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Editor,—To prevent recurrence of pterygia after excision, instillation of 0.04% mitomycin C has been used in Japan and northern America. However, early (less than 14 months) development of serious complications including scleral ulceration has been reported.1-3 Fujitani et alhave reported that corneal perforation developed 33 months after therapy. 1n the present study we report on late complications of mitomycin C treatment.
Four patients were included in this study (Table 1). All patients underwent pterygium excision and postoperative topical instillation of 0.04% mitomycin C four times a day for 2–3 weeks. The patients complained of ocular pain or irritation 18–25 years after treatment. Scleral ulceration with calcified plaque was found. After plaques were removed, uveal tissue bulged, and scleral patch grafts were successfully performed.
A 78 year old woman complained of ocular irritation in the right eye in January 1995. The patient had undergone excision of pterygium in the right eye, and topical instillation of 0.04% mitomycin C four times a day for 2 weeks was administered in 1977 at another eye clinic. Our examination disclosed a visual acuity of right eye 20/20 with correction. Her intraocular pressures were 12 mm Hg in both eyes. A rough surfaced whitish hard plaque, 6 × 4 mm, was seen at the nasal side of the right eye (Fig lA). The conjunctival epithelium was defective and the sclera was thin at the site of the plaque. Wheel-like lenticular opacities were seen bilaterally. Both eyes appeared normal otherwise. Bacterial culture from a scraping sample of the plaque was negative. Laboratory test results including rheumatoid factor were negative or within normal range. On 2 February 1995 the patient underwent excision of the plaque. After the plaque (which was firmly adherent to the underlying sclera) was excised the uveal tissue bulged. A patch graft, 7 × 5 mm, of full thickness sclera, was obtained from an eyebank eye and preserved in 99% ethanol at −20°C rinsed in 0.9% NaCl solution just before use, and secured with l0-0 nylon sutures. Conjunctiva was pulled down over the graft and was sutured with 8-0 polyglactin. The removed plaque stained with alizarin red, suggesting calcification. Thereafter, the patient had no complaints of irritation. Five years later the patient had good visual acuity in both eyes. The scleral graft was covered with conjunctiva in the right eye (Fig 1B).
In our patients, ocular irritation, or pain associated with scleral ulceration with calcified plaque occurred more than 10 years after treatment. To our knowledge, calcified plaque development after simple excision of pterygium is rare. Scleral ulceration with calcified plaque in our patients was quite similar to that reported by Fujitaniet al.4 It is possible that scleral lesions in our patients may be secondary to the topical use of 0.04% mitomycin C. To avoid complications, mitomycin C at a lower concentration should be applied for a shorter period of time, as previously described.5 Recently, mitomycin C has been used as adjunct in trabeculectomy. Eyes treated with mitomycin should be carefully observed for longer than 20 years. We believed that scleral ulceration with calcified plaque following topical mitomycin C instillation could be treated with scleral patch grafting.