Laser Peripheral Iridotomy (LPI)

Laser peripheral iridotomy (LPI) makes a small opening in the far edge of the iris, usually tucked under the upper lid. That opening lets fluid bypass the pupil when pupillary block is crowding the drainage angle. It is standard treatment for pupillary-block angle closure and is used preventively in selected narrow-angle eyes when the anatomy fits.

How LPI Works

The Problem: Pupillary Block

In angle closure:

1. The iris bows forward
2. Blocks the drainage angle
3. Fluid cannot exit the eye
4. Eye pressure rises (potentially very high)

This often happens because fluid has trouble passing between the iris and lens. Pressure builds behind the iris, the iris bows forward, and the drainage angle narrows or closes.

The Solution

LPI creates a small hole in the peripheral iris:

• Allows fluid to flow directly through the iris
• Bypasses the blockage at the pupil
• Equalizes pressure in front and behind the iris
• Iris falls back, opening the drainage angle

Who Needs LPI

Treatment

• Acute angle-closure glaucoma-after pressure lowered medically
• Chronic angle-closure glaucoma-if pupillary block component present

Prevention (Prophylactic)

• Narrow angles at risk for closure
• Fellow eye if one eye had angle closure
• Before cataract surgery in select cases (less common now)
• Before dilating eyes if at-risk (so that future dilation is often safer after the angle is reassessed)

Assessment

Your doctor determines if LPI is needed through:

• Gonioscopy-examining the drainage angle
• Anterior segment imaging
• Assessment of closure risk

The Procedure

Before LPI

• No fasting required
• Take regular medications
• Pilocarpine drops often given to constrict pupil (makes iris easier to treat)
• May receive pressure-lowering drops

During LPI

After LPI

• Vision temporarily blurry
• May have mild discomfort or aching
• Light sensitivity common initially
• Anti-inflammatory drops prescribed for several days
• Pressure checked 30-60 minutes after procedure
• Can usually resume normal activities same day

Recovery

First Few Hours

• Mild blurry vision
• Light sensitivity
• Mild discomfort
• Eye pressure checked before leaving

First Few Days

• Use prescribed eye drops
• Light sensitivity improves
• Vision returns to baseline
• Mild redness may persist briefly

Follow-Up

• Usually checked within 1-2 weeks
• Gonioscopy repeated to confirm angle is open
• Pressure monitored
• May need ongoing glaucoma monitoring

Effectiveness

Success Rates

• Very effective at preventing angle closure from pupillary block
• Over 90% technical success rate
• Reduces risk of acute angle-closure attack dramatically

Limitations

• Some patients have angle closure from mechanisms other than pupillary block (plateau iris)
• May not fully open chronically closed angles with scarring
• Some patients still develop glaucoma requiring treatment

What LPI Does NOT Do

• Does not lower eye pressure in open-angle glaucoma
• Does not treat already damaged optic nerve
• May not prevent all mechanisms of angle closure

Risks and Complications

Common (Usually Temporary)

• Mild pain or discomfort
• Transient eye pressure spike
• Light sensitivity
• Blurry vision
• Small amount of bleeding (usually reabsorbs)
• Inflammation

Uncommon

• Visual symptoms from iridotomy (glare, halos, ghost images)-usually hidden by upper lid
• Pressure spike requiring additional treatment
• Iridotomy closure (may need repeat procedure)
• Corneal damage

Rare

• Significant damage to lens (cataract)
• Retinal damage
• Persistent visual disturbances
• Infection

After LPI: What Changes

Medications That Become Safer

Before LPI, certain medications can trigger angle closure in at-risk patients. After a patent (open) LPI:

• Many pupil-dilating medications become safer when the angle-opening mechanism was pupillary block
• Antihistamines, decongestants, antidepressants: risk is often significantly reduced after confirmed patent LPI, but confirm with your ophthalmologist
• Eye dilation for exams: often safer, but the angle should be reassessed because plateau iris, synechial closure, or other non-pupillary-block mechanisms can persist

Always remind healthcare providers about your eye history. LPI helps, but it does not erase every medication or dilation concern in every narrow-angle patient.

Ongoing Care

• Regular eye exams remain important
• Some patients still need glaucoma monitoring
• Cataract surgery, when eventually needed, often deepens the angle and substantially lowers angle-closure risk, though monitoring may still be needed

Both Eyes

If you have angle closure or narrow angles, both eyes are typically at similar risk:

• LPI usually performed on both eyes
• Sometimes done on same day, sometimes separate visits
• Fellow eye LPI critical after acute closure in one eye

Frequently Asked Questions

Does LPI hurt?

Most patients describe a mild snapping or stinging sensation during the laser. With numbing drops, it is usually tolerable. A brief ache afterward can happen, but severe pain requires prompt medical evaluation.

Will I see the hole in my iris?

The opening is placed in the peripheral iris, usually hidden under the upper eyelid. You typically cannot see it in the mirror or notice it cosmetically.

Can LPI close up?

Rarely, an iridotomy can close over time and need to be repeated. Your doctor will check that it remains open at follow-up visits.

Will LPI cure my glaucoma?

LPI treats or prevents angle-closure mechanism but doesn't cure glaucoma. Some patients need ongoing monitoring and treatment for glaucoma even after LPI.

Do I need LPI in both eyes?

Usually yes, if your anatomy puts both eyes at risk. If one eye has had angle closure, the other is very likely to have a similar event.

Can I drive after LPI?

Vision is often blurry initially from drops and the procedure. Arrange a ride home. Most patients can drive the next day, but ask your doctor.

What if I have symptoms after LPI?

LPI dramatically reduces but doesn't eliminate risk of angle closure, especially if done for narrow angles rather than after an acute attack. Know the symptoms and seek care if they occur.

References