Your eye focuses distant objects in front of the retina instead of on it — so far things blur, near things stay sharp.
Rays converge in front of the retina, before the image can form — distant objects blur.
Think of your eye like a camera that's slightly 'over-zoomed'. In a myopic eye, either the eyeball is a little too long, or the lens curves a bit too much. Both mean light from far-away objects bends too early and meets at a point before it reaches the retina — by the time it actually hits the retina, the image has already spread back out into a blur.
Nearby objects are unaffected because their light rays are already diverging more when they enter the eye, so they still land correctly on the retina.
The fix: a concave (diverging) lens placed in front of the eye spreads the light out slightly before it enters — pushing the focus point back exactly onto the retina.
Key exam points
Watch it explained
Defects of Vision — Myopia & Hypermetropia with Numericals, CBSE Physics · CBSE Physics