Nummular dystrophic calcification of an Ahmed glaucoma valve in a child.

We report the case of an otherwise-healthy 4.5-year-old girl with primary congenital glaucoma who had multiple nummular calcium deposits on the dorsal plate of a previously-implanted Ahmed glaucoma valve. The child had received the implant in the right eye at 6 months of age and developed increased intraocular pressure requiring surgical excision of surrounding fibrous encapsulation. Intraoperative inspection revealed that the dorsal plate surface was covered with multiple white nummular lesions; staining and X-ray microanalysis confirmed the lesions to be calcium deposits. Calcium deposits have been documented for various ophthalmic implants, including silicone scleral buckles and intraocular lenses, but to the best of our knowledge they have not previously been described in association with a glaucoma drainage device.