History

• 29-year-old obese female with chief complaint of her vision being “foggy on the right side”
• Also complaining of chronic frontal headaches and tinnitus
• Denies any trauma or new medications

Exam Findings

• VA: 20/20; 20/20
• IOP: 14 /12
• Pupils: RR OU, no RAPD
• EOM: full, color plates full
• SLE: unremarkable

Differential Diagnosis

• Pseudopapilledema (PPE): optic nerve head drusen
• True Papilledema (PE):
• Idiopathic intracranial hypertension
• Intracranial mass lesion
• Meningitis

Additional Investigations

Diagnosis

• Optic nerve head drusen (ONHD)

Pathophysiology

• ONHD are homogenous, globular concretions within the optic nerve head (1) composed predominately of mucopolysaccharides and proteinaceous material that accumulate anterior to the lamina cribrosa. The primary pathology appears to be an inherited dysplasia of the optic canal or optic disc and its vasculature, impeding normal axonplasmic flow leading to abnormal metabolism with disposition of calcium crystals in mitochondria, which are extruded into the extracellular space. Continuous calcification coalesces to form drusen.

Treatment

• Management goals should focus first on differentiating PPE from true PE
• Buried ONHD produce elevation of the disc and blurring of its margin, mimicking optic nerve head edema. Major features differentiating ONHD include: lack of hyperemia, lack of disc surface microvascular abnormalities and visible retinal vessels at the disc margin.
• Ancillary testing can aid in differentiating PPE and true PE. Fundus photos, fluorescein angiography (FA), fundus autofluorescence (FAF), B-scan ultrasound, CT scan and OCT can all be used to aid in diagnosis.
• FA: true PE may show leakage at the optic disc
• AF: hyper-autofluorescence of superficial optic nerve head drusen
• B-scan: drusen appear as hyperechogenic masses on the optic nerve head with posterior shadowing
• CT scan: drusen appear as areas of increased density at the site of an ONHD
• OCT: drusen appear as focal hyperreflective subretinal masses with adjacent retinal elevation
• Most patients are asymptomatic. They are monitored with serial visual fields, optic nerve fiber analysis and repeat intraocular pressure measurements.
• Treat complications: anterior ischemic optic neuropathy (AION), retinal vascular occlusions, juxtapapillary choroidal neovascularizations

Prognosis and Future Directions

• The evolution of disc drusen is a dynamic process and continues throughout life, (1). During childhood, the affected optic disc appears to become more “full” and acquires a tan or yellowish straw color. The buried drusen gradually impart a scalloped appearance to the margins of the disc and produce subtle excrescences on the disc surface. As they enlarge, they can deflect retinal vessels overlying the disc. In adulthood, the disc elevation diminishes, the disc becomes pale and nerve fiber layer thins. The evolution reflects a slow attrition of the optic axons over decades. The visual prognosis is generally good and patients are observed.
• Recent studies hope to identify the most accurate methodology to classify true PE from PPE and analyze misinterpretation rates, (7). Investigators found FA was superior for classifying pediatric eyes as true PE or PPE owing to the existence of leakage as a clear and easily evaluated marker for true edema.
• Optic nerve head drusen: Clinical tips
• A diagnosis of exclusion
• Rule out treatable conditions such as papilledema and glaucoma
• Vast majority of patients are asymptomatic
• Slow progressive peripheral vision loss over years (inferonasal), enlarged blind spot
• Transient obscurations of vision
• No known effective treatment
• More vulnerable to borderline or high IOP?
• Ocular associations (choroidal neovascularization, AION, RP, angioid streaks)
• Slightly more satisfying diagnosis than idiopathic
• Papilledema vs pseudo-papilledema: Clinical tips for diagnosis
  Methods to make the diagnosis:
• Ultrasound exam
• FA
• CT scan
• Lumbar Puncture
• OCT
• OCT findings in optic nerve drusen:
• Optic nerve drusen
• “lumpy-bumpy” internal contour
• Abrupt transition of subretinal hyporeflective space (SHYPS)
• Normal, mildly increased NFL
• Papilledema
• Smooth internal contour
• V pattern transition of SHYPS
• Thicker NFL

References

• Miller NR, Subramanian PS, Patel VR. Walsh & Hoyt’s Clinical Neuro-ophthalmology, The Essentials, Third Edition. Wolters Kluwer. 2016:61-69.
• Benjamin I, Aleksandar LJ. Congenital and acquired anomalies of the optic nerve head. 3rd ed New York: McGraw-Hill. 2002:209-315.
• Auw-Haedrich C, Staubach F, Witschel H. Optic disc drusen. Surv Ophthalmol. 2002;47(6):515-532.
• Tso M. Pathology and pathogenesis of drusen of the optic nerve head. Ophthalmology. 1981;88:1066-1080.
• Sarac O, Tasci YY, Gurdal C, Can I. Differentiation of optic disc edema from optic nerve head drusen with spectral-domain optical coherence tomography. J Neuroophthalmol. 2012 Sep;32(3):207-11.
• Lee AG, Zimmerman MB. The rate of visual field loss in optic nerve head drusen. Am J Ophthalmol. 2005 Jun;139(6):1062-1066.
• Chang MY, et al. Accuracy of Diagnostic Imaging Modalities for Classifying Pediatric Eyes as Papilledema versus Pseudopapilledema. Ophthalmology. 2017.06.016 [Epub ahead of print].

Contact

• Jonathan Kim, MD, Associate Professor of Clinical Ophthalmology, jonkim@chla.usc.edu
• On-Tat Lee, MD, PGY-4 Ophthalmology resident, on-tat.lee@med.usc.edu

Section Editors

• Vivek Patel, MD, Associate Professor of Clinical Ophthalmology, Program Director, vivek.patel@med.usc.edu
• Jesse Berry, MD, Assistant Professor of Clinical Ophthalmology, Associate Program Director, jesse.berry@med.usc.edu

Produced by: Monica Chavez, John Daniel, Joseph Yim and Dr. Vivek Patel