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Preclinical Optometry > Routine Screening > Flashcards

Routine Screening Flashcards

1
Q

Define heterophoria

A

Fusion free position is different to functional binocular position, therefore lines of sight no longer intersect at fixation target when fusion is eliminated.

Covered eye (CT) turns to regain bifoveal fixation.

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2
Q

Define orthophoria

A

Fusion free position and functional binocular position are identical

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3
Q

Define heterotropia

A

Visual axes do not intersect at fixation point. Axis of normal fixating eye passes through object of interest, but tropic eye does not.

Aka. strabismus
Congenital (poor development; amblyopia) or acquired.
Constant, intermittent, alternating

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4
Q

Unilateral CT

A

Detects oculomotor imbalance (P or T).
D @ 6m; N @ habitual WD (habitual Rx)
Target 1 line above best VA, “clear + single”

Cover placed over 1 eye (≥3s to dissociate fusion)
Tropia if uncovered eye moves to take up fixation

Repeat 3x

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5
Q

Alternating CT

A

Detects magnitude of deviation (P or T)
D @ 6m; N @ habitual WD (habitual Rx)
Target 1 line above best VA, “clear + single”

Cover alternated between eyes (≥1s per eye, ensure no fusion in between)
Phoria if any movement detected in either eye
Px reports if image moving with (exoP) or against (esoP) movement of occluder

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6
Q

Should you do alternating or unilateral CT first?

A

BOTH MUST BE PERFORMED.

Unilateral:

  • potential ocular emergency with sudden onset T
  • impossible to differentiate between T from P if alternating tested first (decompensated P can turn into T)

Alternating:

  • smaller deviations, so easier to see
  • indicates degree of compensation
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7
Q

CT + Prism Bar

A

Record minimum amount of prism required to neutralise movement of phoria/trophia.

Prism placed in front of either eye for P, in front of tropic eye for T.

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8
Q

Maddox Rod

A

Darkened room, fixation light target
Habitual Rx
Uses cylindrical rods of Maddox rod glass to distort retinal image of a point of light to a line
Fusion precluded due to no similar contours
Eyes adopt fusion free position (BE viewing diff images)

Prediction using cyclopean eye - crossed vs. uncrossed diplopia

Troubleshooting:
Unable to see both sim.: suppression, cover each eye, G filter before eye to reduce brightness difference between spot of light and line
Too many lines: scatter of light, choose brightest line
*if too many, unsuitable due to compromised accuracy

Problems: accommodation, peripheral fusion

@N: pen torch @ habitual WD

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9
Q

Von Graefe

A

Dissociating prism in front of 1 eye and Risley prism in front of the other
Target 6/12 line under normal room lights
Typically 6^BU R eye for H deviations and 10^BI L eye for V deviations
‘aligned like buttons on a shirt’ or ‘headlights on a car’

Poorest repeatability

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10
Q

Prentice Card

A

D @ 3m; N @ 33cm

Use of 6^BD in front of RE - blue exoP, yellow esoP

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11
Q

Maddox Wing

A

N only
Dissociation by septum, one eye views tangent scale, other eye sees arrow
Lower scale for cyclodeviations

Cons: scale figures too large to ensure accommodation, therefore may overestimate exo or underestimate eso, peripheral fusion possible

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12
Q

Can Px have a combination of P and T

A

At D or at N: no, they will have one or the other (or neither)

However, can have D tropia and N phoria (or vice versa).

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13
Q

What do we look for in a cover test?

A

Phoria vs. tropia
Direction of deviation
Magnitude of deviation
Speed of recovery of movement (smooth & quick vs. slow & jerky)

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14
Q

Use of bases to correct deviation…

A 
BI = exoP
BO = esoP
BU = lower eye (i.e. BU R/L = L hyperP)
BD = higher eye (i.e. BD R/L = R hyperP)
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15
Q

Normative values for phoria

A

D: 0-2 XP
N: 0-6 XP

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16
Q

Define visual field.

A

The area of one’s surroundings that is visible at one time, with a steadily fixating eye.

Always tested monocularly

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17
Q

Normal VF

A

Sup 60deg
Inf 75 deg
Temp 100deg
Nasal 60deg

18
Q

Amsler grid: indications, setting

A

Indications:

  • useful for central scotoma/metamorphopsia
  • central visual disturbance, unexplained dec. VA, macular pathologies
  • quick, cheap, portable
  • @ 30cm
  • each square subtends 10degrees (grid 1deg)
  • monocular

“Test for central vision. Can you see the central dot, is it clear & single? Whilst looking at the central dot can you see all 4 corners of the big square? Do any of the H/V lines appear blurring, missing, wavy or distorted?”

19
Q

Amsler charts (1-7)

A
  1. Standard chart. Black background, 5mm square white grid, white central fixation target.
  2. Sim. to 1, but has 2 diagonal white lines to assist steady fixation for those with central scotoma
  3. Sim to 1, has red grid. Useful in toxic amblyopias and optic neuritis. Tests for malingerers with R and G filters.
  4. Scattered white dots with central white fixation target, oft. easier for Px to define specific or multiple central scotomas.
  5. White parallel lines only, central white fixation point. Orientation can be adjusted, useful for detection of metamorphopsia.
  6. Sim to 5, black lines on white card with additional lines 0.5deg above & below fixation.
  7. Sim to 1, but with additional 0.5deg in central 8deg. Used for subtle macular disease.
20
Q

Confrontation

A 
MUST BE PERFORMED ON ALL PATIENTS
Testing peripheral vision (30-40deg either side)
Useful for large, absolute scotomas.
9/10 postchiasmal defects
3/10 prechiasmal defects

Mandatory minimum evaluation to ensure Px meets driving licence requirement.

Setting:

  • Eye level @ 75cm (hands 50cm away)
  • Facial amsler first
  • Each Q individually, both hands presented sim.
21
Q

Neglect vs. Extinction

A

Neglect: Px keeps ‘neglecting’ 1Q

Extinction: Px gets correct with individual presentation of that Q

22
Q

Which RS tests are compulsory?

A

VA
Confrontation
Cover test

23
Q

Which RS tests are tested upon indication?

A

Amsler
Red cap testing
Perimetry
Colour vision (if not 1st time presentation)
Stereopsis (if not 1st time presentation)

24
Q

Red cap testing

A

@40cm monocular
Comparison of brightness of red cap (1 to 10) in BE, noting any asymmetry

“Screening of the function of the optic nerve at the back of your eye that allows you to see”

Kinetic VF: tell me as soon as red cap changes colour/disappears
Comparison b/w Q: indicated if asymmetry

25
Q

What is Perimetry? (& what are the indications?)

A

Measures visual function (sensitivity) outside fovea/across the visual field

Indications:

  • glaucoma detection & management
  • imaging of ONH and RNFL
  • detection of neurological disorders + neuroimaging
  • retinal disease
  • allows structural and functional comparison of fundus
  • assessment of visual disability
  • low vision management
  • mobility assessment
  • visual rehab
26
Q

Describe kinetic perimetry.

A

Variable position, constant intensity
Isopters

  1. Bjerrum screen: historic, useful for central scotoma, limited to central 30-50deg, use of 3 targets to fully evaluate scotoma
  2. Goldmann perimeter: 1st standardised perimeter, telescope fixation monitor
  3. Octopus perimeter: full choice of kinetic vectors, 2.5mins full threshold test, automatic eye tracking and fixation control
27
Q

Describe static perimetry.

A

Fixed position, variable intensity (Increment threshold)
Heights measured at specific positions, sensitivity in dB
Performance compared to age-matched normative database

  1. Humphrey VF analyser: 30-1 and 30-2 grid patterns
  2. Medmont VF analyser: radial pattern *nnn, where * =
    - M (macula, 10deg)
    - C (central, 30deg)
    - G (glaucoma, 30 + 50deg nasal)
    - P (peripheral, 50deg)
    - nnn = # of test points
28
Q

Which is better: static or kinetic perimetry and why?

A

Static perimetry

Static perimetry is ideal for measuring the rather flat shape of the central 30° field and is more sensitive than the kinetic method in detecting early visual field loss.

29
Q

Screening vs. threshold static perimetry

A

Screening 2-8 minutes

  • Good: ‘extremely’ elderly, cortical defects, learning/training
  • Bad: early subtle defects, diagnosis, monitoring progression

Threshold
SITA standard - 4min normal / 8 min glaucoma
SITA fast - 3min normal / 5.5 min glaucoma
- Must: confirming defect, monitoring for stability or progression
- Unsuitable: limited attn spans, disabled

30
Q

What is NPC?

A

Measure of the relative position of the visual axes when they intersect at a near point of regard
- accom/vergence interplay
“how well you can bring your eyes inward when you are reading”

Target: 1 line above BCVA + clear & single
Start at habitual WD, move inwards sl. depressed
Break = sustained diplopia
Measure break and recovery

Normal: 6/8cm (habitual Rx)
Repeat 2x

31
Q

NPA

A

Focusing power of eye, monocular
Target: 1 line above BCVA + clear & single
Start at habitual WD
SUSTAINED BLUR

Normal: 15-1/4age (D) (habitual Rx)
Repeat 2x

Uncorrected myopes give falsely high reading
Uncorrected hyperopes give falsely low readings

32
Q

Stereopsis

  • anatomical & physiological requirements
  • test setting
  • normative values
A

Quality of BV
3 anatomical & physiological requirements:
- large bino overlap of VFs
- partial decussation of afferent n’ fibres
- coordinated conjugate EMs

@40cm, binocular, polarised glasses
Global (random dot/fly) & local (contours)
Suppression (R + L)
Different tests have disadv & adv.

≤ 40” of arc: any ocular misalignment not larger than PFA
60” of arc: still within normal limits
> 60” of arc: must determine if accurate bifoveal fixation is still present?

33
Q

Pupils testing

A

Observe size, shape and reactivity of pupils to light and near stimuli
Distant non accom target, no Rx

Tests integrity of iris, optic n’, post. visual pathways, CN3, afferent & efferent pathways

Afferent: RAPD
Efferent defect: anisocoria (DIMSIM)

Normal 2-4mm bright, 4-8mm dim
Smaller pupils with age

34
Q

Colour vision

A

@75cm, normal room lights
No more than 3s per plate
Congenital vs. acquired (difference in severity b/w eyes)
Can indicate ocular pathologies due to drugs/toxicity

Normal 15/15 plates, more than 2 errors = fail
Binocular for screening (/15), monocular for diagnostic (/17)

35
Q

Lid position

A

Evaluation of ptosis
Congenital vs. acquired

Using corneal reflex to observe palpebral fissure aperture, marginal reflex distances, levator function and lid crease

36
Q

Ocular motility

A

Determine if muscle action is normal
Observe any head tilt, pain, DV
@40cm, habitual Rx
9 positions of gaze evaluated

37
Q

What is a REE?

A

Routine eye examination is a comprehensive eye exam that examines the principal aspects of a patient’s vision, including refractive status, binocular vision and eye and systemic health.

38
Q

What factors may alter a REE?

A

Patient age
History
LEE, was it done by yourself?
Prevalence of condition and value of early detection
Education (ie. dilation, use of OCT)
Peers (how REE is performed by fellow optometrists)

39
Q

What are the AOA competency standards for a REE?

A

Examination plan based on Px Hx (info for diagnosis and management)
Suitability
Consideration of Px abilities
Selection of tests that investigate PC
Tests targeted towards Px known conditions
Selection of tests relevant to Px, not nec. indicated by Hx

40
Q

What is an appropriate basic sequence of optometric tests?

A
  1. Hx + general observation
  2. VA + PD

Preliminary testing that rules out anything sinister that would otherwise be missed.

  1. CT / ocular motility / confrontation (facial amsler)
  2. NPA & NPC
  3. Stereopsis
  4. CV
  5. Pupils testing
  6. Refraction (if not cataract/opacities)
  7. BV and accommodation if appropriate
  8. Ocular health assessment (ant + post)
  9. Supplementary testing (OCT, VF, CCT, tonometry, CSF, keratometry/topography, gonio)
  10. Management - @min, a discussion of what you’ve done

Preclinical Optometry (14 decks)

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