A Weiss ring is a specific type of eye floater, which is a small piece of debris that drifts within the eye’s internal fluid. These floaters can appear as spots, threads, or a distinct ring-like or oval shape in your field of vision. The appearance of a Weiss ring is often sudden. It is most noticeable when looking at a plain, light-colored background, like a clear sky or a blank wall, as this floater is a physical object casting a shadow on the retina.
The Cause of a Weiss Ring
The eye is filled with a gel-like substance called the vitreous humor, which helps the eyeball maintain its shape. With age, this vitreous naturally changes, becoming more liquid and shrinking in a process known as vitreous syneresis. This shrinkage can cause the vitreous to pull away from the retina at the back of the eye. This common, age-related event is called a posterior vitreous detachment (PVD).
The vitreous is not uniformly attached to the retina; it has a firmer connection point around the optic nerve head. When the vitreous pulls away from the retina during a PVD, this small, circular piece of tissue can be dislodged. This detached piece of vitreous collagen then floats freely, creating the Weiss ring.
Associated Symptoms and Visual Experience
The Weiss ring will seem to drift and move as you move your eyes, sometimes darting out of view only to float back into your central vision. Its appearance can range from nearly transparent to a darker, more defined shadow or cobweb-like spot.
The onset of a Weiss ring is often accompanied by other symptoms related to the underlying PVD. You might notice a sudden increase in smaller floaters, which can look like dots, specks, or threads. Some people also experience flashes of light (photopsia), caused by the vitreous gel tugging on the retina as it separates.
Diagnosis and When to Seek Medical Attention
While a Weiss ring itself is not considered harmful, its appearance is a clear sign that a posterior vitreous detachment has occurred. A PVD, in a small number of cases, can create complications. The pulling of the vitreous on the retina can sometimes cause a tear in the retinal tissue. If untreated, a retinal tear can lead to a retinal detachment, which can cause significant vision loss.
For this reason, the sudden appearance of a Weiss ring, new floaters, or flashes of light warrants a prompt dilated eye exam by an eye doctor. During this exam, the pupils are widened to allow the doctor a clear view of the entire retina to check for any tears. Immediate medical attention is necessary if you experience a shower of many new floaters, persistent flashes of light, or a dark curtain moving across your vision, as these can be signs of a retinal tear or detachment.