Compared with normal subjects with similar shallow ACD, patients with PACD had narrower angle structures measured by SS-OCT at 250▒μm from scleral spur (very root of iris), especially along oblique and vertical axis.
To examine anterior segment structures in normal subjects whose anterior chamber depth (ACD) was shallow on slit lamp exam but did not meet the diagnostic criteria of primary angle closure disease (PACD), and to compare them with PACD patients with similar ACD.
Patients were recruited from glaucoma clinic at Zhongshan Ophthalmic Center. A total of 40 eyes from 29 PACD patients and 40 eyes from 34 normal subjects received full ophthalmic examination and CASIA SS-1000 OCT tests. PACD eyes and control eyes were 1:1 matched for ACD at 0 degree of scan. Generalized linear model that accounted for inter-eye correlation was used to compare differences between the two groups for intraocular pressure (IOP) and SS-OCT parameters. P values were adjusted for multiple comparisons using the Bonferroni method.
The PACD and control groups had similar age, but the PACD group had a significantly higher IOP (18.4 vs. 14.0▒mmHg, P=0.005). Angle parameters, representative of angle area, such as angle recess area (ARA) and trabecular iris space area (TISA) measured at 250▒μm along axes of 90°, 135°, 225° and 315° were significantly smaller in PACD group than those of control group (adjusted P<0.05), while most of angle parameters at 500▒μm and 750▒μm, volume parameters, and anterior chamber parameters, were similar (adjusted P>0.05).
In PACD patients compared to normal subjects with similar anterior chamber shallowing, OCT findings measured at the iris root 250▒μm from the scleral spur, especially in the oblique and vertical axes, including ARA and TISA, may match gonioscopic findings more closely and provide further insight into mechanisms of PACD.