Eye and Vision Flashcards
What is the Aqueous Humour?
Watery fluid at the front of the eye that helps reflect light towards the lens
Cornea
Transparent and at the front of the eye. Most of the focusing is done at the Cornea!
What % of focusing is done at the cornea?
70%
Iris
Colored part of the eye that contains muscles which relax or contract to adjust the size of the pupil. It controls how much light enters the pupil.
Pupil
Hole in the middle of the Iris. Allows light to pass through as it enters the eye.
Lens
Transparent, flexible disc behind the Iris. It is attached to the cillary muscles. It refracts light to focus it onto the retina.
The amount of refractions can be adjusted by altering the thickness and curviture of the lens.
What % of focusing is done by the lens?
20-30%
Retina
What/Where & what does it contain?
It’s a light sensitive lining at the back of the eye containing two types of light receptor cells - Rods & Cones.
Vitreous Humour
A watery fluid that keeps the shape of the eyeball
Optic Nerve
The optic nerve carries impulses from the retina to the brain
Fovea
(rods or cones?)
- Most sensitive part of the retina
- At the centre of the retina
- Contains only cones and is where the central vision occurs
What is the lenses refractive power measured in?
Also, what is the Average?
Dioptres
16-30 Dioptres = Average
Tear ducts
Washes eyes with anti bacterial solutions
The eye is controlled by muscles.
How many are there and what are they called?
Extraoccular muscles
There are 6 of them
What is another word for focusing and which muscles control it in the lens?
Accomodation
It is controlled by the Cillary Muscles
What do the cillary muscles do?
They control focusing/accomodation of the lens
What affects accomodation?
Age, Fatigue
To focus on distance, the lens becomes rounder/flatter?
The lens becomes flatter (concave).
This is done when the cillary muscles relax/pull the lens
To focus on near objects, the lens becomes flatter/rounder?
The lens becomes thicker&rounder.
This is done when the cillary muscles contract and squish the lens.
What is scoptic vision?
Night vision
What is Photopic vision?
Colored vision