Can white dots appear later on Optical Coherence Tomography (OCT) in patients with White Dot Syndrome?

White Dots on OCT in White Dot Syndrome

Yes, white dots can appear later on OCT in patients with White Dot Syndrome, as they represent disruptions to the photoreceptor outer segments that can evolve over the course of the disease.

Pathophysiology of White Dots on OCT

White Dot Syndrome (WDS) is characterized by inflammatory changes that affect different layers of the retina, particularly the outer retina, retinal pigment epithelium (RPE), and choroid. On OCT imaging, these changes manifest in specific ways:

• Initial presentation: Disruption or irregularity of the photoreceptor inner/outer segment (IS/OS) junction line of varied extent 1
• Later development: Hyperreflective lesions in the outer retinal layers that may not be present at disease onset but can develop as the disease progresses

Evolution of OCT Findings in White Dot Syndrome

The OCT findings in White Dot Syndrome follow a characteristic pattern:

1. Acute phase:

   • Disruption of the IS/OS junction
   • Irregular photoreceptor architecture
   • Decreased photoreceptor outer segment length 2

2. Later phases:

   • Hyperreflective dots in the outer plexiform layer (OPL) and outer nuclear layer (ONL) may appear 3
   • White dots that were not initially visible on OCT may become apparent as the disease evolves
   • These dots can correspond to areas of hyperfluorescence on fluorescein angiography 3

Diagnostic Considerations

OCT is fundamental in the diagnosis and monitoring of White Dot Syndrome:

• OCT provides depth-resolved, histological grade images that help localize the primary pathology 4
• En face OCT can provide additional information about the interrelationship of lesion types 4
• The correlation between OCT findings and immunofluorescence can be remarkable in cases of White Dot Syndrome 3

Recovery and Resolution

The appearance and resolution of white dots on OCT follows a timeline:

• In most cases, the IS/OS line is restored within 1.5 weeks to 6 months (mean 3.4 months) 1
• However, some eyes may have focal disruption that persists even after clinical resolution 1
• Using OCT-based methods, quantitative measurement of photoreceptor outer segment length shows decrease acutely with restoration to normal following disease resolution 2

Clinical Implications

Understanding the evolution of white dots on OCT has important clinical implications:

• Monitoring disease activity: The appearance of new white dots on OCT may indicate ongoing inflammatory activity
• Treatment decisions: The presence of persistent or new white dots may guide treatment with local and/or oral corticosteroids as recommended by the American Academy of Ophthalmology 5
• Prognosis: Complete restoration of the IS/OS line on OCT generally correlates with good visual recovery 1

Potential Pitfalls

Several important caveats should be considered:

• White dots on OCT may be bilateral even when symptoms and fundus lesions appear unilateral 1
• Similar OCT findings can be seen in conditions that mimic White Dot Syndrome, such as Cancer Associated Retinopathy (CAR) 3
• Recent COVID-19 vaccination has been associated with MEWDS-like presentations with similar OCT findings 6

In summary, white dots on OCT in White Dot Syndrome represent photoreceptor disruption that can evolve over time, appearing later in the disease course even if not present initially. Careful monitoring with OCT is essential for diagnosis, treatment decisions, and assessment of recovery.