Diagnostics

Question 1

Hertel exophthalmometry norms

Answer 1

Measuring proptosis
12-22mm for white pts
12-18mm for Asian
12-24mm for African
Abnormal if higher OR presence of >3mm asymmetry

Question 2

Thyroid eye disease

Answer 2

Forced suctions to detect EOM restrictions
CT/MRI to detect enlargement of the EOMs (tendons will be spared)
Exophthalmometry to measure proptosis
Visual fields to detect optic n. Compression
Blood work (T3/T4/TSH)

Question 3

Jones I test

Answer 3

Tests the patency of the nasolacrimal system. Fluorescein is instilled in the inferior fornix and should drain off the ocular surface within five minutes if the nasolacrimal system is functioning properly. Positive Jones I test = patent system. Fluorescein will be seen when pt blows nose or at back of patients throat.

Question 4

Jones II test

Answer 4

Nasolacrimal irrigation with saline following a negative Jones I test (no fluorescein seen). Reflux of fluid through the same punctum indicates an obstruction within the upper or lower canaliculus. Retrograde flow through the opposite canaliculus and punctum indicates nasolacrimal blockage (other side of common canaliculus). If the pt tastes saline, performs a gag reflex, or if fluid is recovered from the nose, the obstruction has been cleared

Question 5

Chocolate agar can dx which pathogens?
(also called Thayer-Martin agar)

Answer 5

Neisseria gonorrhoeae and Haemophilus influenzae
(“Hersheys and Nestle chocolate”)

Question 6

How long does a full field ERG take?

Answer 6

up to 75 minutes

Question 7

what does a reduced amplitude represent on ERG?

Answer 7

reduced number of functioning cells or cell death

Question 8

what does delayed timing represent on ERG?

Answer 8

suggests sick or dysfunctional cells

Question 9

what does EOG evaluate?

Answer 9

tests the outer retina and RPE, records light peak and dark trough

Question 10

what is the Arden ratio?

Answer 10

light peak on EOG / dark trough on EOG, normal amount is > 1.85

Question 11

what disease shows an abnormal EOG but normal ERG?

Answer 11

Best’s disease

Question 12

what is full-field ERG?

Answer 12

objective test which uses diffuse stimulation of the entire retina to test retinal function, in both dark and light conditions

Question 13

what does the a-wave on ERG represent

Answer 13

fast negative deflection by photoreceptors

Question 14

what does the b-wave on ERG represent

Answer 14

slower positive large amplitude deflection by bipolar cells and some Muller

Question 15

oscillatory potentials on ERG

Answer 15

amacrine cells

Question 16

photopic fast flicker on ERG

Answer 16

cone photoreceptors

Question 17

c-wave

Answer 17

subretinal/RPE response

Question 18

PhNR (photopic negative response)

Answer 18

ganglion cells and axons

Question 19

clinical use for ERG, which diseases would warrant ERG testing

Answer 19

RP, Birdshot chorioretinopathy, etc

Question 20

how does a MF-ERG differ from normal ERG?

Answer 20

provides a topographic measure of retinal electrophysiological activity, measures different regions of retina

Question 21

waveform for mfERG

Answer 21

N1: Receptor and bipolar cells (negative wave)
P1: Bipolar
(positive wave)
N2

Question 22

Plaquenil toxicity on mfERG

Answer 22

decreased waveforms in perifoveal bullseye

Question 23

pattern ERG

Answer 23

targets ganglion cell function, only from the macular region.
optic neuropathies, glaucoma, etc.

Question 24

VEP

Answer 24

measures visual cortex (only undilated pupil electrode test)
N75, P100, N135
P100 should be >5uv
peak 90-110msec normal

Question 25

CT is better for

Answer 25

bone and calcification (denser tissue looks white), emergent situations, ex. orbital fractures

Question 26

PET scan is used for

Answer 26

analyzes metabolic activity of tissues, ex. cancer metastasis

Question 27

MRI is better for

Answer 27

visualizing soft tissues