Published in Research

Study: Artificial tears disrupt ocular surface inflammation cycle

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4 min read

New research published in The Journal of Cornea and External Disease assessed the short-term impact of eye drops on dry eye disease (DED).

Give me some background first.

As a multifactorial disease of the ocular surface, DED can have several causes, including:

  • Tear film instability
  • Inflammation
  • Ocular surface damage
  • Hyperosmolarity
  • Neurosensory abnormalities

Attention towards DED has grown as cases have become more globally prevalent.

Now this study.

With this in mind, researchers tested five commercially available, preservative-free artificial tears on 150 participants (300 eyes) to:

  • Gauge each brand’s short-term impact on the hyperosmolar environment and
  • Determine their effectiveness in relieving DED symptoms

Let’s talk participant details.

Participants (aged 18+; mean age of 52) were required to meet the following criteria:

  • Diagnosed with dry eye
  • Ocular surface disease index (OSDI)  of 23+
  • Tear osmolarity of 308 milliosmoles (mOsm) or more, or
  • Difference of 8+ mOsm between the eyes

And which artificial tear brands were used?

  • Freegan PF (0.5% carboxymethylcellulose; Ophta)
  • Hyabak (0.15% sodium hyaluronate; Théa)
  • Optivue Fusion UD (0.5% carboxymethylcellulose + 1% glycerin; Allergan)
  • Siccafluid (carbomer 974p gel; Théa)
  • Systane Ultra UD (propylene glycol 400-polyethylene glycol; Alcon)

Note: An osmolarity test was conducted before application, and 15 minutes after the initial application to test the impact of the artificial tears.

Now the set up.

Participants were randomized into six groups (n = 25, estimated per each) to receive the following:

  • Group 1
    • Freegan PF (n = 25; 50 eyes)
  • Group 2
    • Hyabak (n = 25; 50 eyes)
  • Group 3
    • Optive Fusion UD (n = 25; 50 eyes)
  • Group 4
    • Siccafluid (n = 24; 48 eyes)
  • Group 5
    • Systane UD (n = 26; 52 eyes)
  • Group 6
    • No drops (n = 25; 50 eyes)
    • Control group

Note: For Group 6, only the osmolarity test was repeated 15 minutes following the initial test.


The study concluded that all artificial tear brands that were tested effectively lowered the osmolarity of the tear film within the first 15 minutes of initial application.

And more specifically …

The Siccafluid brand showed the most substantial osmolarity reduction, with an average decrease of 11.54 mOsm/L vs the control group (Group 6) who did not use eye drops experienced an increase in average osmolarity (+0.98 mOsm/L).

A statistical significance was seen in Siccafluid (-211.54 mOsm/L), Optive Fusion (-27.84 mOsm/L), and Systane Ultra (-26.55 mOsm/L) while Haybak (-24.82 mOsm/L)  and Freegren (-20.52) mOsm/L showed lower significance.

Tell me more.

Researchers also identified the osmolarity profile of all five artificial tears tested. Haybak showed an osmolarity of 205 mOsm/L while the other four artificial tears had an osmolarity greater or equal to 308 mOsm/L.

Siccafluid, the best-performing artificial tear in the study, had the highest osmolarity of all the artificial tears tested.

Any notable limitations?

Although the authors did not note any prominent limitations, the study only evaluated participants’ eyes 15 minutes after the initial application.

However: There is no data to show how the artificial tears performed after 15 minutes.

What’s significant about this data?

The study authors noted that this study was one of the first to show that, in post-application, artificial tears may disrupt the ocular surface inflammation cycle and improve the hyperosmolar environment of the ocular surface.

Go on …

Per the authors:  it is crucial to emphasize that disrupting the ocular surface inflammation cycle can prevent the perpetuation of dry eye.

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