Imaging the eye

Question 1

list the 6 different methods of imaging the eye

Answer 1

• OCT
• fundus autoflourescence (FAF)
• flourescein angiography (FA)
• indocyanine green (ICG)
• ultrasound (A or B scan)
• gonioscopy

Question 2

list the 3 different OCT machines and features that they have

Answer 2

• spectralis OCT with FAF, no fundus camera
• topcon OCT no FAF + fundus camera
• zeiss cirrus

Question 3

what does a 830nm infrared laser allow us to see in the eye, and state whether or not the px needs dilation

Answer 3

identifies retinal oedema & pigmentary changes
no need to dilate px

(allows to see through haze/bleeding, e.g. can pass through cataract opacities & blood)

Question 4

what images does a 514nm argon with 500nm barrier filter allow to obtain of the eye and what types of diagnoses can be made

Answer 4

superficial retinal layers - such as nerve fibre layer i.e. loss of ganglion cells in glaucoma
green reflectance images at 514nm
also known as red free

Question 5

which spectrum does the 488nm autofluorescence use and what is it and flourescein angiography used for

Answer 5

• uses laser in blue spectrum
• excites lipofuscin
• gives idea of integrity of RPE/looks for ‘health’ of RPE

Question 6

what does flourescein angiography look at in the eye

Answer 6

leakage of blood vessels or retinal vasculature

Question 7

what does the 795nm diode laser indocyanine green angiography (ICG) allow us to see in the eye

Answer 7

• looks at choroidal structure/vessels

- looks for choroidal neovascularisation (CNV) as it allows to see fine leakages of choroid

Question 8

why is flourescein angiography not essential for looking at the choroidal vessels

Answer 8

it is unable to show the detail of choroidal vessels so cannot investigate things like choroidal neovascularisation

Question 9

what part of the retina does the RPE integrities

Answer 9

the outer segment

Question 10

what is below the RPE

Answer 10

bruch’s membrane, and below is choroid

Question 11

which layers of the retina do most diseases affect & give an example of a disease and how this will look in a OCT image

Answer 11

photoreceptors & RPE
e.g. outer segment disease such as retinitis pigmentosa, in OCT the line will be collapsed & disappear due to disintegration

Question 12

which layer of the retina should be located first when viewing an OCT image, and why

Answer 12

the outer nuclear layer (ONL)

because it is the larger layer, so from that you can locate other layers above & below it