Optic nerve head drusen

A 16-year-old boy presented with blurring of vision in both eyes for 6 months. On evaluation, OU best-corrected visual acuity was 6/6 partial, the anterior segment was normal, intraocular pressure (IOP) was 14 mmHg in both eyes, and fundus examination showed OU elevated disc margins with a lumpy appearance, Cup disc ratio (CDR) 0.1, with the rest of the fundus within normal limits. Ultrasonography revealed well-defined echogenic foci at the optic nerve head. Optical coherence tomography (OCT) showed a hyporeflective core with a hyperreflective cap. Perimetry revealed enlargement of the blind spot with depression of the temporal field in the right eye and enlargement of the blind spot with generalized constriction of fields in the left eye as shown in Figures 1 and 2.Figure 1: Right eye showing optic nerve head drusen: (a) color photo, (b) EDI optical coherence tomography, (c) ultrasound, (d) 24-2 Humphrey visual field grayscale, (e) pattern deviation mapFigure 2: Left eye showing optic nerve head drusen: (a) color photo, (b) EDI optical coherence tomography, (c) ultrasound, (d) 24-2 Humphrey visual field grayscale, (e) pattern deviation mapOptic nerve head drusen (ONHD) derives its name from the German word “geodes” which are benign acellular calcium concretions deposited anterior to the lamina cribrosa. Optic nerve drusen are benign acellular calcium concretions deposited anterior to the lamina cribrosa. ONHD imply disruption of axoplasmic flow in the orthograde direction. Electron microscopy suggests intra-axonal calcium phosphate accumulation with rupture of axons and release of calcium into the interstitium.[1] ONHD are closely associated with retinitis pigmentosa, angioid streaks, and Alagille syndrome. IOP should be closely monitored, as preexisting field defects due to ONHD can confuse the diagnosis of glaucoma.[2] ONHD can cause peripapillary hemorrhage secondary to a compressive effect on peripapillary vessels. However, it is benign and tends to resolve on its own. A more serious complication is Choroidal Neovascular Membrane (CNVM). While OCT and OCT angiography are commonly used for diagnosis, Fundus auto fluorescence (FAF) can be a reasonable option. Subretinal fluid from active CNVM usually presents as hypoautofluorescence, while disciform scarring or fibrosis presents as uneven autofluorescence of the lesion surrounded by hyperautofluorescence. Intravitreal antivascular endothelial growth factor agents are used for the treatment.[3] Patients with ONHD can develop resultant Non-arteritic anterior ischemic optic neuropathy (NAION) as the ONHD crowd the disc even more, leading to a further decline in perfusion pressure. Such NAION is more common in young patients with favorable outcomes compared to traditional NAION. Differential diagnoses include optic disc edema, meningioma, glioma, or astrocytic hamartoma. Although most cases are benign with no visual sequelae, clinicians should be aware of the potential complications that can arise, including vision and field loss, and promote frequent examinations. Multimodal imaging, such as OCT and FAF in addition to standard visual field testing, is strongly suggested in the management of patients with ONHD and ONHD-associated complications. Data availability statement Data will be made available on reasonable request to the corresponding authors. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.