Ophthalmology physiology

Question 1

define intraocular pressure

Answer 1

fluid pressure inside the eye

measured in mmHg

Question 2

define normal intraocular pressure

Answer 2

10-20mmHg

Question 3

define aqueous humour

Answer 3

transparent fluid located inside the eyes
-specifically within the anterior and posterior chamber

Question 4

function of aqueous humour

Answer 4

maintina intraoccular pressure and shpae of globe

providing nutreis and o2 for posteior cornea, trabueclar meshword and lens

remove metabolic bypordcuts

faciliatre passage of light to retina

Question 5

compositoin of aqueous humour 2

Answer 5

protein free liquid

and high level of lactate

Question 6

movement of aqueous humour

Answer 6

constantly produced into the posterior chamber and then flows through into the anterior chamber

then from anterior chamber fluid drained through trabecular meshwork into the canal of schlemm

Question 7

what produces aqueous humour

Answer 7

ciliary body

Question 8

what are the three processes involved in aqueous humour production

Answer 8

diffusion

ultrafiltraiton

active secretion

Question 9

define ciliary muscles

Answer 9

intrinisc muslce of teh eye formed as a ring of smooth muscle in the eyes middle layer the uvea

Question 10

function of teh ciliary muscles

Answer 10

provides accomodation of the eye

Question 11

define eye accomodation

Answer 11

eye changes optical power to maintain a clear image or focus on an object as its distance varies

Question 12

how does eye accomidation vary

Answer 12

varies from far point
-maximum distance from eye for which a clear image of an object can be seen

to the near point
-minimum distance for a clear image

Question 13

define presbyopia

Answer 13

fradula loss of the eyes abiilty to focus on nearby objects

-natal part of ageing

-physiological insufficiency of accommodation

Question 14

common sign of presbyopia

Answer 14

difficulty reading small print which results in having to hold reading material further away

-other syx- headaches, eyestrain

Question 15

pathophys of presbyopia 2

Answer 15

due to age related changes in the lens
-include:
-decreased elasticity
-increased hardness

and ciliary muscle
-decreased strength and ability to move the lens

Question 16

define retinal

Answer 16

polyene chromophore
-bound to proteins called opsins

is the chemical basis of visual phototransduction
-the light detection stage of visual perception

Question 17

how is retinal made

Answer 17

vit A is converted to it

Question 18

function of retinal

Answer 18

captures photon of correct wavelength then changes configurations

-this pushes opsin protein in the retina triggering chemical cascade which results in perception of light by the human brain