Myopia is a vision condition in which nearby objects are clear and distant objects appear blurry. This may be caused by excess corneal curvature or an oblong rather than a spherical shape to the eye, both of which affect the way light is bent upon entering the eye and whether it focuses properly on the retina.
Hyperopia is the condition in which the eye focuses on distant objects better than on objects closer to the eye, so nearby objects appear blurry. This happens when light rays refract, or bend, incorrectly in the eye.
Astigmatism occurs when light does not focus properly in your eye, causing blurred vision. The clear covering on the surface of the eye, the cornea, refracts (bends) light so it focuses on the retina in the back of the eye.
Presbyopia is a natural change in our eyes’ ability to focus. It occurs when the soft crystalline lens of the eye starts to harden. This loss of flexibility affects the lens’ ability to focus light in the eye, causing nearby objects to look blurry.