[Primary iris-ciliary body cyst and its relevancy with the change of anterior chamber angle]

To investigate the characteristics of the size and distribution of primary iris-ciliary body cysts and its associated with the change of anterior chamber angle.

It was a cross sectional study. Patients with shallow anterior chambers found in routine health examinations were evaluated with UBM scan. Any primary iris-ciliary body cysts detected were recorded in the parameters of quantity, size, location, and quadrant. The shape of the angle in the UBM was compared to the surrounding area of angle without the cyst, and also whether the angle was narrowed or closed was recorded. The factors related to the corresponding narrowed or closed angle were analyzed.

The 502 cysts were detected in 134 (29.32%) of the 457 patients, which were all primary iris-ciliary body cysts. The cysts were located in the iridociliary sulcus (41.24%) and pars plicata (58.37%) and distributions were 44.22% situated at the inferotemporal quadrant, 26.88% at the inferonasal quadrant, 23.11% at the superotemporal quadrant and 5.38% at the superonasal quadrant. The largest base size of the cysts was 0.6289 +/- 0.2329 mm and most were mid-sized cysts (86.05%). The incidence of the cysts with corresponding chamber angle narrowing or closure in the iridociliary sulcus was 82.13% (170/207), and in the pars plicata was 22.87% (67/293). The difference between them was statistical significant (chi2 = 170.83, P < 0.01). The relationship between the cyst size and the proportion of the cysts which caused corresponding angles narrowing or closure was analyzed by way of rectilinear correlation, and it was found to be a positive correlation (r = 0.9939, P < 0.01).

The incidence of primary iris-ciliary body cysts in the normal population is high and some may cause corresponding angle narrowing or closure; The location and size of the cysts are the factors to induce narrowing or closure of the angle in the corresponding area.