However, there are many individuals for whom contact lenses should not be recommended; all potential candidates should be thoroughly screened by an ophthalmologist.
Medical conditions in which corneal lenses are recommended include absence of lens or “aphakia,” absence of iris or “aniridia,” congenital absence of pigment, myopia and hyperopia, some types of astigmatism, cone-shaped deformity of the cornea or better known as “keratoconus,” and turned-in eyelashes.
Contraindications include allergic and inflammatory conditions (such as corneal infection), abnormal overflow of tears (epiphora), presbyopia, severe exophthalmus, pterygium, or local neoplasm.
The Structure
The corneal lens is made of lightweight, paper-thin plastic about 10 mm. or less in diameter. “Scleral lenses” are larger and are used for special medical conditions and some sports.
When properly fitted, contact lenses “float” on the fluid layer of the eyeball and are held loosely in place by the capillary attraction of the tears and the upper lid. The lens moves with the eye and is centered over the cornea.
Contact lenses have many advantages over framed lenses. Here is the list of some of the benefits:
1. They do not steam up when the wearer goes from the cold outside to a warm room.
2. They are automatically cleaned with each blink of the eyelid.
3. They can be worn safely during sports.
4. They eliminate the need for less attractive lenses.
5. Peripheral vision is increased
6. The incidence of breakage is extremely low.
Some disadvantages and dangers in wearing contact lenses include the following:
1. The adjustment period in learning to use them properly is longer
2. Contact lenses are more expensive than framed lenses
3. Contact lenses can be lost easily such as down the sink drain or in a swimming pool
4. In the event of a chemical splash to the eye, the chemical agent may seep beneath the lens to cause extensive damage before the contact lenses can be removed.
Moreover, in special cases like driving, the wearer of contact lenses should carry a card indicating that he wears contact lenses. This may help in an encounter with the police, if his license happens to be marked “must wear glasses.”
Should he be involved in an accident or become unconscious and unable to remove the lenses, prolonged wearing may be injurious to the cornea.
Briefly, recommendations for the wearers of contact lenses are:
1. Wash hands thoroughly before touching the lenses, whether applying them or removing them
2. Cleanse lenses only with the recommended sterile solution. It should be “noncaustic.”
3. Dry the lenses when they are removed and to be stored
4. Keep the storage kit clean
5. Do not wear lenses beyond the prescribed time. Usually, the maximal average is 10 to 16 hours.
6. Do not wear lenses when sleeping or suffering from an eye infection.
The improper use of contact lenses can cause corneal abrasions and ulcerations, which result from poorly fitted lenses, improper technique in applying or removing the lenses, and insufficient tear circulation under the lenses.
Although the advantages outweigh the disadvantages, precautions and safeguards must still be understood by everybody and not only the wearer of contact lenses.
The contact lenses must be regarded as a medical prosthesis, not a cosmetic device. The care and precaution given to any medical “prosthesis” must be used with contact lenses.
