dispensing

Question 1

Martins rule (SV lenses)

Answer 1

for every 2 degrees of pantoscopic tilt the OCs should be lowered by 1mm to compensate

e.g., tilt of 10 degrees = OC should be placed 5mm below pupil centre

Question 2

opposite signs for R+L eyes (one plus, one minus)

Answer 2

antimetropia

Question 3

how to work out if anisometropia will be problematic based on VAs?

Answer 3

if VA 6/6 R+L - anisometropia + aniseikonia will be a problem

if VA 6/60 R, 6/6 L - unlikely to be a problem

Question 4

how much vertical prism differential prismatic effect binocularly can px tolerate?

Answer 4

1D but some px can adapt to as much as 3D whereas others can only tolerate 0.25D

Question 5

solutions for differential prism in SV

Answer 5

advise px to tilt head slightly down for NV do still reading through OC

slab off

2 pairs of specs

Question 6

solutions for DP in bifocals

Answer 6

separate SVD + SVN
contact lenses (no OC/ prismatic effect)
slab off bifocals
franklin split bifocals
solid prism segment
bonded prism segment

Question 7

ANISEIKONIA

Answer 7

spec wearers with large degrees of anisometropia and good VAs may experience a difference in size +/or shape of visual images due to unequal spec magnification

Question 8

aniseikonia symptoms

Answer 8

visual discomfort
visual distortion of space
difficulty achieving good BV
headaches
nausea
dizziness

Question 9

what difference in image size would 1D difference in power produce?

Answer 9

1% difference in image size

Question 10

who specifies that if specs needed specifically and solely for VDU the employer must provide these for free?

Answer 10

healthy and safety regulations 1992

Question 11

AOP recommends what standards for VDU users

Answer 11

ability to read N6 from 33-70cm with adequate VA for any task at greater distance
good BV or well established monocular vision
normal NPC
no central field defects in dom eye
clear ocular media

Question 12

DRIVING STANDARDS FOR GROUP 1 PRIVATE

Answer 12

read registration plate with specs/CLs from 20 metres (~6/10)
BCVA at least 6/12 using BE or one eye if only have sight in one eye
120 degrees horizontal VF (at least 50 either side) with no sig defect in binocular field within 20 degrees of fixation

Question 13

GROUP 2 HGV STANDARDS

Answer 13

BCVA 6/7.5 in good eye + at least 6/60 in poor eye
specs cannot be more than +8 in any meridian
horizontal VF at least 160 (70 either side of fixation) and 30 above/ below
fixation
no sig defect within 70 degrees of fixation + NO defect within central 30
no other impairment of visual function