A trabeculectomy bleb is a specific outcome of a surgical procedure designed to manage eye pressure in individuals with glaucoma. This small, raised area on the eye’s surface plays a primary role in creating an alternative pathway for fluid drainage. Understanding this surgical result is helpful for anyone considering this glaucoma treatment.
What is a Trabeculectomy Bleb?
A trabeculectomy is a surgical procedure performed to treat glaucoma when other methods, like medications or laser treatments, have not lowered eye pressure. During this surgery, a small opening is created in the sclera, the white outer wall of the eye, under the upper eyelid. A small flap is created over this opening to regulate fluid flow.
The surgery results in a “bleb,” a small, raised, blister-like area on the sclera. It is usually hidden beneath the upper eyelid and often not visible to others. Its appearance varies, but it is described as white, translucent, or slightly milky. Its size and shape also differ among individuals.
How a Bleb Lowers Eye Pressure
The bleb establishes a new drainage route for aqueous humor, the fluid that fills the front part of the eye. In glaucoma, this fluid does not drain properly, leading to a buildup of intraocular pressure (IOP) that can damage the optic nerve. The trabeculectomy creates a “trapdoor” or “flap valve” in the sclera, allowing aqueous humor to bypass the eye’s natural, often obstructed, drainage system.
Fluid filters out of the eye through this flap into the bleb, which acts as a small reservoir under the conjunctiva, the clear membrane covering the white part of the eye. From this reservoir, the fluid is absorbed by surrounding blood vessels, preventing accumulation. This continuous filtration and absorption reduces IOP, helping to prevent further optic nerve damage and preserve vision.
Recognizing a Healthy Bleb
A healthy bleb exhibits specific characteristics. A healthy bleb is diffuse, meaning it is spread out rather than concentrated, and it may be slightly elevated. Its appearance includes a thin wall or translucency, allowing visibility of the underlying fluid.
A healthy bleb should not appear excessively red or cause significant pain. A bleb that is too flat may indicate insufficient drainage, while one that is overly prominent might suggest excessive filtration. Patients may not feel the bleb, or they might experience only a subtle awareness of its presence.
Common Concerns with Blebs
Trabeculectomy blebs can encounter issues that require medical attention. One concern is bleb failure, occurring when the bleb flattens and eye pressure rises, often due to scarring around the surgical site that obstructs fluid drainage. This can necessitate further interventions, such as breaking up scar tissue or additional surgery.
Another complication is a bleb leak, where fluid leaks out, potentially causing the eye to feel very soft. Leaks can occur days, months, or years after surgery and may lead to infection if not addressed promptly. Blebitis, an infection of the bleb, is a medical emergency characterized by redness, pain, discharge, and vision changes. Over-filtration is a less common issue where IOP becomes too low, potentially resulting in blurred vision or other adverse effects due to excessive drainage. Any of these signs warrant immediate contact with an ophthalmologist.
Caring for Your Bleb
Proper care following trabeculectomy surgery is important for the bleb’s long-term success and to prevent complications. Adhering to the prescribed eye drop regimen, which includes antibiotic and anti-inflammatory drops, is a primary step in promoting healing and reducing the risk of infection and scarring. These drops are often used for several weeks or longer.
Patients should avoid rubbing or applying pressure to the operated eye, as the bleb tissue is delicate. Wearing protective eyewear during activities that could lead to eye trauma, such as sports, is advised. Regular follow-up appointments with the ophthalmologist are necessary to monitor the bleb’s function and adjust treatment, such as releasing sutures if needed, to maintain optimal eye pressure. Promptly reporting any changes in the bleb’s appearance, vision, or discomfort to the doctor is recommended. Activities that could introduce infection, like swimming or gardening, should be avoided for a period after surgery, usually one to two weeks.