Objective: To investigate the ocular blood-aqueous barrier (BAB) alteration after laser peripheral iridotomy (LPI) or surgery peripheral iridectomy (SPI) in patients with primary chronic angle-closure glaucoma (PCACG).
Methods: This was a clinical randomized controlled trial. Sixty eyes of 60 subjects with early stage of PCACG were randomly received either LPI or SPI and followed up postoperatively at day 3, week 1, 2, 3, and 4. Aqueous flare in anterior chamber was measured by FC-2000 flare-cell photometry, intraocular pressure (IOP) measured by tonometer, central corneal endothelium cell counted by endothelioscopy, peripheral anterior synechiae (PAS) detected by gonioscopy. Data were analyzed by using two-way ANOVA for repeated measures, independent samples t-test, paired t-test, nonparametric test, and Spearman rank correlation test.
Results: On follow-ups of pre-operative and post-operative 3 days, 1 week (w), 2w, 3w and 4w respectively, the mean aqueous flare values for LPI group were (5.47 ± 1.09), (11.96 ± 3.07), (8.08 ± 2.18), (5.68 ± 0.83), (5.80 ± 1.00), (5.69 ± 1.12) PC/ms, and for SPI group were (5.43 ± 1.13), (8.44 ± 3.22), (6.42 ± 1.77), (5.35 ± 0.71), (5.53 ± 1.26), (5.45 ± 1.23) PC/ms. During post-operative 1w the flare values in both LPI and SPI groups were significantly higher than that on pre-operation (t = -12.753, -8.101, P < 0.05; t = -5.971, -3.870;P < 0.05) and LPI group had a significantly higher mean flare value than SPI group (t = 4.329, 3.231;P < 0.05). The IOP spike in LPI group was significantly (χ(2) = 5.079, 4.022, P < 0.05) higher than that in SPI group at week 1 of post-operation. Increased IOP was positively correlated with BAB damage (r = 0.899, 0.833; P < 0.05). The numbers of medications required to maintain IOP ≤ 21 mm Hg (1 mm Hg = 0.133 kPa) at week 4 of post-operation in LPI was significantly (Z = -1.984, P < 0.05) more than that in SPI group. There were no significant differences in central corneal endothelium cell count at week 1 (t = -0.696, 0.008) and in extension of PAS at week 4 (Z = -1.270, -1.490) of post-operation when compared to pre-operation (P > 0.05). No obvious complications occurred in both groups.
Conclusions: Our results demonstrated that IOP spike in both of LPI and SPI is due, at least in part, to BAB damage, which appears to be more severe in LPI group and can recover within two weeks. PAS progression and central corneal endothelium cell loss are not aggravated in 1 month after operation.