External limiting membrane angle as a composite predictive index for post-operative ELM closure in full thickness macular holes

Aim: To evaluate pre-operative qualitative and quantitative parameters of external limiting membranes (ELM) and other associated full thickness macular holes (FTMH) features and their predictive values for post-operative anatomical and functional outcomes.

Methods: This was a retrospective study of 48 eyes that underwent vitrectomy with internal limiting membrane (ILM) peeling for FTMH and had type 1 closure. All subjects underwent optical coherence tomography (SDOCT, Heidelberg, Spectralis), and the eyes were divided into complete ELM closure (CEC) and incomplete ELM closure (IEC) groups based on the post-operative OCTs within 2 months, and ROC curves were used to estimate which of the pre-operative parameters could best predict eyes falling in the CEC group.

Results: The mean pre-op ELM defect was smaller in CEC group (594 μm vs 1126 μm, p < 0.001) and so was the pre-op EZ defect (770 μm vs 1186 μm, p = 0.001). The mean ELM angle also was smaller in the CEC group (51.6° vs 102.5°, p < 0.001) and so was the mean hole inlet distance (353 μm vs 596 μm, p < 0.001). The post-operative ELM defect showed a significant negative correlation with visual acuity (r = - 0.319; p = 0.027). The ELM angle was most predictive with an AUROC of 0.958, and a cut-off of 68.3° had a sensitivity of 90% and a specificity of 89%.

Conclusion: Our study introduces a novel parameter called the ELM angle and proves that it has a high sensitivity and specificity in predicting complete ELM reformation post-surgery in the short term as well as the long term.