A new analysis of 1880 eyes from patients with glaucoma or ocular hypertension compared two versions of the common eye drop latanoprost: one with preservatives and one without.
The study found that at 2 weeks, the preserved version lowered eye pressure slightly more (by about 0.43 mm Hg on average). But by 4, 6, and 12 weeks, there was no meaningful difference between the two in how well they controlled eye pressure.
The preservative-free version had a clear advantage in side effects. It lowered the risk of ocular surface hyperemia (eye redness) by 34% compared with the preserved version. The risk of other eye-related side effects was also lower, though that difference did not reach statistical significance.
The evidence is considered low to moderate certainty, meaning more research could change these findings. For people who have trouble with preservatives in eye drops, the preservative-free option appears to be a safe and effective alternative that may cause less eye redness.
