Abstract
Purpose :
To explore and compare changes in schlemm canal (SC), trabecular meshwork (TM) and iridocorneal angle (ICA) configuration during moderate accommodation in young adults with healthy eyes and high myopic eyes.
Methods :
Thirty high myopic eyes (<-8.0D) from 30 patients and 30 healthy eyes with refraction between -3.0D to +1.0D from 30 subjects were recruited in this study. Optical coherence tomography (OCT) was used to image anterior angle structures in both nasal and termporal quadrants. Two sets of images were captured, first with best corrective refraction and the other with an additional 3.0 diopters of accommodation. In each image, following parameters were measured. The ICA parameters included angle opening distance at 500/750 µm, trabecular iris space area at 500/750 µm, and trabecular iris angle at 500/750 µm. The ciliary muscle thickness (CMT) was manually measured at 1, 2, and 3 mm from the sclera spur. The cross-sectional area of SC (SCarea), the anterioposterior SC diameter (SCd), TM thickness (TMt) and TM length (TML) was manually quantified.
Results :
With best correction, all the parameters of iridocorneal angle (p<0.001), SCarea (p=0.003), SCd (p=0.001) and TML (p=0.001) were significant larger in high myopic eyes than that in healthy eyes; while CMT-2 and CMT-3 were significantly smaller in high myopic eyes (p<0.001). In an individual, SCarea and SCd in the nasal quadrants were significantly larger than that in the temporal region in both groups (p<0.001). With accommodation, SCarea, SCd and TML increased significantly in both groups (p<0.001). However, ΔSCarea (p=0.035) and ΔTML (p=0.021) is larger in healthy subjects comparing with high myopic eyes.
Conclusions :
The high myopic eyes present larger SC and less configuration change in reaction to the contraction of ciliary body. It may help to characterize the underlying pathophysiological mechanism of the regulation of aqueous humor in myopia.
This is a 2020 ARVO Annual Meeting abstract.