Corneal scar from previous hydrops

Fleischer's ring (arrowed) around the cone

Vogt's striaes in keratoconus

Enlarged corneal nerves in  keratoconus
This is a favourite corneal case in slit-lamp examination. In early keratoconus, the signs may be subtle. The following 
signs should may you suspect that the patient has keratoconus:
  • presence of periocular eczema or Down's syndrome
  • wearing of hard contact lenses
  • corneal graft in the contralateral eye.
Some candidates have been asked to examine the corneal reflexes with a direct ophthalmoscope, there are often abnromal 
reflexes some of which may resemble subluxation of the lens.

In early cases, the only signs may be thinning of the cornea apex with striation of the stroma and Descemet's membrane 
(Vogt's striaes). There is Fleischer's ring surronding the cone (blue light on the slit-lamp can improve its visualization). The 
corneal nerves are prominent.

In advanced cases, there are cornea scars from previous hydrop.

Other examination:

  • remember to examine the fellow eye which may show a different stage of progression or corneal graft
  • mention tot he examiner that you like to demonstrate the Munson's sign (which is distortion of the lower lid on 

  • down-gaze) and Rizzuti's sign (conical reflection on the nasal cornea when a penlight is shone from the temporal side).
  • look for associated featrues such as Down's syndrome, atopic eczema, connective tissue disorders such as Marfan's 

  • syndrome


1. What is an acute hydrop and is it an indication for urgent corneal graft?

2. What is the histological feature of keratoconus?

3. How would you treat a patient with keratoconus?

4. The following are the corneal topographies of two patients with irregular astigmatism. Which one belongs to the patient with keratoconus and which one to patient with pellucidal marginal degeneration?

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