A recent cross-sectional study discovered a significant reduction in Schlemm’s canal (SC) size and loss of SC dilation during physiological accommodative effort in children who have undergone a lensectomy.

Researchers compared SC and trabecular meshwork in children with healthy eyes and those with and without glaucoma after lensectomy. They examined 50 children (ages four to 16) with healthy eyes and 48 children post-lensectomy (124 healthy and 72 post-lensectomy eyes overall). Of those 72 eyes, 34 had a diagnosis of glaucoma, 18 of which had undergone surgical or laser interventions to lower intraocular pressure. Researchers analyzed anterior segment optical coherence tomography of the nasal iridocorneal angle at two levels of accommodative effort (2.5D and 15D).

The study found that the horizontal diameter of SC and its cross-sectional area were significantly smaller in the post-lensectomy eyes with glaucoma compared with healthy eyes. The same was not true in post-lensectomy eyes without glaucoma.

Researchers believe zonular tension changes and postoperative scarring may affect the elasticity and dynamic responses of structures in the iridocorneal angle, impacting the canal’s size and its dilation in response to accommodative effort.

The study concludes that further research is needed to investigate the mechanisms that lead to SC size changes and fibrosis or disruption of accommodative force transmission. Understanding these mechanisms may lead to prevention of or new treatments for post-lensectomy glaucoma. 

Daniel MC, Dubis AM, Theodorou M, et al. Childhood lensectomy is associated with static and dynamic reduction in Schlemm canal size: a biomechanical hypothesis of post-lensectomy glaucoma. Ophthalmology. August 30, 2018. [Epub ahead of print].