Abstract
Purpose: :
The angle opening is important parameter of glaucoma. Van Herick technique is a simple method in routine examination and gonioscopy is a gold standard method for evaluating the angle opening, but these evaluations are objective and qualitative even examiner-dependent. We developed quantitative and objective evaluating system of the angle opening using data provided by Scanning Peripheral Anterior Chamber Depth Analyzer (SPAC). We compared the angle opening determined by SPAC, Van Herick technique, or Shaffer grading system. We also compared the difference in angle opening between Japanese population and Singapore population.
Methods: :
SPAC mathematically calculated the angle opening using three anterior chamber depth values measured at most peripheral region. The angle opening of 63 Japanese glaucoma patients evaluated by Shaffer grading system or Van Herick technique by glaucoma specialists was compared with that by SPAC. One thousand forty-eight Singaporean subjects visiting community polyclinic and 1098 Japanese subjects visiting public health examinations in Yamanashi were enrolled to compare racial difference in the angle opening.
Results: :
There was a significant correlation between the angle opening and SPAC providing numeric grading in both populations (correlation coefficient r>0.90). The angle opening also showed a significant correlation with the Van Herick technique and the Shaffer grading system. The angle openings of Japanese and Singaporean were 25.5±5.5 degree and 28.9±8.8 degree, respectively (p>0.05). When comparing two populations, there was no significant difference in the angle opening of eyes whose grades were same or less than seven, while Singaporean eyes showed wider angle opening than Japanese eyes when their grade was more than seven.
Conclusions: :
The angle opening determined by SPAC has s good correlation with that by other conventional methods. There was racial difference in angle opening.
Keywords: anterior chamber • imaging/image analysis: clinical • anatomy