Pathological myopia or high myopia

What is myopia Pathological myopia or high myopia?

Myopia is a refractive error (dioptric power) in which distant objects are focused in front of the retina instead of on the retina, making distance vision blurry. Myopia is normally attributed to an increase in the eye's length, particularly at the expense of the most posterior part of the eye. When an eye has myopia greater than 8 dioptres, the problem is known as pathological or high myopia.

When is it diagnosed?

High myopia appears in childhood, between the ages of 5-10 years, and tends to stabilise by the end of adolescence. It affects 2% of the population. However, it is possible that the increase in eyeball length may not stop and myopia may therefore continue to increase. When this occurs, complications may appear in the vitreous humour, retina or choroid, all located in the posterior segment of the eye. This form of myopia, which gets more complicated with age, is called degenerative myopia.

What problems can occur?

The most common problems that may occur in patients with high myopia are:

• Progressive atrophy of the retina and choroid, which may affect the central area of the retina: the macula.
• Retinal detachment. There are often peripheral retinal degenerations due to the excessive antero-posterior length of the eye, facilitating the appearance of holes or tears as a result of posterior vitreous detachment (PVD).
• Macular hole.
• The development of blood vessels beneath the retina (subretinal neovascular membrane), similar to those that appear in the wet form of age-related macular degeneration (AMD).
• Separation of the retinal layers, called macular retinoschisis.
• Changes in the optic nerve.

What symptoms does it cause?

Patients with high myopia may have blurred vision or see distorted lines (metamorphopsia). When this occurs, they must see an ophthalmologist urgently. However, not all retinal lesions affecting myopic eyes cause symptoms and therefore periodic check-ups with a full eye examination are recommended to detect such lesions.

Can it be prevented?

Although the progression of myopia cannot be prevented, we can treat some complications that develop in these patients using vitreoretinal surgery (retinal detachment, macular hole, etc.) or intravitreous injections (subretinal neovascular membrane).

We must not forget that there is a greater risk of developing other diseases, such as early cataracts and chronic glaucoma, in high myopia Additional reasons for periodically seeing your ophthalmologist.