Dynamic Changes in Schlemm Canal and Iridocorneal Angle Morphology During Accommodation in Children With Healthy Eyes: A Cross-Sectional Cohort Study

Abstract

AS-OCT can be used to visualize dynamic morphologic changes in outflow structures with physiologic accommodation. The increase in SC dimensions with accommodative effort may contribute to the regulation of IOP in children.

Glaucoma following cataract surgery in the first 2 years of life: frequency, risk factors and outcomes from IoLunder2

“…This could be complemented by the use of hand-held, non-contact optical coherence tomography (OCT) instruments enabling imaging of Schlemm's canal, trabecular meshwork and angle morphology. 24 Genomic investigation, and identification of molecular biomarkers of glaucoma risk will further enable personalised management of children following early life cataract surgery.…”

“…Future studies of secondary glaucoma should take advantage of the emerging imaging technologies which allow non-contact high resolution imaging of angle morphology. 24 Increased central corneal thickness has been reported following early childhood cataract surgery, possibly due to iatrogenic arrest of normal developmental processes due to either per-operative microtrauma or release of lens proteins. 25 This leads to over diagnosis of ocular hypertension.…”

Childhood Lensectomy Is Associated with Static and Dynamic Reduction in Schlemm Canal Size

“…19 We previously described our setup to acquire high-resolution AS OCT images of the nasal ICA using a Tomey SS-1000 CASIA OCT device (Tomey, Nagoya, Japan). 18 In brief, we used standard device settings, acquiring 64 horizontal raster Bscans and 512 A-scans of a rectangular area of 8Â4 mm centered on the nasal limbus over 1.2 seconds. All images were obtained in a dimmed room by the same observer (M.C.D.)…”

“…We carried out image analysis using defined landmarks as previously described. 18 The point at which optically dark ciliary muscle (CM) changed to brighter TM was defined as the scleral spur; the Schwalbe line was defined as the border between bright corneal endothelium and darker TM; and the horizontal SC diameter was measured as the anteroposterior extent of dark space external to the TM (Fig 1). We acquired triplicate measurements of the CM width at 1, 2, and 3 mm posterior to the scleral spur (CM1, CM2, and CM3), horizontal and vertical SC diameter, SC cross-sectional area (CSA), trabecular meshwork area (defined as the area enclosed by a line connecting the scleral spur, posterior end point of SC, and Schwalbe line), and TM length and height (length defined as the distance from Schwalbe line to inferoposterior edge of TM, and height defined as the distance from the posterior end point of SC to the TM bordering the ICA anterior to the scleral spur).…”

“…4,6,14e17 In an additional proportion of children, secondary ocular hypertension will develop and the children will become glaucoma suspects requiring treatment. 10 We recently showed that in children, physiologic accommodative effort increases the dimensions of Schlemm canal (SC), 18 which may contribute to the regulation of intraocular pressure (IOP) and in part explain why IOP is lower in children than in adults. Zonular tension changes and postoperative scarring may affect the elasticity and dynamic responses of structures in the iridocorneal angle (ICA), impacting the size of SC and its dilation in response to accommodative effort.…”