angle closure glaucoma and gonioscopy

Question 1

which type of patients are most susceptible to getting angle closure glaucoma

Answer 1

it is a disease of the over 50’s and is more common in women and hyperopes ( > +8D smaller eyes)

Question 2

what is the cause of an ACG attack

Answer 2

when the anterior iris comes into contact (blocks) with the trabecular meshwork or the posterior cornea.
this prevents aqueous outflow causing a sudden rise in IOP and is very painful

Question 3

what produces aqueous and where does the aqueous leave through to get into the anterior chamber

Answer 3

aqueous is produced by the ciliary processes and leaves through the canal of schlemm via the venus plexus

Question 4

in an open angle, which route does the aqueous take to leave the eye

Answer 4

aqueous moves from posterior to anterior chamber and leaves the eye via the trabecular meshwork

Question 5

what is the principle factor affecting aqueous outflow and why

Answer 5

the venous pressure, as there are veins here which can resist aqueous outflow

Question 6

what is iris bombe, and what affects can it have

Answer 6

iris bombe is when the iris bows forward and obscures the angle

Question 7

what causes the ability for fluid to leave the eye with age, resulting in increased IOP

Answer 7

with age the trabecular meshwork gets blocked and melanin stays in the eye: cells float off the iris e.g. pigment epithelial cells and can drift into the trabecular meshwork, and the macrophages there will phagocytose the pigment epithelial cells, leaving melanin and granule cells in the trabecular meshwork.

Question 8

what is the cause of angle closure

Answer 8

an increased pressure in the posterior chamber, pushes the iris forwards blocking the trabecular meshwork, this obscures the angle and there is no way for the aqueous to leave the eye = rise in IOP

Question 9

what does the iris become like when it sticks onto the anterior surface of the lens

Answer 9

iris becomes immobile and sluggish

Question 10

what is a indirect goniolens composed of and what are the different versions

Answer 10

• a 90D volk lens
• mirrors

some can have a single lens and others can be 4 mirror versions

Question 11

what does a mirror from each phase show with a indirect goniolens

Answer 11

the opposite angle

Question 12

how do you use a indirect goniolens to assess a patients angle

Answer 12

• place the indirect goniolens on the patient’s eye with lubricating fluid
• too much pressure can distort the angle, so use gentle pressure
• if you want to see the superior angle, you need to look through the inferior mirror and you can see the structures within the chamber
• rotate the mirror to look at all parts of the angle
• the angles will look slightly magnified

Question 13

what part of the indirect goniolens do you need to look through if you wish to view the superior angle on a patient

Answer 13

look through the inferior mirror

Question 14

which indirect goniolens is mainly used by ophthalmologists

Answer 14

koeppe indirect goniolens

Question 15

list the 4 structures that are found in the anterior chamber angle

Answer 15

• schwalbes line (descements membrane)
• scleral spur
• trabecular meshwork (canal of schlemm)
• ciliary processes

Question 16

what is the main thing that you want to see when looking at an angle with a indirect goniolens, which indicates that the angle is open

Answer 16

trabecular meshwork (tells you the angle is open)

Question 17

where does schwalbes line sit in the eye

Answer 17

at the base of he cornea i.e. descements membrane = where light comes in and meets

Question 18

what structure is anything above the scleral spur

Answer 18

trabecular meshwork

Question 19

what structure is fond below the scleral spur

Answer 19

ciliary body

Question 20

what is the scleral spur a marker to show

Answer 20

to show that the angles are open because above it is the trabecular meshwork

Question 21

why is the scleral spur easy to see

Answer 21

because it is white which will always remain white with age

Question 22

which angle is the most open and why should it be viewed first

Answer 22

the inferior angle in the widest and should be through the superior mirror with the indirect goniolens
the major landmarks will be able to be viewed in the inferior angle, so you can familiarise yourself with the structures and then move on to see the more narrow angles

Question 23

what colour is the trabecular meshwork usually, and what colour does it become as you age and why is this

Answer 23

it is usually pink and becomes more brown as you age as it picks up on the melanin and pigmentation from the iris

Question 24

which structures can be viewed in a grade 4, classified by the schaeffer grading system, when using a indirect goniolens

Answer 24

all 4 structures:

• ciliary body
• scleral spur
• trabecular meshwork
• schwalbes line

characteristic of myopia and aphakia
ciliary body can be seen with ease

Question 25

which structure can be seen with ease in a grade 4

Answer 25

ciliary body

Question 26

which structures can be viewed in a grade 3, classified by the schaeffer grading system, when using a indirect goniolens

Answer 26

- scleral spur - trabecular meshwork - schwalbes line but not the ciliary body

Question 27

which structures can be viewed in a grade 2, classified by the schaeffer grading system, when using a indirect goniolens

Answer 27

- trabecular meshwork - only can be viewed you lose view of the scleral spur

Question 28

which structures can be viewed in a grade 1, classified by the schaeffer grading system, when using a indirect goniolens

Answer 28

- schwalbes line - only can be viewed (or maybe the top of trabecular meshwork)

Question 29

which structures can be viewed in a grade 0, classified by the schaeffer grading system, when using a indirect goniolens

Answer 29

can't see anything

Question 30

when viewing the angle on a slit lamp, what indicates that that the angle is closed

Answer 30

the beam of the iris will intersect (be continuous with) the beam of the cornea, so there will be no junction/separation between them = iridocorneal contact

Question 31

when viewing the angle on a slit lamp, what indicates that that the angle is not closed

Answer 31

the beam of the iris and cornea separates at an interface = no iridocorneal contact

Question 32

how is a grade 0 (closed angle) identified

Answer 32

it is a closed angle due to iridocorneal contact and is recognised by the inability to identify the apex of the corneal wedge

Question 33

how does the goniolens distinguish between 'appositional' from 'synechial' angle closure

Answer 33

with appositional angle closure, the goniolens can push the iris away but with synechial (anterior uveitis) angle closure the goniolens cannot push the iris away and the angle will be blocked

Question 34

what structure is the border where light hits descements membrane

Answer 34

schwalbes line

Question 35

what is the white band viewed in the angle

Answer 35

scleral spur

Question 36

what is found sticking on the scleral spur and trabecular meshwork in angle closure glaucoma

Answer 36

iris processes

Question 37

why are hyperopes at a greater risk of having an ACG

Answer 37

because there iris curves forwards (as it has a convex shape)

Question 38

what is a concave iris, or myopes at a greater risk of having

Answer 38

pigment dispersion syndrome | the iris is big, and pigment is flying off

Question 39

what is found in pigment dispersion syndrome

Answer 39

known as the chocolate box line it is excessive pigment in the trabecular meshwork other pigment may also be seen settling onto and anterior to schwalbe's line (onto posterior surface of the cornea) = sampaolesis line

Question 40

what is the name given to excessive on and anterior to schwalbe's line

Answer 40

sampaolesis line

Question 41

what are normal iris blood vessels never attached to and what is the appearance of normal iris blood vessels

Answer 41

never attached to structures anterior to the scleral spur normal blood vessels are thick and have a definite pattern (circumferential or radial), they loop around the base of the iris and always below the scleral spur

Question 42

what is the appearance of normal blood vessels and where do they extend through

Answer 42

they are more feathery and have an erratic pattern (does not follow a radial pattern) and also more thinner and are undirectional they extend past the scleral spur and into the trabecular meshwork

Question 43

what other condition will you look out for if you see a patient with neovascular vessels

Answer 43

a px who had a central retinal vein occlusion as they can have a 90 day glaucoma and then neovascular in the anterior chamber