Abstract: Objective To evaluate the anterior segment parameters in the fellow eyes of acute primary angle-closure glaucoma (PACG) and chronic primary angle-closure glaucoma using ultrasound biomicroscope.  Design Case-controlled study. Participents Two groups, 40 fellow eyes of acute PACG, 42 fellow eyes of chronic PACG, were included in the present study. Methods The related structure parameters of iris, pupil, ciliary body and anterior chamber angle were observed and analyzed with ultrasound biomicroscope.  Main Outcome Measures  Anterior chamber depth(ACD), pupil diameter(PD),  iris thickness (IT)1, IT2, maximal iris thickness(ITM), scleral spur iris distance(SIT), iris-bombe height(IH), angle A, angle B, trabecular-ciliary process distance(TCPD), trabecular-iris angle (TIA) and angle opening distence(AOD) were measured. Results  On ultrasound biomicroscopy the ACD of the fellow eye in acute PACG (FEACG) was shallower than the fellow eye of chronic PACG (FECACG), but was no significant difference (P=0.067). The PD of FEACG 3.094±0.782 mm was less than FECACG 3.613±0.925 mm (P=0.008). IT1, IT2, ITM of FEACG were thinner than FECACG (P=0.005, 0.000, 0.001). There was a positive correlation between IT2, ITM and PD (P=0.000) which were using covariance analysis. SIT of FEACG was bigger than FECACG (P=0.016). IH of FEACG was higher than FECACG (P=0.000). Angle A, and angle B of FEACG was wider than FECACG (P=0.004, 0.017). TIA and AOD of FEACG was wider than FECACG but there were no significant differences between two groups (P=0.417, 0.278). Conclusion There is a difference between the fellow eyes of acute PACG and chronic PACG. Compared with chronic PACG, beside the common features such as shallow anterior chamber depth, narrow anterior chamber angle, ACG has a smaller pupil, thinner iris, higher iris bombe, and a more posterior positioned iris insert and wider ciliary-trabecular-angle. The differences between the anterior segments of acute PACG and chronic PACG may result in the different disease courses of these two types of PACG. (Ophthalmol CHN, 2014, 23: 26-30)

Key words: acute primary angle-closed glaucoma/pathophysiology, chronic primary angle-closed glaucoma/pathophysiology, ultrasound biomicroscopy