Abstract: Comparing artificial tears

This is an in vitro comparison of several artificial tears and how long they protect epithelial cells from dessication. As acknowledged in the abstract, whether it happens this way 'in vivo' is up for grabs. Personally I don't find any of it all that interesting because I don't think we should be satisfied with such brief protection in any case.

Americans will not be familiar with these brands... Artelac and Acuolens are hypromellose drops, Vidisic is a carbomer gel, Hyal Drops are sodium hyaluronate, and Viscofresh is carmellose.

Lubricating agents differ in their protection of cultured human epithelial cells against desiccation.
Paulsen K, Maile S, Giebel J, Tost FH
Med Sci Monit. 2008 Jun;14(6):PI12-16

Background: In dry eye, as a disease of the ocular surface, the instillation of artificial tears should compensate for the deficit in wetting and protect the mucosa against drying.

Material/Methods: The desiccation protection of different pharmacological substances was tested using the conjunctival epithelial cell line Chang 1-5c-4 (series 1) and the corneal cell line 2.040 pRSV-T (series 2). On confluent cell growth the cultures were wetted for 20 min with various preservative-free preparations of artificial tears The cell cultures were exposed to a constant air flow for 0, 15, 30 and 45 minutes. Cells were incubated with the vital dye Alamar Blue and subsequently absorption of the oxidised form of the dye was measured using an ELISA-Reader.

Results: Cell survival rates in series 1 after 0, 15, 30, 45 min were (1.02;0.81;0.35;0.32) for Artelac(R) EDO, (0.82;0.69; 0.63;0.54) for Vidisic(R) EDO, (0.77;0.80;0.67;0.70) for Vidisic(R) Fluid EDO, (0.76;0.70;0.36; 0.34) for Acuolens(R), (0.97;0.46;0.35;0.33) for Viscofresh, (0.88;0.85;0.37; 0.33) for Hyal Drops SDU, (0.71;0.44;0.34;0.33) for PBS and in series 2 (1.03;0.84;-0.21;-0.20) for Artelac(R) EDO, (0.89;0.92;0.93;0.86) for Vidisic(R) EDO, (0.96;0.88;0.85;0.85) for Vidisic(R) Fluid EDO, (1.01;0.75;-0.02;-0.03) for Acuolens(R), (0.98;0.17;-0.22;-0.20) for Viscofresh, (0.97;0.83;0.03;-0.21) for Hyal Drops SDU and (0.96;0.26;-0.24;-0.21) for PBS. Vidisic(R) Fluid EDO and Vidisic(R) EDO showed a significantly better protective effect after a drying period of 30 and 45 min.

Conclusions: The protection capability of pharmacological substances against desiccation can be studied in a standardised cell culture system of human epithelial cell lines. Whether these in vitro results are conferrable to the efficacy of artificial tear drops in vivo has to be evaluated in clinical trials.