The effects of long-term topical glaucoma medication on conjunctival impression cytology

Long-term use of topical drugs can induce changes in the conjunctiva and ocular surface. To determine the conjunctival changes resulting from topical glaucoma medication, patients with glaucoma were selected and classified into seven groups, according to the medication received: 24 eyes were treated with betaxolol, 20 eyes with levobunolol, 32 eyes with timolol maleate, 22 eyes with pilocarpine, 52 eyes with beta-blocker and pilocarpine, 34 eyes with beta-blocker and dipivefrin, and 32 eyes with maximum therapy. Patients who were under 18 were excluded, as were those with any history of ocular surgery and other interventions, long-term use of any topically administered medication except glaucoma drugs, and any history or slit-lamp examination evidence of ocular surface disorders. The changes in the conjunctiva of 216 eyes were evaluated by means of ocular surface impression cytology. The medication group showed statistically significant degrees of conjunctival metaplasia when compared to the control group (p < 0.01). The cytological grading was not correlated with age, sex, type of medication, duration of topical treatment or the number of drugs (p > 0.05). Duration of treatment exceeding three months was not correlated with cytological grading. Thus, as far as surgical treatment was concerned, it was concluded that intervention within the first three months after the diagnosis would be most beneficial in the management of glaucoma. The fact that the presence of the preservative benzalkonium chloride was the same in all preparations suggests that it may be the major factor in conjunctival metaplasia.