An overview of the orthoptist practical demonstration the cover test
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An Overview of the Orthoptist Practical Demonstration The Cover Test. Louise.C.Corp Senior Orthoptist. 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

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An Overview of the Orthoptist Practical Demonstration The Cover Test

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An Overview of the OrthoptistPractical DemonstrationThe Cover Test

Louise.C.Corp

Senior Orthoptist


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


Vision Assessment

‘Hundreds and thousands’ sweet test

Preferential looking with

Cardiff cards


At age 2 years (naming pictures)

Kay single picture

Multiple pictures

At age 3 years (matching tests)

Sheridan-Gardiner

Sonksen-Silver


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


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


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 83% passed 5.4% referred to optician 4.8% referred to CRH 1% referred to community clinic as borderline results 4% absent but offered test at community clinic close to home


Defects of Binocular Single VisionSquints


There are two types of Strabismus


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


Horizontal

  • Convergent - one eye deviates nasally (turns inwards) ESOTROPIA

  • Divergent - one eye deviates temporally (turns outwards) EXOTROPIA


What type of squint do these patients have?

RIGHT CONVERGENT SQUINT

LEFT DIVERGENT SQUINT

Reflex at limbus = 45

Reflex at border of pupil = 15


Pseudo-Strabismus

Pseudo-Esotropia

Pseudo-Exotropia

  • Epicanthic folds

  • Wide interpupillary distance

  • Short interpupillary distance


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


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


The effect of glasses

The effect of accommodation


Ocular Motility Defects

Abnormal Eye Movements


Third Nerve Palsy

  • 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


Sixth Nerve Palsy

Straight in primary position due to partial

recovery

Limitation of right abduction and

horizontal diplopia

Normal right adduction


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


Thyroid Eye Disease

Elevation defect - most common

Abduction defect - less common

Depression defect - uncommon

Adduction defect - rare


Right Brown`s Syndrome

Normal elevation in

abduction

Straight in primary position

Limited elevation in

adduction

Defect to the Superior Oblique Muscle / Tendon


EYE MOVEMENTS PLOTTED USING THE LEES SCREEN

HESS CHART


DIPLOPIA HORIZONTALVERTICAL

MAY REQUIRE THE USE OF FRESNEL PRISMS


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


Does anyone in the group have a squint?

Let`s find out ???


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.


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


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


Possible findings for Manifest Squint


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


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)


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


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


Thank you

Louise.C.Corp

Orthoptic Dept

Calderdale Royal Hospital

01422 222218


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