Quantitative analysis of eyelash lengthening following topical latanoprost therapy

BACKGROUND: There have been several reports, mostly qualitative, of ocular side effects of latanoprost, including lengthening of eyelashes. We investigated changes in eyelash length in patients receiving topically administered latanoprost. METHODS: Seventeen patients (11 men and 6 women aged 63 to 80 years) with glaucoma or ocular hypertension were treated with latanoprost (one drop to one eye daily at bedtime). All had dark brown irises. At the start of treatment and after 2, 6 and 10 weeks of treatment, a single eyelash was removed from the centre of the upper eyelid of the treated and fellow (control) eyes and measured. Adverse events (defined as any undesirable event occurring in a subject, regardless of whether it was considered related to the latanoprost treatment) were monitored carefully. At each examination patients were asked whether they had any ocular or systemic symptoms. RESULTS: For the eyes treated with latanoprost, the mean eyelash length (and standard deviation) was 5.8 mm (0.7 mm) at baseline, 6.5 mm (0.6 mm) at 2 weeks, 6.5 mm (0.9 mm) at 6 weeks and 6.6 mm (0.7 mm) at 10 weeks (p < 0.001 for all differences from baseline). The corresponding values for the untreated eyes were 5.7 mm (0.7 mm), 5.8 mm (0.7 mm), 5.9 mm (0.7 mm) and 5.6 mm (0.7 mm); all differences were nonsignificant. INTERPRETATION: Latanoprost significantly increases eyelash length.