Nervous System - Eye defects + Treatments Flashcards
What is myopia?
When light is focused in front of the retina
Can see close up can’t see distant objects clearly
What is hyperopia?
Light focused behind the retina
can’t see close up objects clearly
Name 3 possible causes of myopia
- eye ball is too long
- cornea is too curved
- lens is too thick
Name 4 possible causes of hyperopia
- eye ball is too short
- cornea is not curved enough
- lens is too thin
- can be caused by diabetes
What type of lens can correct myopia and why
Concave lens
- diverge right rays out before entering the eye
- so that they arrive together in proper focus at the back of the eye.
What type of lens can correct hyperopia and why?
Convex lenses
- refract the right rays
Name 3 treatments for eye defects
- glasses or contact lenses
- laser surgery
- replacement lenses
How does contact lenses work?
- in contact with eye
- works like spectacle lenses:
- refracts/diverges light rays
Name 3 Advantages of contract lenses
- doesn’t restrict peripheral vision
- great for sports, active lifestyle
- clear vision - no condensation, dirty glasses
Name 3 disadvantages of contact lenses
- Temporary - hasn’t fixed the defect
- can cause dry eyes - require frequent eye drops
- irritation / infection of the eyes
How does laser eye surgery work?
- laser beams reshape cornea surgically
- cornea can now focus light correctly
Name 3 advantages for laser eye surgery
- permanent correct to vision
- vision almost corrected immediately —> heals quickly
- little pain during procedure
Name 3 disadvantages of laser eye surgery
- high risk + invasive
- Expensive
- surgery errors can’t be reversed
How does replacement lens work?
- implants artificial lenses to replace natural lenses
- artificial lenses made of clear plastic
- inserted through small cut in the cornea
Name 2 advantages of replacement lens surgery
- permanent solution
- quick procedure - less than 15 minutes
