Paediatric ophthalmology Flashcards
What is the definition of amblyopia?
Vision development disorder in which an eye fails to achieve normal visual acuity, even with prescription eyeglasses or contact lenses; begins during infancy and early childhood, usually only one eye is affected
Which age group is amblyopia unique to?
Children
What is a layman’s term often used to describe amblyopia?
Lazy eye
What does amblyopia lead to if untreated?
irreversible permanent reduction in vision of one or both eyes
What can cause amblyopia?
it is a response to anything that has reduced visual stimulation, but may even occur in the absence of any apparent ocular disease
Why did amblyopia develop evolutionarily?
it is an evolutionary adaptation to prevent complications from one poor eye; if cave child born with squint with one eye in the wrong direction, this would result in intractable double vision, which would be dangerous as couldn’t tell if a sabre tooth tiger was real or false. therefore the brain suppresses vision of the squinting eye and makes it amblyopic.
What are 4 types of amblyopia (based on the cause)?
- Strabismic amblyopia (squint i.e. eyes do not align so one becomes lazy)
- Ametropic amblyopia
- Anisometropic amblyopia
- Form-deprivation amblyopias
What is ametropic amblyopia?
occurs due to large uncorrected refractive errors in the patient’s optic system, but both eyes have a similar refractive error. if severe enough, bot eyes can develop a mild amblyopia
What is anisometropic amblyopia?
there is a significant difference in the refractive error between the two eyes; brain ignores eye producing a less focused image on the retina, and amblyopia develops
What is form-deprivation amblyopia?
usually occurs when here is ocular disease e.g. cataract which prevents good vision, so affected eye becomes amblyopic if cataract not removed
What is the sensitive period during which amblyopia begins?
birth to 9 years old
What are 3 treatment options for amblyopia?
- Treat any identifiable cause e.g. remove cataract, glasses
- Patching of good eye forcing child to use poor eye
- atropic drops to blur good eye
What are 4 possible clues in a history of a baby that can suggest clues as to visual potential/ provide rough visual estimates?
- response to a smile (by 2-3 months of age)
- objects to occlusion: if poor vision in one eye won’t object to it being covered; if cover the single one good eye and have completely taken away sight, they will become agitated and unhappy
- objection to bright lights
- startle response to bright light or sudden surprising visual stimulus
What are 2 ways to perform an objective assessment of infant’s vision?
- Preferential looking
2. simple observation
What is meant by preferential looking in an objective assessment of an infant’s vision?
when given a choice, a baby will look at a more interesting target e.g. more interesting striped card than the blank part; the thinner the stripes, the better the baby’s vision (‘Teller cards’)
Cardiff cards similar but use pictures rather than stripes
What is a limitation of the preferential looking method of visual assessment?
may overestimate vision
What are 5 elements of simple observation when performing an objective assessment of a baby’s vision?
- external examination: large congenital squint (strabismus), buphthalmos
- symmetry between two eyes
- red reflex
- pupil responses
- ophthalmoscopy
What is meant by buphthalmos?
when a pliable infant eye enlarges due to high intraocular pressure of congenital glaucoma
What can be a difficulty with trying to find a baby’s red reflex?
can be hard to do due to wriggling etc.
What simple observation can often give the first indication of pathology in baby’s vision/eyes?
pupil responses
What are three important things that ophthalmoscopy in a baby can show?
optic media, retina, optic nerve
What might poor vision in children be a sign of?
may be a presenting feature of sinister systemic cause
What is often required to diagnose a cause of poor vision in children?
specialist examination and investigaiton i.e. often need to refer to specialist paediatric ophthalmologist
Why is rapid treatment key in loss of vision in children?
the earlier it is treated, the higher chance vision will develop normally and the eye won’t become lazy/amblyopic
What is leukocoria?
name given to the white pupil reflex
What is leukocoria caused by?
opacity of any part of ocular media
What is the management pathway for leukocoria?
urgent referral needed (multiple causes)
What is the most common cause of leukocoria in infants?
congenital cataract
When does congenital cataract appear and what can cause it?
Present at birth, may be associated with ocular or systematic disorders
What are 5 systemic disorders that congenital cataract may be associated with?
- Down’s syndrome
- Toxoplasmosis
- Rubella
- Cytomegalovirus
- Herpes simplex
What is the test for leukocoria?
direct ophthalmoscopy
how many babies per year in the UK have leukocoria?
200
What is there a high risk of if leukocoria is not treated early?
irreversible amblyopia (may be dense and difficult to treat)
What is usually the management plan for leukocoria in babies/children?
urgent referral for prompt surgery
What is the commonest tumour in childhood?
retinoblastoma (is cancer)
What proportion of all childhood tumours does retinoblastoma account for?
3%
What is the cure rate like for retinoblastoma?
best cure rate of all childhood cancers: 95-98%
What is the cause of retinoblastoma?
a single defective RB1 gene is passed on to offspring; controls cell cycle and prevents uncontrolled cell division normally. second hit required to mutate the second copy and allow the tumour to grow
What is the role of the RB1 gene?
gene controls cell cycle and prevents uncontrolled cell division
What are 2 aspects of treatment for retinoblastoma?
- systemic chemotherapy
2. local (ocular treatment)
What effects can systemic chemotherapy have on retinoblastomas?
can have dramatic effects, shrinking even large tumours
What are 3 local (ocular) treatments for retinoblastoma? How are these treatments administered?
- laser
- cryotherapy
- radioactive plaque
concurrently used to prevent local recurrent and save eye+vision
What is sometimes a measure required to treat retinoblasotma and why?
can be necessary to remove child’s eye to prevent spread to optic nerve and into CNS
What are 4 important parts of the history for a sticky eye in a children?
- age: conjunctivitis is a medical emergency in neonates
- itchy? scratching/itching can help distinguish allergic frominfectious
- discharge: watery= viral, sticky= bacterial; sometimes, stringy mucoid= allergic conjunctivitis
- associated symptoms: URTI= viral, atopy= allergic
What is the most common cause of red sticky eyes in both adults and children?
bacterial conjunctivitis
Is bacterial conjunctivitis uni or bilateral?
usually unilateral but may spread
What is the discharge like in bacterial conjunctivitis?
pussy
How is bacterial conjunctivitis usually treated?
settles well with topical antibiotics
is viral conjunctivitis uni or bilateral?
usually bilateral
What is the discharge like in viral conjunctivitis?
water
What type of virus usually causes viral conjunctivitis and what is it therefore associated with?
adenovirus; URTI (pre-auricular lymph node enlargement)
What is the management of viral conjunctivitis?
generally little can help, has to run its course; topical lubricants may help to ease discomfort
use of topical steroids up for debate, some advocate use of mild topical steroids but not without risks e.g. dependency –> disease recurs on stopping the drops
Is allergic conjunctivitis uni or bilateral?
usually bilateral
What is the discharge like in allergic conjunctivitis?
stringy mucus
What are 2 associated features of allergic conjunctivitis?
- itchy
2. associated with atopy e..g eczema
What are 2 treatments for allergic conjunctivitis?
- topical antihistamines
2. mast cell stabilisers e.g. olpatidine
What is the severity of allergic conjunctivitis usually like?
usually mild and transient; esvere cases can be life threatening
What is ophthalmia neonatorum?
any conjunctivitis within the first month of life
How common is ophthalmia neonatorum?
common - most common infection in neonates, in 10% of babies
What are the risks of ophthalmia neonatorum?
can be blinding - needs prompt diagnosis and management to prevent
What are the causes of ophthalmia neonatorum and how can they be distinguished? Give 3
Commonly from birth canal. timing of onset provides clues as to possible bug
0-7 days: gonococcus
week 1-2: herpes
days 6-14: chlamydia
What are 3 aspects of management of ophthalmia neonatorum?
- identify organisms: history, culture: conjunctival swabs
- systemic antibiotics e.g. oral erythromycin
- topical antibiotics
What are 3 possible complications of ophthalmia neonatorum?
- corneal ulceration
- corneal perforation
- blindness if not prompty identified/treated
What proportion of blindness in US blind schools in the early part of the 20th century was caused by ophthalmia neonatorum?
25%
Who must be in control of the management of ophthalmia neonatorum? 3 people
- paediatricians
- ophthalmologists
- microbiologists
How common is a blocked tear duct in infants?
Very common: 5%
What is an important cause of a sticky eye to exclude in a suspected blocked tear duct case? How difficult is this?
Exclude conjunctivitis; the difference is often clear-cut
How can you differentiate between a lacrimal duct obstruction and conjunctivitis in a child?
if eye is red and sticky it is likely infection, if sticky but not read it is likely lacrimal duct obstruction
What are 3 initial management steps for lacrimal duct obstruction?
- majority spontaneously settle (>90% will settle before age 1)
- nasolacrimal sac massage
- if doesn’t settle after a year, intervention required: lacrimal probing
What is the treatment of a blocked tear duct with secondary infection?
topical antibiotics: broad spectrum e.g. chloramphenicol
What does nasolacrimal sac massage for a blocked tear duct involve?
Gentle pressure with finger over common canaliculus, stroking downwards firmly to raise pressure in lacrimal sac and encourage opening of valve. Suggest ten strokes, twice daily.
Regular cleaning of discharge from lids
What are 2 types of lacrimal duct obstruction?
congenital and acquired
What is the diagnostic test for congenital lacrimal duct obstruction?
fluorescein disappearance test (drop of fluorescein should disappear from tear meniscus in 5-10 minutes otherwise suggests blockage)
What are the 2 diagnostic tests for acquired lacrimal duct obstruction?
- lacrimal syringing: use anaesthetic and dilate lacrimal duct with punctum, syringe normal saline in via lacrimal cannula. if passes through nose (patient swallows and tastes salt) patent, if resistance and reflux - common canaliculus stenosed, if no passage - complete obstruction
- Jones fluorescein dye test - significant fluorescein remaining in tear meniscus after 2 or more minutes indicates restricted drainage. check nose to see if any passage
What is the intervention required if a blocked tear duct doe not spontaneously settle before 1 year of age?
Lacrimal probing
What does lacrimal probing to treat a blocked tear duct involve?
metal rod passed into nasolacrimal duct to open the valve
What proportion of first procedures of lacrimal probing (to treat a blocked lacrimal duct) is successful?
90%
What is the success rate like (not specific figure) for the second procedure of lacrimal probing if the first fails for treating lacrimal duct obstruction?
still good
In which 2 groups does retinopathy of prematurity occur? i.e. 2 at-risk groups
Babies born before 32 weeks, or those with low birth weight: <1500g
When is screening performed of at-risk babies for retinopathy of prematurity?
screened after birth on neonatal unit and every 1-2 weeks by paediatric ophthalmologist
What is done during screening of at-risk babies for retinopathy of prematurity?
pupils dilated, indirect ophthalmoscopy to examine posterior pole and periphery of retina
What causes retinopathy of prematurity?
O2 therapy causes abnormal retinal vasculature development, as retinal vasculature is not fully developed at birth
What is the normal development of the retinal vessels in babies?
Vasculature normally develops from centre of optic nerve and grows out along surface of retina into peripheral retina
What complications can unchecked retinopathy of prematurity lead to?
- Ischaemia causes abnormal blood vessels to form, which can bleed with subsequent fibrosis.
- Fibrous scarring bands form and pull on the retina causing retinal detachment and blindness
When is treatment of retinopathy of prematurity indicated?
When there is a risk of complications
What is the treatment for retinopathy of prematurity?
Laser therapy to peripheral avascular retina; by photocoagulating peripheral ischaemic retina, ischaemic stimulus to abnormal vessels is removed
Look at a picture of the canaliculi/ lacrimal duct system
superior and inferior canaliculi join to form common canaliculus, leads into lacrimal sac which leads into lacrimal duct
