Abstract
Abstract: :
Purpose: To investigate the differences in hydraulic conductivity (Lp) response of perfused glaucomatous to non–glaucomatous human trabecular meshwork (HTM) cell monolayers to low fluence diode laser irradiation. Methods: 6 glaucomatous confluent HTM cell monolayers and 6 non–glaucomatous confluent HTM cell monolayers were perfused at a starting pressure of 5 mm Hg. Experimental monolayers were irradiated with a diode laser (λ=810 nm) at a power of 1.2 W over 1.5 sec duration for a fluence level of 0.4286 J/cm2. The fluence level was selected based upon the results of a pilot experimental series in which a change in 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 45 minutes. Both monolayers were then tested to determine post–experimental viability. Results: Non–glaucomatous monolayers irradiated at a fluence of 0.4286 J/cm2 exhibited a statistically significant increase in Lp (P < 0.05), with an average change of 0.241±0.038 µl/min/mm Hg/cm2 from pre–irradiation values. Glaucomatous monolayers irradiated at a fluence of 0.4286 J/cm2 exhibited a statistically significant increase in Lp (P < 0.05), with an average change of 0.099±0.01 µl/min/mm Hg/cm2 from pre–irradiation values. Corresponding control monolayers exhibited an average change over the same time period of 0.005±0.001 µl/min/mm Hg/cm2 for the non–glaucomatous and 0.001±0.002 µl/min/mm Hg/cm2 for the glaucomatous. Both experimental and control monolayers proved to be viable following all procedures. Conclusions: These results indicate that it is possible to promote an increase in hydraulic conductivity in a perfused HTM cell monolayer model using direct, non–destructive diode laser energy in a low fluence regime. However, in the glaucomatous monolayers, not only was the increase in hydraulic conductivity reduced as compared to the increase seen under the same conditions by the non–glaucomatous monolayers, but the absolute values of hydraulic conductivity were reduced with a range of 0.17 – 0.32 µl/min/mm Hg/cm2 for the glaucomatous monolayers as compared to a range of 0.82 – 1.19 µl/min/mm Hg/cm2 for the non–glaucomatous monolayers. This difference was shown to be statistically significant at all time points (P < 0.05).
Keywords: trabecular meshwork • aqueous • outflow: trabecular meshwork