OPTHALMOLOGY 7

Question 1

what are the 4 layers of the lens

Answer 1

capsule
epithelium
cortex
nucleus

Question 2

is lens cpsule thicker at the anterior or posterior edge?

Answer 2

anterior

Question 3

which side of the lens has an epithelial layer?

Answer 3

anterior

Question 4

what are suture lines? [theyre in the cortex]

Answer 4

shape where the cortex fibres meet
Y in front, λ at back

Question 5

What is the function of lens zonules?

Answer 5

collagenous fibres that suspend lens behind pupil
from ciliary body muscle to lens capsule

Question 6

function of ciliary body muscle?
which CN controls it?

Answer 6

accomodation
CN III

Question 7

what are 2 broad categories of diseases of the lens

Answer 7

oapcities
abnormal positon

Question 8

what is the difference in APPEARANCE betweennuclear sclerosis & cataract?

Answer 8

sclerosis: transperant ring on distant direct opthalmoscopy

Question 9

nuclear sclerosis has what effect on vision?

Answer 9

not much. normal ageing change

Question 10

the condition with opacity of the lens is called

Answer 10

cataracts

Question 11

what are two structural changes of the lens due to cataracts

Answer 11

disruption of fibre arrangement
accumulation of insoluble protiens

Question 12

Nuclear sclerosis vs cataracts: which si typically in older animals?

Answer 12

sclerosis

Question 13

Nuclear sclerosis vs cataracts: which can be located anywhere in the lens?

Answer 13

cataracts

Question 14

Nuclear sclerosis vs cataracts: which one blocks tapetal reflection?

Answer 14

cataracts

Question 15

Nuclear sclerosis vs cataracts: which one requires treatment?

Answer 15

cataracts

Question 16

What are the 4 stages of cataracts

Answer 16

incipeint
immature
mature
hypermature

Question 17

how are incipient and immature cataracts classified?

Answer 17

by affected alyer

Question 18

An incipient cataract affects what % of the lens?
is tx indicated?

Answer 18

<15%
no

Question 19

An immature cataract affects what % of the lens?
is tx indicated?

Answer 19

15-80%
if severe end & vision is poor

Question 20

a mature cataract filld the entire lens. is taeptal reflection visible?

is sx indicated?

Answer 20

no

yes

Question 21

what causes a hypermature cataract
is sx indicates?

Answer 21

cataract liquefacation and resorption

lens shrinks in volume, creating wrinkles

sx is risky

Question 22

5 causes of cataracts

Answer 22

• congenital
• hereditary
• diabetes mellitus
• secondary
  *senile/sponaneous

Question 23

what is the physiological cause of a diabetic cataract?

Answer 23

hyperglycaemia –> XS glucose metabolised to sorbitol –> sorbitol cannot diffuse through lens capsule –>draws water into lens

Question 24

what is the apearance of a diabetic cataract?

Answer 24

intumescent cataract
(swollen lens due to fluid accumalation. risk rupture!)

Question 25

secondary cataracts can often be due to atrophy of what other part of the eye?

Answer 25

retina

Question 26

what is the name of a cataract sx? what does it do? (briefly)

Answer 26

phacoemulsification removes opaque lens and replaces with artificial lens

Question 27

2 types of lens luxation?

Answer 27

anterior & posterior (also aetiolgoy is primary and secondar)

Question 28

anterior lens luxation is an emergency because it can lead to _____

Answer 28

glaucoma also its painful

Question 29

posterior lens luxation takes place due to degeneration of the _________

Answer 29

vitreous

Question 30

tx of anterior lens luxation surgical: non-surgical:

Answer 30

A: surgical extraction of lens NS: transcorneal reduction/couching

Question 31

a patient with lens luxation will need which lifetime medication? why?

Answer 31

prostaglandin analogue drop to maintain pupillary constriction