This document provides instructions on how to perform an examination of extraocular movements and squint. It describes how to observe eye movements in 9 cardinal positions of gaze, test convergence, and perform saccadic movements. For squint examination, it outlines the cover-uncover test, alternating cover test, and using a prism bar to measure the degree of tropia or phoria. The goal is to detect any deviations, nystagmus, or restrictions in eye movements.

1. Clinical Methods /Extraocular
Movements, Squint
Prof. Dr. Hussain Ahmad Khaqan
 MD
 FRCS(Glasgow)
 FCPS(Ophth.)
 FCPS(Vitreo Retina)
 MHPE (KMU)
 CICO(UK)
 CMT(UOL)
 Fellowship in Medical Retina (LMU, Munich)
 Fellowship in Vitreo Retinal Surgery (LMU, Munich)
 Consultant Ophthalmologist & Retinal Surgeon
Professor of Ophthalmology
Lahore General Hospital, Lahore
Ameer Ud Din Medical College, Lahore
Post Graduate Medical Institute, Lahore
Shaukat Khanum Memorial Cancer Hospital & Research Centre ,Lahore

2. CLINICAL MEHTOD;
EXTRAOCULAR MOVEMENTS

3. EXTRAOCULAR MOVEMENTS Continue
1. Introduce yourself
2. Observe the eyes for any obvious strabismus,
abnormal head posture, ptosis, anisocoria,
heterochromia. Correct any abnormal head posture
immediately.
3. Shine your torchlight onto the patient’s corneas
from about ½ metre away. Observe for tropias.

4. 4. Ascertain that the patient can see the fixation
target. Move the object into the nine cardinal
positions. Hold the object in each position for at
least 5 seconds and observe for:
a. Any obvious deviation
b. Nystagmus
c. Lid/palpebral fissure abnormalities
EXTRAOCULAR MOVEMENTS

5. TIPS
Test horizontal and vertical gaze first. This will
help to differentiate a neurological from
strabismus case.
If there is obvious ocular deviation, ask the
patient if there is diplopia

6. Remember the rule of diplopia:
I. separation of the images is greatest in the
direction in which the weak muscle has its purest
action. For example, right 6th nerve palsy gives the
greatest image separation on right gaze.
II. The false image is displaced furthest in the
direction in which the weak muscle moves the
eye. For example, a right 6th nerve palsy gives rise
to two images on right gaze and the image further
right disappears when the right eye is covered.

7. 5. Test convergence. Move an object from ½ metre
away toward the patient. Normal people will
achieve a near point of 10 cm.
6. Now complete your examination by performing
saccadic movements both horizontally and
vertically. This is done by getting the patient to look
at your fist and then you finger placed apart (first
horizontally and then vertically) and about ½ metre
in front of the patient.

8. CLINICAL METHOD; SQUINT

9. SQUINT
1. Introduce yourself.
2. Look for any obvious tropia and/or head posture. If
the patient wears glasses, determine if these are
plus or minus lenses. Correct any abnormal head
posture immediately.
3. If the patient wears glasses, ask him to take the
glasses off. Check the glasses for presence of, type
and orientation of prisms

10. 4. Shine a torch into the patient’s eyes about ½ metres
away. Observe the corneal reflexes for presence of
tropia. In the presence of an ESOTROPIA, start with
a NEAR target. In the presence of an EXOTROPIA,
start with a DISTANT target.

11. 5. Perform the cover/uncover test for near:
a. Ask the patient to fixate on a near object
(such as reduced Snellen’s chart or picture).
The right eye is completely covered for a few
seconds and the left eye observed closely for
any movement. If fixation is maintained, the
left eye should not move. If fixation is not
maintained, the uncovered eye will move to
take up fixation. The eye will move outwards
in esotropia and move inwards in exotropia.

12. b. Remove the occluder to assess the
recovery of fixation (spontaneous refixation
of right eye or requires the patient to ‘blink’
in order to re-fixate with right eye), or
whether the tropia is freely alternating.
c. Repeat the cover test, but this time only
observing the covered eye for abnormal
movements including dissociated
vertical deviation (DVD) and nystagmus.

13. TIPS:
• For near fixation, you need an object that can stimulate
accommodation eg. Fixation target. Avoid using your
finger or a torchlight.
• Apart from horizontal movements, the eye may show
vertical or cyclo-movements or a combination of both.
Look carefully!
• Manifest latent nystagmus may occur in a patient with
infantile esotropia. This occurs when one eye is
covered. It is jerky and horizontal with the fast phase to
the side of the fixing or uncovered eye.
• Do not forget to observe the covered eye when the
occlude is removed. The presence of a downward
movement may suggest the presence of dissociated
vertical deviation (DVD)

14. 6. Repeat step 5 for the left eye.
7. Perform the alternating cover test for near (33 cm)
if NO tropia is detected. The cover is moved rapidly
from one eye to another several times, allowing
fixation of the unoccluded eye to occur every time.
This causes dissociation and will reveal any latent
strabismus (phoria). The right eye is occluded and
as the occluder is moved to the left eye, any
movement in the right eye is noted. The right eye
will move outwards to take up the fixation in
esophoria and move inwards in exophoria. Observe
the left eye when the occlude is moved from left to
right.

15. TIPS:
• As in step 5, there may be cyclo or vertical
movements.
• The alternating cover test should allow enough time
for the eyes to be dissociated.
• A common mistake is to move the occluder too fast
from one eye to another.
• The alternating cover test is not essential if a tropia is
present. ‘I will perform the alternating cover test
when I am measuring the amount of TOTAL
deviation.’

16. 8. Perform steps 5, 6, and 7 for a target 6 metres away
and in the distance.
9. If the patient wears glasses, repeat steps 5, 6, 7 and
8 with their glasses on.
10. In the presence of a hypertropia, the Parks-
bielchowsky 3-steps test must be performed. An
alternating cover test is performed in primary
position, left/right head turn and left/right heal tilt
in order to identify the underacting muscle.

17. TIPS:
• Always turn or tilt the head to the lower side first,
before comparing the hypertropia during head
turn/tilt to the higher side.
• Increasing hypertropia on head tilt indicates that an
oblique muscle is underacting.
11. Complete the examination with ocular movements.
Looking especially for the presence of a patterns in
patients with eso- or exotropia.

18. COVER TESTS WITH PRISM BAR
This test is usually performed after you have carried
out cover/uncover tests and alternating cover tests.
Cover tests with the prism bar is useful only if a tropia
or phoria has been detected to grade the degree of
tropia or phoria.
1. After you have performed the cover/uncover test and
alternating cover tests you should know if the patient has
one of the followings: esotropia (phoria), exotropia (phoria),
hyper or hypotropia (phoria).
2. Place the compensating prism in front of one eye. Use base
out (BO) prism to compensate for esophoria or tropia; use
base in (BI) prism to compensate for exophoria or tropia
when covering the deviated eye.

19. 3. Using alternate cover test, increase prism strength from zero
until no movement of the eye is noted. Continue with
alternate cover test (ACT), increase prism amount until
opposite movement from initial estimate is just detected ie
Eso-exo or exo-eso (overcorrection deviation). Continue
using alternate cover test (ACT) and reduce prism amount
until same movement as initial estimated is just detected ie
Exo-eso or eso-exo. The compensating prism is the amount
half-way the values that change the direction eye
movement.

20. 4. In the presence of a hyper or hypotropia or phoria. Place the
vertical prism bar in front of either eye. Use base down (BD)
prism over the eye with hypertropia (pjoria) or the base up
(BU) prism over the eye with the hypotropia (phoria). Using
alternate cover test (ACT), increase prism until opposite
movement from initial is just detected ie. Hyper-hypo or
hypo – hyper. Continue using alternate cover test (ACT) and
reduce prism amount until same movement as initial
estimated is just detected ie. Hypo—hyper or hyper –hypo.
The amount of deviation is the amount half way between
the one needed to create opposite movements.