Measuring changes in Schlemm’s canal and trabecular meshwork in different accommodation states in myopia children: an observational study

Abstract

The aim of the study was to evaluate changes in size of Schlemm’s canal (SC) and trabecular meshwork(TM) in response to accommodation stimuli and cycloplegia states in myopia children. In total, 34 children were enroled in this study. A −6.0 D accommodation stimulus was achieved by looking at an optotype through a mirror. Cycloplegia state was induced with 1% tropicamide. Two states were confirmed by measuring the central lens thickness (CLT), anterior chamber depth and pupil diameter. The size of SC and TM was measured using swept-source optical coherence tomography. The association between changes in SC size and CLT was analysed. Compared with that in the relaxation state, SC size increased significantly under −6.0 D accommodation stimuli. SC area (SCA) increased from 6371 ± 2517 μm 2 to 7824 ± 2727 μm 2 , SC length (SCL) from 249 ± 10 μm to 295 ± 12 μm and SC width (SCW) from 27 ± 9 μm to 31 ± 8 μm. Under the cycloplegia state, SCA decreased to 5009 ± 2028 μm 2 ; SCL to 212 ± 14 μm, and SCW to 22 ± 5 μm. Changes in SCA ( r  = 0.35, P  = 0.0007), SCL ( r  = 0.251, P  = 0.0172) and SCW ( r  = 0.253, P  = 0.016) were significantly correlated with changes in CLT. TM size was not significantly altered compared to that in the relaxation state. TM length (TML) increased from 562 ± 45 μm to 587 ± 47 μm after exposure to −6.0 D accommodation stimulus. SC size enlarged in response to −6.0 D accommodation stimuli and shrunk under cycloplegia. TM length increased under the accommodation stimulus state.