Is axial length a risk factor for idiopathic macular hole formation?

Current theories for macular hole formation implicate antero-posterior and tractional forces at the vitreofoveal interface. It is thought that localized perifoveal defects enlarge from centrifugal forces acting about the axis of ocular rotation. If this is true, eyes with longer axial lengths should have an increased incidence of macular holes. The aim of this study was to determine if axial length is a risk factor for macular hole development. The study group comprised 40 patients with refractive errors from hyperopia to myopia with stage 3 and 4 idiopathic macular holes. Controls matched for age, gender and spherical equivalent (SE) were used for statistical comparison. Axial length (AL) was analyzed using SPSS 13.0 statistical software and compared using Student's t test. P < 0.05 was considered significant. SE ranged from -8.88 to +3.63 dioptres in the macular hole group and -8.50 to +3.63 in controls. In the macular hole group, mean AL ± standard deviation was 23.62 ± 1.20 mm (21.81-27.51); in controls, 23.09 ± 1.16 mm (21.31-26.58). Univariate analysis showed that higher AL is associated with macular hole formation. The mean difference in AL was 0.531 mm (95 % confidence interval -0.1596 to -0.9024). Two-tailed t test: P < 0.006. This study showed that increasing ocular AL is significantly associated with macular holes. Dynamic forces at the macula would be greater in these eyes suggesting this may play a causative role in macular hole formation.