opthalmology Flashcards
What is myopia
near sightedness
Imagine is projected infront of the retina
what kind of lens corrects myopia
concave
What is hypermetropia
farsightedness
image is focussed behind the retina
what kind of lens corrects hypermetropia
convex
What is astigmatism
rugby shaped causing distortion of light causing loss of visual clarity
What kind of lens corrects astigmatism
cylindrical
What is presbyopia
stiffening of the lens from 4th decade effecting accomodation and near vision
What is esotropia
inward deviation
What is exotropia
outward deviation
What is hypertropia
upward deviation
What is hypotropia
inward deviation
Third nerve palsy
down and out
fourth nerve palsy
up and out
6th nerve palsy
medial
What is strabismus
one eye is misaligned with the other
affects 1 in 20 children
When is strabismus normal
under 3 months before normal binocular co-ordination develops
What is a pseudo squint
a broad nasal bridge can give the appearance of a squint however on testing the child does not have strabismus
What is concomitant strabismus
degree of deviation does not vary with gaze as it’s a the balance between two muscles has been lost and not that there is paralysis or limitation of a muscle
What is a nonconcomitant strabismus
Degree of deviation varies with gaze suggesting a neurological or muscular disease causing paresis or paralysis of the extra-ocular muscles
What is a latent strabismus
present only when the use of both eyes is interrupted by covering one eye
What is a manifest strabismus
present when both eyes are being used so when one eye views the object of interest the other is deviated. can be constant or intermittent
What strabismus’ give rise to concern about underlying concern
constant unilateral exotropias any acquired incomitant squint late onset (>3-4yrs) esotropia
What is the most common childhood strabismus
accomodative estropia commonly seen in hypermetropia
What is ptosis
lowering of upper eyelid (levator muscle)
Causes of congenital ptosis
- congenital disinsertion of the levator muscle
- Marcus0Gunn ptosis
Common causes of third nerve palsy in children
trauma - head injury meningitis tumour causing compression raised ICP neurovascular compromise
What is the most common childhood strabismus
accomodative estropia commonly seen in hypermetropia
What is ptosis
lowering of upper eyelid (levator muscle)
Causes of congenital ptosis
- congenital disinsertion of the levator muscle
- Marcus0Gunn ptosis
Common causes of third nerve palsy in children
trauma - head injury meningitis tumour causing compression raised ICP neurovascular compromise
