RETINAL IMAGING

Question 1

FUNDUS PHOTOGRAPHY

Answer 1

photograph of interior surface of eye

i.e. retina, optic disc, macula + posterior pole (fundus)

Question 2

FUNDUS AUTOFLUORESENCE IMAGING

Answer 2

shows metabolic changes at the level of the RPE suggesting areas of high risk for visual function loss

photoreceptors shed their damaged outer segments which are absorbed by RPE through phagocytosis

these molecules are stored in liposomes + form lipofuscin

Question 3

HYPER VS. HYPOFLUORESCENCE

Answer 3

areas of excess lipofuscin accumulation will appear hyperfluorescent

when RPE cells die or are absent lipofuscin disappears leading to hypofluorescence

Question 4

FLUORESCEIN ANGIOGRAPHY

Answer 4

evaluates the blood vessels in eyes with macular or retinal disease

Question 5

A-SCAN ULTRASONOGRAPHY

Answer 5

high frequency sound waves are transmitted from a probe into the eye which are reflected back to probe + converted into an electrical signal

Question 6

OCULAR COHERENCE TOMOGRAPHY

Answer 6

imaging technique that allows a detailed view of living structures within eye non-invasively

non contact, no mydriatic (pupil dilation), non-ionising radiation, fast + reliable

uses reflectivity of light instead of sound to produce detailed images (tomograms)

Question 7

B-SCAN ULTRASONOGRAPHY

Answer 7

oscillating sound beam emitted passing through eye + imaging a slice of tissue

stronger the echo, brighter the dot

Question 8

WHAT CORRESPONDS TO HIGH REFLECTIVITY?

Answer 8

bright colours (red to white)

horizontal retinal structures (nerve fibre layer, plexiform layers, RPE + choroid)

adjacent structures demonstrating large differences in refractive index are highly reflective at their boundaries

(dark colours - blue to black - represent minimal or no reflectance i.e. fluid within retina)

Question 9

TECHNIQUES FOR IMAGING THE RETINA

Answer 9

• fundus photography
• fluorescent angiograms
• ultrasound imaging
• optical coherence tomography