8.1.3 Investigates & manages adult pxs presenting with heterophoria Flashcards
What is heterophoria?
Reason for treating heterophoria – alleviate symptom, prevent phoria from breaking down into
tropia
* Removal of cause of decompensation – long hours of close work, poor illumination or contrast, a sudden increase
in the amount of close work, very close working distance, poor health, poor sensory fusion (unilateral cataract)
* Refractive correction – achieve appropriate levels of accommodation and convergence, Full plus of esophoria and
hyperopia. Near vision tasks more plus in form of add
* Blurring makes fusion more difficult correction of even a small Rx can improve binocular function
* Anisometropia may produce inter ocular differences in accommodation and therefor blurring
* Needs proper balance
What should you ask a px with heterophoria?
- Onset
- FOH – Amblyopia, Strabismus, Hyperopia
- Cause of Tropia – birthing complications, delivery method, prematurity, low birth
weight - Type of Tropia
- Any Treatment? Surgery or Prisms
- Amblyopic?
- Diplopia?
How do you modify Rx to help heterophoria?
o Myopia and SOP – least possible minus for clear distance vision
o Myopia and XOP – Most minus but minimum over correction
o Hyperopia and SOP – Max plus Rx without causing blur
o Hyperopia and XOP – Consider partial correction
o Full Rx can be used in coordination of prism
What do eye exercises do in heterophoria?
if Rx appropriate review in one month if still symptomatic consider orthoptic exercises. 1st line if no
Rx required, re-educate the visual reflexes and acquire proper visual habits. Exercises best for 12-35 year olds,
when symptom marked. Development of fusional reserves and relative accommodation, phoria remains the same
size but it becomes compensated
What is the tx for convergence anomalies?
Insufficiency can be defined as a failure to converge to 6cm or patients who fail
to reach 10cm comfortably and without fatigue. Associated with exophoria at near and asthenopia and diplopia at
near.
o Jump Convergence – two targets are required one at near and the other at distance (at least 3m). Px should
fixate on the near target close to break point of convergence, focus on it maintain single image then swap to
distance target them back to near target ensuring its single and kept clear this should be repeated several
times
o Pen to nose Convergence – Also known as push up exercise. In practice px asked to use a more detailed
target such as a letter on the budgie stick. Px holds the target at arm’s length while fixating slowly move the
target closer at a consistent speed and attempt to maintain binocular single vision. If px reaches a point
where binocular SV cannot be maintained even with effort then move away until made single again. When
binocularity completely fails start from original position. Repeat 3-5 times (1-2 minutes with a break
afterwards
o Dot Card – slim rectangular piece of card with single line in the middle the line carries equal spaced dots
held to px nose at slightly depressed position. Px swaps fixation switching from one dot to the next starting
furthest away slowly moving closer to the eyes maintaining a single image. Once px reach the end begin
again for 3-5 cycles. Px needs appreciation of physiological diplopia dot before and after one being fixed on
will appear double. If this is not the case px is supressing
How do you treat accommodation anaomalies?
Accommodative insufficiency and fatigue are characterised by reduced
amplitude of accommodation in relation to the patients age and signs of fatigue. Treated using jump and push up
exercises
o Jump accommodation – similar to jump convergence essentially using and accommodative target at two
distances except target held at nearest point of blur.
o Accommodative push-up – exercise similar to pen to nose but again using an accommodative target such as
a single word. Can be done monocular or binocular. Once image blurs and cannot be kept clear return to
original position and proceed again.
What might be seen in a decompensating heterophoria?
– may be present with intermittent diplopia and cover test is likely to show
Heterophoria at near or distance dependent on type of deviation with poor or delayed recovery. Exercises based
on increasing either fusional amplitudes or fusional vergence
Describe improving fusional amplitude?
- improving fusional amplitude
o XOP condition develop positive fusional amplitude – practice using a base out prism bar and maintaining
single image on distance target for distance XOP or near target for near XOP at point diplopia occurs without
recovery reduce prism to single once more.
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o SOP condition develop negative fusional amplitude - practice using a base in prism bar and maintaining
single image on distance target for distance SOP or near target for near SOP at point diplopia occurs without
recovery reduce prism to single once more
Describe improving fusional vergence?
aim is to manipulate the amount of convergence exerted relative to amount of
accommodation exerted – predetermined by an individual AC/A ratio and amount of convergence increased or
decreased depending.
o XOP conditions increase the positive relative convergence – this is done by carrying out a near stereogram
where the px fixates on a target in front of the stereogram while attempting to fuse the stereogram.
o SOP conditions increase the negative relative convergence – this is done by carrying out a distance
stereogram where the px fixates on a target in distance while attempting to fuse stereogram at near
Describe developing relative accommodation?
o SOP condition develop positive relative accommodation – view small letters at 40cm and add lenses in -
0.25D increment till blurring occurs – Value is PRA
o XOP condition develop negative relative accommodation – view small letters at 40cm and add lenses in
+0.25D increments till blurring occurs – Value is NRA
Describe prescribing prism in heterophoria?
due to age, ill-health, lack of time and type of phoria (hyper/hypo) -Base IN for XOP, Base OUT
for SOP.
o Mallett unit used to determine strength of aligning prism, always less than degree of heterophoria measured
by dissociation can also use the prism which produces a quick and smooth recovery movement to the
alternating CT.
* Prism Adaptation – People with normal BV adapt to prism, people with abnormal BV do not adapt to prism,
adaptation occurs at the distance the prism is not needed
* Referral to another practitioner – More BV expertise, Poorly Px, Pathology or Head trauma, treatment to date has
not work
Describe esophoric conditions and their management?
Most have an accommodative cause (some are non-accommodative)
o Basic - Mixed
o Divergence Weakness – Most often due to uncorrected hyperopia, symptoms associated with distance
vision unless the hyperopia is high, associated with prolonged use of the eyes and will be less or absent in
the morning.
o If persists after refractive correction try physiological exercises, Prism if other treatments fail
o Convergence Excess – Due to accommodative effort, uncorrected hyperopia, latent hyperopia, spasm of
accommodation, psuedomyopia, close working distance
o Normal AC/A is 4:1 when over 6 will result in convergence excess, incipient presbyopia
o Symptoms – Frontal headache, ocular fatigue, distance focus problem after near work
o Unreliable refraction results indicate latent hyperopia as does lower subjective vs retinoscopy
o Management – Eye exercises – development of PRA – use negative sphere while patient maintain clear SV,
relieving prism not appropriate unless AC/A ratio is low.
Describe exophoric conditions and their management?
o Basic and Convergence Weakness – Similar investigation and management
o Hypertonicity of abductors, uncorrected myopia may build false AC relationship
o Symptoms – Less marked in XOP (associated with suppression), Frontal headache with prolonged use of
eyes, ocular fatigue, sometimes intermittent diplopia particular for near vision
o Management – Improve poor working conditions, adequate illumination and contrast, general health,
medication
o Full myopic or absolute hyperopic correction will assist in compensation
o In hyperopic cases, full Rx may make symptoms worse – partial correction, Full Rx with prisms or exercises,
partial Rx with prisms or exercises, Full Rx with negative add
o Eye exercises – develop convergent fusional reserves, develop appreciation of physiological diplopia, treat
any suppression
o Relieving Prism – Simple and effective, aligning prism or CT prism, subjective improvement in near vision,
worse when prism removed.
o Referral – degree of XOP has to be larger than expected due to accuracy of surgery
o Divergence Excess – Large degree of exophoria at distance which may break into a divergent strabismus,
near vision XOP is at least 7pd and is compensated
o Symptoms – intermittent diplopia – family may notice divergence of one eye in bright lights, poor healthy,
alcohol
o Management – Over minus for distance – bifocal to prevent over convergence at near, short term solution
white convergent fusional reserves being built up
Describe fixation disparity?
Objective: to find the minimal prescriptible prism
1. Optimal rx in trial frame (post refraction)
2. Show patient the target and check alignment of strips,
* for horizontal assessment patient should be able to see the see two
vertical strips
* If suppression is present, the patient will only be able to see one strip
(from the good eye) so stop test and record findings
3. Add polarising filter, check which strip can be seen by each eye by occluding the
opposite eye
4. Ask the px “Are the 2 vertical strips in line with the centre of the dot or has one
(or both) moved to the sides?”
5. If misaligned, add small prism to see if markers are coming closer towards the
centre
6. Continue to do so until both markers appear aligned, this is the minimal prism to
correct patient
* If you give too much prism the strips will overshoot to the opposite
direction
* If patient finds strips are jumping or disappearing, reduce amount of prism
and see if it helps.
Describe horizontal and vertical fixation disparity?
Horizontally
If RE sees bottom marker and LE sees top marker:
o If top marker (LE) is to LHS and bottom marker (RE) is to RHS =
uncrossed à SOP deviation so use Base OUT.
o If top marker (LE) is to RHS and bottom marker (RE) is to LHS = crossed
à XOP deviation so use Base IN.
Vertically
* Check each eye to see which strip they can see
* In this example LE sees line at right side, RE sees line at left side
* If line on RHS is higher à Correct with Base UP LE
* If line on RHS is lower à Correct with Base DOWN LE
* If only one marker is deviated, place prism in the affected eye
Describe maddox rod?
Objective: to quantify the distance phoria method:
1. SVD rx in trial frame
2. Place MR in front of RE
3. Grooves placed horizontally (measures horizontal phoria) = appear as a vertical
streak to the patient.
4. Dim room lights and switch on chart spotlight.
5. Px sees a spot light and a vertical red line.
o If only sees one target = suppression.
6. Is the vertical red line to the right, left or straight through the spot?
Þ With SOP the vertical red line appears R of spot (uncrossed images). Add
Base OUT prism until alignment.
Þ With XOP the vertical red line appears L of spot (crossed images). Add
Base IN prism until alignment.
Repeat with MR grooves vertical (measures vertical phoria) = horizontal streak to the
patient.
1. Is the horizontal red line above, below or straight through the spot?
2. With L/R the horizontal red line appears above spot.
3. Add Base DOWN prism to LE (or BU to RE) until alignment.
4. With R/L the horizontal red line appears below spot.
5. Add Base UP prism to LE (or BD to RE) until alignment.
Describe maddox wing?
Objective: quantifies the near phoria Method:
1. Habitual reading rx and near PD
2. Room lights on and use angle-poise lamp to shine close to towards the Maddox
wing targets (arrows, numbers)
3. Look through the horizontal eye slits.
4. Can you see the red and white arrows and numbers?
* If only sees one target = suppression
5. To measure horizontal phoria’s, check which number the white arrow points to
Þ SOP = odd numbers,
Þ XOP = even numbers
6. To measure vertical phoria’s, check which number the red arrow points to
Þ R/L = odd numbers,
Þ L/R = even numbers
