PurposeTo compare the structural changes, clinical course, and treatment outcomes of vertical and horizontal vitreomacular traction (VMT) induced impending macular holes (IMHs) and full-thickness macular holes (FTMHs).MethodsIn this retrospective study, 23 and 32 cases of IMHs and FTMHs, respectively, were analyzed. The IMH cases were divided into two subgroups: IMH with and without foveal detachment. Vitreofoveal traction angles (TAs) between the inner retinal surface and posterior hyaloid were measured from horizontal and vertical optical coherence tomography (OCT) images by using the trigonometric function (the angle equals the arctangent of the height over the base) after adjustments for magnification factors. The largest angle was defined as the vitreomacular TA for the examined case. The critical angle-the TA differentiating cases with (vertical traction) or without (horizontal traction) foveal detachment (vertical traction)-was determined using regression analysis. Pretreatment and posttreatment OCT images, clinical courses, and treatment outcomes were compared between the two groups.ResultsThe critical angle was 27.2°. Cases of vertical traction had higher foveal height in the IMH group and wider bases in the FTMH group (P<0.05 respectively). IMHs with vertical traction had greater VM attachment than those with horizontal traction. In the FTMH group, postoperative visual improvement was lower (P=0.002); in the vertical traction group, inner segment:outer segment defects persisted longer (P=0.02).ConclusionsThe critical angle separating vertical from horizontal traction was 27.2°. Vertical VMT results in greater foveal structural changes in IMHs and possibly less favorable surgical outcomes in FTMHs.