keratoconus Flashcards
what is keratoconus?
corneal thinning that leads to a protrusion in the form of a cone
onset?
usually in teenage years
is keratoconus sex linked?
no
is keratoconus genetic or sporadic?
can be - autosomal dominant inheritance
BUT most commonly sporadic
how do you know if someone has keratoconus?
spherical over refraction pr x-cyl doesn’t get the vision better
if pinhole improves the vision, what pathology does that exclude?
media opacities
retinal problems
neurological problems
name some corneal signs of KC?
Vogt’s striae
fleischer’s ring
apical scarring
munson’s sign
What is this?
vogt’s striae
What is this?
fleischer’s ring
What is this?
Apical scarring
What is this?
Munson’s sign
does slit lamp examination exclude KC? and explain?
no - early KC patients often dont show signs on slit lamp
what does keratometry show in a KC pateitn?
egg-shaped mires
does keratometry exclude KC?
no - only shows central 3mm of cornea therefore this area may or may not be distored
what does retinoscopy show in a KC px?
scissor reflex , not possible to fully neutralise
what does topography show you in a KC px?
usually inferior steepening
flattening in the opposite meridian
what are the different types of cones?
- central
- oval
- inferior
- superior (rare)
how does the type of cone affect vision?
quality of vision will depend on how close the cone is to the visual axis
which type of cone allows the px to see well?
inferior
what happens with the px post-referral?
topography with ophthalmologist
may carry out OCT and pachymetry
may revommend cross linking if the px is progressing
what is the aim of collagen cross linking?
stabilise KC
when should you do cross linking?
early in the disease before cornea becomes too thin
explain the procedure of cross linking?
topical anaesthetic
epithelium is abraded with a blunt spatula
riboflavin eyedrops are applied and cornea is exposed to UVA radiation
will the px need correction after collagen corss-linking?
if they needed it before they will need it after but will often need re fitting as the cross linking can flatten the corneal curvature
