Clinical Challenge

Ophthaproblem

Stephanie Baxter, MD  Sanjay Sharma, MD, MSC, MBA, FRCSC

A healthy 23-year-old woman came to her family doctor complaining of headaches. Funduscopic examination revealed an abnormality in both her eyes.

The clinical history and the appearance of her optic disks is compatible with the patient’s having which of the following?

1. Optic atrophy
2. Glaucoma
3. Papilledema
4. Pseudopapilledema

Dr Baxter is a fourth-year resident in the Department of Ophthalmology at Queen’s University in Kingston, Ont. Dr Sharma is an Associate Professor in the Department of Ophthalmology and an Assistant Professor in the Department of Epidemiology at Queen’s University.

Answer to Ophthaproblem

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4. Pseudopapilledema

The optic nerve swells for a variety of reasons; swelling is manifest in a funduscopic examination as optic disk edema. When the optic nerve swells because of increased intracranial pressure (ICP), the resulting optic disk edema is specifically referred to as papilledema. Increased pressure can arise from an intracranial process, such as a mass, or idiopathic intracranial hypertension.

True papilledema gives the optic disk a characteristic appearance. When the optic disk has this appearance, but not as a result of elevated ICP, the condition is referred to as pseudopapilledema. Pseudopapilledema can be caused by myelinated nerve fibres around the disk, optic disk drusen (ODD), hyperopic disks, and various congenital anomalies of the optic disk.

Clinical features seen in true papilledema that help to distinguish it from pseudopapilledema include hyperemia of the optic disk with surface telangectatic vessels, congested vasculature, and associated flame hemorrhages; optic disk elevation that begins at the disk margin and progresses centrally (loss of the physiologic cup is a late manifestation of true papilledema); and blurring of the disk margin associated with obscuration of the retinal vessels that traverse it (can be seen in myelinated nerve fibres).1 Lack of spontaneous venous pulsations that can be seen in the retinal veins at the disk margin suggests true papilledema, but their absence is not diagnostic of papilledema because approximately 15% of the general population lack spontaneous venous pulsations.2

This patient has pseudopapilledema associated with ODD. Optic disk drusen account for 75% of clinical cases of pseudopapilledema3 and occur in up to 2% of the general population.4 The condition affects men and women with equal frequency, occurs less frequently in non-white populations, and is often bilateral.5

Optic disk drusen

Optic disk drusen, acellular structures that are typically calcified, round, yellow, and various sizes, tend to be located in the nasal aspect of the preliminary portion of the optic nerve. They can be clinically apparent at the surface of the disk or less visible, buried deeper in the nerve (making diagnosis more difficult).1 The disk has a pseudopapilledematous appearance: full in the centre, elevated with irregular scalloped margins that do not obscure the retinal vessels, and without hyperemia (Figure 1).

Patients with ODD are often asymptomatic, and the condition is found incidentally during funduscopic assessment. Despite usually normal central visual acuity, visual field defects are frequently found.5 Diagnosis is most reliably made by orbital ultrasound examination, but can be made by observing the ODD during clinical examination (ODD might become more apparent with red-free light during ophthalmoscopic examination), by photographing the fundus, or by using a computed tomography scan.6

Most patients’ visual field defects remain stable, and patients remain asymptomatic. Occasionally, ODD are associated with the following complications: slowly progressive visual field defects, disk and retinal hemorrhages, anterior ischemic optic neuropathy, and central retinal artery occlusion.1 Patients are managed by observation and visual field assessment.

Management

This patient was referred to an ophthalmologist to rule out papilledema. Clinically, ODD were apparent and were confirmed by results of ultrasound scan. Colour and red-free photographs of the disk were obtained for documentation. Formal visual field testing showed enlargement of the blind spot. The patient remained stable during follow up.

Recommendation

When the reason for changes in the optic disk is unclear, patients should be referred to an ophthalmologist to rule out papilledema or optic disk edema caused by other conditions.

References

1. Arnold A. Optic disc drusen. Ophthalmol Clin North Am 1991;4:505-17.
2. Levin BE. The clinical significance of spontaneous pulsations of the retinal vein. Arch Neurol 1978;35:37-40.
3. Miller NR. Anomalies of the optic disc. In: Miller NR, editor. Walsh and Hoyt’s clinical neuro-ophthalmology. Baltimore, Md: Williams and Wilkins; 1982. p. 355-65.
4. Friedman AH, Gartner S, Modi SS. Drusen of the optic disc. A retrospective study in cadaver eyes. Br J Ophthalmol 1975;59:413-21.
5. Rosenberg MA, Savino PJ, Galser JS. A clinical analysis of pseudopapilledema. Arch Ophthalmol 1979;97:65-75.6. Kurz-Levin MM, Landau K. A comparison of imaging techniques for diagnosing drusen of the optic nerve head. Arch Ophthalmol 1999;117:1045-9.