What Is an Iridectomy (Peripheral)?

How Does Creating an Iris Bypass Prevent Angle-Closure Glaucoma?

In many eyes with a shallow front chamber, the pupil can act like a "one-way valve," allowing fluid to build up behind the iris. This pressure buildup causes the iris to "bow" forward, physically sealing the drainage angle and leading to a medical emergency. An iridectomy provides a secondary exit for the fluid, ensuring that the pressure stays balanced between the front and back of the eye. This prevents the iris from ever being pushed into the "closed" position, effectively protecting the optic nerve from the catastrophic damage of a sudden pressure spike.

What are the Primary Success Data Trends for Pressure Relief?

Clinical data shows that peripheral iridectomy has a nearly 90 percent success rate in preventing future episodes of acute angle-closure. In patients who are currently undergoing an "attack," the procedure can lower the intraocular pressure from a dangerous 60 mmHg to a safe 20 mmHg within minutes. Statistics indicate that performing an iridectomy in a high-risk "narrow-angle" eye can reduce the lifetime risk of glaucoma-related blindness by over 70 percent. These data points have made the prophylactic (preventative) iridotomy or iridectomy the global standard of care for narrow-angle patients.

Why is Laser Iridotomy the Modern Alternative to Surgical Iridectomy?

A laser peripheral iridotomy (LPI) provides the same clinical result as a surgical iridectomy but without the need for a large incision. The procedure is performed in the office in less than five minutes and involves using a focused beam of light to "punch" a tiny hole in the iris. Laser is preferred for most patients because it has a lower risk of infection and a much faster recovery time. Surgical iridectomy is typically reserved for patients who are already in the operating room for other procedures, such as cataract surgery or complex retinal repair.

What are the Specific Risks of a Malpositioned Iris Opening?

The location of the iridectomy is critical for both the health of the eye and the patient's visual comfort. If the opening is placed too centrally, the patient may experience "dysphotopsias," which are ghost images or horizontal lines caused by light passing through the extra hole. Surgeons aim to place the iridectomy at the "12 o'clock" position, where it is naturally covered by the upper eyelid. If the hole is too small, it can occasionally heal shut or be blocked by pigment, requiring a "re-treatment" to restore the fluid bypass.

How Do Clinicians Use Ultrasound Biomicroscopy to Plan the Procedure?

Before performing an iridectomy, doctors often use Ultrasound Biomicroscopy (UBM) to get a high-resolution "map" of the eye's internal dimensions. This allows the clinician to see exactly how narrow the angle is and if there are other contributing factors like a "plateau iris" or a thick cataract. UBM provides the objective proof needed to justify the procedure and helps the surgeon decide exactly where to place the opening for the best results. Post-operative imaging is also used to confirm that the drainage angle has successfully "opened up" and that the risk of a pressure spike has been eliminated.