The Dry Eye Zone

Rebecca's Blog


Study: Seawater vs artificial tears... who wins?

Seawater vs Celluvisc?

Oh. My.

This study cracks me up, and not least because it strikes close to home

Yes, this really was a study about seawater… sort of, kind of, not really.

A Spanish company takes seawater from the Atlantic. They sterilize it with a cold micro-filtration system. Then they dilute it with spring water to the right salt balance. (Apparently 0.9% sodium chloride, like saline.)

So they compared this with a Refresh Celluvisc lookalike (carmellose 0.5%), and decided the seawater was better. And not arbitrarily: they measured all kinds of stuff, from OSDI (symptom scores) to osmolarity to IL-1.

But WHO did they study?

One thing they DIDN’T do was provide, in the abstract, any explanation at all of what kind of patients they studied.

They simply called them “patients with DES”.

Hmmmm. Last I checked, patients with DES are all over the map from mild, moderate to severe symptoms and clinical signs. Some are aqueous deficient, some lipid deficient, some both, some neither. Some use artificial tears all the time, some use none. It’s a pretty diverse population, so this study doesn’t actually mean much to me without more information.

The one point of connection I have with it is this:

Personally, I do not like and have a low tolerance for artificial tears. As a scleral lens user, I have preservative free saline (a/k/a 0.9% sodium chloride) everywhere in my life, and I use that as an eyedrop any day rather than artificial tears. But then, I don’t have extreme dry eye, and saline drops have no lubricating properties - they’re just, well, wet. That means maybe they’re enough for me at times but they sure wouldn’t be for people with more substantial symptoms, and overusing saline is almost certainly not good for you.

Anyway, here’s the study:

A randomized multicenter study comparing seawater washes and carmellose artificial tears eyedrops in the treatment of dry eye syndrome.

Diaz-Llopis et al, Clinical Ophthalmology, March 2019


To investigate the safety and efficacy of sterile isotonic seawater washes vs standard treatment with carmellose artificial tears in dry eye syndrome (DES).


This is a randomized multicenter prospective study with 12 weeks of follow-up. A group of patients with DES (N=60) were treated with seawater spray (Quinton®) five times daily, and another similar group (N=60) were treated with carmellose artificial tears eyedrops (Viscofresh® 0.5%) five times a day. The parameters studied and measured were as follows: Ocular Surface Disease Index questionnaire score, Schirmer I test (without anesthesia) score, tear osmolarity (TearLab®), tear breakup time, tear meniscus height (meniscography OCT), fluorescein corneal staining score (National Eye Institute scale), lissamine green conjunctival staining score, and levels of IL-1 beta and IL-6 in tears (Luminex® 200).


In the group treated with seawater, symptoms decreased by 68%, and the decrease was 26% statistically superior to the group treated with carmellose artificial tears eyedrops (P<.001). Levels of IL-1 beta and IL-6 in tears significantly decreased in the seawater group compared to the carmellose artificial tears group (19%/17% vs 52%/51%) (P<0.001). There were no statistically significant differences in the other measured parameters. There were no cases of poor tolerance or side effects.


Administration of seawater is more effective than treatment with carmellose artificial tears in reducing symptoms and pro-inflammatory molecules (IL-1 beta and IL-6) in tears of patients with DES.