Topic 5 Correcting Vision Defects Flashcards
What is the medical term for longsightedness
Hyperopia
What do people who are long sighted stuggle with
Unable to focus on near objects
What causes longsightedness
When the lens is too thin and doesn’t refract light enough
When the eye ball is too short
Where are the images of near objects brought to focus if a person is long sighted
Behind the retina
What lenses can be used to correct hyperopia
Convex lens which refracts the light to focus on the retina
What is the medical term for shortsightedness
Myopia
What are shortsighted people unable to do
Unable to focus on distant objects
When does shortsightedness occur
When the lens is too curved and refracts the light too much
When the eye ball is too long
Where are the images of the distant object brought into focus
In front of the retina
What ensues can be used to correct myopia
Concave lenses so that the light rays focus on the retina
What are 3 treatments for vision defects
Contact lenses
Laser eye surgery
Replacement lens surgery
What are contact lenses
Thin lenses that sit on the surface of the eye and are shaped to compensate for the fault in focusing
Why are contact lenses popular
Lightweight and invisible
Why are contact lenses more convenient
More convenient for sports than glasses
What are the main two types of contact lenses
Hard and soft lenses
Pros and cons of soft lenses
Generally more comfortable but higher risk of eye infections
What is done in laser eye surgery
Laser used to vaporise tissue changing the shawl of the cornea (so changing how strongly it refracts light)
What does slimming down the cornea do
Makes it less powerful and can improve short sightedness
What does changing the shape of the cornea so that it is more powerful improve
Long sightedness
What are the risks of laser eye surgery
Can cause complications such as infection or the eye reacting in a way that makes your vision worse than before
What is replacement lens surgery more effective doe
Longsightedness
What is replacement lens surgery
The natural lens of the eye is removed and an artificial lens made of clear plastic is inserted
Why does replacement lens surgery carry higher risks than laser eye surgery
Because it involves work inside the eye and could cause possible damage to the retina which can lead to loss of sight
