Development of OCT (optic coherence tomography) has help clinicians gain a better understanding of the critical role played by the vitreous in macular and retinal vascular diseases.
With early-stage PVD (posterior vitreous detachment), fibrocellular organization of vitreous remnants left on the retinal surface during vitreoretinal separation is the most likely cause of idiopathic epiretinal membrane.
There has been a longstanding interest in developing pharmacologic methods for nonsurgical induction of PVD, a technique known as pharmacologic vitreolysis. Pharmacologic agents are candidates for vitreolysis if they have the ability to induce vitreous liquefaction, weakening the vitreoretinal adhesion or both. A variety of agents have been studies to date, including:
- Tissue plasminogen activator
- Vitreosolve (Vitreoretinal Technologies, Inc., Irvin, CA)
- Arginine-glycerine-aspartate peptide.
- Ocriplasmin (formally microcplasmin)
Recently, two, Phase-3 clinical trials of ocriplasmin in patients with symptomatic vitreomacular adhesions were completed.
Vitreomacular adhesion (VMA) at the macula causes metamorphopsia or visual distortion. Ocriplasmin by ThromboGenics is the only agent that induces both liquefaction and separation of the vitreous from the retinal interface.
VMA = VMT
- Pharmacologic resolution of VMA at 28 days was 26.5%.
- Placebo group (p‹0.001) was 10.1%.
- If patients with epiretinal membranes were excluded, 34.5% versus 14.3%.
There were 7.7% who had unexplained visual loss, which resolved within six months. Other side effects included:
- Floaters – 13%
- Eye pain – 10.5%
- Photopsia – 10%
- Blurred vision – 6.5%
Less than robust results of the ocriplasmin trials point to the complexity of pharmacologic vitreolysis and suggest that the ideal vitreolytic agent, or combination of agents, has yet to be identified. Other options would include:
- Intravitreal gas injection (pneumatic vitreolysis)
- Vitreous surgery
Vitreous surgery currently remains the gold standard for treating significant vitreomacular disorders and likely will continue to be the preferred treatment for some time.
The perfect vitreolytic drug capable of inducing PVDs consistently with a clear retinal surface and no toxicity concerns would be the preferred treatment.