Corticosteroids increase the fluid pressure inside the eye by increasing resistance to the outflow of aqueous humour, which can cause optic nerve damage and glaucoma. Steroid treatment can therefore cause or worsen uveitic glaucoma.Elevated pressure inside the eye typically develops 2 to 6 weeks after starting corticosteroid therapy, but can occur at any time during corticosteroid therapy and may continue for weeks after steroid use has been stopped. According to the Glaucoma Research Foundation, the risk of developing chronic steroid-induced glaucoma increases with every week of steroid use.Around 90% of patients with open angle glaucoma experience a steroid response of elevated intraocular pressure following steroid treatment. Therefore, once uveitis patients have developed uveitic glaucoma, they should ideally avoid steroids wherever possible. Combination of uveitis inflammation and steroid treatment
In some cases, uveitis inflammation and steroid treatment both contribute to elevated pressure inside the eye, which leads to optic nerve damage and glaucoma. Pathogenesis
Uveitic glaucoma as a result of recurring uveitic inflammation
Uveitic glaucoma can develop as a complication of anterior uveitis resulting from the inflammatory response associated with the disease. The inflammatory response can be characterized by occlusion of the trabecular meshwork, or blocking of the tissue that is responsible for draining aqueous humour from the eye. Another characteristic that presents in some patients is peripheral anterior synechiae (PAS), or adhesions between the iris and trabecular meshwork. These two characteristics of the inflammatory uveitic response can lead to an increase in intraocular pressure, and consequently to irreversible optic nerve damage and glaucoma.
Noninfectious uveitis is characterized by an inflammatory process that may be acute, recurrent, chronic or acute-on-chronic. Uveitic glaucoma is associated with an aggressive disease course caused by very high levels of intraocular pressure that wax and wane. When uveitis is acute, the onset of inflammation is rapid, with obstruction of intertrabecular spaces. When uveitis is chronic, recurrent bouts lead to tissue destruction from direct inflammation. Obstruction of the intertrabecular spaces characteristic of acute onset uveitis, as well as the repeated inflammation characteristic to chronic uveitis, can lead to elevated intraocular pressure. This can consequently cause optic nerve damage and glaucoma. Uveitic glaucoma as a response to steroid treatment of uveitis
Uveitic glaucoma can also develop as a response to steroid treatment of uveitis. Corticosteroids cause a rise in the fluid pressure inside the eye. While the pathogenesis of corticosteroid-induced ocular hypertension is not fully understood, it likely involves swelling and remodeling (alterations to the extracellular matrix) of the trabecular meshwork, which leads to increased resistance to aqueous humour outflow and an increase in intraocular pressure. Another possible mechanism by which corticosteroids increase fluid pressure inside the eye is as follows:

Corticosteroids inhibit (partly prevent and slow) the breakdown of glycosaminoglycans (GAGs) in the trabecular meshwork. GAGs accumulate in the meshwork. Fluid drainage is decreased. Fluid pressure in the eye is increased.It has also been suggested that corticosteroids may be capable of modifying the trabecular meshwork cells, modulating their size as well as their cytoskeletal arrangement, which in turn could limit fluid drainage.