The Dry Eye Zone

Rebecca's Blog


Abstract: Sodium hyaluronate and carboxymethylcellulose

This kind of study drives me nuts, because irrespective of the validity of the data, it never tells the real story.

Sounds like a simple proposition: Compare a sodium hyaluronate drop to a carboxymethylcellulose drop. (They're all alike, a dime a dozen, right?) And conclude that they both made people's eyes wetter. Get out. Really? And we all nod and say, I told you so, all artificial tears are more or less the same. But are they?

Back in the days (wave of nostalgia coming...) when I had a little capital and I was able to be more involved with my beloved Dr. Holly's drops, I got a little much-needed education on what goes on in these drops that never shows up on the label... or the study abstract, and probably not even in the whole paper. Take Dwelle for instance. It's povidone and polyvinyl alcohol. Big deal. There's several drops with these ingredients on the market and I think I won't hurt anyone's feelings if I say none of them has ever been thought earth-shattering. Tried one PVA drop, tried 'em, all, right? No, actually, Dr. Holly's drops have a combination of grades of PVA not used in any other drop and this combination (along with the additional polymer) creates uniquely high oncotic pressure values which is what makes his drops effective especially for those with a compromised epithelium.

So circling back to sodium hyaluronate... My industry friends say it's all about the molecular weight. All SH drops are NOT equal, just as all PVA drops are NOT equal.

Bottom line: Do your homework on drops. Don't write them off (and likewise, don't embrace them) just because of a fancy name in the active or in some cases inactive ingredients. Sometimes what's NOT on the label is more telling than what is.

Efficacy of Sodium Hyaluronate and Carboxymethylcellulose in Treating Mild to Moderate Dry Eye Disease.
Cornea. 2010 Oct 28. [Epub ahead of print]
Lee JH, Ahn HS, Kim EK, Kim TI.
From the Department of Ophthalmology, Institute of Vision Research, Yonsei University College of Medicine, Seoul, Korea.

PURPOSE: We compared the efficacy and safety of sodium hyaluronate (SH) and carboxymethylcellulose (CMC) in treating mild to moderate dry eye.

METHODS: Sixty-seven patients with mild to moderate dry eye were enrolled in this prospective, randomized, blinded study. They were treated 6 times a day with preservative-free unit dose formula eyedrops containing 0.1% SH or 0.5% CMC for 8 weeks. Corneal and conjunctival staining with fluorescein, tear film breakup time, subjective symptoms, and adverse reactions were assessed at baseline, 4 weeks, and 8 weeks after treatment initiation.

RESULTS: Thirty-two patients were randomly assigned to the SH group and 33 were randomly assigned to the CMC group. Both the SH and CMC groups showed statistically significant improvements in corneal and conjunctival staining sum scores, tear film breakup time, and dry eye symptom score at 4 and 8 weeks after treatment initiation. However, there were no statistically significant differences in any of the indices between the 2 treatment groups. There were no significant adverse reactions observed during follow-up.

CONCLUSIONS: The efficacies of SH and CMC were equivalent in treating mild to moderate dry eye. SH and CMC preservative-free artificial tear formulations appropriately manage dry eye sign and symptoms and show safety and efficacy when frequently administered in a unit dose formula.