Which condition is characterized by images not focusing properly on the retina?

The condition characterized by images not focusing properly on the retina is ametropia. Ametropia is a general term that encompasses various types of refractive errors in the eye, where the light rays do not focus directly on the retina. This leads to blurred vision and can manifest in different forms such as nearsightedness (myopia), farsightedness (hyperopia), and astigmatism. Essentially, ametropia describes any problem with the eye's optical system that prevents light from being focused accurately on the retina.

Understanding ametropia as a broad term helps clarify how specific conditions like hyperopia, astigmatism, and presbyopia fit within this category. Hyperopia refers specifically to farsightedness, where distant objects can be seen more clearly than close ones. Astigmatism involves an irregular curvature of the cornea or lens, leading to distorted or blurred vision at various distances. Presbyopia, often related to aging, affects the ability to focus on close objects. While each of these conditions affects focusing, ametropia is the overarching term that includes all the different forms of refractive error.