Evaluation of changes in anterior segment morphology of primary angle closure after laser peripheral iridotomy

Abstract

Objective To discover primary angle closure (PAC) in eyes of anatomic narrow angle (ANA),evaluate quantify changes of the PAC in anterior segment morphology after laser iridotomy using ultrasound biomicroscopy (UBM) and explore the therapy of primary angle closure.Methods Prospective interventive observational case series.Twenty-eight eyes of patients presented PAC in the Department of Ophthalmology at Zunyi Medical College Hospital.PAC was presented on iris contacting with trabecular meshwork temporally in one UBM image.The PAC eyes were examined again by UBM in the both same light conditions and items at two weeks after laser peripheral iridotomy (LPI).Results The rate of PAC was significantly decreased after LPI in the same condition,the rate of PAC was 96.43％ before LPI in dark condition,and it was significantly dropped down to 32.14％ after LPI (x2 =14.45,P ＜0.05).In light condition,it was cut down from 67.86％ to 7.14％ after LPI (x2 =15.06,P ＜0.05).The AOD500 and TIA were increased after LPI (P ＜0.001),it indicated that the angle of PAC was widened after LPI.The ILCD of PAC was also added after LPI,but the ILA was decreased after LPI (P ＜0.001).This phenomenon suggested that the pupillary block was relieved after care of LPI.The IT1 was thinner in laser site quadrant in dark condition after LPI which combined Nd-YAG and green laser (P ＜0.05).There were no significant changes of the ACD (P ＞0.05).The ICPD was reduced in dark after LPI (t =2.519,P =0.012).The pupillary block was relieved; it leaded to iris caving backward.But the TCPD was added in light after LPI (t =-2.967,P =0.003).It suggested that the ciliary body removed towards the back after LPI.Conclusions LPI produces a significant widening of the peripheral anterior chamber angle and reducing the power of pupillary block for major PAC eyes,which have not peripheral anterior synechia,but not deeping the central anterior chamber distance.LPI can prevent most PAC from developing to PACG.LPI is an efficient method for PAC in a short time. Key words: Primary angle closure; Laser peripheral iridotomy; Ultrasound biomicroscopy