In laser peripheral iridotomy (LPI), laser energy is used to create a hole in the peripheral iris, providing an alternate pathway for aqueous to pass into the anterior chamber.
Mechanism of Action
As described in Chapter 9, primary angle closure occurs as a result of a relative increase in central iridolenticular contact. This creates greater resistance to aqueous flow through the pupil to the anterior chamber (pupillary block), increasing the pressure posterior to the iris, causing it to bow anteriorly. This, in turn, narrows the anterior chamber angle. An iridotomy provides an alternate pathway for aqueous to pass into the anterior chamber (Fig 3-13), thus relieving the pupillary block and allowing the iris to fall back and subsequently widen the angle.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.