An iridotomy is a precise, minimally invasive procedure that involves creating a small, full-thickness opening in the iris, which is the colored part of the eye. This opening serves as a new pathway for the fluid inside the eye to circulate more effectively. The procedure is primarily used to manage or avert angle-closure glaucoma by addressing a mechanical blockage within the eye’s drainage system. It is typically performed using a laser in an outpatient setting.
Understanding Angle-Closure Glaucoma
The eye constantly produces aqueous humor, a clear fluid that fills the front part of the eye and provides nourishment to surrounding structures. This fluid must drain out at a steady rate to maintain a healthy internal pressure, known as intraocular pressure (IOP). The drainage system is located in the angle where the iris meets the cornea, containing a sieve-like structure called the trabecular meshwork.
Angle-closure glaucoma occurs when the iris bulges forward, physically blocking the trabecular meshwork and preventing the aqueous humor from draining properly. This blockage is caused by a pressure imbalance where fluid is trapped behind the iris in the posterior chamber, pushing the iris forward. When the drainage angle closes, the IOP can rise rapidly, damaging the optic nerve and resulting in permanent vision loss.
The iridotomy procedure eliminates this pressure imbalance between the front and back of the iris. Creating the tiny hole allows the fluid to flow directly from the posterior chamber to the anterior chamber, which equalizes the pressure on both sides. This action causes the iris to fall back into a more natural position, opening the drainage angle and restoring the normal flow of aqueous humor.
The procedure can be used therapeutically during an acute angle-closure attack to immediately relieve pressure, or prophylactically (preventatively) in individuals identified as having a narrow drainage angle. Preventative treatment is offered to people considered at risk of a future acute attack, even if their IOP is currently normal. Timely intervention can significantly reduce the likelihood of vision damage caused by sudden pressure spikes.
How the Laser Procedure is Performed
The iridotomy procedure is usually performed with the patient seated at an instrument similar to the slit lamp microscope, which is equipped with a laser, typically a Yttrium-Aluminum-Garnet (YAG) laser. The eye is first numbed with anesthetic eye drops to ensure comfort during the brief treatment.
To help the surgeon visualize the target area and stabilize the eye, a special contact lens is placed on the eye’s surface. This lens acts as a magnifier and focusing guide for the laser beam. The surgeon aims the laser at the far edge of the iris, often in the upper portion where the opening will be covered by the upper eyelid.
The laser delivers short, high-energy pulses that create a microscopic, permanent opening in the iris tissue. This establishes an alternate route for the aqueous humor to bypass the pupillary block mechanism. The procedure is quick, often lasting only a few minutes per eye, and is completed without a surgical incision. The success of the procedure is confirmed when the iris falls back, deepening the angle and relieving the mechanical obstruction.
Pre-Procedure Preparation and Immediate Aftercare
Preparation for a laser iridotomy is relatively simple, as it is an outpatient procedure that requires no general anesthesia. Patients are instructed to take their regular eye medications, but they may also receive specific drops just before the procedure. These often include a miotic agent, such as pilocarpine, which constricts the pupil to stretch and thin the iris, making it easier for the laser to create the opening.
The patient may also receive a drop to help prevent a temporary spike in intraocular pressure, which can sometimes occur immediately following the laser treatment. After the procedure is complete, the patient’s intraocular pressure is monitored, usually for about an hour, to ensure it remains stable. The eye may feel slightly irritated, and some patients report temporary light sensitivity or blurry vision, which typically clears within a few hours.
Before leaving the clinic, the ophthalmologist usually prescribes anti-inflammatory or steroid eye drops to be used for several days. These drops help control any inflammation caused by the laser energy. Because of temporary blurring and light sensitivity, patients must arrange for someone to drive them home following the appointment.
Potential Side Effects and Long-Term Outlook
Laser iridotomy is considered a safe and highly effective procedure, but patients may experience some side effects, most of which are minor and temporary. Short-term effects include mild eye discomfort, temporary blurred vision, or a feeling of something in the eye. A temporary rise in intraocular pressure is common and is managed with medication before and after the procedure.
Some patients report visual disturbances such as glare, streaks, or halos around lights (dysphotopsias), caused by light entering through the new opening. These symptoms often diminish over time as the patient’s brain adapts, but they can occasionally persist. Rare but serious complications include bleeding from the iris, significant inflammation, or damage to the lens, which could accelerate cataract formation.
The long-term outlook for iridotomy is generally excellent, as the procedure successfully eliminates pupillary block and prevents an acute angle-closure attack. However, iridotomy does not cure glaucoma or eliminate the need for ongoing eye care. Regular monitoring of intraocular pressure and the optic nerve remains necessary to manage the overall risk of vision loss.