Vitreo Retinal Traction (VRT) is an eye condition where the vitreous humor, the gel-like substance filling the back of the eye, adheres too strongly to the retina. This abnormal attachment causes a physical pulling force, or traction, on the delicate retinal surface. VRT is frequently a consequence of the natural aging process, as the vitreous changes its consistency over time. If the pulling force is concentrated or severe, VRT can distort the retina and lead to significant vision problems. Addressing the underlying traction is necessary to prevent permanent damage.
The Anatomical Basis of Traction
The eye’s main cavity is filled with the vitreous humor, a clear, jelly-like substance composed mostly of water. This gel is normally attached to the retina’s inner surface across the back of the eye. The retina is a complex layer of tissue that captures light and converts it into electrical signals sent to the brain.
As a person ages, the vitreous gel undergoes syneresis, where its structure breaks down, liquefies, and shrinks. This shrinkage naturally causes the vitreous to separate from the retina, an event known as a Posterior Vitreous Detachment (PVD). A complete PVD is typically harmless, but VRT arises when this separation is incomplete.
In VRT, certain areas of the vitreous remain firmly glued to the retina, particularly at the macula, the central region responsible for detailed vision. The continued shrinkage of the vitreous exerts a persistent, mechanical tugging force on these points of abnormal adhesion. This concentrated pulling force physically distorts the retinal tissue, disrupting the function of photoreceptor cells and causing visual symptoms.
Common Symptoms of Vitreo Retinal Traction
The symptoms experienced with VRT are directly related to the physical stress the traction places on the retina. Many people with mild cases may not notice any changes to their vision. When the traction is more pronounced, symptoms typically manifest as disturbances in the central visual field.
One common visual complaint is metamorphopsia, the distortion of straight lines, making them appear wavy or irregular. Patients may also observe micropsia, where objects appear smaller than their actual size due to the retina being stretched or swollen. The pulling force can also stimulate light-sensitive cells, leading to brief flashes of light, known as photopsia, often noticed in the peripheral vision.
Patients may also report a new or increased presence of floaters, which are small specks that drift across the field of view. These floaters represent debris within the shrinking vitreous gel. Although symptoms can be intermittent, a sudden onset or worsening of any visual changes warrants an immediate eye examination.
Conditions Resulting from Retinal Traction
The mechanical pulling force of VRT is a mechanism that can lead to several specific clinical conditions, depending on the location and severity of the traction. These resulting conditions represent damage to the retina that compromises visual function.
Vitreomacular Traction (VMT)
VMT occurs when the pulling is concentrated over the macula, the most sensitive part of the retina. The tugging physically lifts the macula’s surface, often causing localized swelling or cyst-like fluid collections within the retinal layers. This deformation disrupts the macula’s ability to process fine detail, leading to blurred or distorted central vision.
Epiretinal Membrane (ERM)
An ERM, sometimes called a macular pucker, involves the proliferation of a thin layer of scar tissue that grows across the surface of the retina in response to damage caused by the traction. As this membrane contracts over time, it wrinkles and puckers the underlying macula, causing significant metamorphopsia and reduced visual acuity.
Macular Hole
The most severe outcome is a Macular Hole, which occurs when intense traction pulls so strongly on the macula that it tears a full-thickness defect in the retinal tissue. This hole results in a significant blind spot and severe loss of central vision. The extent of the vision loss is proportional to the size of the hole and how long the traction has been present. These three conditions—VMT, ERM, and Macular Hole—are progressive forms of damage arising from incomplete vitreous separation.
Management and Treatment Pathways
The clinical approach to VRT depends on the condition’s severity, the degree of vision loss, and the specific resulting pathology. For mild or asymptomatic cases of VMT, observation is often the standard practice, as the traction can spontaneously resolve. Regular monitoring with imaging technology, such as Optical Coherence Tomography (OCT), tracks the traction’s status and any changes to the retinal structure.
Pharmacological Treatment
When the condition is symptomatic but not yet severe enough for surgery, pharmacological intervention may be considered. Ocriplasmin (Jetrea) is a specific enzyme administered via a single injection directly into the eye. This recombinant protease enzyme is designed to dissolve the protein components that form the abnormal adhesion between the vitreous and the retina. This targeted action chemically induces a complete PVD, thereby releasing the traction.
Surgical Treatment
Surgical intervention is typically recommended for cases involving a full-thickness macular hole, severe VMT that does not resolve, or a significantly symptomatic ERM. The definitive procedure is a pars plana vitrectomy, which involves the microsurgical removal of the vitreous gel from the eye. Eliminating the vitreous completely removes the source of the pulling force, immediately resolving the traction. The surgeon will often peel away any epiretinal membrane and may place a temporary gas bubble inside the eye to help flatten a macular hole and allow it to seal during healing.