Ophthalmology - Paeds Flashcards
Define strabismus
Misalignment of eyes - ‘squint’
Define ambylopia
The affected eye becomes passive and has reduced function compared to the other dominant eye (‘lazy eye’)
Define esotropia
Inward positioned squint (affected eye towards the nose)
Define exotropia
outward positioned squint (affected eye towards the ear)
Define hypertropia
upward moving affected eye
Define hypotropia
downward moving affected eye
What is the most common type of squint?
Esotropia (a convergent squint) - the misaligned eye diverges inwards towards the midline
What is the most common cause of strabismus?
Usually idiopathic – no specific underlying cause
Other causes of strabismus?
- Hydrocephalus
- Cerebral palsy
- Space occupying lesions e.g. retinoblastoma
- Trauma
What is the key symptom of strabismus?
Diplopia
What age does treatment for strabismus need to be started before? Why?
Before 8 years old - as up until 8 the visual field are still developing
What are 2 management options for strabismus?
- Occlusive patch over good eye (force weaker eye to develop)
- Atropine drops in the good eye (force weaker eye to develop)
What is the mechanism behind treating strabismus?
Forcing the weaker eye to develop
How do atropine drops work in strabismus?
The purpose of atropine drops is to cause temporary blurred vision in the unaffected eye, thus muting the visual input from the eye to the brain, forcing the deviated eye to focus and therefore align.
What class of drug are atropine drops?
Antimuscarinics
What is ambylopia?
A visual impairment resulting from abnormal visual stimulation during childhood. Also known as a ‘lazy eye’.
What is the most common cause of visual impairment in children?
Ambylopia
How does ambylopia develop?
Occurs 2ary to reduced visual stimulation usually in one eye during the critical years of development, interfering with cortical visual development:
- Squints/strabismus
- Unequal refractive error
- Congenital cataracts
Congenital vs paediatric cataracts?
Congenital - lens opacity which is present at birth
Paediatric - Diagnosed in older babies or children
What are causes of congenital/paediatric cataracts?
- Genetics (FH)
- Conditions e.g. Down’s syndrome
- Infections picked up from mother during pregnancy – chickenpox, cytomegalovirus, herpes, rubella
- Diabetes
- Trauma post-birth
- Drug reactions
Give some complications of congenital/paediatric cataracts
- Lazy eye
- Blindness
What is the red reflex?
This refers to the reddish-orange reflection of light from the back of the eye which is observed when using an ophthalmoscope
how is the red reflex affected in cataracts?
Absent red reflex can result from cataracts
What is retinitis pigmentosa?
A congenital inherited condition where there is degeneration of the rods (responsible for vision at low light levels) and cones (colour vision) in the retina.
Do rods or cones tend to degenerate more in retinitis pigmentosa?
Rods
What tends to be the first presenting symptom in retinitis pigmentosa?
Night blindness tends to be first symptom (i.e. reduced visual acuity in dim light) due to degeneration of rods
Function of rods vs cones?
Rods are responsible for vision at low light levels (scotopic vision). They do not mediate colour vision, and have a low spatial acuity.
Cones are active at higher light levels (photopic vision), are capable of colour vision and are responsible for high spatial acuity.
Describe vision loss in retinitis pigmentosa
Peripheral vision loss then central vision loss – ‘tunnel vision’
Fundoscopy results in retinitis pigmentosa?
- Pigmentation – peripheral ‘bone-spicule’ pigmentation
- Optic disc pallor
- Retinal vessel attenuation (narrowing of arterioles) – mainly thought to reflect decreased metabolic demand of the degenerating retina
What is the most common intraocular tumour of childhood?
Retinoblastoma
What is a retinoblastoma?
Malignant tumour of the retina
What is the defining feature of a retinoblastoma?
leukocoria (white pupil)
Presentation of retinoblastoma?
- Leukocoria (white pupil)
- Deteriorating vision
- Strabismus
- Failure to thrive
- In developing countries, the tumour often presents as eye enlargement
What is keratoconus?
Occurs when the cornea thins and gradually bulges outwards, resulting in loss of vision.
Risk factors for keratoconus?
- FH
- Rubbing eyes vigorously
- Certain conditions e.g. retinitis pigmentosa, Down’s syndrome, Ehlers-Danlos syndrome, hayfever, asthma
Presentation of keratoconus?
- Blurred or distorted vision
- Increased sensitivity to bright light
- Need for frequent changes in eyeglass prescriptions
- Sudden worsening or clouding of vision
