The Kahook Dual Blade (KDB) goniotomy is a minimally invasive glaucoma surgery (MIGS) designed to address elevated eye pressure in certain types of glaucoma. This procedure employs a specialized dual-bladed instrument to enhance the eye’s natural fluid drainage system. By improving fluid outflow, KDB goniotomy aims to lower intraocular pressure and preserve vision. The KDB device was introduced in the United States in 2015.
Understanding Glaucoma and Its Treatment
Glaucoma refers to a group of eye diseases that can damage the optic nerve. Untreated, it can result in vision loss, often called the “silent thief of sight.” A primary factor associated with glaucoma is increased pressure inside the eye, known as intraocular pressure (IOP).
The eye produces a clear fluid called aqueous humor. This fluid normally drains through the trabecular meshwork, a mesh-like tissue located where the iris and cornea meet. In open-angle glaucoma, the most common type, the drainage system becomes less efficient, causing aqueous humor to accumulate and IOP to rise. While a “normal” IOP range is 10-21 mmHg, the level at which optic nerve damage occurs can vary. The main goal of glaucoma treatment is to lower IOP to prevent further optic nerve damage and preserve vision.
How the Kahook Dual Blade Works
The Kahook Dual Blade improves aqueous humor outflow by modifying the eye’s drainage pathway. Its dual-blade design removes a section of the trabecular meshwork, the tissue that often provides the greatest resistance to fluid outflow. This creates a direct pathway for aqueous humor to flow more freely into Schlemm’s canal, a circular channel that collects fluid from the trabecular meshwork.
During the procedure, the KDB’s pointed tip pierces the trabecular meshwork, and a footplate on the blade is seated within Schlemm’s canal. As the device advances along the canal, the trabecular meshwork tissue is stretched and guided towards the dual blades, which cleanly excise a strip of this tissue. Removing this obstructive tissue leads to a reduction in intraocular pressure. This approach does not create a filtering bleb or leave a foreign body within the eye, distinguishing it from some other glaucoma surgeries.
Who is a Candidate for KDB Goniotomy
Patient selection for Kahook Dual Blade goniotomy involves careful consideration by an ophthalmologist. Ideal candidates generally have mild to moderate open-angle glaucoma, particularly when intraocular pressure is not adequately controlled with medications. The procedure is also considered for patients who wish to reduce or eliminate their reliance on daily glaucoma eye drops due to the burden or potential side effects.
The KDB goniotomy can be performed as a standalone procedure or, more commonly, in conjunction with cataract surgery. Combining it with cataract surgery offers the advantage of addressing both conditions through a single surgical session, often utilizing the same clear corneal incision. The procedure’s utility has been demonstrated across various types of glaucoma, including primary open-angle glaucoma, pseudoexfoliative glaucoma, and some cases of angle-closure glaucoma. However, it may not be suitable for patients with very low target IOP goals, as angle-based procedures typically cannot lower pressure below the episcleral venous pressure (approximately 8-10 mmHg).
Preparing for and Recovering from KDB Surgery
Preparation for KDB goniotomy is similar to other eye surgeries. Patients typically undergo a comprehensive preoperative evaluation, including medical and ocular history, IOP measurement, and imaging of the anterior chamber angle. Patients may be advised to adjust certain medications before the procedure, as instructed by their surgeon. The surgery is generally performed in an ambulatory surgery center, with patients going home the same day.
The procedure itself is minimally invasive and relatively short. A small incision, typically 1.5mm, is made in the clear cornea. If combined with cataract surgery, the KDB goniotomy is usually performed after cataract removal using the same incision.
After the procedure, patients receive post-operative instructions, commonly including eye drops (topical steroids and antibiotics) to reduce inflammation and prevent infection. Activity restrictions, such as avoiding strenuous activities or heavy lifting for about two weeks, are also common. Follow-up appointments monitor eye pressure and healing, typically at one day, one week, and one month post-surgery. Patients might experience blurry vision or some redness for a few weeks. The surgery aims to achieve a significant reduction in IOP, with studies showing mean IOP reductions of approximately 20-28% and a decrease in glaucoma medications used.