Hirschberg TEST - Lecture notes 1-3 PDF

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this are the notes that explain the purpose of Hirschberg test and the procedures...

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HIRSCHBERG TEST

INTRODUCTION AND BACKGROUND

The purpose of Hirschberg is to determine the approximate positions of the visual axes of the two eyes under binocular conditions at near. This test is used to identify a strabismus when other more precise methods cannot be used.

Alignment of the eyes during the early years of life is considered critical for development of binocular vision. Amblyopia is a condition that occurs when there is altered visual input or abnormal binocular interaction resulting in diminished vision in one or both eyes.

Amblyopia is unique to children but is preventable if the child receives adequate treatment in childhood. The prevalence of amblyopia is approximately 1% - 4% of preschool children. Strabismus is the most common cause of amblyopia and is the term used to describe any anomaly of ocular alignment. It can occur in one or both eyes and in any direction.

The Corneal Light Reflex test (otherwise known as the Hirschberg Test) is used to detect strabismus. In a young baby both the accommodation and convergence systems are still developing which may cause the Corneal Light Reflex (CLR) to appear intermittently asymmetrical up to three months of age.

Overall vision development is said to be complete by the time the child is eight years of age, however some aspects of visual development will already be complete by the time the child reaches school age. The available evidence suggests that vision screening programs aimed at children aged 18 months to five years of age lead to improved visual outcomes. The CLR Test forms part of the overall vision assessment along with the Cover Test (CT) and testing for visual acuity, as age appropriate.

Procedure 1. Engagement and consent Explain the Encourage parent/caregiver to support procedure

to

the

parent/caregiver

if

sufficient

for

time

child, present.

and and be involved with the procedure if Allow appropriate.

discussion

of

concerns.

2. Preparation 



be at approximately the same

Sit the child comfortably on the

height and square on.

parent/caregiver's lap. An older 

child may prefer to stand. 

you are at the correct distance.

at the same height and square 

aware

of

normal

accommodation if the light is

Observe the child’s eyes, head

closer than 30cm.

posture and alignment while child 

is in a relaxed state.

Be

convergence of eyes due to

– 50 cm away from the child). 

Make sure that both eyes are in the sphere of the light to ensure

Position of examiner should be

on and about an arm’s length (30

The child and examiner should

Ensure room lighting is not too bright (Preferably dim), as this may

confound

results

(for

example if testing is done in a school library with all lights on). 

Note any abnormalities with the child’s eyes including the size and symmetry of pupils.



Abnormal head posturing may

indicate a visual difficulty The object used to attract child’s

3. Testing strategies

attention must remain still. The child 

The examiner should attract the needs to look toward the light or toy to child's

attention

to

the

pen achieve the measurement. A normal

torchlight by holding a small toy light reflex is slightly towards the nose on top of the torch.

and not central, due to the position of



The light is shone into the child’s the maculae in the retina. In some eyes and the position of the light young children, a wide, flat nasal bridge reflections is observed on the with prominent epicanthal folds gives cornea.



the eyes a crossed appearance. These

It is important to identify the are false squints and are not evidence location of the light reflexes from of strabismus. the centre of the pupil: o where the position of the Divergent squint: the light reflection is reflection of the light in positioned medially. both eyes is symmetrical

Convergent squint: the light reflection is

and located just slightly positioned laterally. nasal to the centre of the pupil, the Hirschberg Test is

negative

and

no

strabismus is present. o where the light reflections are positioned asymmetrically the Hirschberg test is positive and strabismus is suspected. 4. Explain results to parent/caregiver (if

present)

or

inform

parent

by

telephone or in writing. 5. Documentation

With Asymmetrical, record the eye that

Documentation of CLR should identify if is deviated, the size of the deviation, the reflexes are: Symmetrical/ortho Asymmetrical.

and the direction of the deviation.

BRUCKNER TEST

Bruckner test is vital for early detection of refractive errors especially in children. It uses the transmission of light from an ophthalmoscope through the eye which reflects off the ocular fundus and transmitted back through the ophthalmoscope and imaged in the eye of the examiner as red reflex. An abnormal red reflex may be present in corneal or vitreous opacities, foreign bodies, iris abnormalities, cataracts, retinal abnormalities or tumors, refractive errors and strabismus. Emmetropic eyes reveal a homogeneous red reflex that fills the pupil whereas inferior crescent is present in patients with myopia, superior crescent in patients with hyperopia, any asymmetry of the reflex indicates anisometropia.

Significant refractive errors are the most prevalent and treatable vision problems in children and presence of uncorrected refractive errors may be difficult to identify in young children. The American Academy of Pediatrics currently recommends red reflex assessment as a component of the eye evaluation in the neonatal period and during all subsequent routine health supervision visits. Refractive error requires detection and treatment in the form of glasses, contact lenses or refractive surgery.

Bruckner test is very useful and highly accurate for rapid screening of refractive errors in children including myopia, hyperopia and anisometropia.

It is easy to

perform. It needs a direct ophthalmoscope and it can be performed in less than 15 seconds. However, Bruckner test has certain limitations, as it is observer dependant; there are variations in observation by different observers. If the child is unable to follow the command to see a distant object, the size of pupil may be too small to comment on the presence and size of the crescent....