Which LPI Location Is Best?
Ophthalmology, August 2021
Laser peripheral iridotomy (LPI) is a common treatment for angle closure. However, consensus is lacking on the optimal location for iridotomy. Xu et al. looked at anatomic changes after LPI and developed statistical models to determine predictors of angle widening and angle opening. They found that angle widening was significantly greater when the LPI location was superior as opposed to temporal or nasal.
The study population included Chinese patients between 50 and 70 years (84% female), identified from the Zhongshan Angle Closure Prevention study. At baseline, all patients were suspected of having primary angle closure, defined as inability to visualize pigmented trabecular meshwork in two or more quadrants on static gonioscopy. Each patient had LPI performed on one eye in the superior location (between 11 and 1 o’clock; n = 219) or the temporal or nasal location (at or below 10:30 or 1:30 o’clock, respectively; n = 235). OCT imaging of the anterior segment and gonioscopy were performed at baseline and two weeks after LPI. One or two images per eye, oriented along the horizontal and/or vertical meridians, were analyzed with software that automatically segmented anterior segment structures and produced biometric measurements that corresponded to scleral spur markings. Thirteen biometric parameters that describe the anterior segment were explored.
The analyses showed significant differences in all biometric parameters from baseline to two weeks post-treatment (p < .006), except for iris thickness at 2,000 μm from the scleral spur. Residual signs of angle closure after LPI were evident in 120 eyes (26.4%). According to multivariate regression analyses, predictors of greater angle widening were superior LPI location, smaller angle-opening distance measured 750 μm from the scleral scar, and greater iris curvature. Predictors of insufficient widening were temporal and nasal LPI locations and smaller mean gonioscopy grades.
Based on these findings, the authors recommend that eye care providers consider the superior LPI location to optimize anatomic changes after LPI. Even so, they cautioned that long-term clinical outcomes and potential risks are unclear at this time.
The original article can be found here.