Physiology Of Optics

Question 1

Describe cornea

Answer 1

Transparent
Non vascularized
Provide protective coating

Question 2

Effect of the obstruction of aqueous humor

Answer 2

Increase intraocular pressure

Glaucoma - leads to damage of retina and optic nerve, cause blindness

Question 3

3 functions of aqueous humor

Answer 3

Maintain eye pressure

Maintain cornea shape

Nourish lens and cornea

Immunological function

Question 4

Function of lens

Answer 4

Focuses light ON the RETINA

Question 5

Pupil and muscle of iris in bright light

Answer 5

Circular muscle of iris contract

Pupil constrict

Question 6

Pupil and muscle of iris in dim light

Answer 6

Circular muscle of iris relax

Radial muscle of iris contract

Pupil dilates

Question 7

Dilation of pupil

Answer 7

Sympathetic stimulation : mydriasis

Question 8

Pupil constriction

Answer 8

Parasympathetic stimulation : miosis

Question 9

Functions of vitreous humor

Answer 9

Mainatain posterior pressure to lens

Clear debris by phagocyte

Help clean the retina

Question 10

Describe emmetropia

Answer 10

Normal eye : light rays from object are parallel and focus on the retina without effort

Question 11

Describe the lens in distance vision (3m)

Answer 11

Ciliary muscle relax

Zonular ligament contract / stretch

Lens is thin

Question 12

Describe lens in near vision (3m)

Answer 12

Ciliary muscles contract

Zonular ligaments relax

Lens is thicker

Question 13

Describe visual axis

Answer 13

Midpoint of visual field to fovea

Question 14

Describe optic axis

Answer 14

Longest A-P diameter of the eye, middle of cornea to posterior pole

Question 15

Describe presbyopia and how it is corrected

Answer 15

Loss of accomodation of lens because decrease in elasticity as aging

Corrected by convex lens

Question 16

Describe agtimatism and how it can be corrected

Answer 16

Non uniform curbpvature of the cornea

Corrected by cylindrical lens

Question 17

Describe error of refraction : HYPEROPIA and how it can be corrected

Answer 17

Light rays focused on the POSTERIOR to the retina
Eye ball too short
Farsightedness

Corrected by convex lens

Question 18

Describe error of refraction : MYOPIA and how it is corrected

Answer 18

Light rays focused ANTERIOR to retina
Eye ball too long
Nearsightedness

Corrected by concave lens

Question 19

Describe visual acuity

Answer 19

Sharpness of the eye ; degree to which details and contours of objects are perceived

Question 20

Visual acquity influenced by

Answer 20

Optical factors

Retinal factors

Stimulus factors

Question 21

How visual acquity is determined

Answer 21

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