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D.M. Grzybowski, C.J. Roberts, B.K. Rivera, P.A. Weber; Pressure Effect on Hydraulic Conductivity of Human Trabecular Meshwork Cells . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1159.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Examine the influence of driving pressure on the efficacy of low fluence laser irradiation upon hydraulic conductivity of a monolayer of trabecular meshwork endothelial cells (TMEC). Methods: Confluent TMEC monolayers were perfused using an in vitro perfusion model at a starting pressure of 5, 10, 15 or 25 mm Hg. Experimental monolayers were irradiated with a diode laser (=810 nm) at a fluence level of 0.4286 or 0.3571 J/cm2. The fluence level was selected based on results of an experimental pilot series in which a change in conductivity(Lp) was noted, and viability of the cells was preserved. Each irradiated monolayer was run simultaneously with a non–irradiated control monolayer under the same environmental conditions. Irradiation took place following 15 minutes of steady state perfusion, after which perfusion and data collection continued for 60 minutes. Results: The treatment effect for the 0.4286 J/cm2 fluence level becomes statistically significant (p<0.01) at time interval 4 (1830–2100 sec.) when comparing all experiments to control. A statistically significant difference is found between the three increased pressure levels, with increase in Lp due to tissue irradiation decreasing with increasing pressure. This effect becomes statistically significant (p<0.01) at the 7th time interval (2730–3000 sec.). In previous studies, the lower fluence level, 0.3571 J/cm2, was found to be at or below irradiation threshold, producing an inconsistent cellular response. Therefore, the resultant pressure effect in the current study was confounded by the conflicting tissue interaction factor. The effect of increasing driving pressure was not found to be statistically significant at this lower fluence level. Conclusions: An increase in driving pressure produces a statistically significant reduction in the enhanced hydraulic conductivity response of the monolayer at a fluence level of 0.4286 J/cm2. We have shown that the 0.3571 J/cm2 fluence level represents trans–threshold irradiation, producing an inconsistent result. These results add further evidence that it is possible to promote an increase in hydraulic conductivity in a perfused human TMEC monolayer model using direct, non–destructive diode laser energy in a low fluence regime.
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