Correlation between functional staging and DDLS in primary open angle glaucoma patients in Vietnam

Background: Clinically, there are many systems of visual field staging parallel exist. The agreement between glaucoma function and appearance is still uncertain. This study was to compare visual field staging classifications (as function staging) with disc damage likelihood scale (DDLS as appearance staging) in primary open angle glaucoma (POAG). Methods: Cross-section study on 55 patients (90 eyes) examined and treated in Vietnam National Institute of Ophthalmology from 9/2016 – 9/2017. The MD (mean deviation), PSD (pattern standard deviation), VFI (visual field index) indexes were recorded and were used to classify glaucoma staging according to categories of eGSS (enhance glaucoma severity staging), mGSS (modified glaucoma severity staging), HPA (Hoddaps – Palmela – Adersons), AGIS (advance glaucoma intervention study) and DDLS. Using SPSS 16.0 software, statistically significance was tested with proper tests as Chi – square test, Fisher exact test, Kappa (to assess the agreement - disagreement), Spearman Rank (to assess the level of correlation). Results: Mean visual field indexes were -11.49 dB (MD), 5.85 dB (PSD), 74.2% (VFI). Compared to the DDLS, all systems had slight agreement (K < 0.2). The disagreement percentage was highest in eGSS (70%) then followed by mGSS (50%) and HPA (48.9%). In terms of definitive diagnosis, HPA and mGSS showed a substantial agreement (K > 0.6) with AGIS which is higher than that between eGSS and AGIS (retrospectively 0.773 and 0.75 vs 0.399) with p < 0.001. In terms of staging detection, the agreement between HPA &mGSS and AGIS was substantial (K > 0.6) while that between eGSS and AGIS was fair (K < 0.4). Conclusion: mGSS and HPA tend to show the stronger agreement with standard classifications than eGSS. mGSS should be used in clinical practice and research.