When it comes to myopia, the eye is too long in reference to its refractive index, or its refractive index (ability to focus beams of light on a single point) is too strong in reference to its length.
The image of a distant object therefore forms in front of the retina, which leads to blurry vision in the distance.
The stronger the myopia is, the shorter the distance of sight. Punctum remotum, which refers to the farthest point from the eye at which images are clear without accommodation, is extremely far away for an eye without visual impairment. For a nearsighted eye, it’s less than 5 meters away.
Myopia is considered to be weak between –1.00 and –3.00 dpt, medium between –3.00 and –6.00 dpt, and strong above –6.00 dpt.