Orthokeratology is a method of changing refraction in myopic patients by using rigid contact lenses to reduce the curvature of the cornea. This treatment was in use in the two cases of corneal ulcer described in this paper and appears to have contributed to the development of their disease. As with extended wear contact lenses, patients undergoing orthokeratology treatment are frequently advised to wear the orthokeratology lenses overnight increasing the risk of corneal ulceration and infection. Patients should be adequately warned of the associated risks and advised that any envisaged benefits of the procedure are temporary.

Corneal crystals may be the initial presentation in a patient with monoclonal gammopathy, a rare, but significant, clinical finding.