Goniotomy is a minimally invasive procedure designed to address glaucoma by improving the eye’s natural drainage system. This surgical technique is often classified as a Minimally Invasive Glaucoma Surgery (MIGS) due to its precise nature and relatively quick recovery time. The primary purpose of goniotomy is to lower the intraocular pressure (IOP), the principal cause of optic nerve damage and vision loss in glaucoma. It achieves this by creating a direct pathway for fluid to exit the eye, circumventing the initial obstruction in the drainage angle. While the procedure is increasingly used in certain adult glaucoma cases, it remains a foundational and highly effective treatment, particularly for infants and young children.
Who Needs Goniotomy and Why
Goniotomy is the preferred initial surgical treatment for infants diagnosed with primary congenital glaucoma (PCG). This condition is characterized by a developmental abnormality in the eye’s drainage angle, present from birth, leading to elevated intraocular pressure. The drainage structure, the trabecular meshwork, is often covered by an abnormal membrane or tissue that blocks the normal flow of aqueous humor.
The procedure is highly effective in this patient population because the underlying issue is a physical barrier that can be surgically incised. This differs significantly from the widespread degenerative changes seen in most adult glaucoma cases. By incising this obstructive tissue, the surgeon directly restores the natural outflow pathway of the aqueous humor into Schlemm’s canal and the eye’s external circulation. This restorative action is most successful when performed early, typically in infants under two years of age, before the elevated pressure causes irreversible damage to the optic nerve.
Achieving long-term control of the eye pressure is essential to prevent the progressive enlargement of the eyeball and optic nerve damage resulting from untreated pediatric glaucoma. A significant advantage is that goniotomy leaves the conjunctiva, the clear membrane covering the white of the eye, mostly undisturbed. This preserves the tissue for more complex filtration surgeries, such as trabeculectomy, should they be needed later.
The Surgical Process
The goniotomy procedure is performed in an operating room setting, requiring the patient to be completely still. For infants and young children, this necessitates the use of general anesthesia to ensure patient safety and surgical precision. The surgeon begins by making a tiny incision in the cornea, which allows access to the anterior chamber of the eye where the drainage angle is located.
A specialized contact lens, called a goniolens, is then placed on the cornea to provide a magnified, clear view of the interior angle structures. This lens is essential because the angle is an internal structure that cannot be viewed directly without specialized optical assistance. Once the drainage angle is clearly visible, the surgeon introduces a fine surgical instrument, often a goniotomy knife or a microcatheter, through the corneal incision.
The instrument is carefully advanced across the anterior chamber to the opposite side, where the abnormal trabecular meshwork is located. The surgeon then uses the tip of the instrument to make a precise incision through the meshwork membrane. This controlled cutting action opens the obstructed pathway, allowing the aqueous fluid to flow more freely into the collector channels and reducing the intraocular pressure. The instrument is withdrawn, and the small corneal incision is designed to be self-sealing, often requiring no sutures.
Preparation and Recovery Timeline
Pre-operative preparation involves standard protocols for general anesthesia, including a period of fasting before the procedure to prevent complications. Parents or caregivers receive detailed instructions regarding the timing for discontinuing food and liquids prior to the scheduled surgery time. The procedure is often performed on an outpatient basis, though a brief overnight stay may be recommended for very young patients requiring close pressure monitoring.
Immediately following the surgery, a protective eye shield is placed over the operated eye to prevent accidental rubbing or trauma. This shield must be worn, especially during sleep, for up to two weeks to protect the delicate surgical site. Post-operative care centers on a regimen of topical eye drops, which typically include both antibiotic drops to prevent infection and steroid drops to manage inflammation and promote healing.
Internal recovery takes longer, with pressure control determined around six weeks after the operation. Activity restrictions are imposed for at least two weeks to minimize pressure spikes and reduce the risk of bleeding; patients must avoid heavy lifting, strenuous exercise, and bending over with the head below the heart. Swimming is also restricted to prevent infection. Caregivers should monitor for signs that require immediate medical attention:
- Worsening pain not relieved by medication.
- A sudden decrease in vision.
- Fever.
- Excessive discharge from the eye.
Success Rates and Complications
Goniotomy has demonstrated high success rates, particularly when treating primary congenital glaucoma in young patients with clear corneas. Success rates range from 70% to over 90% in ideal candidates, especially those diagnosed in the infantile stage (three to twelve months of age). The effectiveness of the procedure is significantly influenced by the age of the patient and the severity of the glaucoma at the time of the operation.
Despite its high success rate, the procedure carries a low risk of complications, which are typically minor and manageable. The most common complication is a hyphema, a collection of blood in the anterior chamber of the eye resulting from the incision into the vascularized drainage tissue. This bleeding is usually mild and resolves on its own within a few days or weeks.
Infection and scarring of the newly created drainage pathway are possible, though rare, concerns. If a single goniotomy does not achieve adequate pressure control, the patient may require a repeat goniotomy or a different type of glaucoma surgery in the future. The procedure’s advantage is that it is less invasive than traditional filtering surgeries, preserving the external eye tissues and allowing for additional surgical options.