Abstract
Purpose: :
To compare the anterior chamber morphology between fellow eyes of APACG and normal eyes with shallow anterior chamber depth (ACD), so as to find out the possible predictors in attack of APACG and to define cutoff values for occludable angles (OA).
Methods: :
45 participants were selected in sequence with one eye APACG attack in glaucoma clinics of Beijing Tongren Hospital. Their fellow eyes had no attack history with normal optic nerve head and visual field. Eyes with other anterior segment diseases and secondary glaucoma were excluded. The 43 controls came from the Beijing Eye Study with ACD less or equal to 2.1 mm, of whom with glaucoma, any anterior segment abnormality or with sugery history were excluded. The 2 groups were matched by gender and age. Both groups underwent a complete eye examination. Slit lamp adapted optical coherence tomography (SL-OCT) was used to measure the anterior chamber. ACD, anterior chamber angle (ACA) and angle open distance at 500 microm (AOD500) of four quadrants were measured using software in the apparatus itself. ROCcurve, discriminant analysis and Chi-square test were used in statistical analysis.
Results: :
The area under the ROC curve of anterior chamber depth, anterior chamber angles and means for four quadrants' AOD500 were 0.699, 0.828 and 0.833. From the formula by Discriminant analysis (Y=0.576AODnasal+0.523ACAtemporal +0.466ACD) we could have riginal grouped cases correctly classified more than 80%. According to Shaffer system less or equal to 1 (that is ACA less or equal to 10°) define narrow angle, narrow angle more or equal to 1 quadrant, or 20° as cutoff value for narrow angle, narrow angle more or equal to 2 quadrants define OA, Chi-square test had significance (p=0.003 and 0.008 , respectively).
Conclusions: :
ACA and AOD500 are good predictors for detection APACG in shallow ACD eyes. Using the criteria of ACA ≤ 10° in more than 1 quadrant or ACA ≤ 20° in more than 2 quadrants to define occludable angle are resonable from our statistics. Nasal anterior chamber angle is more significant in the attack of APACG than other three quadrants.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • anterior chamber