Refractive errors in children

Refractive, or optical, errors – myopia, hyperopia and astigmatism – cause blurred vision due to an inability to focus images on the retina. If not corrected, their consequences can be particularly harmful for children, since vision is developed in the first years of life.

Any cause of poor vision in one or both eyes during childhood, as is the case with refractive errors, can lead to the condition known as “lazy eye”. When the child has hyperopia, astigmatism or myopia, the image that reaches the brain is not sharp.

Video in Spanish / When the brain does not receive adequate visual stimuli from the affected eye, it selects the vision from the eye with less refractive error and suppresses or ceases to use the other.

The dioptric power of the eye is determined by two main factors:

• The cornea and crystalline lens: they provide the eye with its convergence ability, since it is through the cornea and lens that light passes and converges to focus the image on the retina
• The axial length: the distance between the anterior and posterior poles of the eyeball, which governs the need for greater or lesser convergence of light, depending on whether the eyeball is longer (myopic) or shorter (hyperopic)

Myopia can increase as the child develops. If the axial length of the eye increases, so does the degree of myopia. In contrast, hyperopia does not increase as the child develops, but can decrease if the eyeball lengthens.

Refractive errors cannot be prevented, but it is important to detect them early (at home, school or at the paediatrician’s).

The problem will then need to be diagnosed by means of an eye examination performed by an ophthalmologist or optometrist. The child’s vision is examined with the aid of dilating eye drops, which prevent the eye from focusing and compensating for the optical error, thus enabling the eye’s optical power to be measured in dioptres.