What is myopia?
Myopia is an optical refractive defect caused by biological variations that give rise to non-correlation between the different components of the eye: corneal curvature, lens power, depth of anterior chamber and axial length.
Two types of myopia may be distinguished:
- Simple myopia: this is more frequent and cannot be prevented. It is corrected with glasses, contact lenses or surgery.
- High or pathological myopia: This is more than 6.5 dioptres. It is usually caused by excessive elongation of the eye ball. Sometimes, this type of myopia can lead to degenerative changes. It is believed to be hereditary.
Symptoms of myopia:
Myopia can develop in childhood or adulthood, although it tends to stabilise from the age of 18 years. In addition, it may be associated with other eye conditions, such as astigmatism.
Myopia manifests as blurred vision of distant objects. There may also be headaches, eye strain and the need to get close to objects or scrunch one’s eyes to see them. Children who develop myopia will often complain of not being able to read the whiteboard at school.
What are the causes of myopia?
Myopia develops when the eye ball is too long in comparison to the focusing power of the cornea and lens. This means that light rays are focused at a point in front of the retina rather than directly on its surface.
Another possible cause of this optical defect is when the cornea, the lens, or both, are too curved for the length of the eye ball.
Can myopia be prevented?
Simple myopia cannot be prevented. There has been an increase in this eye condition in recent years, and this may be related to use of computers and other practices that entail prolonged close vision.
What is the treatment?
There are different ways to treat myopia, depending on its degree:
- Contact lenses
- Refractive surgery, which reduces or even eliminates the need for the two previous techniques. The most common techniques are PRK and LASIK.