Article
To develop a new lubricant and nutrient tear substitute
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Authors
Published: | September 22, 2004 |
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Outline
Text
Objective
Tear substitutes, the most widely used therapy for dry eye, usually only provide lubrication for the ocular surface. We aimed to produce a new tear substitute capable of providing lubrication and nutrition in one, based on a defined keratinocyte serum free cell culture medium and supplemented with various lubricants also included in commercially available tear substitutes.
Methods
Hydroxypropylmethylcellulose (HPMC), carbopol 980, and Sodium Hyaluronate (SH) were dissolved in the medium to the concentrations of 0.4%, 0.2%, 0.1%, 0.05%, 0.025% and 0.0125%. PH, osmolarity, viscosity and surface tension were measured for all the formulations. Two human corneal epithelial cell lines (HCE-T and CEPI-17-CL4) and two conjunctival epithelial cell lines (Chang and IOBA-NHC) as well as primary rabbit corneal epithelial cells were used to investigate cell proliferation, viability and migration in response to the formulations by means of a luminescence based ATP-assay, a LIVE/DEAD viability/cytotoxicity assay and a colony dispersion assay.
Results
The pH of the medium was 7.2, osmolarity was 278 mOsm/L, surface tension was 73 mN/m and viscosity was 25 mPa.sec. The surface tension of medium was reduced by adding HPMC, but not by carbopol 980 and SH. All additives increased the viscosity of the medium significantly at all the concentrations. An HPMC containing formulation supported cell proliferation and viability better than carbopol 980 and SH, especially at concentrations higher than 0.1% and with exposure time longer than 96 h. None of the formulations supported cell migration.
Conclusions
DKSFM with HPMC shows superior lubricant and nutrient properties and could be an ideal tear substitute for dry eye. The optimal concentration is 0.2%, since HPMC-adjusted culture medium at this concentration could provide moderate viscosity, has a surface tension similar to natural tears and supports cell proliferation best. Its effect on severe ocular surface disease should be evaluated in a randomised controlled clinical trial.