[Application of Ultrasound Biomicroscopy in Longterm Follow-up Post Modified CO₂ Laser-assisted Sclerectomy Surgery]

Objective To observe the role of ultrasound biomicroscopy(UBM)in two-year post-operative follow-up for primary open-angle glaucoma patients with modified CO₂ laser-assisted sclerectomy surgery(CLASS).Methods This was a case series study.A combination of modified CLASS and preoperative laser iris management was administered to 28 eyes.Visual acuity,intraocular pressure(IOP),and slit-lamp examinations,visual field testing,and gonioscopy were carried out at baseline and until 24 months postoperatively.UBM examination was performed at 1,3,12 and 24 months postoperatively.Results Compared with the mean preoperative IOP [(30.61±10.59)mmHg],the IOP at each time point after operation was significantly lowered [(15.15±5.87),(12.56±3.24),(13.15±2.73),(13.75±2.55)and(13.75±2.46)mmHg at 1,3,6,12 and 24 months,respectively;all P<0.001].Complete success rates and qualified success rates at 12 months and 24 months were 60.71%,89.29% and 53.57%,85.71%,respectively.UBM images can present "dolphin head sign" after successful CLASS.The thickness of trabeculo-Descemet's window was(0.13±0.03)mm,which had no significant correlation with postoperative IOP at 12(r=-0.278,P=0.144)and 24 months(r=0.026,P=0.895).UBM examination revealed a severe scleral lake diminution(a change > 50%)in 1 eye(3.57%)at 12 months and 3 eyes(10.71%)at 24 months.There was no statistical significance detected between the size of the scleral lake and IOP after CLASS.Non-founctional blebs were found in 16 eyes(57.14%)at 12 months and 25 eyes(89.28%)at 24 months.Two eyes(7.14%)demonstrated severe peripheral anterior synechiae at 24 months,requiring surgical intervention.Conclusions UBM can effectively observe the morphology of the scleral lake,anterior chamber angle and filtering blebs in post-operative follow-up after modified CLASS,and give early warning of complications.It plays an important role in ensuring the success of CLASS.