May 19, 2020
5 min read
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Girl presents with bilateral blurry vision, mild headaches

Posterior pole examination demonstrated elevated optic nerves.

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A 7-year-old girl presented to the pediatric ophthalmology clinic complaining of blurry vision in both eyes. She reported that her blurry vision started approximately a year ago and was worse at distance. She denied diplopia and any ocular pain. She has had mild headaches that do not change with position and have not been associated with any intracranial noises. She denied any fevers, chills and night sweats. She was born full-term and had an otherwise unremarkable medical history. She did not have any personal ocular history nor family ocular history.

Alison J. Lauter
Alison J. Lauter
Sarah E. Thornton
Sarah E. Thornton

Examination

On initial examination, the patient’s unaided visual acuities were 20/60 in the right eye and 20/40 in the left eye. She had a refractive error of –2.75 +3.50 × 90 in the right eye and –1.75 +3.50 × 90 in the left eye, with best corrected visual acuity of 20/25 in both eyes. Color plates were full in both eyes. Pupils were equal, round and reactive without an afferent pupillary defect. Extraocular movements and confrontation visual fields were full and intact in both eyes. There was no significant strabismus noted. IOP was 19 mm Hg and 17 mm Hg in the right and left eyes, respectively. Anterior segment examination was unremarkable. Posterior pole examination demonstrated elevated optic nerves and no other unremarkable findings (Figure 1). OCT of the optic nerve and retinal nerve fiber layer analysis demonstrated average retinal nerve fiber layer (RNFL) thicknesses of 158 µm in the right eye and 149 µm in the left eye (Figure 2).

Posterior pole examination
Figure 1. Posterior pole examination of the right eye (left panel) and left eye (right panel) demonstrating elevation of the optic nerves bilaterally without significant hyperemia or obscuration of the disc vessels.
Source: Eleni Konstantinou, MD, and Catherine S. Choi, MD
RNFL analysis
Figure 2. RNFL analysis demonstrating average RNFL thicknesses of 158 µm in the right eye and 149 µm in the left eye.

What is your diagnosis?

See answer on next page.

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Blurry vision

The patient was found to have bilateral optic nerve elevation/edema. She was not taking any systemic medication and denied any recent weight gain. She did have headaches that did not change in quality with position.

The differential diagnosis of bilateral optic nerve elevation includes papilledema secondary to increased intracranial pressure or compressive lesion, optic nerve inflammation (optic neuritis) and pseudo-papilledema. Hyperopic eyes with shorter axial lengths can present with small, crowded optic nerves that appear elevated (pseudo-papilledema). Additionally, optic nerve drusen, both visible and buried, can also give the appearance of pseudo-papilledema. True papilledema often presents with optic nerve hyperemia with obscuration of disc vessels and venous congestion. Patton’s lines, which are retinal striae created by the edematous optic nerve, can also be observed.

OCT with sections
Figure 3. OCT with sections through the optic nerve head of the right eye (a) and left eye (b). Peripapillary hyperreflective ovoid structures were observed in both optic nerves, suggestive of optic disc drusen.

Clinical course continued

Our patient had only mild headaches that did not change with position, did not have vision loss or transient vision obscuration. The patient did not have any recent weight gain, and she was not on any medication that could lead to increased intracranial pressure. In order to exclude a compressive lesion, an MRI of the brain was obtained, which was unremarkable. Further testing was obtained, including OCT of the optic nerve (Figure 3), which demonstrated small hyperreflective ovoid structures at the optic nerve head. B-scan ultrasonography demonstrated hyperechoic lesions on both optic nerve heads consistent with buried disc drusen (Figure 4). Humphrey visual field 30-2 was essentially full in both eyes with enlargement of the blind spot in the right eye (Figure 5).

B-scan ultrasonography
Figure 4. B-scan ultrasonography of the right eye (a) and left eye (b) demonstrating hyperechoic material consistent with optic disc drusen.
 Humphrey visual field
Figure 5. Humphrey visual field 30-2 of the left eye (a) and right eye (b). Both fields are grossly full with an enlarged blind spot in the right eye.

Discussion

Optic nerve head drusen (OND) are composed of mucopolysaccharides and proteinaceous deposits within the optic nerve head anterior to the lamina cribrosa. The pathogenesis of OND is believed to be related to axoplasmic flow stasis or axonal degeneration in patients with congenitally crowded optic nerves. OND are found in 1% of the population and can be bilateral in 75% to 85% of cases. They may be observed more frequently in patients with pseudoxanthoma elasticum, retinitis pigmentosa and angioid streaks.

On examination, OND may be superficial and clinically apparent, or buried and less obvious, as in this case. Buried drusen are more common in younger children and may cause the affected disc to appear “full.” In adulthood, as the nerve fiber layer thins and OND enlarge, they may become more visible. In these cases, OND may be evident as yellow depositions on and around the optic nerve, often causing the edges of the optic disc or cup to appear distorted.

To confirm the diagnosis of OND, additional testing may be helpful. On fundus autofluorescence, OND appear hyperautofluorescent. On B-scan, OND can be seen as hyperechoic material within the optic nerve head. Polarimetric nerve fiber analysis can detect loss of optic nerve fibers, especially in eyes with dense drusen that compress the nerve fiber layer. Calcified drusen may also be evident on CT scan, which reveal a focus of increased density at the optic nerve head.

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Humphrey visual field
Figure 6. Humphrey visual field 30-2 of the left eye (a) and right eye (b) within normal limits.

Patients with OND are often asymptomatic and may be diagnosed on routine eye examination. In some cases, OND may become large enough that the vascular supply to the optic nerve head and nerve fibers can be compromised. This can lead to disc hemorrhages, vascular occlusion, anterior ischemic optic neuropathy and possible visual field defects. Central retinal artery occlusion and central retinal vein occlusion have been reported in association with OND, although this is rare. OND may also be complicated by juxtapapillary choroidal neovascularization leading to potential central visual acuity loss.

There is no definitive treatment available for OND. However, if visual field loss occurs secondary to RNFL loss, lowering the IOP with topical medication to prevent progression of field defects has been suggested. Laser photocoagulation has also been recommended for choroidal neovascularization when central visual acuity is compromised.

Clinical course continued

Our patient was monitored initially every 6 months and then yearly for annual examinations. Her blurry vision was attributed to significant refractive error, for which she was corrected with prescription glasses and with which her visual symptoms resolved. At her 3-year follow-up after the initial diagnosis, her optic nerve elevation was stable to her initial presentation, and she remained asymptomatic, without RNFL loss and with normal visual fields (Figure 6).