advertisement
Detecting the presence and progression of glaucoma in myopia is challenging because of structural changes derived from axial elongation. On the other hand, these structural changes may contribute to the pathogenies of glaucoma. Excessive axial elongation in high myopic eyes leads to temporal dragging and enlargement of the Bruch's membrane opening, which leads to the optic nerve head (ONH) deformation.1,2
Jiang et al. classified characteristics of ONH structural abnormalities into three major types and 12 subtypes in a large cohort of 1389 eyes with non-pathologic high myopia by utilizing swept-source optical coherence tomography (SS-OCT). Peripapillary hyperreflective ovoid mass-like structure (PHOMS), visible retrobulbar subarachnoid space, and prelaminar schisis were the most common subtypes, respectively. More importantly, the association of these features was assessed with visual field (VF) defects of which the characteristics were subdivided into glaucomatous and myopic changes. Glaucoma-like VF defects were common in eyes with deep optic cups and optic disc pit/pit-like change, while myopia-related defects were commonly found in those with PHOMS, peripapillary retinal detachment, and peripapillary retinoschisis. This large cohort study provides an essential reference for assessing morphologic and functional features of eyes with high myopia, especially regarding glaucomatous damage.
Of note, this study raises the question of whether high myopes with glaucomatous VF defect are 'glaucomatous optic neuropathy' or 'high myopic optic neuropathy'. Several myopic eyes with glaucoma-like morphologic changes of the lamina cribosa (LC), retinal nerve fiber layer (RNFL), and VF defects were reported to have stable disease status.3,4 The differentiation of the two disease entities is important for the decision of the treatment and underlying mechanism of glaucomatous optic neuropathy. Although OCT findings including LC, Bruch's membrane opening, and anterior scleral canal features, and OCT angiography findings such as patterns of superficial and deep-layer microvasculature can be a candidate to distinguish glaucomatous from myopic optic neuropathy,1 it is still challenging because of the complexity and compounding mechanisms of the two disease entities. Future large-scale longitudinal prospective studies and detailed assessment of the ONH morphology are warranted.