation, keratokonus = rare kind of inherited irregular corneal deformation, can be compensated.

Why do hard contact lenses compensate complicated errors?

As already suggested by the name, inherently stable lenses maintain their shape. Since the lenses are floating on the tear fluid of the cornea, they are able to balance out unevennesses of the corneal surface. Thus, a fluid layer of different thickness originates between cornea and contact lens, which is also called fluid lens or tear lens in ophthalmological terminology.

Disregarding the advantages of contact lenses - who once had contact lenses does no longer wish to do without them - nevertheless, problems are found relatively often; and not only in inherently stable lenses.

What are the most frequent problems and what is the prevention?

Every third user feels in the evening that the lenses scratch the conjunctiva with every blink. There is only one quick remedy: Remove the contact lenses and put on your spectacles. The dryness sensation is very discomforting. However, it is not necessary, because there are broad and sound scientific findings regarding the alleged dry eyes in the meantime. The main causes for dry eyes are: Environmental conditions, changed work conditions and nutrition: Ophthalmologists found that not only the volume of the tears but also their composition is important.

Which substances are important to allow a good tear fluid formation which is capable to protect our eyes efficiently?

These are mainly the vitamins A, B and C as well as the minerals Ca (calcium) and zinc.

So, what is the right nutrition for contact lens wearers?

In contact lens wearers, the following is of special importance: Eat fresh fruit, vegetables, milk and whole grain products. Especially dark green, red and yellow vegetables contain a lot of vitamin A. Vitamin B and calcium are primarily contained in nuts, bananas and whole grain products. Drink large quantities of low sodium mineral water, natural juices and/or fruit teas.

Are vitamin tablets sufficient for this purpose?

There are no reasons against them, but be careful: sometimes deposits are formed on the contact lenses, e.g. calcium deposists as a result of crystal formation after the intake of multivitamin tablets. These lead to a deterioration of the visual acuity and to increased foreign body sensation.

Recommended vitamin combinations: Vitamin C, vitamin E, multivitamin. Regularly have the fat and cholesterol values of your blood controlled by your physician and do not drink too much alcohol. Who fails to, takes the risk of conjunctival inflammation which might turn very severe.

If all of this was done and there are still complaints, what else can be the cause?

Possibly changed working conditions. If there is too much time spent in rooms with too little humidity content, our mucous membranes become dry. The consequences are not only dry eyes but in many cases also diseases of the respiratory tract.

If you are sitting in front of a monitor, you are staring fascinated onto the monitor. Your blinking frequency is decreased. Since the ocular surface is newly wetted with every blink, the protective fluid film is missing. If you do not close your eyes deliberately once in a while and relax, a process which usually happens automatically independent from our willpower, like our heart beat or breathing, the above problems may originate.

Whoever has these problems can use alleged artificial tears or similar fluids. High-quality solutions which can also be applied without removal of the contact lenses do not contain any preserving agents and contribute to the wearing comfort.

Another tip - not only for your eyes: Take a daily walk outside, especially after a short walk the tear production of the eyes is speeded up due to the humidity of the air.

Another factor in intolerances of contact lenses are side-effects of drugs, especially when prescribed for the first time.

A sudden intolerance quite frequently occurs due to hormonic changes, such as administration of contraceptives. A recent study shows, however, that women who used contraceptives for a longer period of time showed a better quality of the tear film than those who had stopped the contraceptives years ago.

Also air travel is likely to produce intolerance due to the dry air and the higher ozone content of the air in jet planes. The best is to remove the lenses and to take enough solutions and eye drops with you.

Make-up: Only allergy-tested products, no eye liner, please!

Summary: Which lenses, soft or hard ones?

Ask your ophthalmologist, he knows the situation of your cornea, the composition of your tear film, your refractive power and which lens type is most suitable for your eyes best.

Only confidence, expert advice and controls by a specialized physician, the ophthalmologist, who is also in charge of all other important medical questions, often together with other specialists, e.g. for internal diseases or allergies, will be able to guarantee optimum advice and care.

So: Hard or soft?

Even though about 60 % of the contact lens users are wearing soft lenses, hard contact lenses are preferrable, as already mentioned. Especially in dry air soft lenses are less suitable, because they consist of hydrogels, i.e. they absorb humidity, literally suck it. And even more: They absorb pollutants from the air, store them in the material like a mushroom and then release larger quantities of these substances onto our eyes. The potential results are red eyes, irritated eyes and allergies.

Consequence:
Principally throw away soft contact lenses after two years, only use antiallergic cosmetics. Calculate the costs and decide, if possible, on single-use or exchange systems.

With single-use contact lenses, you do not need any chemical purifiers at all, with exchange systems, depending on the system you will receive new contact lenses upon return of the used ones every few weeks or every three months.

How often should contact lenses be controlled?

Generally: In all problems and changes of e.g. the visual acuity: Immediately go and see your ophthalmologist.

  • First control: 8 to 10 days after fitting
  • Second control: 3 weeks after
  • Third control: after three months
  • Then every 6 months: ophthalmological control examination

Does health insurance pay for contact lenses?

In relatively many diseases, such as different refractive powers and higher visual deficiency, health insurance in Germany will pay for contact lenses within the defined amounts. Ask your ophthalmologist.

The last question: Is there an age limit for wearing contact lenses?

No

The contact lense

Brief summary of contact lens history

As it is often the case, nobody knows who was the first! In 1801, the English physician Thomas Young removed small lenses from his microscope, coated their edges with soft wax and placed them onto his own eyes. As a consequence, he became highly short-sighted by artificial means. He then calculated the power of missing refraction.

It must have been the merit of the Zurich ophthalmologist Fick, who tried to make spectacles with their glasses directly in contact with the ocular surface via a fluid layer for a rare corneal disease. He called this visual aid contact spectacles. All other developments at that time were made of glass! Shortly before the beginning of World War II, the American W. Feinbloom described the manufacture of the first polymer contact lenses.