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Asymptomatic patient has bright, round optic nerve head
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A 51-year-old white male presented to the Veterans Affairs clinic for a periodic eye exam with no complaints of decreased vision or ocular pain. The patient’s systemic history was negative for any health issues, and he was taking no medications. No allergies were reported at the time of the visit.
Images: Smith W
The patient reported that about 20 years prior he experienced an episode of complete loss of vision in the right eye; the vision returned after 6 weeks without treatment. During that episode, the patient was seen at a military base and diagnosed with optic neuritis of the right eye. A visual field was performed, which showed an enlarged blind spot, and fluorescein angiography showed no leakage of the optic nerve. No treatment was initiated, and no further study was performed.
Preliminary findings yielded best-corrected visual acuity of 20/25 in the right eye and 20/20 in the left eye. No restrictions of his extraocular muscles were noted. Pupils were equally reactive with no relative afferent pupillary defect. Confrontational visual fields were full in each eye. Ocular tension was normal, at 9 mm Hg in each eye. Anterior segment examination was unremarkable.
A dilated fundus examination showed a well-perfused retina in each eye with a flat and avascular macula in the left eye. The right macula displayed mild striation characteristic of epiretinal membrane. No exudate, hemorrhages, nor areas of ischemia were present. The patient’s right optic nerve appeared to be elevated with chorioretinal pigment surrounding it 360 degrees. The center of the optic nerve head (ONH) appeared to be bright and round, giving it a radiating appearance of the vascular ONH, which had a unique straightened course. Overall cupping was unappreciable. The left optic nerve showed minimal cupping with flat appearance and a normal vascular course.
Optical coherence tomography imaging was attempted but unobtainable in the right eye. Humphrey Visual Field 24-2 SS (Carl Zeiss Meditec) showed an enlarged blind spot of the right eye. Magnetic resonance imaging (MRI)/magnetic resonance angiography (MRA) study was performed of the head and neck and was mostly unremarkable; however, the A1 segment of the right anterior cerebral artery (ACA) was absent. The imaging report stated that this was “likely congenital,” and the remainder of the right ACA filled via the left internal carotid artery. These studies suggested the anatomy was stable, so no further study was indicated.
What’s your diagnosis?
See answer on next page.
There are no clinically diagnosable causes of optic disc elevation that are considered normal with normal vision; all cases require investigation. Investigation may be managed differently with various history and presentation.
Pseudo vs. true disc swelling
It is best to classify elevated discs with normal vision as either pseudo-swelling or true swelling. The distinction is whether the elevation extends beyond the disc margin/scleral ring.
Disc pseudo-swelling occurs when one or both optic discs appear elevated or have unclear margins but there is no optic nerve axon swelling. This may be caused by a small disc, tilted disc, elevated disc with superficial or buried drusen, or an elevated disc without drusen.
With disc pseudo-swelling there is no attributable blurred vision, vision loss or pulsatile tinnitus. Normal color acuity is expected. The disc is not hyperemic or pale. The disc is elevated, but the area of elevation does not extend beyond the disc margin. Perimetry is normal in both eyes. No leakage on fluorescein angiography is demonstrated; however, some abnormalities may present. Giuffre reported of early visualization of the choroidal vessels due to atrophy of the peripapillary pigment epithelium and delayed filling of the retinal arteries and veins. In the late venous phase, the walls of the staphyloma were hyperfluorescent.
True disc swelling with normal vision may result from many causes, many of which are life-threatening. It is ideal if the patient can be referred urgently (same day) to a neuro-ophthalmologist or neurologist for investigation.
Check the blood pressure; severe hypertension is a rare cause of disc swelling. Check temperature; patients with infectious optic neuritis, perineuritis or meningitis may have a fever. Order a blood work-up, at minimum, a full blood count, electrolytes and liver function test, ESR, CRP, ACE and ANA. In most cases, refer for urgent MRI of the optic nerves and brain with contrast, plus MRV. If the MRI is unremarkable, a lumbar puncture with opening pressure is indicated.
This patient’s diagnosis
Given the patient’s history, normal vision and field, urgent investigation was not indicated. Further review of the findings and presentation of the ONH yielded a diagnosis of morning glory disc anomaly (MGDA).
This rare congenital anomaly is thought to only exist in ocular textbooks; however, it does exist clinically. (As Lou Catania, OD, famously noted: “It’s not rare if it’s in your chair.”)
MGDA is a congenital anomaly of the optic disc that is typically unilateral. These patients have reduced visual acuity of 20/200 to counting fingers; however, a few cases of 20/20 vision have been reported. Vision is likely spared because of the relative sparing of the papillomacular bundle.
Clinical appearance
The term “morning glory disc” comes from its similar appearance to the morning glory flower (Brodsky). The anomaly is usually diagnosed by funduscopic examination alone due to the unique optic nerve presentation. By observation, one could expect to see a white, elevated, hyperplastic glial tissue occupying the central disc; excavation of the posterior globe; straight vessels radiating from the disc margins; and a variable amount of peripapillary pigment. It is thought that MGDA may be a primary mesenchymal disorder or an abnormality in the relative growth between the mesoderm and ectoderm, given findings of a scleral defect, vascular anomalies, central glial tuft, and adipose and smooth muscle tissue in histopathological specimens. Increased risk of non-rhegmatogenous serous retinal detachment exists for these patients; however, no progressive ocular disease has been documented.
In severe cases of vascular abnormality, transient ischemic attacks and strokes are seen in children, but intracranial hemorrhage is more likely in adults. The aforementioned provides a reason for MRI/MRA to be performed on patients with these ONH anomalies. Carotid artery narrowing or absence in patients with MGDA has been reported several times in the literature. In most cases, this carotid artery damage is detoured with collateral vessel formation to serve underdeveloped areas.
There is adequate documentation to support a relationship between MGDA and vascular abnormalities; however, MRI/MRA is rarely studied in these patients. It seems brain imaging is more academic than clinically relevant. One report noted a possible increased risk of multiple sclerosis in patients presenting with MGDA. I chose to image the patient on curiosity alone.
- References:
- Baer CA, et al. Br J Ophthalmol. 2003;87:363-365 doi:10.1136/bjo.87.3.363-a.
- Brodsky MC. Surv Ophthalmol. 1994;39(2):89-112.
- Dempster AG, et al. Ophthalmologica. 1983;187:222-230.
- Giuffre G. Br J Ophthalmol. 1986;70:229-236.
- Kindler P. Am J Ophthalmol. 1970;69:376-384.
- Massaro M, et al. Arch Ophthalmol. 1998;116(2):253-354.
- For more information:
- William Smith, OD, practices at the Veterans Affairs Clinic in Jacksonville, Fla., and is an associate professor of optometry at the University of Incarnate Word. He can be reached at William.Smith30@va.gov.
- Edited by Leo P. Semes, OD, FAAO, a professor of optometry, University of Alabama at Birmingham and a member of the Primary Care Optometry News Editorial Board. He may be reached at lsemes@uab.edu.
Disclosure: Smith has no relevant financial disclosures.