Anterior chamber angle imaging with Automatic Gonio-Photography

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Abstract Purpose : ssessing the anterior chamber angle (ACA) is essential when evaluating patients with suspected or diagnosed glaucoma. The aim of this study was both to assess inter-observer agreement on Automatic Gonio-Photography (AGP) - true color images of the ACA - and inter-device agreement by comparing AGP to gonioscopy. Methods :prototype AGP device (Gonioscope NGS-1; Nidek Technologies srl) was used to acquire 360-degree images on both eyes of twenty consecutive patients recruited from the glaucoma service at the University Eye Clinic of Genoa (Italy). Two masked observers graded the apparent iris insertion for each of the four quadrants of the ACA and reported ACA abnormalities in AGPs randomly presented. All patients underwent dynamic gonioscopy and the 4 quadrants were graded again using the Spaeth Classification. Inter-observer and inter-device agreement for apparent iris insertion were determined by using Cohen's linearly weighted κ (KW) coefficient of concordance. Statistical analysis was performed using MedCalc 15.11 (MedCalc Software, Ostend, Belgium). Results : wenty (12.5%) of the 160 quadrants were excluded from statistical analysis because of poor image quality. AGP showed substantial inter-observer agreement (KW, 0.77; 95% CI, 0.67-0.87) with regards to apparent iris insertion. Both observers correctly identified ACA abnormalities, i.e. iridotrabecular contact in two or more quadrants (5), iridectomy (3), internal ostium of the trabeculectomy site (2), EX–PRESS® device (1), tube (1), anterior chamber IOL (1), and angle recession (1). All abnormalities were confirmed at gonioscopy. Differentiating between appositional and synechial iridotrabecular contact was only possible with dynamic gonioscopy. Results of AGP and gonioscopy showed almost perfect inter-device agreement on apparent iris insertion evaluation (KW, 0.92; 95% CI, 0.86 to 0.98). Conclusions :P using the NGS-1 gonioscope is a reliable method for assessing apparent iris insertion and proved useful in detecting pathological and postoperative ACA findings in glaucoma patients. This technique also appears to be reliable when recording ACA structures. This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016. Angle recession obtained with AGP.

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