Fig. 2From: Postoperative results of ventilation tube insertion: a retrospective multicenter study for suggestion of grading system of otitis media with effusionComparison of the nature of the middle ear effusion. The ratio of non-glue to glue ear was 78% and 22% in grade I, 54% and 46% in grade II, 50% and 50% in grade III, 32% and 68% in grade IV, and 38% and 62% in grade V, respectively. Statistically, the higher the grading, the higher the ratio of glue ear (p < 0.001)Back to article page