1. An Overview of the Orthoptist Practical Demonstration The Cover Test
Louise.C.Corp
Senior Orthoptist

2. The Role of the Orthoptist
Assess and Manage:
Vision Defects (Amblyopia)
Vision Screening
Defects of Binocular Single Vision (Squint)
Ocular Motility Defects
Low Vision Assessment
Glaucoma Clinics

3. Vision Assessment ‘Hundreds and thousands’ sweet test
Preferential looking with
Cardiff cards

4. At age 3 years (matching tests) At age 2 years (naming pictures)
Kay single picture
Multiple pictures
Sheridan-Gardiner
Sonksen-Silver
At age 3 years (matching tests)
At age 2 years (naming pictures)

5. Expectations of a baby
To be able to fix and follow small toys ( e.g. mobile whilst in their cot), lights.
Respond to facial expression ( e.g. confirmed by baby smiling, laughing, following parents face on movement ).
Baby will attempt to grasp for small toys whilst fixating on them (e.g play frame over the child whilst laying on their back on the floor)
At birth - VA approx 6/240 - Improvement rapid in first 6mths with a slower rate up until 12mths

6. Managing Vision Defects
AMBLYOPIA – “Lazy Eye” – Reduced vision in one or both eyes
Causes – refractive error, squint, stimulus deprivation (ptosis or cataract)
Patches
Atropine Penalisation
Glasses
Blenderm
Optical Penalisation

7. Vision Screening Reception Class (4 - 5yrs)
Vision, Check for Squint, Assess BSV, Ocular Motility
Pass / Fail Criteria
Absentees offered appointment at Community Clinic or re-visit school
Referred to: Orthoptic Clinic, Hospital Optician, Consultant, High street Optician
96% coverage % passed % referred to optician % referred to CRH % referred to community clinic as borderline results % absent but offered test at community clinic close to home

8. Defects of Binocular Single Vision Squints

9. There are two types of Strabismus

10. Manifest Strabismus Also known as HETEROTROPIA
When one eye focuses on an object, one eye deviates away from the object
Squint is caused by failure of two eyes to look at objects in a coordinated manner. Depends on the normal functioning of brain, optic nerve and twelve muscles around our eyes enabling the two images to superimpose on each other and to form a three dimensional image.
HORIZONTAL
VERTICAL
TORSIONAL

11. Horizontal
Convergent - one eye deviates nasally (turns inwards) ESOTROPIA
Divergent - one eye deviates temporally (turns outwards) EXOTROPIA

12. What type of squint do these patients have?
RIGHT CONVERGENT SQUINT
LEFT DIVERGENT SQUINT
Reflex at limbus = 45
Reflex at border of pupil = 15

13. Pseudo-Strabismus Pseudo-Esotropia Pseudo-Exotropia Epicanthic folds
Wide interpupillary distance
Short interpupillary distance

14. Essential Infantile Esotropia
Presents within first 6 months
Signs
Angle large and stable
Nystagmus in some cases
Normal refraction for age
Poor potential for BSV
Amblyopia in about 30%
Cross fixation

15. Constant Exotropia Congenital Sensory
Presents at birth
Disruption of binocular reflexes by
acquired lesions, such as cataract
Large angle
Alternating fixation
Normal refraction for age
Consecutive - follows previous surgery for esotropia

16. The effect of glasses
The effect of accommodation

18. Ocular Motility Defects
Abnormal Eye Movements

19. Third Nerve Palsy THE PATIENT WILL SUFFER DIPLOPIA
Ptosis, mydriasis and cycloplegia
Abduction in primary position
Normal abduction
Intorsion on attempted
downgaze
Limited adduction
Limited elevation
Limited depression
THE PATIENT WILL SUFFER DIPLOPIA

20. Sixth Nerve Palsy Straight in primary position due to partial recovery
Limitation of right abduction and
horizontal diplopia
Normal right adduction

21. NERVE PALSIES (III,IV,VI) Be aware in Children
Present with acute onset Squint
Complaining of Diplopia
Parents notice closing of one eye
Urgent referral
Serious Pathology
More common 6th Nerve Palsy

22. Thyroid Eye Disease Elevation defect - most common
Abduction defect - less common
Depression defect - uncommon
Adduction defect - rare

23. Right Brown`s Syndrome
Normal elevation in
abduction
Straight in primary position
Limited elevation in
adduction
Defect to the Superior Oblique Muscle / Tendon

24. EYE MOVEMENTS PLOTTED USING THE LEES SCREEN
HESS CHART

25. DIPLOPIA HORIZONTAL VERTICAL
MAY REQUIRE THE USE OF FRESNEL PRISMS

26. What to refer to an Orthoptist ??
Yes
Vision concerns – baby not fixing/following small toy / lights
Squint
Ocular Movement concerns
Poor cooperation of patient to ensure no defects
Parental Concern
BE CAREFUL!! No
Family History alone – distant relatives
If ? A squint in a child < 4 months old if obvious squint seen then refer if not ask HV to check at 6mths, if still doubtful then refer

27. Does anyone in the group have a squint?
Let`s find out ???

28. The Cover Test
“An objective dissociation test to elicit the presence of a manifest or latent deviation. It relies upon the observation of the eyes whilst fixation is maintained and each eye is covered and uncovered in turn”.
Firstly, check for a manifest squint before progressing to find a latent squint.

29. Detection of a manifest squint
Ensure patient is looking straight ahead
A light is used initially as the position of corneal reflections may indicate a manifest squint  should be central / symmetrical or both displaced slightly nasal
Hold fixation target on a level with patients eyes at a 1/3m and ask them to look at it
Introduce occluder in front of one eye and watch for any movement of the other eye

30. Continued……………..
If there is no movement, repeat with the occluder in front of the other eye
If no movement visible then the patient DOES NOT have a manifest squint at that fixation distance
Repeat CT at 6m and far distance if necessary

32. Possible findings for Manifest Squint

33. Continued………… Performed at 1/3m, 6m and far distance
Using accommodative/non-accommodative fixation targets
With and without glasses
With or without any Abnormal Head Posture
In 9 positions of gaze if required

34. Detection of a latent squint
Use appropriate accommodative/non-accommodative targets on a level with the patients eyes at 1/3m
Introduce occluder in front of one eye
Observe for any movement of the eye behind the occluder once it is removed
Repeat with other eye
If no movement seen, alternate the occluder from eye to eye (make sure binocularity is avoided)

35. Continued………...
A movement maybe more obvious as alternate eyes are occluded
Size and direction of movement of the occluded eye as it is moved over to the other eye should be noted
Speed at which the eye moves back to the normal position as the occluder is completely removed should be noted (rate of recovery) – indicates strength of BSV or vision level
Repeat at 6m

36. Remember……………. Position of eyes on appearance
Check corneal reflections first
Ensure no manifest deviation present first
Estimate size of deviation (minimal,slight,mod,mkd) and direction of deviation
Fixation targets-light,small picture or toy, 6m picture/object
Can the manifest deviation alternate or hold fixation

37. Louise.C.Corp Orthoptic Dept Calderdale Royal Hospital 01422 222218
Thank you
Louise.C.Corp
Orthoptic Dept
Calderdale Royal Hospital