Longitudinal Rates of Change in Structural Parameters of Optical Coherence Tomography in Primary Angle Closure Glaucoma following Laser Iridotomy along with Peripheral Iridoplasty

Abstract

Background: This study aimed to investigate longitudinal rates of change (LRCs) of structural parameters from optical coherence tomography (OCT) in patients with primary angle closure glaucoma (PACG) after laser iridotomy (LI) along with laser peripheral iridoplasty (PI).

Methods: Among 146 patients diagnosed with PACG, thirty-two subjects (32 eyes) who underwent LI plus PI and accomplished more than five times of reliable OCT tests were included in the current retrospective study. Retinal nerve fiber layer (RNFL) and Bruch's membrane opening-minimum rim width (BMO-MRW) were measured by spectral-domain OCT with three month interval. LRCs of global and six Garway-Heath sectors were investigated using the linear mixed-effects model which adjusted BMO area, sex, and age. Imaging of dual Scheimpflug analyzer was performed before and at 1 week after LI with PI and yearly thereafter.

Results: The mean follow-up period was 32.28 ± 13.34 months with a mean number of 10.18 ± 3.33 OCT images. Baseline characteristics are as follows: age, 63 ± 7.9 years; female, 62.5%; intraocular pressure(IOP), 15.48 ± 4.79 mmHg; anterior chamber depth, 2.09 ± 0.18 mm; and mean deviation, -7.97 ± 8.48 dB. Global LRC of BMO-MRW was 0.86 ± 1.34 μm/yr and RNFL was -0.64 ± 0.22 μm/yr. IOP decreased significantly to 13.06 ± 2.21 mmHg (p=0.001) while anterior chamber volume (p=0.011) and mean anterior chamber angle (p=0.022) increased significantly after LI along with PI compared to the baseline at the final visit.

Conclusions: LRC of a new parameter, BMO-MRW, and LRC of RNFL were relatively low in patients with PACG, following LI along with PI. After widening of the anterior chamber angle and decrease of IOP due to LI plus PI, PACG might show stable structural prognosis assessed by OCT.

Figure 1

A representative case of a 72-year-old female patient with primary angle-closure glaucoma who underwent laser iridotomy (LI) combined with peripheral iridoplasty (PI). Slopes of BMO-MRW and RNFL from January 2018 to June 2021 are shown. Simple regression analysis estimating the slope of merely the global BMO-MRW (a) and the RNFL (b) by installed automated software of OCT is displayed. Note that the slope of BMO-MRW was +0.7 μm/yr, while the slope of the RNFL was −0.6 μm/yr. Global BMO-MRW was 179 μm at the initial visit (c) and that of the last visit (d) was 187 μm. Note that global BMO-MRW increased after LI combined with PI until the last visit, which was 3 years and 5 months after the first visit. ^∗BMO-MRW: Bruch's membrane opening-minimum rim width, RNFL: retinal nerve fiber layer.