the eye: defects accommodation Flashcards
(14 cards)
What happens to the lens during near vision (object < 6 m)?
Ciliary muscles contract, ligaments loosen, lens becomes more convex.
What happens to the lens during distant vision (object > 6 m)?
Ciliary muscles relax, ligaments tighten, lens becomes flatter.
What happens to the pupil in bright light?
Circular muscles contract, radial muscles relax, pupil constricts.
What happens to the pupil in dim light?
Radial muscles contract, circular muscles relax, pupil dilates (widens).
What is short-sightedness (myopia)?
A condition where nearby objects are seen clearly, but distant ones are blurry.
What causes short-sightedness?
Eyeball too long or cornea too curved; light focuses in front of retina.
What corrects short-sightedness?
Concave lenses.
What is long-sightedness (hyperopia)?
A condition where distant objects are seen clearly, but near ones are blurry.
What causes long-sightedness?
Eyeball too short or lens too flat; light focuses behind retina.
What corrects long-sightedness?
Convex lenses.
What is astigmatism?
Uneven curvature of the cornea or lens, causing blurred vision.
What are the treatments for astigmatism?
Prescription glasses, contact lenses, or laser therapy.
What are cataracts?
Clouding of the lens, leading to blurry vision.
How are cataracts treated?
Spectacles in early stages; surgery to replace lens in later stages.
