Case 4:
May is Macular Month, so our “Eyes of the Month” case study discusses a young woman who experienced “blue sprinkles” in her eyes, leading to a diagnosis of Bilateral Acute Macular Neuroretinopathy.
Patient Visit:
A 22-year-old female was referred to Queensland Eye and Retina Specialists after one night experiencing “blue sprinkles” in her vision. Upon waking the next morning, she noticed a small blurred patch in her paracentral vision in both eyes. These patches of relative scotomas had remained unchanged for 3 days.
Previous ocular history was unremarkable. There was a family history of macular degeneration. Her general health included previous eczema, treated as necessary with cortisone creams. A week earlier she had mild flu-like symptoms, including a runny nose, sore throat, fever, headache, and myalgia.
Ocular exam revealed the following:
Unaided Visual Acuity:
RE: 6/6 LE: 6/4.5-
Intraocular Pressure (IOP):
RE: 15mmHg LE: 15mmHg
Pupils: EA, DCN No RAPD
External examination with slit lamp was within normal limits.
Ishihara Colour Vision Test:
RE: 14/17 LE: 13/17
Internal examination via slit lamp fundoscopy was unremarkable. Optical coherence tomography (OCT) revealed symmetrical bilateral hyper-reflectance in the outer nuclear (ON) and outer plexiform (OP) layers, with underlying ellipsoid layer changes. Visual field testing (HVF 10-2) demonstrated “C” shaped scotomas in both eyes, corresponding to the OCT changes mentioned above.
Diagnosis and Discussion
Diagnosis:
Bilateral Acute Macular Neuroretinopathy in the context of viral prodrome.
Differential Diagnoses:
- • Acute Retinal Pigment Epitheliitis
• Multiple Evanescent White Dot Syndrome (MEWDS)
• Acute Posterior Multifocal Placoid Pigment Epitheliopathy (APMPPE)
• Central Serous Chorioretinopathy
• Optic Neuritis
• Paracentral Acute Middle Maculopathy
Discussion:
Acute Macular Neuroretinopathy (AMN) is an uncommon condition affecting the macular and perifoveal region of the retina. Currently, the exact underlying pathophysiology of AMN has not been identified, however, there is strong evidence to suggest some form of vascular compromise of the deep retinal capillary plexus results in corresponding damage at the photoreceptor level. As a result, patients with AMN will most commonly experience paracentral scotoma and/or reduced visual acuity. In a majority of cases, the fovea seems to be spared.
At initial onset, there may be little to see with a fundoscopic examination. Roughly 3 days after symptoms begin, clinicians may be able to see evidence of reddish-brown, oval or petaloid lesions surrounding the fovea. On OCT imaging hyper-reflectivity can be seen in the ON and OP layers of the retina, indicating damage to the photoreceptor cell bodies. As time passes these hyper-reflective plaques will reduce and instead be replaced with outer neural layer thinning.
Patients are overwhelmingly healthy females in their teens to 30s. Commonly associated risk factors include a preceding viral or flu-like illness, excessive caffeine intake, hormonal contraceptive use or hypotensive episodes. There are some reported cases of AMN following COVID-19 vaccination.
Treatment:
There is currently no known treatment for AMN or the associated scotomas and vision loss. Despite evidence that excessive caffeine and hormonal contraceptives may be associated, ceasing these has not been shown to be beneficial. Some scotomas may partially resolve over time, while others may persist permanently. There is no evidence of meaningful visual acuity loss.
Follow-Up:
On examination one week later, our patient reported improvement in visual acuity and a reduction in opacity of the scotomas. Objectively, the pattern of hyper-reflectivity had significantly lessened in intensity.
If your patient is experiencing unusual symptoms with their vision, refer them to Queensland Eye & Retina Specialists.
Have any questions about patient eye care?
Contact Queensland Eye & Retina Specialists for more information.
Queensland Eye & Retina Specialists
accepts referrals via email, Oculo, Medical Objects and fax.