Pharmacotherapy of Vitreomacular Traction

Vitreomacular traction occurs due to incomplete or anomalous posterior vitreous detachment. Over time, the vitreous pulls anteriorly and causes retinal distortion and eventually reduced vision. Traditionally, vitreomacular traction was treated with vitrectomy surgery. In the past few years, there is a paradigm shift towards pharmacologic vitreolysis, which involves the intravitreal injection of enzymatic and non-enzymatic agents that facilitate posterior vitreous detachment. Many agents have been investigated and trialled including plasmin, microplasmin (Ocriplasmin), hyaluronidase, nattokinase, chondroitinase and dispase. This review will focus on the progress and current status in this research.

The Pathophysiology of Vitreomacular Interface Disease

Anomalous posterior vitreous detachment is an important step in the pathogenesis of vitreoretinal interface diseases. In order to understand the pathophysiology of vitreoretinal interface diseases, the structure and biochemistry of the vitreous body, and its relation with the retina should be investigated. Having a clear understanding of the pathophysiology of these diseases may help to develop new pharmacologic or surgical treatment modalities.

Retinal Changes Induced by Epiretinal Tangential Forces

Two kinds of forces are active in vitreoretinal traction diseases: tangential and anterior-posterior forces. However, tangential forces are less characterized and classified in literature compared to the anterior-posterior ones. Tangential epiretinal forces are mainly due to anomalous posterior vitreous detachment (PVD), vitreoschisis, vitreopapillary adhesion (VPA), and epiretinal membranes (ERMs). Anomalous PVD plays a key role in the formation of the tangential vectorial forces on the retinal surface as consequence of gel liquefaction (synchysis) without sufficient and fast vitreous dehiscence at the vitreoretinal interface. The anomalous and persistent adherence of the posterior hyaloid to the retina can lead to vitreomacular/vitreopapillary adhesion or to a formation of avascular fibrocellular tissue (ERM) resulting from the proliferation and transdifferentiation of hyalocytes resident in the cortical vitreous remnants after vitreoschisis. The right interpretation of the forces involved in the epiretinal tangential tractions helps in a better definition of diagnosis, progression, prognosis, and surgical outcomes of vitreomacular interfaces.