2335 Evaluation of anterior chamber angle: Gonioscopy, ultrasound biomicroscopy and scheimpflug photography

m In addition to gonioscopy ultmsound biomicmscopy and Scheimpflug photography can be used to measure the imterior chamber angle width. The same subjects were measured with all three diagnostic tools and then the values were compared. v The anterior chamber angle width was measured in eight meridians in bath eyes of 20 volunteers without any history of ophthalmological problems. Gonioswpy was performed osb.< a Goldmann three-mirror contact lens. Scheimpflug photographs were recorded on Kodak T-max 400 black-and-white film using a Topcon 9.45 camera. The chamber angle was messwed with the aid of selfprogrammed PC soflware. Ultrasound biornicroscopic measurements were obtained using a Humphrey UBM 840 system with a 50 MHz transducer. The chamber angle was measured as described by Pavlin et al.. The Scheimpflug photography and ultrasound biomicroscopy data were correlated and analyzed for statistically significant differences using a paired t-test (level of significance P< 0.05) and compared to gonioscopy. Buul$; Cioniascopy only allows the chamber angle width to be graded in classes of IO’. but it does not facilitate morohological examination of all visible struchtres. All n&ods showed similar changes .&d w&e able to document a variation in angle width with regard to location. The correlation between Scheimpflug photography and ultmsoond biomicmscoov was 0.64. In 4 meridians sienifiesnt differences were found between these two &hods. Scheimpflug photography was tivquently unable to visualize directly the angle itself. In cootnwt, ultrasound biomi-py was even able to visualize retmiridial stmctures. All methods are limited by the fact that the anele is defined by curvolincar structures, i.e., posterior comeal surf& and anterior iris s&ace &&&& Gonioxopy allow grading of the chamber angle width and examination of all visible chamber angle stwhres. Scheimpflug photography is also able to document changes in angle configuration despite the limitation of not documenting the chamber angle itself Ultrasound biomicmscopy is a more precise method of measuring angle width bccaose it allows direct visualization of all chamb-z angle stmctwcs. However, as a result of its knavn inability to shoiv minor pathological changes like early angle neovascularization, it should only be used in addition to gonioscopy.