Refractive error occurs if the eye cannot focus light properly on the retina. It may cause blurry vision. If your child shows any signs of eye problems, you should take him or her to an eye doctor for a complete eye exam.
There are several types of refractive errors:
In this condition, the eyeball is too short for the normal focusing power of the eye. In children, the lens in the eye accommodates for this error and provides clear vision for distance and usually near viewing, but with considerable effort that often causes fatigue and sometimes crossed eyes (strabismus).
Astigmatism results primarily from an irregular shape of the front surface of the cornea, the transparent "window" at the front of the eye. Persons with astigmatism typically see vertical lines more clearly than horizontal ones, and sometimes the reverse.
Presbyopia is a decreased elasticity of the lens due to advancing age which moves the near point of vision farther from the eye, making it difficult to focus on near objects (farsightedness).