Abstract:

Objective To quantitatively measure the changes in anterior segment morphology by using ultrasound biomicroscopy (UBM) after laser peripheral iridotomy (LPI) with or without laser peripheral iridoplasty under the guidance of angle closure mechanisms in eyes with primary angle closure suspect (PACS). Design Prospective case series. Participants Sixty-five eyes in 50 PACS consecutive patients with PACS were enrolled from Jan. to Nov. 2016 in Handan Eye Hospital. Methods Each pre-operated eyes was evaluated by UBM according to the different mechanisms of angle closure. All selected patients were first treated with LPI. UBM examination were performed again 3 days after LPI. If there are still at least one quadrant angle contact closure, laser peripheral iridoplasty (LPIP) will be combined. Three days after LPLP, UBM was reviewed, and the therapeutic effects were evaluated according to the changes of UBM measurement parameters. Main Outcome Measures The parameters of anterior chamber angle in UBM images, including central anterior chamber depth (ACD), angle of anterior chamber opening distance(AOD), trabecular iris angle(TIA), angle crypt area(ARA)、trabecular ciliary body distance (TCPD)、iris thickness (IT). Results Forty-seven eyes were only treated by LPI, which showed pure pupillary block. AOD, TIA, ARA, TCPD were significantly widen after LPI than that at presentation in eyes (all P<0.01). IT were unchanged after LPI than that at presentation in eyes (P=0.465). Eighteen eyes were treated by LPI combined LPIP, which presented multiplemechanism, the AOD, TIA, ARA, TCPD were significantly widen after LPI+LPIP than that at presentation in eyes (all P<0.01). IT were thinner after LPIP than that at presentation and after LPI in eyes (P<0.01). Conclusion After LPI, UBM can be used to determine the mechanism of angle closure, and to consider whether combined LPIP, which can further improve the efficacy of multiplemechanism PACS.

Key words: primary angle closure suspect, ultrasound biomicroscopy, laser peripheral iridotomy, laser peripheral iridoplasty