Preclin: Normal Values

Question 1

Emmetropia:

Answer 1

-0.25 to +0.75DS

Question 2

Myopia:
Low:
Medium:
High:

Answer 2

• less than -0.50DS
• low: -2.00DS
• medium: -2 to -4.00DS
• high: less than -6.00DS

Question 3

Hyperopia:

Answer 3

over +0.75DS

Question 4

PD:

Answer 4

53-72mm for distance (2-3mm less at near)

Question 5

minimum best VA to drive:

Answer 5

6/12

Question 6

Discrimination:

Answer 6

line subtending 0.5sec of arc

Question 7

Resolution:

Answer 7

30-40 arcsec

Question 8

Recognition:

Answer 8

1 arcmin

Question 9

Vernier:

Answer 9

10 arcsec

Question 10

VA (18-42yrs)

Answer 10

6/4.5 (-0.13 logmar conversion) (SD 0.05)

Question 11

Abnormal VA:

Answer 11

if decrease of 5 or more letters

Question 12

Orthophoria H and V:

Answer 12

H: less than 1 prism diopter
V: less than 0.25 prism diopters

Question 13

Normal H and V:

Answer 13

H: 3 prism diopters V: 1 prism diopter

Question 14

NPC:

Answer 14

6/8cm break/recovery - for all ages

Question 15

NPA:

Answer 15

15-1/4(age) min

or 18-1/3(age) avg

Question 16

Steropsis:

Answer 16

40 arcsec

Question 17

What if stereopsis worse than 40”?

Answer 17

any ocular misalignment cannot be larger than PFA; 60 is still within normal limits. If worse than 60”, see if bifoveal fixation still present and check for binocular vision problems

Question 18

Ocular motility:

Answer 18

no pain or DV, no head tilt, no over/underaction/restriction/jerky movements

Question 19

Pupil size (in light) vs (in dim)

Answer 19

in light: 2-4mm

in dim: 4-8mm

Question 20

Colour vision Ishihara:

Answer 20

more than 2 errors is a fail

Question 21

Palpebral fissure aperture (distance between upper and lower eyelid):

Answer 21

9-10mm (less than 9mm is abnormal)

Question 22

Marginal reflex distances (distance between superior/inferior lid and corneal reflex):

Answer 22

4-5mm
less than 4 = abnormal
less than 2.5 = visually impairing
difference of 1.5mm b/w sup and inf = abnormal

Question 23

Levator function (distance b/w excursion of upper lid margin from full down gaze to full up gaze without brow movement - how much the upper lid margin moves when looking down – looking up):

Answer 23

more than 10mm = normal
8-10mm = good
5-7 = moderate
less than 4 = poor

Question 24

Lid crease (distance from upper lid margin to lid crease) for men and women:

Answer 24

women: 10-11mm
men: 8-9mm

If lid crease is higher than normal or if there is a deeper upper lid sulcus = sign of aponeurotic disinsertion

Question 25

Motolity/pupils/colour vision/vis. fields/lids: what may abnormal results indicate?

Answer 25

neurological disorders – to CN assessment, CT scan, MRI, blood workup – refer to GP, neurologist, neuro-ophthalmologist, determine urgency of referrel

Question 26

Pelli Robson: for over and under 50yr olds

Answer 26

under 50: 1.80 log units

over 50: 1.65 log units (peak of CSF drops with age)

Question 27

Melbourne edge test: for over and under 65yr olds

Answer 27

under 65: 19-22dB
over 65: 16-18dB

less than 15dB is abnormal (significant CS loss and needs differential diagnosis)

More than 2dB change between tests = abnormal

less than 10dB = severe impairment (trouble with everyday activities)

severe if can’t do first line. moderate if can’t do second line. mild if can’t do 3rd line

Question 28

Aus. Vision Chart: for under and over 65yr olds

Answer 28

under 65: 0.21 logmar/2 lines difference
over 65: 0.24 logmar/2.5 lines difference

more than 3 lines difference is abnormal (significant CS loss)

3 or more lines difference between tests is also abnormal

Question 29

Ishihara tracing plate: When fail?

Answer 29

If fail to trace within 10 seconds

Question 30

Ishiahara screening: When fail?

Answer 30

If more than 2 errors

Question 31

Farnsworth F2: how distinguish tritan from RG?

Answer 31

Tritan: if see blur square clearer/only see blue square

congenital RG: if only see green square

Question 32

Farnsworth D15: When fail?

Answer 32

2 or more diametrical crossings (except a single one aroud cap 7)

orientation of crossings tells you if protan/deutan/tritan

Question 33

Lanthony H16: when fail?

Answer 33

3 or more diametrical crossings

Question 34

Medmont C100: what classifies as protan/duetan?

Answer 34

Anything outside of -2 to +2 is protan/deutan

Question 35

Anomaloscope: when fail?

Answer 35

When can match RG to yellow at multiple points

Question 36

near retinoscopy (posture of acc):

Answer 36

+0.50DS +/-0.25

Question 37

Binoc cross cyl:

Answer 37

+0.50DS +/-0.25

Question 38

NPA:

Answer 38

15 - 1/4age

Question 39

Acc. Range (PRA and NRA):

Answer 39

+/-2.00 at distance

-2.00 at near

Question 40

Acc. facility flippers:

Answer 40

8cpm at near with +/-2.00 filipper

record preference for puls or minus with +/-1.00 flipper

Question 41

AC/A ratio

Answer 41

4+/-2pd/D *pd = prism diopters

Question 42

Near phoria and distance phoria (verg posture)

Answer 42

near phoria: 3pd exo +/-3

distance phoria: 1pd exo +/-1

Question 43

Verg. Range. Near: for BI and BO

Answer 43

BI: more than10/16/10, BO: more than 10/16/10

blur/break/recovery

Question 44

Verg. Range. DIstance: for BI and BO

Answer 44

BI: -/6/4, BO: 10/16/10

Question 45

Verg. facility flippers: at near

Answer 45

15cpm at near of 3pd BI/12pd BO flipper

Question 46

Phorial/vergence-range consideration 1:

Answer 46

opposite reserve more than 2x phoria

Question 47

Phoria/vergence-range consideration 2:

Answer 47

phoria within mid 1/3 of fusional range

Question 48

Fixation disparity:

Answer 48

curve type 1, fixation disparity 4’exo +/-6’, Assoc, phoria 0 + 2pd