Vitreous syneresis is a common, natural change that occurs inside the eye with age. The eyeball’s central cavity is filled with a clear, gel-like substance called the vitreous humor, which helps the eye maintain its round shape. Syneresis is the gradual process where the structure of this gel transforms over many years.
The Process of Vitreous Change
In youth, the vitreous humor has a firm, gel-like consistency. It is composed of about 98% water held in a complex network of collagen fibers and hyaluronic acid molecules. This combination creates the transparent gel filling the posterior chamber of the eye between the lens and the retina. The collagen provides a scaffold, while hyaluronic acid binds water to maintain the gel’s consistency.
Vitreous syneresis is the process where this stable structure breaks down. Hyaluronic acid molecules release the water they hold, leading to a liquefaction of the once-solid gel. As the gel becomes more liquid, the collagen fibers, previously suspended uniformly, lose their support and begin to clump together. This transformation is similar to a gelatin dessert separating into watery pools and lumpy portions over time.
Associated Symptoms and Visual Disturbances
The most common symptom of vitreous syneresis is the appearance of “floaters.” These are not external objects but are the shadows cast by clumped collagen fibers drifting inside the eye. As light enters, these clumps block it from reaching the retina, creating an image the brain interprets as a floating object.
Floaters are often described as small black dots, specks, cobwebs, or squiggly lines that move as the eye moves. They are more noticeable when looking at a bright, plain background like a clear sky or a white wall.
Another visual disturbance is photopsia, or the perception of flashing lights. These flashes appear as brief sparkles or streaks of light in the peripheral vision. This occurs when the shrinking vitreous gel tugs on the retina, which stimulates retinal cells to send a light signal to the brain.
Causes and Contributing Factors
The primary cause of vitreous syneresis is the natural aging process. By age 70, a significant percentage of people will have experienced the biochemical changes that lead to a collapse of the vitreous gel.
Certain factors can accelerate these changes. High myopia, or significant nearsightedness, is a contributing factor because the elongated shape of a myopic eye places additional strain on the vitreous, speeding up its liquefaction. Previous eye surgeries, particularly cataract surgery, can also hasten these changes, as the manipulation can disturb the vitreous gel. Direct trauma to the eye or inflammatory conditions can also trigger syneresis prematurely.
Potential Complications and When to Seek Help
While vitreous syneresis is a normal part of aging, it can lead to more serious conditions. The main event associated with syneresis is a posterior vitreous detachment (PVD), which occurs when the shrinking vitreous gel pulls away from the retina. In most cases, this separation happens cleanly without negative consequences.
A concern arises when the vitreous does not detach cleanly. In some instances, the collagen fibers are strongly attached to the retina, and as the vitreous pulls away, it can create a retinal tear. If fluid from the eye’s interior passes through this tear and accumulates behind the retina, it can lead to a retinal detachment, a sight-threatening condition.
It is important to distinguish between normal symptoms and warning signs of a complication. A gradual increase in long-standing floaters is not a cause for alarm. However, a sudden shower of many new floaters, the onset of new and persistent flashes of light, or the appearance of a dark curtain moving across the field of vision are urgent signs that require immediate evaluation by an eye doctor.
Diagnosis and Management Approaches
Diagnosing vitreous syneresis and related conditions requires a comprehensive dilated eye examination. An ophthalmologist uses drops to widen the pupils for a clear view of the back of the eye. Using specialized lenses with a slit lamp or an indirect ophthalmoscope, the doctor inspects the vitreous for liquefaction and debris and examines the retina for potential tears or detachment.
For most people with uncomplicated syneresis or a PVD, management involves observation and reassurance, as no specific treatment is required for the process itself. Over time, the brain often learns to ignore floaters through a process called neuroadaptation, making them less intrusive.
Treatment is reserved for complications. If a retinal tear is found, a laser procedure or cryotherapy (a freezing technique) can seal it to prevent a full retinal detachment. A retinal detachment requires more extensive surgical intervention to reattach the retina and preserve vision.