We read with interest the article “Clinical Characteristics of Posterior Staphylomas in Myopic Eyes With Axial Length Shorter than 26.5 Millimeters” by Wang and associates. In their study, the authors discuss clinical and imaging features of 16 eyes with posterior staphyloma, which do not fit the criteria for pathologic myopia.
The study is indeed interesting and provides newer insights into pathogenesis of posterior staphyloma in general. The authors propose their findings to be a part of “atypical form of pathologic myopia, which share a similar pathogenesis derived from decreased choroidal thickness.” However, it may be difficult to relate posterior staphyloma as the cause or the effect of decreased choroidal thickness, as even the mean axial length of these patients was around 25 mm, only marginally above the normative distribution. This minor difference can be explained even by shallow posterior staphylomas themselves rather than a generalized elongation of the eyeball. The posterior pole changes like “chorioretinal atrophy, Fuchs spots, and macular retinoschisis” noted by the authors can also be due to the focally elongated eyeball in the region of the staphyloma. Previous studies have noted “posterior staphyloma as the cause of the development of myopic maculopathy and not the reverse.” Hence these cases may be an independent entity in themselves, an idea also pondered by the authors, because the major mechanical support preventing ectasia is sclera, and perhaps its weakening with concurrent aging might be the cause of the disease. Previous literature, too, hypothesizes changes in scleral collagen to be associated with the pathogenetic factors, including inheritance in myopia development. Therefore, genetic evaluation of such patients might reveal susceptibility of these individuals to scleral thinning and exaggerated loss of scleral support owing to aging.
A retrospective or a cross-sectional design might lead to difficulty in deciding between the cause–effect relationship of posterior staphyloma. However, if the authors have noted presence of peripheral retinal degenerations or severe peripheral diffuse choroidal thinning away from the staphylomatous area, it would strengthen their conclusions of the staphyloma being an atypical presentation of pathologic myopia. It would really be valuable if an optical coherence tomography–based analysis of the choroid at the junction of the staphyloma with “normal” eyeball could be done to support such a theory.
The authors have presented a unique group of cases of posterior staphyloma and we hope our observations add value to their discussion.