CORNEAL ECTASIA Flashcards
general characteristics for all corneal ectasias?
- bilateral
- asymmetrical thinning
- all cause Hydrops
what is KCN?
- It is non-inflammatory central corneal ectasia resulting in a steepened conical shape.
Onest of KCN?
puberty
what contributes to KCN?
- genetics (AD)
- environment
what is KCN associated with?
- atopy conditions (allergies, dry eye)
- systemic conditions
what systemic conditions are associated with KCN? what is the pneumonic?
TDOME:
* Turner’s syndrome
* Down syndrome
* Osteogenesis imperfecta
* Marfan’s syndrome
* Ehlers Danlos syndrome
what is KCN severeity classification scale?
- Mild - <48D
- Moderate - 48D -54D
- Severe - >54D
what are symptoms of KCN?
- blurry vision
- Monocular diplopia
- Ghost images
- Eye rubbing
- Pain - if hydrops
what are signs of KCN?
- Classic sign of inferior, central or paracentral stromal thinning that is bilateral but asymmetrical.
Early signs:
* Retinoscopy - scissor reflex
* Keratometry - irregular mires
* Topography - inferior, central or paracentral steepening.
* Fleischer ring - best seen w/ cobalt blue filter.
Late signs:
* Vogt’s striae - vertical lines in deep stroma.
* Munson’s signs - lower lid protrusion on downgaze.
* Rizzuti’s sign - conical reflection on the nasal cornea when a light is shown from the temporal side.
* Hydrops - rupture in Descemet’s membrane causing an influx of aqueous into the cornea that results in rapid, painful edema and rupture of epithelium (defect).
* Central corneal scarring.
tx for KCN?
- topical cycloplegic (pain) + Abx (prophylactic) – if acute corneal hydrops.
- Muro 128 ung – for ongoing hydrops
- corneal CXL – to stregthen & slow progression.
- CLs (GP or Scleral) - to correct vision.
- INTACS – supportive measure for cornea.
- corneal transplant (DALK/PK) – in severe cases.
what is pellucid marginal degeneration (PMD)?
- It is progressive thinning that affects the peripheral inferior cornea (1-2mm from the limbus) and leads to corneal protrusion that is superior to the area of thinning.
onset of PMD?
age 20-40
PMD vs KCN?
- PMD has no Fleischer ring, no cone, no Vogt striae.
signs of PMD?
- Thinning 1-2mm from the inferior limbus (4 to 8 o’clock).
- Corneal protrusion above the area of thinning.
- Leads to high ATR astigmatism.
- Topography pattern – “kissing doves,” “crab claw.”
tx for PMD?
- can be managed with glasses or CLs (soft or RGP)
- corneal transplant (DALK/PK – in severe cases
