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.
In particularly rare cases, people may develop behavioral changes, seizures, irritation of the cerebellum or meninges, oculomotor nerve palsy, or paralysis of the eye muscles.Newborns are susceptible to particularly severe effects of Chikungunya infection. Signs of infection typically begin with fever, rash, and swelling at the extremities. Around half of newborns have a mild case of the disease that resolves on its own; the other half have severe disease with inflammation of the brain and seizures. In severe cases, affected newborns may also have issues with bleeding and bloodflow, and problems with heart function.In addition to newborns, the elderly, and those with diabetes, heart disease, liver and kidney diseases, and human immunodeficiency virus infection tend to have more severe cases of Chikungunya. Around 1 to 5 in 1,000 people with symptomatic Chikungunya die of the disease. Cause
Virology
Chikungunya virus (CHIKV), is a member of the genus Alphavirus, and family Togaviridae. It was first isolated in 1953 in Tanzania and is an RNA virus with a positive-sense single-stranded genome of about 11.6kb. It is a member of the Semliki Forest virus complex and is closely related to Ross River virus, Onyongnyong virus, and Semliki Forest virus. Because it is transmitted by arthropods, namely mosquitoes, it can also be referred to as an arbovirus (arthropod-borne virus). In the United States, it is classified as a category B priority pathogen, and work requires biosafety level III precautions. Transmission
Chikungunya is generally transmitted from mosquitoes to humans.