Myopia

Myopia is a very common vision defect that leads to blurred vision of images from a distance; in myopic patients, near vision can be good.

Myopia occurs when the focus of the images does not fall on the retina (as it does in the normal eye), but in front of the retina, thus causing blurred vision of distant objects.

Together with astigmatism and hypermetropia, myopia belongs to the group of ametropias (disorders relating to the refraction of the eye).

The causes of myopia can be both genetic and environmental, i.e. lifestyle-related.

Myopia generally occurs from childhood and tends to increase during the developmental period, with the disorder “stabilising” around 20-25 years of age (unless there are particular eye diseases).

Myopia is conventionally measured in dioptres: mild myopia is defined as requiring correction with lenses up to 3 dioptres, moderate myopia from 3 to 6 dioptres and high myopia over 6 dioptres. Lens power (often called “gradation”) should not be confused with visual acuity (i.e. how small are the details of an object that can be perceived by one eye), which in distance vision is measured in “tenths”. For example, a person with mild myopia, wearing the appropriate glasses to compensate for his or her defect, can see up to the last line of the commonly used chart for assessing maximum visual acuity (ten/tenths).

The most common symptoms related to myopia vary depending on the severity of this vision defect, and are:

• blurred vision from a distance;
• fatigue and burning of the eyes;
• necessity to squint to see more clearly;
• headaches;
• difficulty in night vision.

It is very important to have regular check-ups at an ophthalmologist from an early age and, if this sight defect is detected, to correct it as soon as possible in order to reduce the symptoms described.