OCT

Question 1

Optic Disc Morphology is analyzed at how many points on the ONH circumference

Answer 1

255 points

Question 2

A smaller disc is more likely to produce false ___ on OCT

Answer 2

Positives

Question 3

A larger disc is more likely to produce false ___ on OCT

Answer 3

Negatives

Question 4

On OCT, what RNFL thickness readings are most often affected in early GLC?

Answer 4

Avg and Inferior

Question 5

Avg RNFL thickness between fellow eyes should be within how many microns?

Answer 5

10 microns

Question 6

RNFL thickness graph:
White indicates…

Answer 6

THICKEST 5%

Question 7

RNFL thickness graph:
Green indicates…

Answer 7

90% of NORMALS

Question 8

RNFL thickness graph:
Yellow indicates…

Answer 8

THINNEST 5%

Question 9

RNFL thickness graph:
Red indicates…

Answer 9

THINNEST 1%

Question 10

RNFL thickness graph:
Gray indicates…

Answer 10

Disc area did not match normative data or no normative comparison available

Question 11

T/F: if a patient’s RNFL thickness falls within the ‘white’ they do not have GLC

Answer 11

FALSE; can start with really thick RNFL

Question 12

What is considered and ‘abnormal’ RNFL thickness?

Answer 12

Overall avg below 5% (red or yellow)
Any quadrants below 5% (red or yellow)
Any clock hour below 1% (red)

Question 13

Where is the best place to look for GLC/dips on the TSNIT curve?

Answer 13

Between Temp & Sup and between Inf & Temp

Question 14

Large discs have ___ (higher/lower) sensitivity fir early GLC detection, resulting in more false ___

Answer 14

Lower; negatives

Question 15

ERM may ___-estimate RNFL and mac thickness

Answer 15

OVER

Question 16

CAT may ___-estimate RNFL thickness

Answer 16

UNDER

Question 17

What is the relationship between axial length and RNFL?

Answer 17

The longer the eye, the thinner the RNFL

**for every 1mm inc in axial length, RNFL thickness decreases by 2.2µm

Question 18

Longer axial length is associated with risk of OCT false ___

Answer 18

POSITIVES

(Thinness is caused by longer axial length, not by GLC)

Question 19

T/F: it is not possible to to increase RNFL thickness over time

Answer 19

TRUE!

If thickness appears to increase, it is not a reliable scan!

Question 20

Vignette artifact is usually due to

Answer 20

A really really small nerve

Question 21

How can you tell if the OCT is decentered to the macula (instead of the ON)?

Answer 21

Lack of BV in RNFL deviation map

Question 22

Shifted nerve bundles can cause false ___

Answer 22

Positives