Blue field entoptic phenomenon

The Blue field entoptic phenomenon or Scheerer's phenomenon (pronounced: /ʃɪərərz fɪˈnɒmɪnən/) is a visual effect that can be observed in the human eye. It is named after the German ophthalmologist Richard Scheerer, who first described it in 1924.

Etymology

The term "entoptic" comes from the Greek words "ἐντός" (entos, "within") and "ὄψ" (ops, "eye"), meaning "within the eye". The "blue field" part of the name refers to the phenomenon being most noticeable when looking at a bright, blue sky.

Description

The Blue field entoptic phenomenon is characterized by the appearance of tiny bright dots moving quickly along squiggly lines in the visual field, especially when looking into bright blue light such as a clear sky. The dots are short-lived, visible for a second or less, and traveling short distances along seemingly random, curvy paths. Some people are able to see this phenomenon without aid, while others require a special viewing apparatus.

Cause

The phenomenon is caused by White blood cells moving in the Capillaries in front of the Retina of the eye. The white blood cells, which are larger than the red ones, create gaps in the blood column, which in turn cause the entoptic phenomenon. The blue light (short-wavelength) enters the eye and is absorbed by the red blood cells in the capillaries. When a white blood cell, which does not absorb blue light, passes through the capillary, a small amount of light is scattered onto the retina, creating the appearance of a bright dot.

Related terms

Entoptic Phenomena: Visual effects whose source is within the eye itself.
Floaters: Small specks or clouds moving in your field of vision.
Phosphenes: The phenomenon of seeing light without light actually entering the eye.
Purkinje images: Reflections of objects from the structure of the eye.

External links

Medical encyclopedia article on Blue field entoptic phenomenon
Wikipedia's article - Blue field entoptic phenomenon

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Blue field entoptic phenomenon