The mean anterior chamber depth ( ACD ) measured by UBM was significantly increased from 1,983.8176.8 microns to 3335.0174.2 microns ( p < 0.001 ) by clear lens extraction , but decreased from 2,000.2214.5 microns to 1975.8218.2 microns ( p = 0.001 ) by trabeculectomy .