Multiple evanescent white dot syndrome

Overview

Multiple Evanescent White Dot Syndrome (MEWDS) is a rare, self-limiting inflammatory eye condition that primarily affects young, healthy women, often in their second to fourth decades of life. It is characterized by the sudden onset of visual disturbances, usually in one eye, accompanied by multiple small white spots visible in the retina and retinal pigment epithelium (RPE). MEWDS is considered part of the “white dot syndromes,” a group of posterior uveitis disorders marked by the presence of white inflammatory lesions in the back of the eye.

MEWDS was first described by Jampol et al. in 1984. The condition is generally benign, and most patients recover visual function within several weeks without the need for intensive treatment. However, understanding the signs and course of the disease is important to distinguish it from other, more serious causes of vision loss.

Causes

The exact cause of Multiple Evanescent White Dot Syndrome is unknown, but it is believed to be related to an immune-mediated inflammatory process, possibly triggered by a viral or flu-like illness. It is not a hereditary or contagious condition.

Proposed Contributing Factors

• Viral infection: Many patients report a recent upper respiratory tract infection or flu-like symptoms prior to the onset of visual issues.

• Immune system activation: The syndrome is thought to involve a transient autoimmune reaction that targets photoreceptors or the outer retina.

• Genetic predisposition: Though not directly inherited, certain genetic or immunological factors may increase susceptibility.

No specific environmental or occupational exposures have been linked to MEWDS, and recurrence is uncommon.

Symptoms

MEWDS typically presents with a sudden onset of visual symptoms in one eye. These symptoms can be distressing but usually resolve over time.

Common Symptoms

• Blurry vision or mild visual acuity loss (usually unilateral)

• Photopsia: Perception of flashing lights or shimmering

• Paracentral scotomas: Small blind spots near the center of vision

• Dyschromatopsia: Altered color perception in the affected eye

• Mild eye discomfort: Occasional but not a prominent feature

Ophthalmic Findings

• Multiple small, white dots scattered in the outer retina and RPE, mostly in the posterior pole

• Foveal granularity (grainy appearance at the center of the retina)

• Mild vitritis (inflammation in the vitreous humor) in some cases

• Absent or minimal anterior chamber inflammation

The white dots typically fade over several weeks and may not be visible by the time of diagnosis if delayed.

Diagnosis

Diagnosis of MEWDS is largely clinical, supported by characteristic findings on ophthalmic imaging. There is no specific laboratory test for the condition, but imaging studies play a key role in confirming the diagnosis and ruling out other causes.

Clinical Evaluation

• Thorough patient history, including recent illness or systemic symptoms

• Slit-lamp examination to evaluate anterior and posterior segments of the eye

Imaging Techniques

• Fundus photography: May show small, grey-white lesions at the posterior pole

• Fundus autofluorescence (FAF): Reveals hyperautofluorescent spots corresponding to white dots

• Fluorescein angiography (FA): Shows punctate hyperfluorescent spots with late staining in the affected areas

• Indocyanine green angiography (ICGA): May demonstrate hypofluorescent lesions not visible on FA

• Optical coherence tomography (OCT): Shows disruption of the ellipsoid zone and possible subretinal fluid

Differential Diagnosis

• Acute posterior multifocal placoid pigment epitheliopathy (APMPPE)

• Punctate inner choroidopathy (PIC)

• Birdshot chorioretinopathy

• Serpiginous choroiditis

• Ocular histoplasmosis syndrome

Lab tests may be ordered to exclude infectious or systemic inflammatory conditions but are usually normal in MEWDS.

Treatment

In most cases, MEWDS is a self-limiting condition that resolves spontaneously within 6 to 12 weeks. Therefore, treatment is generally conservative, focusing on observation and reassurance.

1. Observation

• No specific therapy is required in the majority of cases

• Close follow-up to monitor visual recovery and rule out complications

2. Medications (rarely needed)

• Short courses of oral corticosteroids may be considered in severe or atypical cases

• Anti-inflammatory drops if there is significant vitritis (uncommon)

3. Supportive Measures

• Patient education and reassurance regarding the benign and temporary nature of the condition

• Referral to a retinal specialist if diagnosis is uncertain or symptoms worsen

Because recurrence is rare, long-term treatment is not typically required unless the condition mimics or evolves into another white dot syndrome.

Prognosis

The prognosis for MEWDS is excellent in most cases. Visual acuity generally returns to normal or near-normal within a few weeks to months without permanent damage. The retinal white dots fade, and most patients regain full visual function.

Favorable Prognostic Indicators

• Early diagnosis and correct identification to avoid unnecessary treatments

• No involvement of both eyes (most cases are unilateral)

• No systemic disease association

Possible Complications

• Persistent scotomas (rare)

• Recurrence in the same or contralateral eye (extremely rare)

• Misdiagnosis leading to overtreatment or unnecessary anxiety

Overall, MEWDS is a transient and benign condition with excellent visual outcomes, and awareness of its features helps avoid unnecessary interventions and ensure proper patient counseling.