Orthoptics I - Heterophoria

Define heterophoria

both visual axes are directed towards the fixation point but deviate upon dissociation

What is concomitance?

measurement of deviation similiar in all gaze positions

What is incomitance?

measurement of deviation changes dependent on gaze position

What is often the cause of incomitance?

nerve palsy
mechanical restrictions

What are the types of esophoria?

Convergence excess, divergence weakness, non-specific

What are the types of exophoria?

convergence weakeness, divergence excess, non-specific

What are the types of hyper/hypophoria?

alternating

What are the types of cyclophoria?

incyclo and excyclo

How do we clinically see an esophoria?

outward movement to fix

convergence excess esophoria

esophoria bigger at near

divergence weakness esophoria

esophoria bigger at distance

non-specific esophoria

no diff in size at near and distance

What could a divergence excess esophoria suggest?

6th nerve palsy

How do we clinically see an exophoria?

inward movement to fix

convergence weakness exophoria

exophoria greater at near

divergence excess exophoria

exophoria greater at distance

non-specific exophoria

no diff in near and distance measurements

What may a convergence weakness exophoria indicate?

convergence/accommodation dysfunction

What is DVD?

dissociated vertical deviation

When is a hetereophoria problematic?

when decompensated - poor control resulting in asthenopic symptoms due to effort needed to maintain BSV
- could result in an intermittent heterotropia

What is necessary to maintain a compensated heterophoria?

appropriate fusional amplitude

How do you determinate a decompensated heterophoria?

symptomatic? uncrossed or crossed diplopia
is it monocular
is motor fusion in a normal range

What is the normal horizontal fusion range for near?

35BO - 20BI

What is the normal horizontal fusion range for distance?

15BO - 10BI ish

Medical aetiology of a decompensated heterophoria

poor general health
high blood pressure
diabetes
alcohol/drug use
trauma

Optical aetiology of decompensated heterophoria

uncorrected refractive error
under/overcorrected refractive error
prismatic effect due to ill-fitting glasses
aniseikonia

Occupational aetiology of decompensated heterophoria

prolonged close work
prolonged monocular work

Age-related aetiology of decompensated heterophoria

muscle laxity

Ophthalmic conditions impacting decompensated heterophoria

cataract
glaucoma
AMD
epiretinal membrane

What is the appropriate investigation for a decompensated heterophoria

VA - lower = more chance of decompensation
CT - what is the deviation
OM - comitant?
PCT - size and classification of deviation
History - GH, FH, POH etc
Refraction
Convergence - reduced in exo, increased in eso
Accommodation - same as convergence

How do you manage a decompensated heterophoria?

conservative treatment
- orthoptic exercises for deviations <20D
- prism application
- surgical management

Orthoptic exercises for esophoria

aim to increase negative relative vergence
- distance stereograms
- BI prism

Orthoptic exercises for exophoria

aim to improve positive relative vergence and accommodation/convergence
- pen push up
- jump convergence
- near stereograms
- BO prism