Impression Cytology Study of Conjunctival Cytotoxicity Caused by Instillation of Low-Dose Mitomycin C

ABSTRACT

We conducted a prospective case-control study to evaluate the conjunctival cytotoxicity of low-dose mitomycin C instillation by impression cytology which was performed preoperatively, postoperative 1 week and 2 weeks in patients undergoing pterygium excision. The case group consisted of 35 patients with postoperative 0.02% topical mitomycin C for 1 week and the control group consisted of 10 patients without postoperative mitomycin C. Impression cytologic findings were graded to 4 scores. Compared to preoperative values there was stastically significant difference in grading scores at postoperative 1 week and 2 weeks (P=0.001, 0.0026) between the groups. Within the case group, the grading scores after 1 week were significantly higher than preoperative values (P=0.0001), but grading scores a 2 weeks decreased significantly compared to those at 1 week and the prevalence of grade 2 or more was also decreased from 40% to 20%. The patients over 50 years of age showed significantly higher gading scores than the patients below 50 years of age (P=0.0038) up to 2 weeks within the case group. Our results revealed that the conjunctiva could be damaged by lowdose mitomycin C and this damage may be more severe and persist longer in elderly. This study suggests that the possible conjunctival cyotoxicity should be considered when using topical mitomycin C eyedrops in management of glaucoma.