New glaucoma surgeries: Minimally Invasive Glaucoma Surgery (MIGS)
When the eye pressure is too high for long-term control of glaucoma, despite maximal treatment with eye drops and laser treatment, surgery is often recommended. Eye pressure is the balance between fluid produced inside the eye and fluid drained out of the eye through the eye’s natural drain. In glaucoma, the natural drain becomes “clogged” over time, slowing outflow and raising the pressure. Traditional glaucoma surgeries lower pressure by constructing a new drain in the eye to let fluid out. Some newer surgeries attempt to partially restore the natural drain.
Traditional surgery: Trabeculectomy and Tube-Shunt (Glaucoma Drainage Implant)
Trabeculectomy is a surgery in which a new outflow drain is created to lower eye pressure. It is the most effective surgery to achieve a very low eye pressure and is the most common one performed in severe glaucoma. During this procedure, a path (often called a “filter” or “scleral flap”) is surgically created for fluid to flow out of the eye to the space under the conjuctiva (the subconjunctival space). This path bypasses the eye’s natural drain. A medicine called mitomycin, which prevents scarring, is often used to increase the success rate of this surgery. While it is very effective in preventing blindness from glaucoma, it also has significant risks including causing eye pressure that may be too low (hypotony) and a risk for infection that persists for life (endophthalmitis).
Tube-shunt surgery (also called Glaucoma Drainage Implant surgery) is similar to trabeculectomy in that a new drain is created in the eye. The tube-shunt involves inserting a small tube inside the eye which drains to a device that is placed under the eyelid. This is performed in patients who are unlikely to achieve good results with a trabeculectomy due to the type of glaucoma they have, scarring from previous surgeries, or other reasons. Tube-shunts have similar risks to trabeculectomies. Your surgeon will discuss which surgery is more likely to be successful for you.
New glaucoma surgeries:
New techniques, called “minimally invasive glaucoma surgery,” attempt to restore the eye’s natural drainage system. Because there is no surgically created permanent pathway to the subconjunctival space, the risk of serious infection is less. Because the eye’s natural drainage system is used, the risk of pressure that is too low (hypotony) is much less as well. The trade-off is that eye pressures may not be as low after these procedures as traditional glaucoma surgeries. Your surgeon will need to determine your ideal intraocular pressure and decide if a minimally invasive glaucoma surgery may be a good option for you.
The iStent Inject® Trabecular Micro-Bypass Stent is the smallest implant in all of medicine. It may be implanted at the time of cataract surgery to reduce intraocular pressure (IOP) in patients with mild to moderate glaucoma. The iStent is placed in the eye’s natural drain to improve the outflow of fluid. Your surgeon will determine if you are a good candidate for this surgery. If this surgery doesn’t succeed in lowering intraocular pressure, other glaucoma surgeries may be performed later if needed.
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