No abstract

Glaucoma is a heterogeneous group of optic nerve diseases with a global prevalence of 3.54% in individuals aged 40-80 years and is the leading cause of irreversible blindness (Kolko et al., 2015;Tham et al., 2014). Normal tension glaucoma (NTG) is a subtype of primary openangle glaucoma (POAG) characterized by progressive optic neuropathy despite untreated intraocular pressure (IOP) in the statistical normal range (Weinreb & Tee Khaw, 2004). In addition to IOP ≤21 mmHg, the diagnostic criteria are based on structural and functional parameters, such as retinal nerve fibre layer (RNFL) thinning, disc cupping of the optic nerve head (ONH), narrowing of the neuroretinal rim and visual field loss (VFL). Glaucomatous VFL can be described as progressive reduction of the visual field; typically in patterns affecting already abnormal areas both in the macula and more peripheral regions, even in early glaucomatous damage (De Moraes et al., 2017). Optic disc drusen (ODD) are calcified deposits consisting of extruded axonal material located in the prelaminar region of the ONH (Hamann et al., 2018). A prevalence of ophthalmoscopically visible ODD of 0.2%-0.3% has been reported in clinical studies, while autopsy studies have reported ODD prevalence of 1.8%-2.0%, indicating a more frequent occurrence of buried (non-visible) ODD (Friedman et al., 1975;