Background: In healthy fundi, glistening whitish dots (so-called Gunn's dots) can often be seen, especially in young subjects. They are commonly attributed to the reflectance of Müller cell's footplates. However, despite their potential interest as biomarkers of retinal diseases, Gunn's dots have received little attention in the scientific literature.
Methods: Scanning laser ophthalmoscope reflectance imaging and adaptive optics infrared flood imaging were performed in 18 healthy subjects (age range, 18-58 years) to analyze the localization, density, and shape of Gunn's dots.
Results: Gunn's dots were more easily observed in the midperipheral retina along temporal vessels, although in two subjects, they could be detected in the macula. The reflectance of Gunn's dots showed a strong directional variability, which paralleled that of the inner limiting membrane. The mean (±SD) diameter of Gunn's dots was 13.3 µm (±3.5). Their density peaked at ∼120 per square millimeter and decreased with age to become barely detectable after 50 years.
Conclusion: Gunn's dots are highly anisotropic structures close to the inner limiting membrane. Their density, size, and age-related decline are closer to the characteristics of hyalocytes than those of Müller cells. Further studies are necessary to progress in the determination of their origin and interest as biomarkers of retinal diseases.
Trial registration: ClinicalTrials.gov NCT01546181.