Ophthalmology

Question 1

Periorbital cellulitis epidemiology and RF?

Answer 1

Ex:

• Mean age of hospitalisation 7-12 years
• When not immunised caused by Haemophilus influenzae (type B) - may also be accompanied by infection at other sites (e.g. meningitis)
• In older children in may spread from paranasal sinus infection or dental abscess.

RF:

• Previous sinus infection
• Not vaccinated for H. influenzae type b

Question 2

Clinical presentation of periorbital cellulitis?

Answer 2

1) Fever with erythema
2) Tenderness and oedema of eyelid
3) ALWAYS (almost) UNILATERAL

Question 3

Ddx and Dx of periorbital cellulitis?

Answer 3

Ddx: Orbital pseudotumour, thyroid eye disease

Dx: Clinical

Question 4

Treatment of periorbital cellulitis?

Answer 4

1) MRSA NOT suspected: Cefazolin IV
2) MRSA suspected: Vancomycin, Cefotaxime, Clindamycin
3) PROMPT treatment required to prevent posterior spread of infection resulting in orbital cellulitis.

Question 5

Presentation of orbital cellulitis?

Answer 5

1) Proptosis, painful or limited Ocular movement and reduced visual acuity
2) Complications: abscess formation, meningitis, cavernous sinus thrombosis
3) CT SCAN WHEN SUSPECTED - assess posterior spread of infection and LP to rule out meningitis

Question 6

What does loss of red reflex, and loss of white reflex in pupil indicate?

Answer 6

Loss of red reflex - cataract

Loss of white reflex - cataract, retinoblastoma, retinopathy of prematurity (ROP)

Question 7

What is Strabismus?

Answer 7

• Squint: Misalignment of the visual axes - person cannot align eyes simultaneously
• Transient misalignment/squint is normal up to 3 months of age - beyond this age refer to specialist

Question 8

Classification of Strabismus (Manifest):

Answer 8

• Strabismus is present all the time:
  1) Esotropia - towards nose
  2) Exotropia - away from nose
  3) Hypotropia - downwards
  4) Hypertropia - upwards

Question 9

Classification of Strabismus (Latent):

Answer 9

• Strabismus is only present when eye is covered/shut:
  1) Esophoria - will deviate towards nose when covered but deviate away when uncovered
  2) Exophoria - will deviate away from nose when covered but deviate nasally when uncovered
  3) Hypophoria - will deviate downwards when covered but upwards when uncovered
  4) Hyperphoria - will deviate upwards when covered but back down when uncovered
  (When you uncover in latent strabismus you see recovery of eye, the actual strabismus is the opposite of what you see when uncovered)

Question 10

Causes of pseudostrabismus?

Answer 10

1) Wide epicanthic folds give appearance of squint towards nose - but corneal reflections show they are normal
2) Unilateral ptosis
3) Facial asymmetry
4) Deep set or prominent eyes

Question 11

Paralytic Strabismus (RARE) info?

Answer 11

• Strabismus varies with gaze direction due to paralysis of motor nerves.
• Can be sinister due to possibility of space occupying lesion.
• Diplopia is most on looking in the direction of pull of the paralysed muscle.

Question 12

3rd nerve palsy (Oculomotor) in paralytic strabismus?

Answer 12

1) Ptosis, proptosis (protrusion of eye since muscles lose tone), fixed pupil dilation
2) Eye looking DOWN and OUT
Causes: Cavernous sinus lesion, diabetes, posterior communicating artery aneurysm.

Question 13

4th nerve palsy (Trochlear) in paralytic strabismus?

Answer 13

SUPERIOR OBLIQUE
1) Diplopia, head tilted
2) Eye looking UP and IN
Causes: Trauma, diabetes, tumour

Question 14

6th nerve palsy (Abducens) in paralytic strabismus?

Answer 14

LATERAL RECTUS
1) Diplopia
2) Eyes looking IN - cannot move laterally
Causes: Tumour, trauma, MS

Question 15

Aetiology of Strabismus?

Answer 15

• Hereditary - 60% of children affected have a close relative strabismus
• Refractive errors: Uncorrected hypermetropia (Long sighted) - MOST COMMON - Children will try to accommodate esotropically whereby they converge their eyes in order to see better - Strabismus
• Neurological deficits - higher incidence seen in those with cerebral palsy
• Craniofacial synastosis: Premature fusion of the sutures of the skull leading to abnormal shaped skulls which in turn impacts orbit shape and thus ocular muscles resulting in abnormal movement/ cranial nerve palsies.

Question 16

RF of Strabismus?

Answer 16

1) Family History

2) Cerebral palsy, Down syndrome, space-occupying lesion

Question 17

Diagnosis of Strabismus?

Answer 17

1) Unusual to have Acute Onset Strabismus - in these cases urgent neuro referral + look for other neuro signs and symptoms.
2) Corneal light reflex test - Pen torch shone into eyes and reflections observed. Light reflection should appear in the same position in both pupils, if it does not - squint is present. (minor squint difficult to detect)
3) Cover test - When a squint is present and the fixing eye is covered the squinting eye moves to take up fixation.
- Test should be performed with an object near (33cm) and distant (6m) as certain squints are present only at one distance
- To detect manifest strabismus just do cover test on each eye, for latent need to do cover and uncover rapidly to detect.

Question 18

Treatment of Strabismus?

Answer 18

1) Glasses to correct refractive error
2) Orthoptic patch - covering the good eye encourages use of the strabismus eye
3) Surgery: Resection and recessions of rectus muscles
4) Botilinum toxin - paralyses muscles - will need repeat injections due to temporary effects.
Use of surgery/botox not only provides good cosmetic results but also helps with psychosocial problems, anxiety and depression associated with strabismus.

Question 19

Amblyopia brief:

Answer 19

• Affects 2-3% of children
• Defective visual acuity that persists even after correction of refractive error (with glasses) and removal of any pathology (cataract)
• Potentially permanent loss of visual acuity in an eye that has not received a clear image.
• Unilateral in most cases (rarely both)

Question 20

Cause of Amblyopia?

Answer 20

Any interference with visual development can cause amblyopia such as:

1) Strabismus
2) Refractive errors
3) Visual deprivation (ptosis or cataract)

Question 21

Treatment of Amblyopia?

Answer 21

1) All patients should have a refraction (glasses) test and a fundus & media check
2) Refractive adaption - wear glasses for 16-18 weeks
3) Occlusion of the better seeing eye in order to stimulate weaker eye to develop and ensure brain starts using it more.
4) Atropine drops/ointment: alternative to eye patch, drops placed into better seen eye and dilate pupil and paralyse accommodation thereby making vision blurry. This forces use of the weaker eye - without the need for an eye patch (useful in older children)
5) Younger the treatment commences the better the prognosis - after 7 years of age it is unlikely vision will improve with treatment. Longer treatment is delayed less likely it is that normal vision will be obtained.