Physiology Of Vision

Question 1

What are the accessory structures of the eye?

Answer 1

Palpebrae -continuation of skin
Superficial epithelium of eye -lacrimal caruncle and conjuctiva
Lacrimal apparatus -produces and removes tears

Question 2

What are the chambers of the eye?

Answer 2

Cillary body and lens divides into the vitreous humor and aqueous humor
The anterior and posterior chamber

Question 3

What are the 3 layers of the eye?

Answer 3

Outer fibrous layer
Intermediate vascular layer
Deep inner layer

Question 4

What is the vascular layers function?

Answer 4

Provides a route for blood vessels and lymphatic that supply tissues of the eye
Regulates amount of light into eye
Secretes and reabsorbs aqueous humor
Controls shape of lens which is essential for focusing

Question 5

What does the vascular layer contain?

Answer 5

Iris
Cilallary body
Choroid

Question 6

What is the aqueous humor?

Answer 6

Fluid that circulates within the eye and diffuses through walls of anterior chamber into clearly Venus sinus

Question 7

What is intraocular pressure?

Answer 7

Fluid pressure in the aqueous humor and helps retain eye shape

Question 8

What is the function of the Fibrous layer?

Answer 8

It consists of the sclerosis,cornea,corneal limbus
And it supports and protects the eye
And serves as an attachment site for extrinsic eye muscles and contains structure that assist with focusing

Question 9

Where do tears pass through?

Answer 9

Lacrimal Puncta
Lacrimal conaliculi
Lacrimal sac
Nasolacrimal duct

Question 10

What is the inner layer called?

Answer 10

Retina (neural part).contains rods and cones as photo receptors

Question 11

What us the outer layer called?

Answer 11

The pigmented part

Question 12

What are rods?

Answer 12

They are highly sensitive to light and don’t discriminate against colours

Question 13

What are cones?

Answer 13

They provide colour vision and densely clustered in fovea at the sender of macula

Question 14

What does the nunnery neural part contain?

Answer 14

Bipolar cells that synapse with ganglion cells
Horizontal cells where photo receptors synapse with bipolar cells
Amancrine cells where bipolar cells synapse with ganglion cells
They facilitate or inhibit communication between photo receptors and ganglion cells and alter sensitivity of retina

Question 15

What is the lens?

Answer 15

It lies at the back of the cornea and is held by suspension ligaments
It contains lens fibers which are cells inside of lens and filled with crystallins which are transparent proteins

Question 16

What is a cataract?

Answer 16

When the balance of lens is disturbed and transparency is lost

Question 17

When does the greatest amount of refraction occur?

Answer 17

When light passes from the air into corneal tissue and additional refraction occurs when light passes from aqueous humor into the relatively dense lens and lens provides extra refraction needed to focus the light rays from object towards a focal point on retina

Question 18

What is focal point?

Answer 18

Specific point of intersection on retina

Question 19

What is focal distance?

Answer 19

Distance between center of lens and its focal point

Question 20

What is focal distance determined by?

Answer 20

Distance of object from lens
Closer the object the greater the focal distance
Shape of lens
The rounder the lens the more the refraction and shorter focal distance and flatter one

Question 21

What is the accommodation for far objects?

Answer 21

Shape of lens changes to focus image on retina
Rounder to focus the image of nearby objects and flatter to focus on distant objects
Lens is held by suspensory ligaments originating at cillary body when cillary muscles relax the syspensory ligaments pull at the circumference of lens making it flatter

Question 22

What is the accommodation for near objects?

Answer 22

Smooth muscle fibers on the cillary body act like sphincters when the cillary muscles contact cillary body moves towards the lens thereby reducing tension in suspensory ligaments the elastic capsule then pulls the lens into a more spherical shape that increases the refractive power of the lens this brings lights from nearby objects into focus on the retina

Question 23

What is astigmatism?

Answer 23

When cornea is unequal think and light passes through cornea and lens is not refracted properly and visual image is distorted

Question 24

What is myopia?

Answer 24

Eyeball being too deep or resting curve of lens is too great and can be corrected with diverging concave lens

Question 25

What is Hyperopia?

Answer 25

When eyeball is too shallow or lens is too flat and colliers muscle must contact to focus at a close range the Ken’s cannot provide enough refraction to focus on the image and can be corrected by a convex lens

Question 26

What is glaucoma?

Answer 26

When there’s increase intraocular pressure because there’s blockage of Schlemns canal and damage to the optic nerve which leads to irreversible vision loss

Question 27

What is Retintis pigementosa?

Answer 27

It is a genetic disorder
Progressive loss of rod photoreceptor cells at back of eye

Question 28

What is Macula densa degeneration?

Answer 28

Blurred vision or no vision in the center of the visual field