Source: Hong Kong Med J  |  Posted 6 years ago

By Earl R. Nichols

FT. LAUDERDALE, FL -- May 5, 2005 -- A novel study among glaucoma patients has shown that patients may have different responses to drugs that lower intraocular pressure (IOP) when those drugs are used in opposite eyes - even when used at the same time.

A further finding of the research, presented here May 3[^]rd[] at Association for Research in Vision and Ophthalmology Annual Meeting was that the eyes do not function in tandem, but each eye may respond differently to a particular medication.

The study involved a cohort of 83 glaucoma patients who were treated in one eye with bimatoprost 0.03% daily while in the other eye they were treated with latanoprost 0.005% daily.

This appears to challenge the belief that both eyes respond in concert to any specific drug -- i.e., that if bimatoprost is used in one eye, the second eye would respond with a similar reduction in intraocular pressure.

Dr. Robert Noecker, professor of ophthalmology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States, led a team of researchers who evaluated IOP at baseline and again at 1 and 2 months post-treatment.

The researchers found that after 1 month of treatment, IOP decreased by 26.4% in the latanoprost-treated eye, compared with a decrease of 31.5% from baseline in the bimatoprost-treated eye. This 1.3 mmHg difference was statistically significant (P <.001)

The reductions in IOP after 2 months of treatment also favoured the bimatoprost eye (28.5% vs. 23.4%). This difference was also significant P <.001.

Adverse events, especially conjunctival hyperemia, were more common in the bimatoprost-treated eyes compared to the eyes treated with latanoprost (25% vs. 15%).

Dr. Noecker said this proves what has been suspected for some time; that patients do not respond to all drugs in the same way. For example, almost 60% of patients using bimatoprost had a positive response to therapy compared with 23% of those using latanoprost.

A positive response was defined as a decrease in IOP of at least 20% from baseline. In fact, he added, 16% of patients responded equally well to either drug.

While the difference in responses was small (1.3 mmHg), this could represent an important advantage. A previous well-known study of glaucoma concluded that for every 1 mmHg reduction in IOP, the risk of progressing to glaucomatous damage of the optic nerve is reduced by 10%

[Presentation title: Evaluation of Bimatoprost 0.03% versus Latanoprost 0.005%: A Paired Comparison Study. Poster 2452/B5]