Contact lenses are small plastic menisci that are applied on the cornea from which they are separated by a thin tear film. They may have optical role (for correction of refractive errors: myopia, hyperopia, astigmatism), aesthetic role (for change of colour of the iris) or therapeutic role (keratoconus, persistent corneal epithelial defects, recurrent corneal erosions, bullous keratopathy, etc.).

Depending on the material they are made of they may be hard (rigid gas permeable) and soft (e.g. silicon, silicone hydrogel).

a) Hard contact lenses

Advantages: they are indicated in irregular astigmatism and keratoconus providing a good visual acuity. They have high durability and can be used in the presence of tearfilm deficiency.

Disadvantages: high mobility, instability when blinking, more difficult adaptation, low hydrophilia.

b) Soft contact lenses

Advantages: high degree of hydration; high oxygen permeability; better tolerability; some contact lenses may be prescribed for a prolonged wearing, adaptation is fast, they are comfortable and stable (e.g. they may be indicated for children, athletes and active people in general).

Depending on the use, the contact lens can be prescribed for discontinuous, extended or prolonged wearing and some can also be worn during the night.

Indication of contact lens wearing must be done following a specialist consultation.

• Contact lenses allow patients to see objects in real size (glasses that correct myopia shrink the objects).
• The visual field is larger when wearing contact lenses as compared to wearing glasses. It is not limited by the frame of the glasses and no glasses weight is felt on the nose.
• Contact lenses do not mist up.
• They can be worn during sports activities without restriction as in the case of glasses.
• Patients can use sun, ski, swimming glasses, etc.

CAUTION:
Contact lenses can cause eye problems if not used properly. Contact lenses, and even cosmetic lenses, must be purchased after a thorough eye examination. The doctor will indicate the diameter, radius of curvature and type of contact lenses after such examination.

The ophthalmologist can decide whether or not someone can use contact lenses, after a proper consultation. There are certain conditions that contraindicate the use of contact lenses (inflammatory or allergic ocular disorders, glaucoma, tear film disorders, etc.). The doctor must be visited periodically (at the beginning more often, then less frequently - every 6 months) for observing the eye behaviour over time, as well as of the lens, or whenever needed (if the eye is red, becomes painful or ocular discomfort sets in, the patient should immediately remove the contact lenses and go for a check-up).

Hygiene is a major problem for maintaining and extending the use of contact lenses. Hands shall be washed before handling and the eye should be cleaned carefully; long fingernails can damage the lens and makeup shall be less abundant (to be applied after inserting the lens and to be removed before removing the lens). Lens washing will be made using special solutions, and they must be preserved in special containers.

• The patient must wear contact lenses as long as it is indicated by the physician;
• The patient should not wear contact lenses longer than the period for which they are prescribed, even if he/she feels comfortable with them;
• The patient must go to regular eye exams;
• The patient must change daily the special solution in which the lenses are kept;
• For cleaning and preservation the patient must not use anything else than lens special solution; e.g.: not to use spray for lens cleaning, tap water, saliva.
• The container in which lenses are kept should be rinsed only with lens solution and not water or other solutions;
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  Do not use makeup on the eyelid side.