Scanning laser tomography of full thickness idiopathic macular holes.

Aim: We used a retinal tomographic analyser to study the profile of the retinal surface in patients with stage 3 and 4 idiopathic macular holes, to attempt to elucidate the direction of forces present.

Methods: The Heidelberg retina tomograph was used to acquire a three-dimensional tomographic image of the macula in each eye of 21 consecutive patients with full thickness macular hole.

Results: The surface profile showed an elevated rim around the 24 macular holes imaged, with a gently sloping outside edge and a steeply sloping inside edge. In addition, a ring of elevated tissue around the edge of the hole was observed in all the holes and also in two of the fellow 'normal' eyes. This ring of elevated tissue was presumed to represent a ring of persistent vitreo-retinal traction around the fovea in the presence of a perifoveal posterior vitreous detachment. This is consistent with antero-posterior traction persisting in stage 3 and 4 full thickness macular holes. The mean ring diameter was 480 mum, when present in the fellow eye but was 950 microm in the presence of a macular hole, which we argue is suggestive of centrifugal displacement of retinal tissue on the formation of a stage 3 macular hole and provides evidence for tangential traction.

Conclusion: We suggest that antero-posterior traction forces are the primary cause of full thickness macular holes, with these forces persisting in stage 3 and 4 macular holes, while tangential forces serve to enlarge the hole at this later stage.