Vitreomacular adhesion (VMA) is a condition in which the vitreous gel of the eye is adhering abnormally to the underlying retina in the macula area that controls central vision. It is a common finding in older eyes. A new injectable treatment for resolving symptomatic vitreomacular adhesion promises to help a significant number of patients avoid surgery.
The vitreous is a gel-like fluid that fills approximately two-thirds of the eye, helping to maintain its shape. It is composed mostly of water, but also has collagen fibres, hyaluronic acid and proteins which can be perceived as floaters in our vision. In young eyes, the vitreous is attached to the surface of the retina, but as we age the vitreous begins to slowly liquefy and shrink. It eventually separates from the retina in a process call posterior vitreous detachment.
For most people, a posterior vitreous detachment is uneventful and results in a clean separation of the vitreous; however if the separation of the vitreous is uneven or incomplete then areas of adhesion can occur. These areas of focal attachment tend to cause traction and pulling on the retina. In the peripheral retina this can cause a retinal tear. In the macula area the condition is known as vitreomacular adhesion (VMA).
In mild cases, VMA has no symptoms and does not require treatment. But in some cases the resulting traction will cause distortion and blurring of vision. In severe cases a tear can form and lead to a macular hole. Diagnosis of VMA is made by eye examination with your optometrist or ophthalmologist, and should include imaging of the retina and vitreous with optical coherence tomography (OCT).
Up until recently, the only treatment options available for VMA were careful monitoring or surgical removal of the vitreous from the eye to release the adhesion (pars plana vitrectomy). Although a vitrectomy procedure is effective, it is a very delicate intraocular surgery that can potentially cause damage to the macula, or lead to other complications such as retinal detachment, infection or cataract development. Usually a patient with WMA was observed until the traction resolved on its’ own, or the condition worsened to the point where the benefit of surgery outweighed the risk.
We now have a new option – a drug called JETREA (ocriplasmin) that is a proteolytic enzyme genetically engineered from blood plasmin. When injected into the vitreous, ocriplasmin dissolves the proteins that cause the vitreous to adhere to the retina. In many patients this releases the VMA and makes surgery unnecessary. JETREA is administered under local anesthetic, and is generally painless. The traction is usually released within a week or two. As with any intravitreal injection there are risks for intraocular pressure elevation, inflammation or bleeding.
Clinical trials showed that JETREA resolved VMA in about 30% of patients, and allowed 40% of macular holes associated with VMA to close without surgery. If vitrectomy surgery was later required, treatment with JETREA did not interfere with the procedure.
With a safer alternative to vitrectomy, we can now treat patients earlier and before significant damage to the retina has occurred. Earlier and less disruptive treatment of symptomatic VMA promises to be a great advance for patients.