Joint Effects of Intraocular Pressure and Myopia on Risk of Primary Open-Angle Glaucoma: The Singapore Epidemiology of Eye Diseases Study

Glaucoma is a leading cause of global irreversible blindness. Primary open angle glaucoma (POAG) is the most common form of glaucoma and affects 44.1 million individuals worldwide1. Furthermore, there is a disproportionate burden of POAG in Asia, with Asians accounting for 53% (23.5 million) of POAG cases worldwide1,2. While early detection of POAG is important in delaying or halting the progression of the disease3,4, a better understanding of the interplay between major risk factors for POAG is crucial3. Intraocular pressure (IOP) is an established risk factor for POAG3,5, and is the only modifiable risk factor for the development and progression of POAG6,7. It has been postulated that elevated IOP exerts mechanical stress on the optic nerve head (ONH) and lamina cribrosa, and its adjacent tissues4,8. In addition, IOP-induced strain may also compress the lamina cribrosa and disrupt axonal transport of trophic factors which are essential to the autoregulation and survival of retinal ganglion cells4,8,9. As lamina cribrosa is the site where retinal ganglion cell axons congregate before traversing to the brain10, excessive mechanical strain at this structure may initiate glaucomatous damage4,11. Many previous studies have also reported myopia as another important risk factor for POAG12,13,14,15. This association is stronger in individuals with moderate-to-high myopia (