Is homatropine 5% effective in reducing pain associated with corneal abrasion when compared with placebo? A randomized controlled trial.

To compare the change in visual analogue scale (VAS) pain ratings over 24 h following mechanical corneal abrasion between patients receiving sixth hourly drops of either 5% homatropine or placebo. A triple blind randomized controlled trial was conducted on a convenience sample of eligible consenting adults who were randomized to receive either sixth hourly 5% homatropine (active) or 0.5% hypromellose (placebo) eye drops. VAS pain ratings were performed at 0, 6, 12, 18 and 24 h whereas the study drug was instilled at 0, 6, 12 and 18 h. The primary outcome was attainment of a clinically significant reduction in pain on the VAS (>20 mm decrease) from enrolment to each time point. There were no significant differences in baseline variables or VAS pain ratings at any time point between those in the homatropine (n= 20) and placebo (n= 20) groups. The percentages of patients reporting a >20 mm VAS decrease at 12 h were 50% (95% CI -27.2-72.8) and 60% (95% CI -36.1-80.9) for the homatropine and placebo groups, respectively. We found no significant difference in pain score reductions between the two groups but some level of therapeutic benefit is not excluded.