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A 48-year-old woman developed a crystalline stromal lesion four years after a penetrating corneal graft, with few signs of ocular inflammation. An initial diagnosis of fungal keratitis was made because of the appearance of the lesion. An excisional biopsy revealed the presence of Gram-positive cocci lying between the stromal lamellae in the posterior third of the cornea. Large numbers of Gram-positive cocci were observed on light and transmission electron microscopy but no organism could be cultured from the biopsy. The replacement graft has remained clear over the subsequent two years.Key words: Infectious crystalline keratopathy, penetrating keratoplasty. Case reportA 48-year-old woman developed an area of white opacity on the edge of a penetrating corneal graft. At the margin of the opacity, delicate crystalline processes extended into clear stroma (Figure 1). The patient had originally had bilateral lens extraction for congenital cataract at the age of 24. She subsequently had bilateral secondary lens implants in 1969 after which both corneas decompensated. In 1983, she had a right corneal graft, vitrectomy and intraocular lens removal following similar successful surgery on the left eye.After four years, during which time she was treated with topical prednisolone phosphate 0.5% between one and four times a day, the continuous suture was removed. Six months later, she presented with a stromal opacity, confined to the corneal graft, associated with delicate crystalline processes extending into the clear surrounding stroma. She was asymptomatic apart from a slight decrease in visual acuity. The epithelium over the opacity was intact and there was no associated limbal injection or anterior chamber activity. Over the next two months, the lesion was observed to increase in size and to begin to encroach on the visual axis. There was an associated decrease in visual acuity.Due to concern about the possibility of fungal keratitis, the confinement of the disease process to the graft, the intact corneal epithelium but steady progression of the lesion, repeat keratoplasty was performed in November 1987. Following the procedure, the patient was treated with topical prednisolone phosphate 0.5% four times per day and a short course of topical chloramphenicolO.5% four times per day. Her graft has since remained clear with less-frequent doses of steroids. There has been no suggestion of recurrence and she retains a corrected visual acuity of 6/9. PathologyThe resected corneal button was bisected, half was submitted for microbiology and the other half for histopathology.