8.1.4 Manages adult pxs with heterotropia

Question 1

What questions do you ask when px has squint?

Answer 1

• 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?

Question 2

What looking for in cover test?

Answer 2

-size
-eye
-direction

Question 3

Describe fixation disparity?

Answer 3

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.

Question 4

Describe 20^ BO test?

Answer 4

20 PD BO prism is used to test motor fusion as a patient should be able to overcome the
power.
In a patient with binocular vision, you will see:
1. The eye with the prism flick out, then in,
2. The eye without the prism also flick out then back in
3. And the patient reinstates binocular vision.

Question 5

What is the management of squints?

Answer 5

• Fully correct the refractive error with full time glasses wear
  o Eso: +
  o Exo: -
• Prisms for Diplopia
  o Eso: BO
  o Exo: BI
• Refer if sudden onset
• Squint Surgery/Botox
• Monitor

Question 6

Describe maddox rod?

Answer 6

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.

Question 7

Describe maddox wing?

Answer 7

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

Question 8

What are the types of squint surgery? What are the +ves and -ves?

Answer 8

Under General Anaesthetic
o Recession à Weakens the muscle
o Resection à Strengthens the muscle
Benefits
Eyes Aligned for Cosmesis
Eliminates:
* Diplopia
* Eyestrain
* Compensatory Head Postures
* Headaches
Disadvantages
* Post-operative Diplopia
* Loss of BV
* Failure to correct à over/under corrected
* Eye may begin to drift again with time

Question 9

Describe exercises for heterophoria?

Answer 9

For deviations of 15D or less, exercises may be helpful for the patient.
Exercises are the main/better treatment:
* Jump convergence
* Near point convergence à pen to nose
* Voluntary convergence exercises
Pen to Nose
1) Start with pen at 50cm
2) then bring it closer until the patient experiences diplopia/practitioner observes the eyes
diverging
3) The patient should then move the pen away from their eyes until they see a single image
4) Then bring it in close again, & repeat
* This should be performed by the patient for 2 minutes, 5 times a day
Þ The patient must be able to recognise diplopia
Brock String Exercise
1. The patient holds one end of the string to their nose
2. The other end is held away & down slightly
3. The patient must converge onto each bead on the string in turn
4. Once the patient has reached their NPC & can’t converge any further, then they diverge,
following each bead in turn
* This should be conducted for 2 minutes a time, 5 minutes a day
Jump Convergence
Need two targets, one at distance & the other at near
Þ A target with high detail will also stimulate the accommodative response
The patient is asked to jump converge between the two targets
This should be conducted for 2 minutes at a time, 5 times a day