Causes of Vitreomacular Traction
Vitreomacular traction occurs when the posterior vitreous cortex incompletely separates from the retina during posterior vitreous detachment (PVD), remaining abnormally adherent to the macula while the surrounding vitreous detaches, creating tractional forces on the fovea. 1
Primary Pathophysiologic Mechanism
The fundamental cause is incomplete or anomalous posterior vitreous detachment 1:
- The vitreous is most firmly attached at three anatomical sites: the vitreous base, optic nerve head, and macula 1
- During normal PVD evolution over years, the posterior vitreous initially partially detaches but remains attached within the macular region 1
- Eventually, complete detachment should occur when vitreous separates from the macula and finally from the optic nerve head 1
- VMT develops when the perimacular vitreous continues to separate from the posterior retina yet remains adherent to a region near the center of the macula 1
Unknown Underlying Mechanism
The pathologic mechanism responsible for abnormal adhesion within the macula that leads to VMT remains unclear 1:
- Why certain eyes develop persistent macular adhesion during PVD while others achieve complete separation is not well understood 1
- The combination of focal macular attachment with surrounding vitreous separation creates the tractional forces 1
Age-Related Risk Factors
VMT is fundamentally an age-related condition tied to the natural evolution of PVD 1, 2:
- PVD most commonly occurs between ages 45-65 years 2
- VMT prevalence increases significantly with advancing age, affecting 0.4% to 2.0% of U.S. adults over age 63 1, 2
- Peak prevalence occurs in the 7th and 8th decades of life 2
- The condition is relatively uncommon before age 50 2
Secondary Causes and Associated Conditions
While most VMT is idiopathic, certain conditions may contribute 3, 4:
- Exudative age-related macular degeneration: High coincidence between VMT and choroidal neovascularization has been documented 3
- Anti-VEGF therapy: Rare cases of VMT formation during anti-VEGF treatment have been reported, potentially due to VEGF inhibition inducing fibrosis in eyes with adherent vitreous cortex 4
- Diabetic retinopathy: VMT can occur in the context of diabetic macular edema 4
Clinical Consequences of the Traction
The persistent macular attachment with surrounding separation creates pathologic changes 1:
- Macular thickening and distortion 1
- Intraretinal cystoid changes 1
- Subretinal fluid accumulation 1
- Potential tractional macular detachment 1
- Progression to macular hole formation 5, 6
Important Clinical Caveats
Distinguish VMT from normal vitreomacular adhesion (VMA): VMA represents physiological attachment of posterior cortical vitreous to the macula with completely preserved foveal depression and no tractional changes, whereas VMT involves pathological structural alterations 1, 6
Vitreopapillary traction can occur when raised edges of adherent vitreous are seen around the optic nerve head, which can be confused with papilledema 1