Intravitreal Gas for Vitreomacular Adhesion

Symptomatic vitreomacular adhesion (sVMA), also known as Vitreomacular traction (VMT) is thought to occur due to an anomalous or incomplete posterior vitreous detachment (PVD).1 Typical symptoms of VMT include decreased reading vision and metamorphopsia. Ultra-high resolution spectral-domain optical coherence tomography (SD-OCT) has greatly enhanced our understanding of the spectrum of the vitreomacular interface disorders ranging from focal adhesions, macular cysts, impending macular holes, full thickness macular holes, lamellar holes, and epiretinal membrane.2 Generally, pars plana vitrectomy (PPV) surgery is the preferred treatment for many of these conditions with high success rates.3 However, surgical intervention is not without risk and includes the potential for infection, retinal detachment, cataract progression, and patient discomfort from post-operative prone positioning in cases of macular hole.4 Despite the high success rate with vitrectomy, the risks of surgery have led researchers to search for non-surgical treatments of VMT such as pharmacologic vitreolysis. Ocriplasmin (JetreaTM, ThromboGenics, Inc. Iselin, NJ) was recently approved by the United States Food & Drug Administration (FDA) in October 2012 as a non-surgical, pharmacologic agent for the treatment of symptomatic VMA.5 Pooled data from two phase III clinical trials of ocriplasmin (MIVI-TRUST)5 demonstrated that approximately 26% of eyes treated with a single intravitreal injection of ocriplasmin (125 ug) compared to 10% of eyes treated with vehicle alone (placebo) resulted in resolution of VMA on OCT at 28 days. Potential side effects of ocriplasmin include transient floaters, zonular instability, and transient vision loss.6 Although the primary outcome of the study achieved a statistically significant result compared to placebo, the less than robust results compared to surgical intervention with the associated high cost of the medication have led retina specialists to question the clinical utility of this medication.

Previous small case series' have demonstrated that an intravitreal gas bubble injection alone (i.e. pneumatic vitreolysis) may lead to macular hole closure through the induction of a PVD.7-9 Additional small cases series' have shown that an intravitreal gas bubble alone may induce a PVD in patients with non-proliferative diabetic retinopathy10 and diabetic macular edema11 in nearly 100% of cases. One small case series showed that an intravitreal gas bubble in combination with an anti-vascular endothelial growth factor agent can cause resolution of VMA in patients with wet macular degeneration in 4/4 (100%) of eyes.12 However, there is a paucity of literature on the specific treatment of isolated VMT with intravitreal gas alone. Recently, Rodriques et al13 demonstrated that a single intravitreal injection of perfluoropropane (C3F8) gas injection may cause VMT resolution in 5/7 (70%) eyes with isolated VMT and in 3/6 (50%) eyes with diabetic macular edema. Although this initial study demonstrated efficacy, the overall success rate of the procedure as well as the visual acuity benefit was limited due to the heterogeneous patient population. Pneumatic vitreolysis may offer a potential safe, low cost, and effective procedure that may pose an alternative to treatment in patients with symptomatic vitreomacular adhesion.

The purpose of the present study is to evaluate the efficacy and safety of the administration of a single intravitreal injection of sulfa hexafluoride (SF6) gas for patients with symptomatic vitreomacular adhesion without concomitant macular hole. Key differences between the present study and that by Rodriques et al.10 are the use of a shorter acting gas bubble (SF6 vs C3F8) and the inclusion of a homogenous patient population with VMA alone.