Cornea: Ectasia

Question 1

What is corneal ectasia & give examples?

Answer 1

Abnormal distortion of shape of cornea – normally cornea is nice, smooth dome prolate shaped surface

Keratoconus
Pellucid marginal degeneration
Keratoglobus
Posterior keratoconus
Cornea plana

Question 2

Describe keratoconus?

Answer 2

• Cone shaped cornea
• Light not going to come to a point of focus on retina
• Phenotypical diagnosis – occurs as result of many different genetic abnormalities or environmental factors
• In West of Scotland, most commonly occurs on its own or as result of atopy or as result of habitual eye rubbing
• Take detailed history: ask about family history, history of atopy (hayfever, eczema, allergic eye disease (eye rubbing))
• No matter what you do to help them, if px continues to rub eyes in future, continues to get worse
• Look for:
  o Scissor reflex on retinoscopy
  o Munson’s sign – cone creates a nipple effect on edge of lid
  o Fleischer ring – iron deposit on cone – forms circular brownish arc
• Corneal Topography: increased inferior steepening and increased thinning of cornea
• Acute Hydrops:
  o Cornea becomes so thin that there is rupture of Descemet’s membrane – resulting in rush of fluid into stroma – resulting in cornea becoming oedematous
  o Hazy cornea
  o Eye not red
  o Px may have mild irritation

Question 3

Describe keratoconus management?

Answer 3

• Refer px
• Maximise level of vision
• Pxs vary
  o Some can achieve 6/6 vision w/ glasses
  o Early keratoconus can also be managed using a standard CL
   With time, cornea becomes more distorted and soft CL can also distort the vision
• After a standard CL, consider an RGP lens or a scleral CL
• Eventually, cornea becomes so distorted that not really able to achieve a good level of vision or px becomes intolerant to the CL
• Final option for tx: Corneal transplantation
  o Only if px feels their vision is blurred enough on a day to day basis that they would be happy to take the risk of corneal transplantation
  o If px has 6/6 vision in other eye and even if they cannot get a good level of vision in the keratoconic eye – they may feel it is not bad enough to have an operation
• Halt progression
  o Keratoconus develops more quickly in younger pxs (teens & 20s)
  o Some pxs will not be affected by it
  o Cross-linking: artificially tries to stabilise cornea  only really effective in pxs who know their keratoconus is getting worse (e.g. in 20s or 30s & keratoconus is progressing), no point doing it in someone who is older & keratoconus is likely to have stabilised on its own

Question 4

Describe band keratopathy?

Answer 4

• Calcium deposits underneath epithelium
• Often at periphery but can move to centre
• Can cause epithelium to break down, causing exposure & pain
• Can obscure vision in more severe cases
• Can scrape calcium away
• Can happen for many different reasons
• Most often happens on own or can occur in pxs with dry eye or long-term glaucoma tx
• Can occasionally be associated with systemic parathyroid disease or any calcium metabolism (v rarely)
• Management:
  o Removed through EDT – apply onto cornea & scrape away with scalpel
   Not pleasant & can be sore

Question 5

Describe Salzmann’s Nodular Degeneration?

Answer 5

• Deposition under epithelium
• Often associated with chronic ocular surface disease & dry eye
• Greyish, hazy nodule that are slightly elevated
• If associated with ocular surface inflammation can see corneal vascularisation as well
• Can result in epithelial breakdown because of irregular surface
• Can be scraped off
• Main aim of tx: control inflammation
  o Mild topical steroid and lots of lubrication to improve health of ocular surface

Question 6

Describe penetrating keratoplasty?

Answer 6

• Type of corneal transplant
• Full thickness of cornea is removed – epithelium, stroma, endothelium & is sutured in place
• Vision may not improve in first 6months to 1 year as the stitches take while to heal -> can induce astigmatism
  o May not get 6/6 unaided

Question 7

What are 3 new techniques used for corneal dystrophies?

Answer 7

• Superficial Anterior Lamellar Keratoplasty (SALK) – for conditions affecting epithelium (e.g. Fuch’s dystrophy)
• Deep Anterior Lamellar Keratoplasty (DALK) – if px has healthy endothelium but has problem with stroma e.g. has scar from previous infection or keratoconus having effect on vision then can perform this -> replaces just the anterior layers of cornea
• DSAEK – for conditions affecting endothelium

Question 8

What should you do with a px who has a corneal transplant & develops a red, painful eye?

Answer 8

MUST be seen promptly

Question 9

Describe graft rejection?

Answer 9

• Risk of rejection or infection if had previous infection or if ongoing ocular surface inflammation, risk is less if there is no signs of inflammation e.g. keratoconus
• Any px who has corneal transplant & develops a red, painful eye MUST be seen promptly
• Graft rejection is manageable if treated properly & px will have no long term effects
  o If graft rejection not managed properly then px may need another transplant

Question 10

Describe khoudadoust line (cornea)?

Answer 10

• Type of corneal endothelial rejection
• Separates an area of oedematous cornea from clear cornea
• Best seen with retro illumination