4- Ophthalmology (Chilhood orthoptic conditions) Flashcards
Childhood orthoptic conditions
- Strabismus
- Amblyopia
orthoptic assessment in children
Vision testing
- visual acuity
- colour
- classification of squint e.g. cover tests
Cycloplegic refraction (used in children because can’t give accurate answers)
- Cyclopentolate and Tropicamide are drugs used to induce relaxation of the accommodation (focusing) system and mydriasis (pupil dilation) to allow for objective measurement of refractive error.
Fundus and media examination
- to ensure strabismus is not a result of eye pathology e.g. cataracts, retinoblastoma
Visual development
- The visual system at birth is immature.
- The eyes of a full term infant are relatively well developed compared to other organs. The axial length is less than an adult; the retina is fully differentiated but the fovea not fully developed until 4-6 months of age.
- The development of normal vision depends on normal anatomical development and on an adequate stimulus.
- The visual cortex remains plastic up to approximately age 7-9.
strabismus and amblyopia are
not the same thing
describe strabismus
Strabismus is a problem with eye alignment, in which both eyes do not look at the same place at the same time
describe amblyopia
Amblyopia is a problem with visual acuity or eyesight (usually in one eye, but can be bilateral)
how are strabismus and amblyopia related
- Strabismus is the most common cause of amblyopia
- Amblyopia caused by poor visual acuity in one eye can cause strabismus
strabismus is also known as
a squint and cross eye
strabismus background
Ophthalmic condition where the eyes do not align properly with each other when focusing to look at an object (poor fusion), which results in the eyes taking different positions, this means the images on the retina do not match and the person will experience double vision
why do children not tend to have double vision if they have congenital strabismus
when strabismus occurs in childhood, before the eyes have fully established their connections with the brain, the brain will cope with misalignment by reducing the signal from the less dominant eye
- This results in one eye they use to see (dominant eye) and one eye they ignore (lazy eye)
- If not treated this lazy eye can become progressively more disconnected from the brain
- This is called amblyiopia
onset of childhood strabismus can be caused by
1) Idiopathic
2) Congenital
- Hydrocephalus
- Cerebral palsy
- SoL
- Trauma
- Prematurity
- Family history
- Refractive error e.g. amblyopia
onset strabismus in adulthood can be caused by
- Cranial nerve palsy (extraocular muscles)
- Intracranial infection
- Intracranial, intraorbital and intraocular masses
- Orbital fracture
- Myasthenia gravis
- Thyroid eye disease
Psuedostrabismus
(false strabismus) is where the eye may appear turned, often in children- but is due to structural causes that resolve over time e.g. broad, flat nose
key definitions to think about with strabismus
- Manifest vs Latent
- Concomitant (non-paralytics) or incomitant (paralytic)
Types of heterptropia
- Esotropia/ esophoria
- Exotropia/ exophoria
- Hypertropia/ hyperphoria
- Hypotropia/ hypophoria
summary of cause and presentations of strabismus - very helpful
manifest squint
Easily discovered on inspection
- presents when the eyes are open and being used
- single- cover test used to determine heterotropia
- can be classified as vertical or horizontal
manifest squints can be classified based on whether they are
horizontal or vertical
latent strabismus (-phoria)
Hidden squint
- the eye only turns when it is covered or shut