BVP - Introduction to Clinical Management of Binocular Vision Disorders - Week 5 Flashcards
What is the tradeoff of having a greater vs a smaller binocular field?
The greater the binocular field, the better the stereopsis, but the smaller the peripheral field
The smaller the binocular field, the poorer the stereopsis, but the greater the peripheral field
What 5 sensory input problems can compromise normal binocular vision?
Disease process affecting the retina centrally
Strabismus
Amblyopia
Lack of sensory funsion (idiopathic)
Monocular
What 2 motor output problems can compromise normal binocular vision?
EOM - anatomical/neurological
Poor sensory motor integration
What 3 accommodation vergence problems can compromise normal binocular vision?
Accommodation problem
Vergence problem
Accommodation vergence crosslink problem
When blur stimulates accommodation, what happens as a result and how is this process crosslinked to vergence? what does it eventually result in (2)?
Fast accommodation integration occurs, which is crosslinked with vergence, resulting in a vergence error.
This leads to slow vergence integration and eventually a vergence response.
When disparity stimulates vergence, what happens as a result and how is this process crosslinked to accommodation? what does it eventually result in (2)?
Fast vergence integration occurs, which is crosslinked with accommodation, resulting in a focus error.
This leads to slow accommodation integration and eventually an accommodation response.
What are 5 conditions that can result in unworkable or no binocular vision?
Suppression
ARC
Eccentric fixation
Ambylopia
Visual efficiency problem
Define the following:
Visual integrity
Visual efficiency
Visual information processing
Visual integrity - eye health and visual acuity
Visual efficiency - clear and comfortable vision
Visual information processing - understanding and analysing what we see
List some typical symptoms of BV issues (14).
Headaches associated with near work
Blurred vision
Diplopia
Avoidance of near tasks
Inability to sustain near vision
Difficulty concentrating on near tasks
Symptoms with prolonged near work
Eyestrain or fatigue with near work
Near/distance blur with changing fixation
Words moving or running together
Blinking, tearing, redness
Squinting/rubbing with near work
Poor attention with reading/homework
Loss of place, slow reading speed, using finger to read
Poor reading comprehension, avoiding reading
List three assessments for accommodation.
Posture
Range/amplitude
Facility
List three assessments for vergence.
Posture
Range/amplitude
Facility
List five assessments for binocularity.
Stereopsis
Suppression
Visual acuity differences
Fixation
Diplopia awareness
List three objective tests of binocularity and what they evaluate.
Cover test - evaluates the alignment in all directions of gaze
Hirschberg test - evaluates alignment and estimates the magnitude of any deviation
Oculo-motility - evaluates versions in all directions to rule out any dysfunction of the EOMs
What are some tests to assess stereopsis?
Stereopsis - titmus ( ͡° ͜ʖ ͡°), fly, randot, fly, frisbee
List 4 tests for suppression.
Worth four dot
Diplopia awareness
Prism doubling
Polarised tests
List the four major factors that stimulate accommodation. Name the primary one.
Blur - primary driver
Proximal awareness
Vergence
Tonic accommodation
Define proximal awareness.
Accommodation based on where the object is in space or where one thinks the object is
Define tonic accommodation.
Occurs from theabsence of any of the stimuli above andreflects baseline neural activity
What can night myopia be considered to come from?
Tonic accommodation
Rate the three states of refractive error (including emmtropes) by their amplitude of accommodation, from highest to lowest.
Myopes > emmetropes > hyperopes (after correction)
Do hyperopes need to accommodate more or less through their glasses? What about myopes?
Hyperopes need to accommodate more
Myopes need to accommodate less
How does luminance affect accommodation (dim light specifically)?
In dim light, the accommodative response is reduced relative to the accommodative demand
What neurological deficit can cause an issue with amplitude of accommodation?
Any 3rd nerve deficit
List an objective assessment for accommodation.
MEM retinoscopy
List two subjective assessments for accommodation and what they measure.
NPA - measures range/amplitude
± flippers - measures facility
What three anatomical factors can influence vergence.
Size or shape of the globe
Position of EOM insertion
What neurological factor can influence vergence?
Any lesions affecting innervation of cranial nerves III, IV, VI
What 5 general factors can influence vergence?
Fatigue
Alcohol
Tobacco
Medications
Prism in glasses
What is the tonic state of vergence?
17^ beyond parallel when all innervation to the EOM is cut
Tonic vergence brings it back to parallel or lightly eso in the absence of stimuli
List two objective tests for vergence and what they assess.
Cover test - measures posture
Hirschberg test - measures a decompensated deviation
List three subjective tests for vergence and what they assess.
Phoria - measures posture
Prism flippers - facility
PRC/NRC - measures amplitude
List an objective combined skills test and what it evaluates (2).
NPC
Evaluates ability to maintain alignment and focus at very close range
Measures break point distance
List two subjective combined skills tests and what it evaluates (2).
AC/A
Measures the effect of accommodation on vergence posture
PRA/NRA - measures the range of accommodation binocularly
Is PRA/NRA purely accommodative?
No, because binocularity is involved
What is the normal value for MEM retinoscopy?
0.50 ±0.25 SD lag
What is the normal value for binocular X cyl?
0.50 ±0.50 SD lag
What is the normal value for binocular accommodative facility?
10cpm ±5 SD (8cpm cutoff)
What is the minimum and normal value for NPA?
Minimum - 15 - age/4
Normal - 18- age/3
±2 SD
What is the normal value for near and distance phoria?
Near - 3exo ±3^
Distance - 1exo ±1^
What is the minimum expected for near and distance PRC?
Near/distance - 10/16/10
What is the minimum expected for near and distance NRC?
Near - 10/16/10
Distance -/6/4
What is the normal value for vergence facility?
12BO/3BI
Near - 15cpm
What are the normal values for NRA and PRA?
NRA - +2.50D
PRA - -2.50D
What is the normal value for AC/A?
4^/D ±2 SD
What are the normal values for NPC for adults and children?
Adult - >8cm
Children - >5cm
What is a red flag for accommodative facility?
<6cpm
What is a red flag for accommodation posture?
> +0.75D
What is a red flag for phoria?
> 2 eso
6 exo
What is a red flag for NPC?
> 10cm
What is a red flag for PRA/NRA?
<2.00D
List three characteristic signs of accommodative insufficiency.
High lag
Low amplitude
Poor facility
List three characteristic signs accommodative excess.
Variable VA
No lag or lead
Fails + facility
List three characteristic signs of accommodative spasm.
Reduced VA
Lead
Fails + facility
List two characteristic signs of ill-sustained accommodation.
High variable lag
Slow facility
List two characteristic signs of accommodative in-facility.
Slow facility + and -
List three characteristic signs of convergence insufficiency.
N exo > D
Reduced PRC
Slow BO facility
List three characteristic signs convergence excess.
N eso > D
Reduced NRC
Slow BI facility
List three characteristic signs of divergence insufficiency.
D eso > N
Reduced NRC at D
Distance blur/diplopia
List two characteristic signs divergence excess.
D exo > N
Reduced PRC at D
List the characteristic sign of basic esophoria.
D = N esophoria
List the characteristic sign of basic exophoria.
D = N exophoria
List the characteristic sign of vergence infacility.
Reduced BI/BO facility
