Background/Objectives: Posterior staphyloma (PS) is a hallmark of pathological myopia
corresponding to a circumscribed outpouching of the eyeball with choroidal thinning and inward
scleral deformation at its edges. Its pathogenesis is still unclear, thus constituting a research priority
as the prevalence of myopia is increasing worldwide. Recently, it has been suggested that the optic
nerve sheaths or oblique muscles are potential promoters of PS through the traction or compression
effect that they apply to the eye wall. The inferior oblique muscle (IOM) inserts 1-2 mm from the
macula. The projection of its insertion is accessible by Optical Coherence Tomography (OCT).
Before launching prospective studies, we sought to detect any choroidal thinning (ChT) in the
temporal vicinity of the macula and to measure the distance between it and the fovea (FT-distance).
Methods: This retrospective cross-sectional pilot study included 120 eyes. Using Spectralis-OCT,
the area centered by the Bruch’s membrane opening-fovea axis was analyzed for ChT and FT-
distance. Results: Of the 112 defined eyes, 70% (78 eyes) had ChT. Pachymetry was significantly
thinner (p = 0.018) in eyes with than without ChT. The mean FT-distance was 3601.9 ± 93.6µm.
Conclusion: The location of ChT coincided with the insertion distance of the IOM, suggesting a link between them. The association between the presence of ChT and thinner pachymetry suggests reduced scleral resistance as thinner pachymetry is related to thinner sclera. Our results support a possible involvement of the IOM in the pathogenesis of certain PS, warranting further investigation.