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Verena Juncal, Felipe A Jorge, Augusto Paranhos, Tiago S Prata; The role of the fourth drug in patients with glaucoma: is it worth it?. Invest. Ophthalmol. Vis. Sci. 2014;55(13):542.
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To evaluate how effective is the fourth drug regarding intraocular pressure (IOP) control in patients with primary glaucomas.
We prospectively enrolled consecutive patients with primary glaucomas [primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG)] treated concomitantly with a topical prostaglandin analog, a beta-blocker, an alpha-adrenergic agonist and a carbonic anhydrase inhibitor. Exclusion criteria were: history of ocular trauma or surgical procedures besides cataract extraction or glaucoma surgeries, secondary glaucomas, ocular diseases other than glaucoma and poor treatment adherence. Patients were recruited from August 2013 to November 2013 for a first evaluation and were submitted to a complete ophthalmologic examination. Using Goldmann applanation tonometry, IOP was measured at 8am, 10am and 12pm. Afterwards, patients underwent a 15-day washout of the anhydrase carbonic inhibitor and had their IOP measured again at 8am, 10am and 12pm by another examiner using the same device and methodology.
A total of 25 patients were enrolled and most were women, white, with a mean age of 66.4 ± 9.7 years old and had moderate functional damage on average. The removal of the fourth drug had a statistically significant effect on the IOP peak (increase of 1.20mmHg) and mean (increase of 1.23mmHg; p<0.01). On the other hand, it did not interfere significantly with morning fluctuation of the IOP (p=0.83). Following discontinuation of the fourth drug, the IOP increased ≥2mmHg in 32% of the patients and there was a significant increase of the IOP (defined as an IOP change ≥20%) in only 5 patients (20%). Older patients were more influenced by drug interruption. Age by itself was responsible for approximately 20% of the IOP change (R2=0.19; p=0.03). Other tested variables (patients’ diagnoses, previous surgeries and disease stage) were not significantly associated with the magnitude of IOP change.
Even though it was identified a statistically significant effect on the IOP peak and mean after the fourth drug removal, we believe that its clinical relevance is actually low due to the fact that most patients had an IOP increase below 20% (or below 2mmHg). Age was the only significant predictive factor of IOP change within the evaluated variables, which suggests that it might be worth it to invest on a fourth drug in the older population.
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