Unit 4.4 - The Eye Flashcards
What is the cornea?
The transparent covering of the anterior chamber. It can be scratched or injured.
What is the iris?
The coloured part of the eye that surrounds the pupil. It has a fibro-vascular layer and stroma or sphincter.
What does constriction mean?
Iris becomes larger while pupil becomes smaller to allow for less light to come in.
What does dilation?
Iris becomes smaller and pupil becomes larger, to allow for more light to come in.
What is at the pupil?
The opening to the eye that allows light to pass through.
What is constriction and dilation for pupils?
Constriction occurs when there are bright lights, so there pupil becomes small to reduce the over-stimulation of information. Dilation occurs when it is dark to let more light in and there is interest or arousal.
What do the lens do?
Refracts and bends light to hit retina. It also inverts images; top of the vision field hits bottom of the eye and vice versa. It helps focus on objects near and far, and can change shape via muscles.
What do the lens do optimally?
The lens focuses light to meet the retina in the back of the eye.
What do lens do when near-sighted?
Lens bends too sharply so it does reach the back of the eye. Requires a concave correction.
What do lens do when far-sighted?
Lens do not bend enough, reaches too far back in the eye and does not focus. Requires a convex lens correction.
What is the retina?
It is a thin layer rich with photoreceptive neurons; cones and rods.
What do the cones do?
They are photoreceptive, cone-shaped, and consist of blue, green, and red. Takes in colours and wave lengths.
What do rods do?
They are photoreceptive, they take in contrasts, light and dark, and movement and shadow and are rod-shaped.
What is the fovea?
Central pit in retina, filled with tightly packed cones. Most clear ‘central vision’.
What is the peripheral vision?
It is the vision outside of point of fixation or target.
