Changes to Outflow Structures After Pilocarpine in Primary Open Angle Glaucoma Compared With Healthy Individuals...

Area of Science:

• Ophthalmology
• Glaucoma Research
• Ocular Anatomy

Background:

• Primary open-angle glaucoma (POAG) is a leading cause of irreversible blindness.
• Understanding the mechanisms of intraocular pressure (IOP) regulation is critical for glaucoma management.
• The response of the aqueous humor outflow pathway to miotic agents like pilocarpine may offer insights into POAG pathophysiology.

Purpose of the Study:

• To investigate the morphologic changes in the trabecular meshwork (TM), Schlemm canal (SC), scleral spur (SS), and ciliary muscle following pilocarpine-induced miosis.
• To compare these changes between patients with POAG and healthy controls.

Main Methods:

• Recruited 30 POAG patients and 26 healthy controls for ophthalmologic examinations.
• Administered 2% pilocarpine eye drops and performed swept-source optical coherence tomography (OCT) before and 1 hour after.
• Measured TM thickness/width, SC diameter/area, SS length, ciliary muscle thickness, and ciliary muscle angle (CMA).

Main Results:

• Healthy controls exhibited decreased IOP, reduced SS length, decreased TM thickness, and increased SC diameter/area after pilocarpine.
• POAG patients showed no significant changes in IOP or OCT parameters post-pilocarpine.
• Baseline CMA correlated with IOP in normal eyes; post-miosis, TM thickness changes correlated with IOP changes in normal eyes, while SS length and CMA changes correlated with IOP changes in POAG eyes.

Conclusions:

• Pilocarpine induced significant morphologic changes in ocular outflow structures in healthy individuals but not in POAG patients.
• The diminished response in POAG patients may be a key factor in understanding IOP dysregulation in this condition.