Abstract
Purpose: :
To evaluate the anterior chamber volume, iris volume and iridolenticular contact area before and after laser peripheral iridotomy (LPI) in eyes with pigment dispersion syndrome (PDS) using the anterior segment optical coherence tomography (AS-OCT).
Methods: :
Cross-sectional study in 21 eyes of 21 patients with PDS and 30 eyes of 30 age-, sex- and refraction-matched subjects. AS-OCT imaging was performed in control eyes, and in eyes with PDS before and 1, 4 and 12 weeks after LPI. At each visit, 4 cross-sectional images of the AS were taken in bright conditions with accommodation (accommodation), in bright conditions without accommodation (physiological myosis) and then under dark conditions (physiological mydriasis). Anterior chamber volume, iris volume and iridolenticular contact area were estimated using AS-OCT radial sections and a customized image-processing software.
Results: :
Before LPI, PDS eyes had a significantly greater anterior chamber volume and iridolenticular contact area than the control eyes (p < 0.01), and a significantly smaller iris volume than the controls (p < 0.05). After LPI, anterior chamber volume and iridolenticular contact area of the PDS eyes decreased significantly. Iris volume increased significantly after LPI (p < 0.01), and was not significantly different from that of the controls. The biometric changes were stable over time. Iris volume decreased significantly from accommodation to mydriasis and from myosis to mydriasis, both in the PDS and control eyes (p < 0.01). In PDS eyes, iridolenticular contact area decreased significantly from accommodation to mydriasis, both before and after LPI (p < 0.01). Based on multivariate analysis, significant predictors of a larger iridolenticular contact before LPI were greater AC volume (p < 0.01) and larger AC depth (p < 0.02).
Conclusions: :
In eyes with pigment dispersion syndrome, the iris is not abnormally large for the anterior segment, but anterior chamber volume is increased compared to controls, and correlates with iridolenticular contact area.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)