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 and Method
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 EDO, (0.82;0.69; 0.63;0.54) for Vidisic EDO, (0.77;0.80;0.67;0.70) for Vidisic Fluid EDO, (0.76;0.70;0.36; 0.34) for Acuolens, (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 EDO, (0.89;0.92;0.93;0.86) for Vidisic EDO, (0.96;0.88;0.85;0.85) for Vidisic Fluid EDO, (1.01;0.75;-0.02;-0.03) for Acuolens, (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 Fluid EDO and Vidisic 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.

Keywords: Protective Agents - pharmacology, Tears - drug effects, Lubricants - pharmacology, Desiccation, Epithelial Cells - drug effects, Conjunctiva - drug effects, Cell Survival - drug effects