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| CASE REPORT |
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| Year : 1995 | Volume
: 43
| Issue : 2 | Page : 75-76 |
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Scleral changes due to mitomycin C after Pterygium excision: A report of two cases
Shabbir Saifuddin, Alaa El Zawawi
From Department of Ophthalmology, Khorfakkan Hospital, Sharjah, United Arab Emirates
Correspondence Address:
Shabbir Saifuddin
P.O.Box 2896, Dubai, United Arab Emirates
 Source of Support: None, Conflict of Interest: None  | Check |
PMID: 8818315 
How to cite this article:
Saifuddin S, Zawawi AE. Scleral changes due to mitomycin C after Pterygium excision: A report of two cases. Indian J Ophthalmol 1995;43:75-6 |
The use of topical mitomycin C after pterygium excision is becoming popular since its introduction in Japan. With a success rate of 89 to 97%[1][2][3][4] and fewer complications reported,[1],[3] it has become a favoured form of pharmacologic therapy following pterygium surgery.
We report two cases of scleromalacia and scleral calcification which developed more than a year after pterygium excision and topical treatment with mitomycin C.
| Case reports | |  |
| Case 1 | | |
In 1990, a 35-year-old male had a recurrent pterygium excised followed by mitomycin C (0.5 mg/ml) instillation 3 times daily for 15 days. The postoperative course was uneventful until the patient presented 14 months later with severe pain, irritation and redness in the affected eye. He noticed a black spot on the "white of his eye" for the previous one month. Examination showed normal cornea. There was a 7 X 3-mm epithelial scleral defect with 70% thinning with the uveal tissue visible through it. It was associated with superficial neovascularisation [Figure - 1].
The patient was treated with topical lubricants 4 times daily, gentamicin drops 4 times daily, cycloplegic drops twice daily, and analgesics. The patient wa.s referred to another centre for a scleral graft. He refused to undergo the scleral graft operation but agreed to undergo conjunctival autograft. Two weeks later the conjunctival graft retracted, exposing the sclera. A scleral conjunctival autograft surgery from the fellow eye was performed with good postoperative result and relief of symptoms.
| Case 2 | | |
A healthy 52-year-old Japanese male sailor underwent excision of primary pterygium with postoperative application of mitomycin C drops (1 mg/ml) 4 times daily for 5 days and then twice daily for another 5 days in June 1989. There were no reported complications during a two-year follow-up. When seen by us in August 1993, he complained of foreign body sensation accompanied by pain and lacrimation. On examination, a 3 X 3-mm scleral epithelial defect associated with 10% scleral thinning on the medial limbal sclera was evident. Surrounding the lesion was a white, shiny avascular elevated area representing a calcified plaque, which extended almost upto the limbus. There was no evidence of any inflammation [Figure - 2].
The patient was started on treatment with cycloplegics, lubricating drops and ointment (without preservatives), prednisolone-neomycin drops, oral ibuprofen and pressure patch. The patient was seen two days later with reduced symptoms but was subsequently lost to follow-up.
| Discussion | | |
Mitomycin C is an antimetabolite agent produced by a strain of Streptomyces caespinosus. It inhibits synthesis of DNA, RNA and proteins. This drug is referred as "radio-mimetic" as its action mimics that of ionising radiation. Thus, the use of mitomycin C leads to complications such as scleromalacia, scleral ulcer, and cataract, as has been described after pterygium excision and beta-irradiation. Other less common complications are necrotizing scleritis, perforation, iridocyclitis, glaucoma, scleral calcification[1],[2],[4][5][6][7] and lower lacrimal punctal occlusion.[3] Recently, many studies have reported the efficacy of mitomycin C in minimising recurrences of surgically excised pterygia when used as an adjunctive therapy. The method of use and the dosage is not yet standardised but different reports indicate dosages ranging from 0.2 to 1 mg/ml.[2][3][4][5],[8] The lowest possible effective dosage required to prevent recurrence is a single intraoperative subconjunctival injection of 0.1 ml of 0.5 mg/ml (personal communication: Alfred Anduze, St.Croix, USA - based on a short-term pi lot study which needs further investigation). Some investigators have used mitomycin C in the dosage of 0.2 to 0.4 mg/ml and a follow-up for three years has shown a recurrence rate of 6.6 to 13% with
similar complications. [2,8]
Scleral thinning after mitomycin C instillation may be due to suppression of development of collagen fibres in the process of wound healing. It inhibits the formation of granulation tissue and growth of new vessel formation on the wound surface. Hence, scleral thinning indicates a decrease in fibrous connective tissue formation. Although the pathogenesis of scleral calcification is not known, it may represent an extreme form of mitomycin-induced degenerative changes in the tissue.
Based on the findings in the above patients and a few common complications reported in the literature,[1],[5],[6] we alert the surgeons to evaluate the benefits and risks of using this drug. It should never be used in the patients with Sjogren syndrome, atopic keratoconjunctivitis, acne rosacea or in aged patients. It should be used mostly in aggressive or large vascularised pterygia only. It may be used as a 0.5 mg/ml topical solution to be applied with a sponge on the sclera at the time of surgery. The duration of application should never exceed 3 minutes. The above dosage used by us in a pilot study involving 14 patients has shown encouraging results.
There was an interval of more than one year between the surgery and the appearance of complications in both the cases. Because of this latent period between application of the drug and the appearance of deleterious effects, any study on the use of mitomycin C must include a regular and long-term follow-up.
| References | | |
| 1. | Rubinfeld RS, Pfister RR, Stein RM, et al. Serious complications of topical mitomycin C after pterygium surgery. Ophthalmology 92:1647-1654, 1992.  |
| 2. | Singh G, Wilson MR, Foster CS. Mitomycin eyedrops as treatment of pterygium. Ophthalmology 95:813-821, 1988. |
| 3. | Singh G, Wilson MR, Foster CS. Long-term follow-up study of Mitomycin C eyedrops as adjunctive treatment for pterygium and its comparison with conjunctival autograft transplantation. Cornea 9:331-334, 1990. |
| 4. | Chayakul V. Prevention of recurrent pterygium by Mitomycin C. Fortschr Ophthalmol 84:422-424, 1987. |
| 5. | Yamanouchi U, Takaku I, Ysuda N. Scleromalacia presumably due to mitomycin C instillation after pterygium excision. Jpn J Clin Ophthalmol 33:139-144, 1979. |
| 6. | Fukamachi Y, Hikita N. Ocular complication following pterygium operation and instillation of mitomycin C. Folia Ophthalmol Jpn 32:197-201, 1981. |
| 7. | Yamanouchi U, Mishima K. Eye lesions due to mitomycin C instillation after pterygium operation. Folia Ophthalmol Jpn 18:854-861, 1967. |
| 8. | Hayasaka S, Noda S, Yamamoto Y, Setogawa T. Postoperative instillation of low-dose mitomycin C in the treatment of primary pterygium. Am J Ophthalmol 106:715-718, 1988. |
[Figure - 1], [Figure - 2]
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