Cluster analysis reveals patterns of age‐related change in anterior chamber depth for gender and ethnicity: clinical implications

Abstract

Purpose To identify patterns of age‐, gender‐ and refractive‐ related changes in Scheimpflug‐based anterior chamber depth across the central 8 mm of chamber width, to derive normative models, potentially useful for angle closure disease diagnosis. Methods This was a retrospective, cross‐sectional study. Scheimpflug photography was used to obtain anterior chamber depth measurements at 57 points across the central 8 mm of the chamber width from one eye of each healthy subject (male Caucasians (n = 189), female Caucasians (n = 186), male Asians (n = 165) and female Asians (n = 181)). Sliding window and nonlinear regression analysis was used to identify the age‐related changes in chamber depth. Hierarchical cluster analysis was used to identify test locations with statistically identical age‐related shifts, which were used to perform age‐correction for all subjects, resulting in normative distributions of chamber depth across the chamber width. The model was examined with and without the contribution of spherical equivalent refractive error. Results Distinct clusters, demonstrating statistically indistinguishable age‐related changes of chamber depth over time, were identified. These age‐related changes followed a nonlinear regression (fifth or sixth order polynomial). Females tended to have a greater rate of chamber depth shallowing. Incorporating refractive error into the model produced minimal changes to the fit relative to the ground truth. Comparisons with cut‐offs for angle closure from the literature showed that ageing alone was insufficient for identifying angle closure disease. Conclusions Age‐, ethnicity‐ and gender‐related differences need to be acknowledged in order to utilise anterior chamber depth data for angle closure disease diagnosis correctly. Ageing alone does not adequately account for the angle closure disease process.

Prevalence of Primary Angle Closure Glaucoma in the Last 20 Years: A Meta-Analysis and Systematic Review

“…Various studies had associated shallow anterior chamber and narrow chamber angle with female sex ( 67 – 69 ). Moreover, females were shown to have greater ACD shallowing with aging than males ( 70 ). The mean ACD values were significantly different from men [2.59 mm (2.56; 2.62)] to women [2.42 mm (2.39; 2.44)] in elderly Chinese (older than 50 years old) ( 71 ).…”

Anterior Chamber Angle Assessment Techniques: A Review

“…Indeed, previous studies have demonstrated a poor correlation between gonioscopic angle grading and other quantitative measurements, when evaluating angles that are at the edges of the ordinal gonioscopic scale, i.e., closed/narrow angles and wide-open angles [25,70]. As a consequence, while differentiating between very narrow and wide-open angles may be obvious for the clinician, and consequently highly repeatable, classification of the anatomical continuum between these two extremities into an ordinal gonioscopic scale may be difficult, if not impossible [70,71].…”

“…A major issue with SP and other non-contact imaging techniques (e.g., AS-OCT), is the lack of normative databases, against which the acquired data may be compared. Other than decreasing diagnostic accuracy [71], this may be perceived as a strong limitation, especially by the general clinician in search of clear advice in every-day clinical practice. Building a normative database for these instruments may be challenging.…”

“…Building a normative database for these instruments may be challenging. Indeed, since ACA parameters are influenced by age, gender, ethnicity, refractive errors, and other anthropomorphic characteristics, specific patterns of changes related to these factors should be acknowledged, in order to derive normative models, useful in the diagnosis of anterior chamber pathological changes [71].…”

Letter to the Editor

“…This is in reference to the recent article entitled"Cluster analysis reveals patterns of age-related change in anterior chamber depth for gender and ethnicity: clinical implications". 1 We read this article, which deepens understanding of expected changes in anterior chamber depth (ACD), with great interest. The authors mentioned that while skilled gonioscopy is the gold standard for angle evaluation, an objective measurement provided by superior technology such as the rotating Pentacam Scheimpflug camera (Oculus, www.pentacam.com) is not a substitute, but a valuable complementary measurement to complete glaucoma and anterior chamber assessment.…”