Effect of low fluence diode laser irradiation on the hydraulic conductivity of perfused trabecular meshwork endothelial cell monolayers

Objective: To determine the effect of low- fluence diode laser irradiation upon the fluid perfusion characteristics of cultured human trabecular meshwork cell monolayers when placed in a specially designed testing apparatus and subjected to fluid flow driven by a hydrostatic pressure gradient. Methods: Two experimental series were conducted. In the first series, six low- fluence diode laser irradiation experiments were conducted using cultured human trabecular meshwork cell monolayers grown on filter supports. Upon reaching a steady state perfusion condition at approximately 5.0 mmHg, monolayers were irradiated at fluencies ranging from 0.2619 to 0.8571 J/cm(2) using a diode laser (lambda = 810 nm). Perfusion and data collection continued for 45 minutes post- irradiation, after which the monolayers were tested to determine post- experimental viability. Hydraulic conductivity values were analyzed for post- irradiation response in 2.5- minute intervals, grouped by viability. In the second series, a total of six irradiated experiments and six simulataneous nonirradiated control experiments were conducted. Fluence values of 0.3571 J/cm(2) ( n = 3) and 0.4286 J/cm(2) ( n = 3) were used. Hydraulic conductivity values were analyzed for post- irradiation response in 2.5- minute intervals, grouped by irradiated vs. nonirradiated control groups. Results: In the first series, analysis showed that the viable monolayers exhibited a statistically significant increase in hydraulic conductivity ( p < 0.001) from 10 minutes post- irradiation onward. The non- viable monolayers exhibited a statistically significant decrease in hydraulic conductivity. In the second series, irradiated groups showed a significant difference ( p < 0.001) from nonirradiated controls from 10 minutes post- irradiation onward. Conclusion: Low- fluence diode laser irradiation increases hydraulic conductivity in viable perfused TM cell monolayers when compared to baseline values or simultaneous nonirradiated controls while decreasing hydraulic conductivity in nonviable monolayers.