In the case of long-sightedness the refractive power in the eye is too small in relation to the length of the eye. Therefore, the images focus on a point behind the retina.
Long-sightedness is common and even more so than both short-sightedness and astigmatism.
If you are long-sighted, you have trouble reading. Until the age of 40, the eye can increase the refractive power by changing the curvature of the lens. Therefore, in the case of starting long-sightedness, you are able to read but after some time reading fatigue and headache arise. When the muscles of the eye tense – when trying to read – the eyes turn inward.
Children with long-sightedness often compensate for their visual difficulties. They will typically be able to read but tire quickly and may complain about headache. At closer inspection, it will often show that they squint inwards. Children, whose long-sightedness has not been taken care of, can develop permanent reduced eyesight on the squinting eye. With children, there is a possibility of training the squinting eye into full eyesight – further reading in the section about squinting.
Far from all children develop squinting even though they are long-sighted. It is important that children who have trouble reading and complain about headache when studying a text up close are evaluated by an ophthalmologist.