Abstract
Purpose :
Anterior segment optical coherence tomography (AS-OCT) is a non-contact imaging method that yields quantitative measurements of intraocular structures. Numerous AS-OCT parameters have been introduced to describe features of the anterior chamber and iridocorneal angle. A number of these parameters have been identified as risk factors for primary angle closure glaucoma (PACG), the most severe stage of primary angle closure disease (PACD). This study examines the correlations between AS-OCT parameters and how these relationships vary based on stage of PACD.
Methods :
AS-OCT and clinical data were derived from the Chinese American Eye Study, a population-based study conducted in Los Angeles, CA. Four AS-OCT images per eye were analyzed for 634 subjects in four clinical categories: normal (n = 79), primary angle closure suspect (PACS, n = 439), primary angle closure (PAC, n = 105), and PACG (n = 11). Angle parameters included angle opening distance (AOD), angle recess area (ARA), trabecular iris space area (TISA), trabecular iris angle (TIA), scleral spur angle (SSA). Anterior chamber parameters included iris curvature (IC), iris area (IA), anterior chamber depth (ACD), lens vault (LV), anterior chamber width (AW), pupil diameter (PD). Relationships between pairs of AS-OCT parameters were calculated using Pearson correlation coefficients (PCC) and 1-Pearson hierarchical clustering.
Results :
All angle parameters were strongly correlated in the normal eye (PCC > 0.90). Dense clustering (node distance < 0.27) of all angle parameters except TIA persisted regardless of PACD severity. The strength of correlation between angle parameters and most anterior chamber parameters varied with PACD severity. ACD, which was positively correlated with angle parameters in normal eyes, became negatively correlated in PACG. IC and IA, which were negatively correlated with angle parameters in normal eyes, became positively correlated in PACG. ACW and PD were uncorrelated in normal eyes and negatively correlated in PACG. Correlations of LV with angle parameters remained relatively stable.
Conclusions :
Correlations between AS-OCT parameters are dynamic and vary with severity of angle closure. The relative contributions of different anatomical features to angle closure may help to differentiate between different stages of PACD.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.