Accomodation Of The Eye Flashcards
What is accomodation
Accomodation is the process of changing the shape of the lens to focus on near of distant objects
How does the eye accomodate for near focussing
During near focussing the lens becomes thicker and round ( and refracts light more strongly)
- The suspensory ligaments become lax
- the ciliary muscles contract
How does the eye accomodate for distant focussing
During distant focussing, the lens becomes thinner ( light rays are only slightly refracted)
- The suspensory ligaments pull tight
- The ciliary muscles contract
What is the problem with the eyeball in short sightedness (Myopia)
In short sightedness the eyball is too long
What is the problem with the lens in short sightedness (myopia)
In short sightedness the lens is too curved and it refracts light too much
How do objects appear with short sightedness
With short sightedness distant objects appear blurry
Where is the image foccused in short sightedness
In short sightedness the image is foccused in front of the retina ( as the light rays are refracted too much)
What is the problem with the eyeball in long sightedness (hyperopia)
In hyperopia (long sightedness)the eyeball is too short
What is wrong with the lens in hyperopia
In hyperopia (long sightedness)the lens is too flat and so cannot refract light strongly enough
What is wrong with objects in hyperopia
In hyperopia(long sightedness) close objects appear blurry
Where does the image focus in long sightedness
In long sightedness , the image foccusses behind the retina ( as light rays are not refracted enough)
What do convex lenses do to light rays
Convex lenses converge light rays (bring them together ) so that they focus on the retina
-This fixes hyperopia ( long sightedness)
What do concave lenses do to light rays
Concave lenses diverge light rays ( spread them out more) so that they converge on the retina
-This fixes myopia ( short sightedness)
