Changes Of UBM Parameters Before And After LPI In Primary Angle-closure Glaucoma

Purpose:To compare the anterior segment parameters between acute angle-closure glaucoma(AACG)patients and chronic angle-closure glaucoma(CACG)patients before and after laser peripheral iridomtomy(LPI)by ultrasonic biomicroscopy(UBM).To evaluate the efficacy of LPI by comparing the changes of anterior segment structure and the degree of Angle opening before and after LPI in two types of glaucoma.Method:In this prospective study,53 patients(72 eyes)with primary Angle closure who were diagnosed as unilateral or bilateral without LPI and surgical treatment in our hospital from July 2021 to December 2022 were selected.Example according to the signs and symptoms points APAC group of 35 cases(42 eyes)of CPAC group 18cases(30 eyes).Respectively to observe the LPI preoperative and postoperative 1month,3 months after operation of the IOP,anterior chamber depth(ACD),lens vault(LV),angle opening distance(AOD500,AOD750),iris thickness(IT500,IT750,IT2000),trabecular iris angle(TIA500,TIA750)changes.Parameter measurement:the images of each patient in the superior,inferior,nasal and temporal directions of each eye were measured and averaged.Result:1.LV,IT500,IT750,IT2000,AOD500,AOD750,TIA500 and TIA750 in APAC group were increased compared with preoperative,and IT500,IT750,AOD500,AOD750,TIA500 and TIA750 were significantly increased(P<0.05).2.In APAC group,AOD500,AOD750,TIA500 and TIA750 were significantly increased before operation and at 1 month and 3 months after operation.There was no significant difference at each time point after operation.3.The changes of LV,ACD,IT500,IT750 and IT2000 in CPAC group were not significant before and after surgery(P>0.05).IOP was lower than that before operation but the difference was not statistically significant.AOD500,AOD750,TIA500 and TIA750 increased significantly after surgery(P<0.05).4.In CPAC group,IOP,LV,ACD,IT500,IT750 and IT2000 did not change significantly before and after operation(P>0.05).However,there were significant differences in the parameters of AOD500,AOD750,TIA500 and TIA750 before operation and 1 and 3 months after operation,with statistical significance(P<0.05).5.The difference of preoperative LV between APAC group and CPAC group was statistically significant(P<0.05).There was no significant difference in IOP,ACD,AOD500,AOD750,TIA500,TIA750 between the two groups at 1 month after operation(P>0.05).There was statistical significance in the three groups of parameters reflecting iris thickness(P<0.05).Three months after surgery,two groups in the IOP,ACD,AOD750,TIA750 differences on these parameters have no statistical significance(P>0.05);There were statistically significant differences among IT500,IT750,IT2000,AOD5000 and TIA500 groups(P<0.05).Conclusions:1.Both APAC group and CPAC group can effectively widen Angle and reduce IOP in the short term after LPI.2.Thicker IT and higher LV will reduce the Angle opening after LPI,and affect the long-term efficacy of LPI.3.By measuring the parameters of the anterior segment,the scope of application of LPI can be expanded,and more flexible personalized treatment plans can be provided for different patients,thus reducing the application of drugs and other surgeries,delaying the progress of PACG,and increasing patient satisfaction.