Systane vs. Thealoz DUO 2015 Study

Artificial tears are not all the same, and dry eye patients often notice that quickly. A small clinical study published in Therapeutics and Clinical Risk Management compared Thealoz DUO with Systane in adults with moderate to severe dry eye.

Both drops helped, but Thealoz DUO came out ahead on several important patient-centered measures.

The study was a randomized, open-label, crossover trial involving 17 adults with moderate to severe dry eye. Patients used one product first, then after a washout period switched to the other. This type of design is useful because each patient effectively serves as their own comparison. The primary outcome was patient satisfaction, measured on a 0 to 100 visual analog scale after 7 days of treatment. Secondary outcomes included OSDI score, dry eye symptoms, staining, tear breakup time, Schirmer testing, and overall patient and investigator impressions.

The headline finding was patient satisfaction. Satisfaction improved with both products, but it improved more with Thealoz DUO. Average satisfaction increased from 44.5 to 70.2 with Thealoz DUO, compared with 47.2 to 57.1 with Systane. The difference in improvement, 13.2 points in favor of Thealoz DUO, was statistically significant.

That does not mean Systane performed poorly. In fact, both products improved symptoms and several clinical measures over the short study period. OSDI scores dropped in both groups, and staining, ocular signs, Schirmer testing, and tear breakup time all tended to improve. However, in this study, Thealoz DUO consistently trended better, and Systane did not show a statistically significant advantage on any measured parameter.

Two secondary outcomes were especially notable. Thealoz DUO showed statistically significant advantages for overall dry eye symptoms and for the impact of dry eye on work. The symptom charts shown in study shows a clearer downward trend with Thealoz DUO across multiple symptom categories, even when some of those differences did not reach statistical significance. That is often clinically meaningful, because patients care about comfort, function, and how their eyes feel during normal daily activities.

Patient preference also favored Thealoz DUO. At the end of the study, 64.7% of patients preferred Thealoz DUO, compared with 11.8% who preferred Systane, while 23.5% had no preference. No adverse events were reported during the study.

That said, this was still a small and short study. Only 17 patients were included, treatment periods were brief, and the trial was open-label rather than masked. The authors themselves noted that the small sample size and short duration likely explain why some outcomes only showed trends rather than clear statistical separation. The study was also sponsored by Laboratoires Théa, the maker of Thealoz DUO, which is worth acknowledging whenever interpreting results.

Clinical Pearl from Dr. Jason Morris: In clinic, I have found much the same thing. In patients with mild to moderate dry eye, Thealoz DUO consistently outperforms Systane in real-world comfort and satisfaction. That does not mean every patient will respond the same way, but it matches what this study found: both products can help, yet Thealoz DUO often leaves patients feeling the results last longer.

The takeaway is simple. This study does not suggest that Systane is ineffective. It does suggest that Thealoz DUO may provide better overall satisfaction and symptom relief for many dry eye patients, especially when comfort and day-to-day function matter most.

Reference: Therapeutics and Clinical Risk Management 2015 Apr 13;11:595–603. doi: 10.2147/TCRM.S77091  A randomized crossover study comparing trehalose/hyaluronate eyedrops and standard treatment: patient satisfaction in the treatment of dry eye syndrome