2.15, 2.16 and 2.17 **Biology Only** - Structure and Function of the Eye and Defects of the Eye and their Treatment Flashcards
What is the eye?
The eye is a sense organ containing receptors sensitive to light intensity and colour.
What is accommodation in the eye?
Accommodation is the process that allows the eye to change its shape to focus on near or distant objects.
What is the retina?
The retina is a layer of light sensitive cells found at the back of the eye.
What happens when light hits the retina?
When light hits the retina, the cells are stimulated, and impulses are sent to the brain to create an image.
What types of cells are found in the retina?
The retina contains rod cells and cone cells.
What is the function of rod cells?
Rod cells are more sensitive to light and are better for seeing in low light.
What is the function of cone cells?
Cone cells allow for colour vision.
What is the cornea?
The cornea is the see-through layer at the front of the eye that allows light through.
What is the function of the cornea?
The cornea bends and focuses light onto the retina.
What is the iris?
The iris consists of muscles that surround the pupil.
How does the iris control pupil size?
The iris muscles contract or relax to alter the size of the pupil.
What happens to the pupil in bright light?
In bright light, the circular muscles contract and radial muscles relax to make the pupil smaller.
What happens to the pupil in dim light?
In dim light, the circular muscles relax and radial muscles contract to make the pupil larger.
What are ciliary muscles and suspensory ligaments?
Ciliary muscles and suspensory ligaments hold the lens in place and control its shape.
What is the lens?
The lens is a transparent, curved surface on the front of the eye.
What is the function of the lens?
The lens reflects light onto the retina.
How does the lens change shape to focus on a near object?
To focus on a near object, the ciliary muscles contract, suspensory ligaments loosen, and the lens becomes thicker and more curved.
How does the lens change shape to focus on a distant object?
To focus on a distant object, the ciliary muscles relax, suspensory ligaments tighten, and the lens becomes thinner.
What is myopia?
Myopia, or short sightedness, occurs when the lens is too curved, causing distant objects to appear blurry.
What is hyperopia?
Hyperopia, or long sightedness, occurs when the lens is too flat, preventing it from refracting light enough.
What are cataracts?
Cataracts means clouding of the lens of the eye. This can occur congenitally or develop over time, restricting vision. Treatment involves replacing the lens in surgery.
What is colour blindness?
Colour blindness is the inability to see certain colours. Full colour blindness is rare, while specific colour blindness (e.g., red-green) is common. It usually occurs due to a lack of cone cells in the retina and is often genetic.
What are spectacle lenses used for?
Spectacle lenses are used to treat vision problems: concave lenses spread out light for myopia, while convex lenses bring rays together for hyperopia.
What are contact lenses?
Contact lenses work like glasses but allow for activities like sports. They come in hard or soft varieties, which last for different lengths of time.
