Refractive defects: what are they and how to intervene?

Pubblicato il

Friday, 9 March 2018

Argomento

Surgical Area

I refractive defects are very common eye disorders and are due to anatomical conditions whereby light is not properly focused on the retina, leading to a blurred vision. Refractive defects are responsible for approximately 43% of cases of visual impairment and, if neglected, can lead to visual problems that impact the quality of life of the affected person. The main refractive defects include:

1. Myopia

2. Hypermetropia

3. Astigmatism

Myopia

The myopia affects approximately 20% of the population and results in blurred vision at a distance and sharp vision at a near distance. The onset of myopia can be caused by many factors, but the most frequent cause is a eyeball more elongated than normal or a cornea, i.e. the front part of the eye, that is too curved. It follows, therefore, that the focusing of light occurs in front of the retina.

Myopia can be present from birth, and in this case we speak of congenital myopiaor it can be acquired, i.e. it can appear later and then stabilise around the age of 30. If neglected, myopia can lead to serious complications, such as retinal detachment, glaucoma or cataracts.

Hypermetropia

The onset of thehypermetropia can be due to both a reduced length of the eyeball and a reduced curvature of the cornea. Those suffering from hypermetropia have blurred vision for both near and far as light rays are focused behind the retina, exactly the opposite of what happens with myopia.

Hypermetropic individuals, especially young ones, often do not experience any symptoms because the crystalline lens, the lens that allows vision, has the ability to 'accommodate', i.e. to zoom in on the image to the central portion of the retina and allow sharp vision. In the long run, however, the crystalline loses this ability and hypermetropic individuals begin to experience symptoms of blurred vision especially after intense exertion. Hypermetropia is often a contributory cause of visual fatigueheadaches and burning eyes.

Astigmatism

Astigmatic subjects, as well as hypermetropes, have poor vision from a distance as well as close up, but in this case because light rays are focused at different points on the retina. L'astigmatism affects approximately 20% of the Italian population and can often be associated with myopia or hypermetropia. Astigmatism is commonly present from birth and only in some cases may occur as a consequence of a traumatic event to the eye or as a complication of a eye surgery. Symptoms associated with astigmatism, besides a reduction in the quality of vision, may include headaches, burning eyes and finally photophobia, namely excessive sensitivity to light.

What can be done about refractive defects?

First of all, it must be remembered that in order to prevent refractive defects from impairing vision irreparably, regular check-ups with a specialist should be carried out every 1-2 years. In general, refractive defects can be corrected through the use of glasses, contact lenses or with refractive surgery.

Glasses are the most traditional choice for correcting refractive defects as they do not require any invasive intervention and do not lead to complications.

Contact lenses, on the other hand, are a valid alternative to spectacles and many people prefer them for aesthetic reasons. It is good to bear in mind that, the contact lenses, if not used correctly, can lead to certain disorders such as infections and inflammations of the eye.

Finally, refractive surgery represents an innovative and effective treatment strategy that aims at the total elimination of glasses and contact lenses. L'surgery may involve a laser modification of the corneal curvature or, in the case of cataract surgery, the insertion of a intraocular lens correcting anomalies of the natural lens (refractive cataract). Today, there are several surgical techniques for resolving refractive defects, the choice of which depends on the patient's clinical condition and the doctor's assessment.