What does it involve?
The optical correction by means of glasses or contact lenses is the most common way to correct refractive errors (myopia, hyperopia and astigmatism) and presbyopia.
In which cases is it indicated?
Glasses or contact lenses correct distance vision in patients with myopia; blurred vision, especially at a short distance, in patients with hyperopia; poor vision of near and far objects caused by astigmatism, using convex lenses; and presbyopia, or eyestrain, caused by loss of elasticity of the crystalline lens that usually appears after the age of 40-45.
Even if the degree is small, correction is still advisable to prevent secondary problems, such as headaches or eye irritation.
Types of contact lenses
The types of contact lenses which are most commonly used to correct refractive errors and presbyopia are as follows:
- Soft contact lenses: They are the best known and are used to compensate for moderate refractive defects in patients with myopia, hyperopia and astigmatism.
- Semi-rigid contact lenses: They are smaller, harder and, therefore, less flexible than soft contact lenses. They are used when the astigmatism is very high or there are irregularities in the cornea.
- Hybrid contact lenses: They are a mixture of both previous types and are used, when it is not possible to adapt a semi-rigid lens, because the patient does not tolerate it, it does not focus well or does not reach the peripheral irregularities of the cornea.
- Scleral: They are used in the same cases as a hybrid contact lens and are also recommended for patients with severe dry eye, because, being more rigid and large, they can fill up with artificial tears, hence creating a reservoir that keeps the eye permanently moist.
A visual assessment of the patient has to be carried out to determine how many dioptres are required. These tests include a visual acuity and refraction test, as well as a comprehensive ophthalmic examination.
In the case of glasses, precautions are limited to not playing sport or doing risky activities while wearing glasses because of the risk of contusions.
In the case of contact lenses, some precautions that must be taken when using them are as follows:
- Do not wear contact lenses upon awakening: wait at least 20 minutes. Similarly, remove them at least 20 minutes before bedtime.
- Never go to sleep with your contact lenses on and, if you do so by mistake, moisten the contact lenses with artificial tears before removal to avoid causing any injury to the cornea.
- Moisten the cornea throughout the day with the artificial tears prescribed by your specialist, especially indoors, if you have the heating or air conditioning on.
- Always carry your lens case with you with clean all-in-one solution so that you can rinse and store the contact lenses safely for whenever needed.
It is also important to have regular check-ups and adapt the prescription.