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TEST ROOM Flashcards

1
Q

how does corneal thickness affect IOPs?

A

thin corneas have pressures that are underestimated (lower)

thick corneas have pressures that are overestimated (higher)

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2
Q

parasympathetic efferent pathway

A

brain to eye

  1. Edwinger-Westphal nucleus
  2. Cranial nerve III (oculomotor nerve)
  3. iris sphincter muscle
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3
Q

sympathetic efferent pathway

A

brain to eye

  1. hypothalamus
  2. ciliospinal centre
  3. iris dilator muscle
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4
Q

horner’s syndrome

A

problem with sympathetic nerve supply (dilator affected)

miotic pupil, ptosis on same side, failure to sweat on affected side

urgent referral

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5
Q

adie’s tonic pupil

A

anisocoria greater in light conditions - affected pupil cannot constrict

affects parasympathetic nerve supply

dilated pupil with poor light reaction, reacts better when accommodating

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6
Q

argyll robertson pupil

A

bilateral miosed + irregular pupils, dilate poorly in darkness

accommodates but not reactive to light

caused by neurosyphilis

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7
Q

CNIII palsy pupil signs

A

impaired parasympathetic efferent innervation

impaired direct + consensual response

diplopia, ptosis - eye down + out

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8
Q

presbyopia

A

gradual loss of the eyes ability to focus on things up close

when you are younger, the lens is very flexible and can easily change shape depending on whether looking at something near or far away

as time goes on the lens becomes less flexible making it more difficult to focus on near objects

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9
Q

domestic waste

A

paper, cardboard, used tissues/paper towels, disposable CLs

disposed in normal black bag waste stream

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10
Q

sector specific non-hazardous healthcare waste

A

e.g., disposable tonometer probes, expired CLs, empty CL solution bottles which don’t present a risk of infection

disposed of as offensive waste (tiger stripe bags)

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11
Q

non-hazardous pharmaceutical waste

A

used or expired minims - need to be incinerated and discarded in medicine disposal box (usually yellow)

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12
Q

hazardous waste

A

computer monitors, fridges, batteries, chloramphenicol - special requirements

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13
Q

dichromat vs anomalous trichromat

A

dichromat have an absent cone (e.g., protanope has same number of cones as everyone else but instead of red cones they have green cones)

anomalous trichromat - defective cone

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14
Q

S-cone

A

short wavelength = blue (tritan)

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15
Q

M-cone

A

middle wavelength = green (deutan)

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16
Q

L-cone

A

long wavelength = red (protan)

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17
Q

ishihara test

A
  • uses pseudoisochromatic plates
  • doesn’t grade severity, classification only
  • present in random order
  • 3-4 secs per plate
  • test distance 75cm
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18
Q

ishihara plate types

A

transformation = CVD sees diff figure
vanishing = CVD doesn’t see number
hidden digit = CVD sees figure (normal doesn’t)
classification = differentiates protan from deutan

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19
Q

city university test

A
  • colour confusion test (10 plates)
  • can be used to detect protan, deutan or tritan defects
  • grades severity
  • pages shown for 3 secs @ 35cm
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20
Q

dichromats

A

absent cone - 2/3 present

protanopia - L cone missing (red deficient) - 1% of males
deuteranopia - M cone missing (green deficient) - 1% of males
tritanopia - S cone missing (blue deficient) - 0.001% of males

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21
Q

anomalous trichromacy

A

defective cone - 3/3 present but 1 anomalous

protanomalous - 1% of males
deuteranomalous - 5% of males
tritanomalous - 0.0001% of males

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22
Q

SIGN referral guideline for IOPs

A

IOPs >25mmHg irrespective of CCT

IOP 21-25 + CCT <555nm + 65 or under

IOP <26 + CCT equal or > 555 = monitor

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23
Q

why is only 1 measurement required for Goldmann?

A

Goldmann takes ocular pulse into account

NCT requires at least 3 readings to take an average so ocular pulse is accounted for

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24
Q

outer lipid layer

A

secreted my meibomian glands

prevents tear evaporation

acts as a lubricant to smooth eyelid movement on globe

25
Q

middle aqueous layer

A

secreted by lacrimal glands

supplies oxygen to avascular cornea

contains antibacterial enzymes

washes away debris from ocular surface

26
Q

inner mucin layer

A

mucous secreted by conjunctival goblet cells

converts corneal surface to hydrophilic surface and allows wetting

27
Q

afferent pupil pathway

A

eye to brain

retina —> optic nerve —> optic chiasm
—> optic tract —> pretectal nucleus

if affected RAPD present

28
Q

efferent pupil pathway

A

from brain to eyes

controlled by autonomic NS

sympathetic - fight or flight (iris dilator)
parasympathetic - rest + recovery (iris sphincter)

29
Q

absent direct vs absent consensual

A

absent direct = significant ocular or neurological disease (either afferent or efferent pathway affected)

absent consensual = if direct present then afferent pathway unaffected + must be impaired parasympathetic efferent pathway to affected eye

30
Q

hand magnifier advantages

A
  • low cost
  • compact, lightweight, portable
  • can have long eye-to-magnifier
    distance
  • used with DV rx as emergent light
    parallel
31
Q

hand magnifier disadvantages

A

difficult for px with arthritis etc

increased distortions as lens held further from eye

32
Q

hand magnifier px instructions

A

lay magnifier on page + slowly pull away until image clear

use SVD rx

larger FOV holding magnifier closer to eye

33
Q

stand magnifier advantages

A
  • incorporated illumination
  • good for px with hand tremors
  • small and portable
  • relatively inexpensive
34
Q

stand magnifier disadvantages

A

can be bulky

limited field of view

px must have adequate accommodation or suitable SVN

35
Q

bar/ flat field magnifiers advantages

A

normal reading posture possible

very bright - light gathering

useful for px with hand tremor

clear image across while lens (minimal aberrations

36
Q

bar/ flat field magnifier disadvantages

A

large lenses (heavy)

low mag

reading material must be flat + on firm surface

must wear SVN or accommodate

37
Q

CCTV advantages

A
  • aberration free
  • max mag up to 70x
  • zoom control
  • contrast reversal
  • binocular viewing
  • normal viewing distance/ posture
38
Q

CCTV disadvantages

A
  • cost to buy + service/repair
  • size can be large/bulky
  • practice required
  • depth of field limited by focal length of camera, reading material needs to be flat
39
Q

corneal arcus

A

white/grey crescent shape made of lipid deposits that curves around outer edge of cornea

occurs in ~60% of those aged 50-60yrs

can be related to HBP, high cholesterol

40
Q

AVERAGE RX + VA FOR 1 YR OLD

A

+2D and approx 6/24

41
Q

AVERAGE RX FOR 3 YR OLD

A

+1D and 6/9

42
Q

AVERAGE RX FOR 4-6 YR OLD

A

+0.50D and 6/6

43
Q

STEREO 1YR OLD

A

170-210 Frisby

44
Q

STEREO 3YRS

A

55-85 Frisby

45
Q

STEREO 5YRS

A

20-30 Frisby

46
Q

STEREO 6YRS

A

5-10 Frisby

47
Q

SAME DAY EMERGENCY REFERRAL

A
  • Acute angle closure glaucoma
  • retinal detachment
  • acute 3rd nerve palsy (pupil involved)
  • papilloedema
  • penetrating/ chemical injury
  • CRAO
  • hypopyon/ hyphaema
  • endophthalmitis
  • sight threatening keratitis
  • pre retinal haemorrhage
48
Q

DIURNAL IOP VARIATION

A

higher IOPs in the morning

diurnal variation usually 4-5mmHg

49
Q

ARMY/ NAVY/ PILOT COLOUR VISION

A

army - ishihara test pass is 2 or less on screening plates

navy - impaired CV = restricted branches

pilot - pass first 15 plates (random order) without error or further CV testing required

50
Q

POLICE/ ELECTRICIAN COLOUR VISION

A

police - mild anomalous trichromat acceptable

electrical engineer - some companies allow no more than 2 errors on ishihara

51
Q

how common is congenital CVD?

A

1 in 12 males (~8%) and 1 in 200 females (~0.5%)

52
Q

congenital CVD

A

caused by variants in genes on X chromosome (male XY, female XX)

one altered copy of the gene is sufficient to cause CVD whereas female variant must occur in both copies of gene to cause CVD

fathered cannot pass X-linked recessive conditions to their sons

53
Q

CCTV

A

closed circuit television

54
Q

EVES

A

electronic vision enhancement systems

55
Q

AMBLYOPIA CAUSES

A
  • stimulus deprivation (ptosis, cataract)
  • strabismus (manifest)
  • anisometropia
  • ametropia (high degrees)
  • meridional (uncorrected astigmatism)
56
Q

amblyopia mechanisms

A

light deprivation - no stimulus to retina

form deprivation - retina received defocused image

abnormal binocular interaction - non-fusible images on foveae

57
Q

prisms for heterotropia

A

only prescribed when px symptomatic

long term solution when stable angle of deviation - prescribe smallest amount that relives symptoms

58
Q

sheards criterion

A

is more than half fusional reserves need to be used to control the phoria then visual system will be under stress and phoria decompensates - manifest

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