Pathogenesis of Glaucoma | Encyclopedia MDPI

Pathogenesis of Glaucoma: History

Please note this is an old version of this entry, which may differ significantly from the current revision.

Contributor:

Jason Macanian

Glaucoma, a neurodegenerative disease, has a varied pathogenesis scenario, including elevated intraocular pressure (IOP), and hypoxic conditions in the retina. Consequently, degenerating optic axons at the optic nerve head are observed clinically when extensive damage has already occurred. Following elevated IOP, changes in retinal ganglion cells lead to apoptosis immediately followed by degeneration of their optic axons. Degradation of axons leads to cupping of the optic nerve head and visual field losses. Here we emphasize that it is the retinal ganglion cells that are initial targets of elevated IOP, and, together with hyperactivity of retinal astrocytes, create the ischemic conditions which represent the earliest sign in the pathogenesis of glaucoma.

elevated IOP
reactive astrocytes
apoptosis
retinal ganglion cells
glaucoma

Glaucoma is a group of progressive eye disorders that is characterized by damage to the optic nerve head because of the breakdown of retinal ganglion cells and their axons which merge to form the optic nerve. Glaucoma is the leading cause of irreversible blindness, with more than 80 million people estimated to be affected by the disease worldwide. This number is projected to exceed 110 million by 2040 ^[1].

Glaucoma is associated with numerous risk factors including, but not limited to, age, gender, smoking history, race, and elevated intraocular pressure. Reports show a 36% greater prevalence of glaucoma in males than in females ^[2]. Risk of developing glaucoma has also been shown to increase with age ^[3]. Of individuals aged 40 years and above, 5.7% of Blacks have glaucoma whereas only 2.2% of white people do ^[4]. It is worth noting that, perhaps due to lack of access to glaucoma screening and to treatment, glaucoma is often undiagnosed. Previous reports have indicated that more than 50% of people with glaucoma are undiagnosed ^[5]^[6]. In an effort to address this public health crisis, it is important to establish methods for screening patients for risk factors of glaucoma worldwide.

Glaucoma is strongly associated with increased intraocular fluid pressure (IOP), as the aqueous humor exerts increased force per area than usual on the internal surface of the eye. This may occur in glaucoma because of blockages in the trabecular meshwork (TM) of the eye, which normally functions to drain aqueous humor from the anterior chamber. Poor drainage results in the accumulation of aqueous humor and causes IOP elevation. Glaucomatous eyes with elevated intraocular pressure have been shown to exhibit abnormalities in both the extracellular matrices of the retina and lamina cribrosa, which result in decreased function of the optic nerve and therefore lower visual acuity ^[7].

This entry is adapted from the peer-reviewed paper 10.3390/encyclopedia2040124

References

Allison, K.; Patel, D.; Alabi, O. Epidemiology of Glaucoma: The Past, Present, and Predictions for the Future. Cureus 2020, 12, e11686.
Tham, Y.-C.; Li, X.; Wong, T.Y.; Quigley, H.A.; Aung, T.; Cheng, C.-Y. Global Prevalence of Glaucoma and Projections of Glaucoma Burden through 2040: A Systematic Review and Meta-Analysis. Ophthalmology 2014, 121, 2081–2090.
McMonnies, C.W. Glaucoma history and risk factors. J. Optom. 2017, 10, 71–78.
Kelly, E.; Wen, Q.; Haddad, D.; O’Banion, J. Effects of an Aging Population and Racial Demographics on Eye Disease Prevalence: Projections for Georgia Through 2050. Am. J. Ophthalmol. 2020, 210, 35–40.
Topouzis, F.; Coleman, A.L.; Harris, A.; Koskosas, A.; Founti, P.; Gong, G.; Yu, F.; Anastasopoulos, E.; Pappas, T.; Wilson, M.R. Factors Associated with Undiagnosed Open-Angle Glaucoma. Am. J. Ophthalmol. 2008, 145, 327–335.
Quigley, H.A. Number of people with glaucoma worldwide. Br. J. Ophthalmol. 1996, 80, 389–393.
Wallace, D.M.; O’Brien, C.J. The role of lamina cribrosa cells in optic nerve head fibrosis in glaucoma. Exp. Eye Res. 2016, 142, 102–109.

© Text is available under the terms and conditions of the Creative Commons Attribution (CC BY) license; additional terms may apply. By using this site, you agree to the Terms and Conditions and Privacy Policy.