Abstract: Objective To evaluate the short-term changes of anterior chamber depth and angle parameters in acute angle closure glaucoma underwent low dose trans-scleral cycloplasty (LDCP). Design Prospective case series. Participants 15 eyes from 12 patients were diagnosis as cute angle closure glaucoma patients with sudden attack at the Eye Hospital of Wenzhou Medical University from May 2018 to November 2019. Methods LDCP is a treatment adopting few laser points (1200~2000 mW energy, 2 seconds duration) that burns the ciliary body over two hour-positions to shrink ciliary body and release ciliary block.  Acute angle closure glaucoma patients underwent low dose trans-scleral cycloplasty (LDCP). The mean age was (54.7±14.1) years old (22~72 years old), including 5 males and 7 females. Data before LDCP and one week, one month, three months after LDCP were collected. Main Outcome Measures Intraocular pressure, central anterior chamber depth, angle opening distance 500 (AOD500), trabecular-iris angle 500 (TIA500), maximum ciliary body thickness (CBTmax), trabecular-ciliary angle (TCA) and number of medications. Results The mean number of laser burns was (13.3±2.3) (9~16). The median preoperative IOP (range) was 26.6 (7.3~60.0) mmHg  with the median medication number of 3 (0~5). The median postoperative IOP was 10.6(6.1~53.9) mmHg (Z=-2.726, P=0.006) with the median medication number of 0 (0~3) (Z=-3.078, P=0.002). The central anterior chamber depth measured by ultrasound biomicroscopy (UBM) was increased from (1.44±0.48) mm preoperatively to (1.66±0.34) mm postoperatively, respectively (t=-2.783, P=0.015). And the AOD500 and TIA500 values measured by UBM had a significant difference between preoperative and postoperative (all P<0.05). The CBTmax and TCA values measured increased from preoperation topostoperation (CBTmax: P=0.060；TCA: P=0.004). The deepen of peripheral anterior chamber was observed by van Herick technique respectively in thirteen eyes (86.7%). 8 eyes underwent cataract surgery for different reasons within one month after LDCP. Among 7 eyes without secondary surgery, the median IOP was 15.5 mmHg and mean anterior chamber depth was 1.73 mm three months after LDCP. Conclusion Preliminary study shows that LDCP can significantly deepen the central and peripheral anterior chamber of acute angle closure glaucoma and reduce the intraocular pressure quickly, which provides a new idea for the treatment of angle closure glaucoma in acute phase. However, the safety of this treatment needs to be further observed. (Ophthalmol CHN, 2021, 30: 30-35)

Key words: angle closure glaucoma, low dose trans-scleral cycloplasty, intraocular pressure；anterior chamber