How does 'lack of accommodation' differ from short or long-sightedness?

Question

How does 'lack of accommodation' differ from short or long-sightedness?

Answer 1

Accommodation refers to one's ability to focus, most often at near. We lose this as we get older, typically with the need for readers at the age of 40. As we lose our accommodation, this is referred to as "presbyopia". Short and long sightedness are terms used in countries such as India to describe the American "near and far sightedness" which are still lay terms. Near sightedness is technically called" myopia" and far sightedness is called "hyperopia. "  A myope requires glasses to see at distance and may sometimes require them up close depending on the severity of the problem. A hyperope requires glasses to see up close, and also usually at distance depending on the severity.

I hope this helps!

Adam Koenigsberg MD FACS

Adult and Pediatric Ophthalmology

Jacksonville FL

Answer 2

Lack of accommodation involves the lens and the ciliary muscle that controls it inside our eye.  When we are young, the muscle is very good at contracting and relaxing which allows the lens to change its thickness.  This in turn allows us to change our focus from distance to near.  As we age, the muscle doesn't work as well and we lose this focusing ability.  This is called presbyopia and it's why people need reading glasses.

Short and long-sightedness are caused by the strength of the cornea (front curve of the eye) and/or the length of the eyeball.  Short-sighted people have corneas that are too strong for the length of their eyes.  This causes images to be focused in front of the retina (the layer in the back of the eye where images need to fall) and are therefore blurry.  Long-sighted people have corneas that are too weak for the length of their eyes.  This causes images to be focused behind the retina, also causing blur.