Global prevalence of POAG From systematic reviews of published population based studies Global prevalence (2013): 3.05% of the 40-80 year population has POAG Highest : Africa with 4.2% Estimated number globally(2013) : 44 million Highest : Asia with 23.5 % ( mostly related to the largest population) Tham et al. Ophthalmology 2014;121:2081-209

Tham et al. Ophthalmology 2014;121:2081-209

Risk factors Older age Male gender Urban residence African ancestry Most glaucoma is undetected ( 40- 90%, depending on the region) Tham et al. Ophthalmology 2014;121:2081-209

Pathophysiology of Primary open angle glaucoma (POAG) Primary open angle glaucoma is considered to be a chronic, progressive optic neuropathy characterised by typical optic nerve head and nerve fibre layer changes. Progressive ganglion cell loss and visual field changes are characteristic of the disease. Damage to the optic nerve is most commonly intraocular pressure dependent. Elevated IOP occurs secondary to changes in the trabecular meshwork

Components of the trabecular meshwork (TM ) TM beams Endothelial Cells lining TM Juxtracanalicular space Extracellular matrix Glycosaminonglaycans (GAG) Originally thought to fill all the empty spaces – now thought to only coat them

TM and IOP fluctuations Changes in the structure

TM and IOP fluctuations Low IOP High IOP Collapse of TM Widening of Schlemn’s canal Expansion of TM Collapse of Schlemn’s canal

In POAG Different theories Changes seen in the Trabecular meshwork are consistent

Tabecular meshwork beams

Trabecular meshwork

Increased resistance to outflow Increased IOP

Low IOP High IOP Schelmn’s canal Schelmn’s canal Trabecular meshwork Trabecular meshwork

Low IOP High IOP Schelmn’s canal Schelmn’s canal Trabecular meshwork Trabecular meshwork Collapse of Schlemn’s canal with Persistently high IOP

Changes in POAG TM beams : Thicken Cells lining TM : get lost – fusion of beams ? Also increase buildup of GAG Plaque deposition Juxtacanalicular space extracellular matrix Glycosaminonglaycans (GAG) Originally thought to fill all the empty spaces – now thought to only coat them Collapse of Schlem’s canal with repeated high IOP