The image in a nearsighted eye forms in front of the retina, whereas in farsighted eyes, the image forms behind the retina.

Nearsightedness means seeing clearly up close but blurry at a distance. When nearsighted, appropriate measures such as pupil dilation, optometric examination, and corrective lenses should be taken, or orthokeratology may be used. Once the degree stabilizes and no further progression occurs, surgical treatment can be considered after the age of 18. When the eye is unaccommodative, and parallel light rays enter, they focus in front of the retina. After these occurrences, with proactive treatment and proper rest, efforts should be made to prevent further increase in the degree. Especially in children, attention should also be paid to the development of strabismus and amblyopia.