Subtypes of primary angle closure disease based on age-independent anterior segment optical coherence tomography parameters.
Umapathi Ruthra, Yu Marco, Cheng Ching-Yu, Najjar Raymond P, Husain Rahat, Ho Ching Lin, Wong Tina T, Boey Pui Yi, Perera Shamira, Vithana Eranga N
AI Summary
This study identified three distinct angle closure subtypes using ASOCT. A spacious anterior chamber subtype was linked to stable PACS, while smaller dimensions were associated with glaucoma progression.
Abstract
Objective
To identify subgroups of angle closure disease by considering age-independent anterior segment parameters.
Methods
Anterior-segment optical coherence tomography (ASOCT) was performed in primary angle closure suspect (PACS) and primary angle closure glaucoma (PACG) patients. Clustering analysis using age-independent parameters, anterior chamber width (ACW), anterior vault (AV), posterior corneal arc length (PCAL), and iris area was performed. The optimum number of subgroups was determined using Bayesian Information Criterion and subjects were classified into subgroups by Gaussian Mixture Model methods.
Results
A total of 650 PACS and 411 PACG were analysed. The optimal number of subgroups of the combined PACS and PACG dataset was 3. Subgroup 1 (n = 186, 29.3%) has the largest anterior chamber dimension with large AV and total anterior chamber area, subgroup 2 (n = 16, 2.5%) has the widest ACW and shallowest anterior chamber depth (ACD), and subgroup 3 (n = 432; 68.1%) has large iris area with the smallest anterior chamber dimensions, characterised by a small ACW, AV, and PCAL. Subgroup 3 comprised a significantly greater proportion of PACG compared to PACS (74.2% vs 64.6%, p = 0.04) while subgroup 1 had the greatest proportion of PACS ≥ 70 years old, yet to have progressed to PACG.
Conclusion
We identified 3 subgroups of angle closure eyes, each characterised by distinct structural components based on ASOCT. A greater proportion of older PACS yet to have progressed to PACG belonging to the subgroup with the largest anterior chamber dimensions suggests that a more spacious anterior chamber may be associated with PACS that remains stable.
MeSH Terms
Shields Classification
Key Concepts6
Subgroup 1 (n = 186, 29.3% of combined PACS and PACG dataset) was characterized by the largest anterior chamber dimension with large anterior vault and total anterior chamber area.
Subgroup 2 (n = 16, 2.5% of combined PACS and PACG dataset) was characterized by the widest anterior chamber width and shallowest anterior chamber depth.
Subgroup 3 (n = 432, 68.1% of combined PACS and PACG dataset) was characterized by a large iris area with the smallest anterior chamber dimensions, specifically a small anterior chamber width, anterior vault, and posterior corneal arc length.
Subgroup 3 comprised a significantly greater proportion of primary angle closure glaucoma (PACG) patients compared to primary angle closure suspect (PACS) patients (74.2% vs 64.6%, p = 0.04) in a combined dataset of 650 PACS and 411 PACG patients.
Subgroup 1, characterized by the largest anterior chamber dimensions, had the greatest proportion of primary angle closure suspect (PACS) patients aged ≥ 70 years old who had not yet progressed to primary angle closure glaucoma (PACG), suggesting that a more spacious anterior chamber may be associated with stable PACS.
Clustering analysis using age-independent anterior segment parameters (anterior chamber width, anterior vault, posterior corneal arc length, and iris area) identified 3 optimal subgroups among 650 primary angle closure suspect (PACS) and 411 primary angle closure glaucoma (PACG) patients.
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