Proliferative vitreomacular traction (VMT) is marked by static contraction forces of a thickened posterior vitreous at the macula, according to an investigation published in the American Journal of Ophthalmology.
In 2013, the International Vitreomacular Traction Study Group used optical coherence tomography (OCT) to more accurately image and describe VMT based on anatomic features. Subsequent studies using OCT to define the anatomical changes associated with VMT reported that tractional force on the macula is strongly associated with the development and progression of VMT.
Based on this data, researchers focused their study on the proliferative changes at the vitreoretinal interface that may impact the tractional forces created by mobile posterior vitreous currents. They characterized VMT cases as either proliferative or nonproliferative depending on the presence of a thickened posterior vitreous.
Wide-angle montage OCT images of horizontal and vertical scans through the fovea were taken of 50 eyes from 46 patients with VMT. In addition, baseline fundus and eye-tracking scans were also performed. Then, the 3 types of scans were superimposed to compare changes in the contour and position of the posterior vitreous.
Researchers found that 48% of patients in the group had proliferative VMT, while 52% had nonproliferative VMT. They noted an epiretinal membrane in 26.9% of nonproliferative eyes and 95.8% of proliferative VMT eyes (P =3.6×10-7). In addition, eyes with proliferative VMT did not have wavy-contoured posterior vitreous, and none showed motion-induced changes of posterior vitreous following eye movement. However, 57.7% of nonproliferative VMT eyes have wavy-contoured posterior vitreous, and 91.7% presented motion-induced changes of posterior vitreous following eye movement. Lastly, posterior vitreous detachment extended beyond the scanned area in 34.6% of non-proliferative eyes and 8.3% of proliferative VMT eyes (P =.040).
“In eyes with nonproliferative VMT, the posterior vitreous is flexible and mobile with eye motion,” the study says. “In the second subtype, proliferative VMT, patients have a static, thickened and taut posterior vitreous.”
The static contractile forces of the thickened posterior vitreous at the macula also may play a role in macular pathology, according to the researchers. In patients with proliferative VMT, pathological changes — characterized by points of strong vitreoretinal adhesion at fibrous anchors that limited posterior vitreous detachment — developed primarily in the macula and paramacular region.
Ito Y, Takatsudo Y, Gehlbach PL, et al. Mechanistic Insights into the Pathogenesis of Proliferative and Non-proliferative Vitreomacular Traction. Am J Ophthalmol. Published online December 10, 2021. doi: 10.1016/j.ajo.2021.11.026.