We thank Drs Azad and Takkar for their interest in our article. We believe that posterior staphyloma in eyes with axial length shorter than 26.5 mm can be considered either as an “atypical form of pathologic myopia” or as “another disease entity” resulting from age-related scleral changes.
We examined a large series of patients with extreme myopia and found that posterior pole changes usually developed in eyes with decreased choroidal thickness. We have shown previously that choroidal thickness is a better indicator of the severity of myopic maculopathy than axial length or refractive error. Further study showed that choroidal thickness has the strongest association with lacquer crack formation vs axial length and refractive error. Drs Azad and Takkar cited the statement “posterior staphyloma as the cause of the development of myopic maculopathy and not the reverse” from a review article by Silva, which cited a study by Hayashi and associates. In fact, the latter study found that posterior staphyloma was observed more frequently in eyes that showed progression than in those without it. In that study, a posterior staphyloma was identified in 65.8% of eyes with myopic maculopathy; therefore, not all the eyes with myopic maculopathy had a posterior staphyloma.
Next, Drs Azad and Takkar stated that posterior pole changes such as “chorioretinal atrophy, Fuchs spots, and macular retinoschisis” can also be caused by a focally elongated eyeball in the region of the staphyloma. In our study, patients presented with a low degree of myopia and some patients did not have it before their 40s. Lateral protrusion and angulation could be detected in 3-dimensional magnetic resonance imaging (3D-MRI) of some eyes among our cases, which have not been reported in eyes with a high degree of myopia. Patients in our study usually presented for decreased vision resulting from maculopathy, and peripheral eyeball changes—which do not cause visual disturbances—can only be identified by 3D-MRI. We assumed that some genes might be involved in changes in scleral susceptibility during aging, which result in similar macular pathology at older ages as seen in pathologic myopia. However, these genes are not necessarily the same as those involved in the development of myopia because there is no obvious axial elongation, and the eyes show different clinical features.
In this study, we showed decreased choroidal thickness and reflectivity in the ellipsoid zone using spectral-domain optical coherence tomography (SDOCT) scans through the areas and junctions of staphylomas (Figures 1–3). The SDOCT technique can show decreased choroidal thickness in very myopic eyes; however, decreased reflectivity in the ellipsoid zone is not common in such eyes without a staphyloma. Although our study was the first to demonstrate this unique group of cases, it could not arrive at a firm conclusion on the pathophysiology involved, because it was a retrospective cross-sectional study.