Factors related to future peripheral anterior synechiae formation on ultrasound biomicroscopy: 7-year follow-up in eyes with shallow peripheral anterior chambers

PURPOSE:: To study factors associated with future peripheral anterior synechiae (PAS) formation on ultrasound biomicroscopy (UBM) in eyes with a shallow peripheral anterior chamber. PATIENTS AND METHODS:: Fifteen subjects with a shallow peripheral anterior chamber but no PAS in both eyes, in 2001, that had no medical or surgical intervention until 2008 were included in this study. The same examiners performed gonioscopy and UBM at the 3, 6, 9, and 12 o'clock limbal positions under dark and light conditions in 2001 and 2008. A masked examiner performed a quantitative evaluation of the angle configurations in the UBM images. The presence or absence of PAS was determined by compression gonioscopy. The UBM parameters and the number of appositional closures per eye were compared between PAS-positive eyes and PAS-negative eyes. RESULTS:: One eye from 15 subjects were randomly selected and included in the analyses. The gonioscopic gradings and UBM parameters did not change significantly (P>0.1) between 2001 and 2008. Seven (47%; 95% confidence interval, 25-70) of 15 eyes developed PAS. In 2001, under dark conditions, the appositional angle closure in 3 to 4 quadrants was found more often (P=0.026) in 7 eyes where PAS developed during the following 7 years than in other 8 eyes. CONCLUSIONS:: In eyes with a shallow peripheral anterior chamber but no PAS, PAS developed in 47% of eyes followed without intervention for 7 years. PAS was significantly more likely to develop in eyes with the appositional angle closure found in 3 to 4 quadrants under dark conditions.