paeds ophthal Flashcards
snellen acuity at birth
6/300
snellen acuity at 12 months
6/24
snellen acuity at 36 months
6/9-6/6
what age can start using snellen chart (6m) to test VA
4 yo and above
visual assessment in preverbal children
- fixation preference
- forced preferential looking (teller cards)
visual assessment in older children
- allen pictures
- kay pictures
- sheridan gardner matching test
- snellen
amblyopia (lazy eye) definition
Unilateral (or rarely bilateral) BOV due to disruption in normal visual development, caused by abnormal visual stimulation during sensitive period of visual development
VA criteria for amblyopia
- Unilateral amblyopia: difference in BCVA is 2 or more Snellen lines between 2 eyes
- Bilateral amblyopia: BCVA of 6/12 or less
pathophysiology of amblyopia
*Development of lateral geniculate nucleus and primary visual cortex is incomplete at birth and persists into postnatal period
*During critical period when there’s plasticity within visual system esp visual cortex, external factors can modify its development
causes of amblyopia
- strabismus (commonest)
- stimulus deprivation
- refractive error (anisometropia (2 eyes diff RE), ammetropia (both eyes deg high), astigmatism)
criteria for anisometropia
any of:
hyperopia > 1.5D
myopia > -3-4D
astigmatism > 1.5D
criteria for ammetropia
hyperopia >5D
myopia <-8D
criteria for astigmatism
> 2.5D
screening for amblyopia
- measure VA
- Holler test - child upset when good eye covered
principles of management for amblyopia
- provide clear retinal image
- correct ocular dominance
- parental counselling
how to provide clear retinal image
*identify and correct RE
*fulltime spectacle wear for refractive amblyopia
how to correct ocular dominance
*occlusion therapy (gold std): patch good eye to force fixation by amblyopic eye
*topical atropine cycloplegic eyedrops in good eye (paralyses accommodation causing blurring in good eye): use amblyopic eye, not useful in dense amblyopia or myopes (near vision preserved even on eyedrops)
when is tx possible for amblyopia
critical period <7-8yo, best time to correct during infancy or early childhood (<4-5 yo)
what is strabismus
ocular misalignment
heterophoria vs heterotropia
heterophoria: latent strabismus, deviation not seen when pt focusing with both eyes
heterotropia: strabismus, deviation seen even when pt using both eyes
assessment for strabismus
- visual acuity
- Hirschberg corneal light reflex
- cover test
- simultaneous red reflex (check ocular alignment)
- extraocular eye movements in all 9 positions of gaze
- stereoacuity (3D vision)
- full eye and neurological examination
complications of strabismus
- amblyopia: squint eye becomes amblyopic (if child develops fixation preference)
- poor binocular vision
- abnormal head posture
comitant vs incomitant strabismus
comitant: non paralytic
incomitant: paralytic (eye movement limited due to EOM paralysis)
management of strabismus
- botulinum toxin injection
- corrective/prism glasses
- strabismus surgery
leukocoria
white pupil or white reflex
urgent referral
abnormal red reflexes
*Absent red reflex/ asymmetry (1 eye no red reflex, other eye RR present)
*White reflex (1 eye white, other eye RR present)
normal RR: both eyes RR present
5 causes of leukocoria
- retinablastoma (most impt TRO)
- congenital cataract
- persistent fetal vasculature / persistent hyperplastic primary vitreous (PHPV) - small eye
- advanced retinopathy of prematurity (with tractional retinal detachment stage IV/V)
- coat’s disease/exudative retinal telangiectasis
retinoblastoma age
before 3yo
inx for retinoblastoma
CT and MRI (CT if only for dx)
mx of retinoblastoma
*Local Tx (e.g. cryotherapy/laser) for small tumours
* Radiotherapy
* Chemotherapy
* Enucleation (eye removed) for very large tumours in eyes of no visual potential
*Intra-arterial chemotherapy
* Screen siblings, genetic counselling
ophthalmia neonatorum time period
first 28 days of life
organisms involved in ON
Neisseria gonorrhea
chlamydia trachomatis serovars D-K
*do conjunctival swab
presentation on ON
- Purulent conjunctivitis
- profuse exudate/discharge
- eyelid swelling
cx of ON
Infection can extend from superficial epithelial layers into subconjunctival connective tissue and cornea –> corneal ulceration, corneal scarring, blindness
mx for ON
- Admit child for observation
- IM ceftriaxone + PO azithromycin for Neisseria, PO erythromycin for Chlamydia
- Treat mother, screen her sexual partners for sexually transmitted diseases and treat
Disseminated disease by organisms causing ON
sepsis, septic arthritis, meningitis