the eye structure

Question 1

Conjunctiva

Answer 1

1.Its pain receptors cause EYELIDS to close ∴ PREVENT foreign bodies from entering.
2.PRODUCES lubricating mucus ∴ PREVENT eyes from DRYING out.

Question 2

Sclera

Answer 2

1.PROTECTS internal parts of eye
2.PROVIDES points of attachment for the 6 extrinsic eye muscles
3.Inelastic nature helps MAINTAIN SHAPE of eye

Question 3

Cornea

Answer 3

1.Is transparent ∴ ALLOWS 🔆 pass through light sensitive cells.
2.Causes CONVERGING REFRACTION of these light rays.
3.Pain receptors cause EYELIDS to CLOSE preventing foreign matter from touching surface if eye.

Question 4

Choroid

Answer 4

1.Pigment = ABSORBS excessive () () preventing their reflection within the eye which would cause blurring.
2.Blood vessels = SUPPLY food + O2 to cells of retina.

Question 5

Ciliary body

Answer 5

1.Ciliary muscles = control CURVATURE of lens during ACCOMODATION

Question 6

Iris

Answer 6

1.CONTROLS AMOUNT of 🔆 entering eye by pupillary mechanism.
(View picture File 1010)

Question 7

Retina

Answer 7

1.Has Rods that allow for vision in dim light and provides peripheral vision.
2.Has Cones that allow for colour vision and vision in bright light.
3.Its nervous layer has photoreceptors that CONVERT light stimuli into NI.
4.Its neural layer has the optic nerve that CONDUCTS impulses to occipital lobe of the cerebral cortex where they’re interpreted as SIGHT.

Question 8

Blind spot

Answer 8

Not sensitive to light stimuli

Question 9

Yellow spot

Answer 9

Region of highest visual acuity (sharpest vision)

Question 10

Lens

Answer 10

Transparent body which severs to REFRACT and FOCUS image on retina.

Question 11

Vitreous Humour: In Anterior Cavity

Answer 11

Jelly-like substance that maintains the shape of the eyeball

Question 12

Aqueous Humour: In Posterior cavity

Answer 12

1.Maintains shape of eyeball in front of the lens and refracts light.
2.Bathes the lens

Question 13

Short- sightedness (Myopia)

Answer 13

⏩Clear vison on close objects
⏩Can’t focus on distant objects
⏩WHY: Eyeball = Too long and Light Rays from distant objects come into focus sharply in front of retina
⏪FIX: Concave Lens

Question 14

Long-sightedness (Hyperopia)

Answer 14

⏪Difficulty focusing on close objects
⏪WHY: Eyeball = Too short () Close objects come sharply into focus behind the retina () image on retina is blurred
⏪FIX: Convex lens

Question 15

Astigmatism

Answer 15

⏪Cornea/ Lens = Unequal curvature () () ⏪ONLY part of image is sharply focused
⏪FIX: Use lens that’s closely matched to defected part of eye.

Question 16

Cataracts

Answer 16

⏪When lens becomes cloudy, and vision is impaired.
⏪Mainly in older ppl, diabetics, and ppl with hypertension
⏪FIX: Surgically. Consents of lens = removed and replaced with synthetic lens.