Images/Investigations Flashcards
What frequency does US?
10MHz
Depth of anterior chamber
3.1mm
Where is the standard reference plane taken in Heidelberg retinal topography (HRT) of the optic disc?
50 um below the optic nerve head boundary line at the temporal disc edge along the horizontal midline
it corresponds to the centre of the papillomacular bundle of the RNFL.
ERG - Increased a wave
alibinism
ERG - Reduced b wave
CRAO, congenital stationary night blindness
Retinoschisis
ERG - no response
Batten’s disease, Leber’s congenital amaurosis
Pattern ERG
detects local MACULAR disease
N35
P50 - macular PRs
N95 - ganglion cell layer
Best vietlliform ERG and EOG
ERG normal
EOG reduced, diminished arden ratio
Pattern VEP
V1 of cortex
Flash VEP
V2 of cortex
VEP in ambylopia
pattern abnormal
Flash normal
Background and maximal illumination in Humphrey’s
31.5apostolib
Maximal - 10,000 apostolib
0 means needed maximal illuminance in order to see the point
Corneal refelx displacement
Reflex displaced to:
pupil edge = 2 mm = 15 degrees = 30 PD
midway from pupil to limbus = 4mm = 30 degrees = 60PD
limbus = 6mm = 45 degrees = 90PD
Wegeners
c-ANCA
During which phase of the fluorescein angiogram does a cilioretinal artery fill
Choroidal
dacryoscintigraphy
FUNCTIONAL information
Gold standard for fundus autofluoresence?
Scanning Laser Ophthalmoscopy
Biometry <22mm
Haigis, Hoffer Q
Biometry 22-26mm
SRK/T, Barrett
Biometry >26mm
Haigis, SRK/T
What difference in biometry in eyes do we need to re-check?
> 0.3mm
What do the roman numerals in goldmann VF mean?
Roman numerals( I-V) indicate the size of the target. With every drop in number the diameter halves. V is the largest.
What do the numbers in goldmann VF mean?
Number (1-4) indicates the brightness of the stimulus. The larger the number, the brighter the target. Each consecutive drop represents a 5db change
On the Goldmann perimeter, the test objects can be varied in both size and intensity by using different filters.
Size: of the test object is represented by the Roman numeral (I-V). Each increment of the Roman numeral doubles the radius (and quadruples the area) of the test object.
Light intensity: can be altered using different neutral density filters. Filters 1-4 are in increments of 5 dB each. Filters a-e are in increments of 1 dB each.
Thus, the III4e test object will have twice the radius and four times the area of the II4e test object, with the same light intensity.
Amsler grid - large square size?
10cm
B scan
Dense tissues are brighter - hyperechogenic
Higher gain settings allow weak signals to be visualized ( small foreign body, posterior vitreous detachment, vitreous opacity)
High frequency ultrasound produces image with better resolution, but poorer penetration
Four quadrants of the eye are typically denominated with the following nomenclature based on clock hours 1) T12 ( superior quadrant) 2) T9 ( lateral quadrant) 3) T3 ( nasal quadrant) 4) T6 ( inferior quadrant)
OCT
Time Domain - quicker, mirror moves
Fourier Domain - higher resolution, mirror fixed
Cystoid macula edema
caused by muller cell necrosis, and cystic fluid spaces
ONL
Retinal laser treatment
Hyper-reflectivity in ONL
Microaneurysms
occur in the IPL/INL
Hard Exudates
ONL/OPL
LA 30Hz ERG
look at 30Hz flicker
if delay: general cone problem
if no delay but reduce amplitude: Focal cone problem
Selective laser trabectulectomy complications
Transient rise in IOP: Most evident one hour postoperatively Anterior uveitis Hyphaema Cornea complications Oedema Reactivation of HSV
Anterior chamber depth
Average depth 3.11mm
Volume 220 μl
posterior chamber depth
Average depth 0.52mm
Volume 60 μl
Vitreous cavity depth
Average depth 16.5mm
Volume 5.5 ml
Abnormalities in ERG
Vit A deficiency
Ushers syndrome
mfERG
Regional loss of retina
EOG + BEST disease
In cases of maculopathy with marked FAF changes
If flash ERG is normal but the EOG light-rise reduced, think bestrophinopathy ~ BEST 1 mutation
CI ICG and FFA
both CI if pregnant
breastfeeding in FFA
Seafood in ICG
Haigis
Additionally uses AC depth
