[Comparison of different power-density krypton laser combined with Nd:YAG laser peripheral iridotomy]

To compare the influence of krypton laser with different power densities combined with Nd:YAG laser peripheral iridotomy (LPI) on the intraocular pressure, blood-aqueous barrier and inflammatory of anterior chamber as well as the therapeutic effect.

Using a laser flare cell meter and Goldmann tonometer, the level of aqueous protein, the number of cells in the anterior chamber and intraocular pressure of 31 patients (62 eyes) who underwent krypton laser with different power densities combined with Nd:YAG laser peripheral iridotomy were examined and recorded preoperatively and postoperatively.

The mean preoperative and 1-hour, 3-day, 7-day, 1-month postoperative intraocular pressure (IOP) of the high power-density group were (15.68 +/- 2.41), (27.13 +/- 3.48), (20.97 +/- 5.27), (16.35 +/- 1.14) and (15.06 +/- 2.02) mmHg, while those of the low were (15.35 +/- 1.78), (22.77 +/- 3.26), (16.26 +/- 2.41), (15.68 +/- 2.06) and (15.06 +/- 1.36) mmHg. The mean preoperative and 3-day, 7-day, 1-month postoperative flare intensity of the high power-density group were (4.65 +/- 1.50), (10.41 +/- 2.47), (7.31 +/- 2.31) and (6.15 +/- 2.16) pc/ms, while those of the low were (4.45 +/- 1.19), (6.47 +/- 1.11), (4.81 +/- 0.55) and (4.98 +/- 1.48) pc/ms. The number of aqueous cells of the high was (0.47 +/- 0.42), (36.22 +/- 9.16), (18.54 +/- 3.60) and (6.29 +/- 0.98), while that of the low was (0.58 +/- 0.52), (24.73 +/- 6.09), (10.61 +/- 1.70) and (2.96 +/- 1.35). The mean 1-hour and 3-day postoperative IOP of the high was higher than that of the low. Both the mean flare intensity and the mean number of aqueous cells of the high power-density group were higher than those of the low. The differences were of statistical significance (P < 0.05). The mean flare intensity of the high power-density group in the 1-month postoperative follow-up was still higher than the baseline. The mean number of aqueous cells of both the high and the low power-density groups in the 1-month postoperative follow-up was still higher than the baseline. During 1-month follow-up, no obvious visual damage, diffuse corneal endothelial burns or corneal decompensation, lens injury and closure of the peripheral iris incision were observed.

When krypton laser combined with Nd:YAG laser peripheral iridotomy is under consideration, relatively low power-density krypton laser is recommended because it can achieve the similar therapeutic effects as high power-density krypton laser but leads to less complications and a briefer recovery. More follow-ups are needed after LPI, because the number of aqueous cells in 1-month follow-up was still abnormal.