Laser Peripheral Iridotomy (LPI) is a swift, non-surgical laser procedure used to prevent or treat angle-closure glaucoma. The procedure involves using a focused beam of light to create a microscopic opening in the iris, the colored part of the eye.
This small opening acts as a bypass, allowing fluid inside the eye to move more freely and equalize pressure. The goal of LPI is to maintain normal internal eye pressure, protecting the optic nerve from damage and preserving sight. It is a highly effective treatment often performed in an eye doctor’s office setting.
Understanding Angle-Closure Glaucoma Risk
The need for LPI stems from a condition where the eye’s internal drainage system is at risk of blockage. The eye continuously produces a nourishing fluid called aqueous humor, which fills the front part of the eye. This fluid must drain out at the “angle,” the junction where the iris meets the cornea.
In people with narrow angles, the iris tissue lies unusually close to this drainage angle, which can slow the flow of fluid. This anatomical configuration creates a risk that the iris may suddenly bunch up and completely obstruct the drainage pathway, a situation called acute angle-closure. The resulting immediate and sharp rise in intraocular pressure is an ocular emergency that can cause rapid and irreversible vision loss.
The LPI procedure effectively addresses the root cause of this blockage mechanism, known as pupillary block. By creating a tiny hole in the peripheral iris, the LPI establishes an alternative route for the aqueous humor to pass from the back chamber of the eye to the front chamber. This new passage releases the pressure differential that pushes the iris forward, causing the iris to fall back from the drainage angle. This retraction of the iris widens the natural drainage pathway, preventing the physical obstruction that leads to acute angle-closure glaucoma.
The LPI Procedure: Step-by-Step
The LPI procedure is typically performed as an outpatient treatment, often taking less than 10 minutes per eye. The process begins with the administration of topical anesthetic eye drops to numb the surface of the eye. Prior to the laser application, eye drops such as pilocarpine may be used to constrict the pupil, which helps to tighten and thin the iris tissue.
The patient is then seated at a specialized instrument called a slit lamp. The ophthalmologist places a special contact lens onto the eye, which helps to magnify the target area and focus the laser beam precisely onto the peripheral iris. This lens also helps to keep the eye stable during the treatment.
The surgeon uses a YAG laser to deliver several concentrated bursts of energy to the targeted area of the iris. This energy creates a small, microscopic opening—roughly the size of a pinhead—near the edge of the iris. During the laser application, the patient may see a bright flash of light and feel a very brief, slight pinch of discomfort.
The small opening is positioned far enough away from the center of vision to avoid any visual disturbance. Once the opening is confirmed, the special lens is removed, and the eye is rinsed. The entire process creates a permanent, functional opening that restores the fluid dynamic within the eye.
What to Expect During Preparation and Recovery
Preparation for the LPI procedure is straightforward, often beginning with pre-treatment eye drops prescribed by the doctor. These drops may include medications to constrict the pupil and pressure-lowering drops to manage any potential pressure spike immediately after the laser. Patients are advised to eat and drink normally before the procedure, as no general anesthesia is required.
Following the procedure, patients are monitored for a short period, typically up to an hour, to check the intraocular pressure. It is common to experience temporary side effects, such as mild blurred vision, slight light sensitivity, or minor discomfort, all of which usually resolve within hours to a day. The use of the focusing lens may also leave a feeling of heaviness or slight blurring that dissipates shortly after.
Patients are prescribed anti-inflammatory or steroid eye drops for a few days to a week to manage inflammation caused by the laser. While most normal activities can be resumed immediately, a follow-up appointment is necessary within a few days to one week. This ensures the new opening is functioning properly and the eye pressure is stable. Serious complications are rare.