Eyelids & the Anterior Segment:
                     Case thirty six

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This is the right eye of a 25 year-old man who was seen in the eye casualty for an unrelated condition.

a. What does the picture show?

Krukenberg's spindle.
The slit-lamp shows the vertical and central deposition of melanin pigment on the posterior surface of the cornea.

b. What is responsible for this appearance?

The vertical arrangement of the melanin is caused by the aqueous circulation within the anterior chamber. The aqueous humour rises posteriorly due to its proximity to the warm iris but falls anteriorly on contact with the cooler cornea. This downward flow causes sedimentation of particles such as melani in a vertical fashion.

c. What other physical signs would you be looking for in this patient?

Krukenberg's spindle in young persons should prompt a search for pigment dispersion syndrome which typically affect myopic males.
The main signs include:

• mid-periphery iris transillumination
• pigment on the trabecular meshwork (Sampaolesi's line)
• glaucoma

Other signs:

• posterior bowing of the iris at the periphery (seen on ultrasound)

d. What is the differential diagnosis?

Krukenberg's spindle can occur in any conditions where there is release of pigment from the iris.

• pigment dispersion syndrome
• pseudoexfoliation syndrome
• iris melanoma
• trauma
• following cataract surgery