Pathologic myopia is a major cause of irreversible visual impairment worldwide, especially in East Asian countries. META-analysis for Pathologic Myopia (META-PM) classification is an international photographic grading system for myopic maculopathy. However, the diagnosis of diffuse atrophy is solely based on its yellowish appearance and other lesions such as myopic traction maculopathy (MTM) and dome-shaped macula (DSM) are not included. It is important to determine if optical coherence tomography (OCT) can be used as an objective method to assess and classify myopic maculopathy. We analyzed choroidal thickness (CT) at the subfovea and at 3 mm nasal, temporal, superior and inferior to the fovea in 1,487 eyes of 884 highly myopic patients. We found that, as the severity of the myopic maculopathy increased the CT in all locations decreased from normal to tessellated fundus, to peripapillary diffuse choroidal atrophy (PDCA), and to macular diffuse choroidal atrophy (MDCA). However, the CT was not significantly different in eyes with MDCA and with patchy atrophy. For the progression from MDCA to patchy atrophy, other factors than further choroidal thinning such as a development of Bruch membrane holes may be playing an important role. In our series, the subfoveal CT was found to decrease by 1.75 μm per year of age and 9.87 μm per mm of axial length. The choroid was thinnest and maintained at its extreme thinness unless choroidal neovascularization (CNV) -related macular atrophy (MA) developed. We also found that the subfoveal CT was not an independent indicator of the visual acuity, particularly in pathologic myopia and in eyes without CNV. Using receiver operating characteristic curves, we determined that the optimal CT was 56.5 μm nasally for predicting PDCA and was 62 μm subfoveally for predicting MDCA. Combined, these OCT findings in pathologic myopia, can establish OCT-based classification of myopic maculopathy.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 125: 1035-1047,2021.