DNA replication in the cat trabecular meshwork after laser trabeculoplasty in vivo

The in vivo response to laser trabeculoplasty (LTP) was evaluated by measuring the incorporation of [³H]thymidine (³HT) into DNA in the nuclei of trabecular meshwork cells.³HT incorporation into DNA was analyzed by light microscopic autoradiography and by scintillation counting of trabecular extracts. Sixteen cats received argon LTP at a power setting of either 0.3 or 1.0 watt with the contralateral eye serving as a control; a 48-h exposure to³HT began 1, 5, or 12 days later. The level of³HT incorporation into DNA for LTP-treated eyes was significantly higher than controls for the earliest labeling period, but not at the later time points. This pattern was observed for both 0.3-and 1.0-watt treatments. In a second experiment, LTP was performed on six animals; a power setting of 0.3 watt was used in the left eye, and a power setting of 1 watt was used in the right eye. All 12 eyes were radiolabeled for 48 h with³HT beginning 1 day after LTP. A small but significant difference in³HT incorporation levels was found between these two power settings. Trabecular cell division may play a role in the therapeutic efficacy of LTP in glaucoma patients. Key Words: Laser trabeculoplasty-Trabecular meshwork-DNA replication-Aqueous outflow pathway-Glaucoma.