Myopia is a refractive error where light from distant objects focuses in front of the retina, causing blurred vision for faraway objects. This happens because either the eyeball is too long or the cornea/ lens is too powerful (converging light too much). A concave lens is a diverging lens; it spreads out incoming light rays before they enter the eye's lens. This divergence causes the light to focus further back, precisely on the retina, correcting the vision.