EFFECT OF TIMOLOL WITH AND WITHOUT PRESERVATIVE ON THE BASAL TEAR TURNOVER IN GLAUCOMA

Aims-The purpose of this study was to assess whether the preservative benzalkonium chloride (BAG 0.01%) present in timolol induced a decreas e in basal tear turnover and a deterioration of precorneal tear fim in patients with glaucoma and ocular hypertension using topical timolol. Methods-The basal tear turnover of 20 patients with open angle glauco ma or ocular hypertension was measured by computerised objective fluor ophotometry when using topical timolol preserved with BAC and 2 weeks after changing to topical timolol containing no preservative. Evaluati on of the precorneal tear film was done by measuring the break up time (BUT) before and 2 weeks after changing medication. Results-The tear turnover of the patients before the change was 32% lower than that of healthy controls (mean tear turnover values (SD) (%/min): 10.7 (3.0) a nd 15.6 (5.4), respectively, p<0.0001). A mean increase of 28% (47%) i n the individual tear turnover values was found after the change to th e preservative-free timolol (p=0.04). The BUT values before the change of medication did not differ significantly from those after the chang e (p=0.5) but both values were significantly lower than the values of healthy controls (p=0.009 and p=0.003, respectively). Conclusion-Prese rvative-free timolol solution has a favourable effect on the tear turn over of patients with glaucoma and ocular hypertension in comparison w ith timolol containing BAG. The integrity of the precorneal tear film persisted to be affected when using timolol without BAG. Timolol witho ut preservative can be recommended in those patients who have keratoco njunctivitis sicca or a borderline tear production since BAC may exace rbate a dry eye state.