Preservative-free artificial tear preparations. Assessment of corneal epithelial toxic effects
G. J. Berdy, M. B. Abelson, L. M. Smith and M. A. George
Eye Research Institute, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston.
Scanning electron microscopy was used to evaluate the corneal epithelium of
rabbit eyes after administration of two preservative-free ocular
lubricants, preservative-free artificial tear-1 (Hypotears PF) and
preservative-free artificial tear-2 (Refresh), and 0.02% benzalkonium
chloride. Animals were randomly assigned to either mild or exaggerated use
regimens. A quantitative rating system was used to assess epithelial
damage. With mild use, scanning electron microscopy revealed normal
epithelial morphologic characteristics for both preservative-free
artificial tear solutions (mean relative damage score, solution 1, 0.75 +/-
0.16; solution 2, 1.02 +/- 0.23), which were not significantly different
from eyes treated with phosphate-buffered saline (1.38 +/- 0.38) or a mild
dosage regimen of 0.02% benzalkonium chloride (1.20 +/- 0.12). Exaggerated
use with preservative-free artificial tear solutions (solution 1, 1.31 +/-
0.21; solution 2, 1.35 +/- 0.08) induced minimal damage that was not
different from control eyes treated with phosphate-buffered saline (1.26
+/- 0.13). Compared with an exaggerated use of 0.02% benzalkonium chloride
(4.0 +/- 0.16), both preservative-free artificial tear solutions induced
significantly less epithelial damage (P = .0001). These results suggest
that with frequent-dosage regimens, preservation-free artificial tear
solutions-1 and -2 are free of the toxic effects associated with preserved
solutions.
