Intermediate uveitis is a form of uveitis localized to the vitreous and peripheral retina. Primary sites of inflammation include the vitreous of which other such entities as pars planitis, posterior cyclitis, and hyalitis are encompassed. Intermediate uveitis may either be an isolated eye disease or associated with the development of a systemic disease such as multiple sclerosis or sarcoidosis. As such, intermediate uveitis may be the first expression of a systemic condition. Infectious causes of intermediate uveitis include Epstein–Barr virus infection, Lyme disease, HTLV-1 virus infection, cat scratch disease, and hepatitis C.
Permanent loss of vision is most commonly seen in patients with chronic cystoid macular edema (CME). Every effort must be made to eradicate CME when present. Other less common causes of visual loss include retinal detachment, glaucoma, band keratopathy, cataract, vitreous hemorrhage, epiretinal membrane and choroidal neovascularization. Signs and symptoms
Clinical signs include redness of the eye, pain, blurring of vision, photophobia and floaters. However, some individuals, particularly children, can present with few to no symptoms. Associated conditions
Associations of the disease with such entities as multiple sclerosis, sarcoidosis, or inflammatory bowel disease suggest an autoimmune component in at least a subset of patients. The clustering of familial cases has led to the investigation of human leukocyte antigen (HLA) associations. The inciting event appears to be peripheral retinal perivasculitis and vascular occlusion leading to ocular inflammation, vitritis and snowbank formation. The etiology of the antigenic stimulus is not clear and may be either vitreal or perivascular in nature.
Monochromacy (from Greek mono, meaning "one" and chromo, meaning "color") is the ability of organisms or machines to perceive only light intensity, without respect to spectral composition (color). Organisms with monochromacy are called monochromats. Many mammals, such as cetaceans, the owl monkey and the Australian sea lion (pictured at right) are monochromats. In humans, absence of color vision is one among several other symptoms of severe inherited or acquired diseases, including achromatopsia or blue cone monochromacy, together affecting about 1 in 30,000 people. The affected can distinguish light, dark, and shades of gray but not color. Humans
Human vision relies on a duplex retina, comprising two types of photoreceptor cells. Rods are primarily responsible for dim-light scotopic vision and cones are primarily responsible for day-light photopic vision. For all known vertebrates, scotopic vision is monochromatic, since there is typically only one class of rod cell. However, the presence of multiple cone classes contributing to photopic vision enables color vision during daytime conditions. Most humans have three classes of cones, each with a different class of opsin. These three opsins have different spectral sensitivities, which is a prerequisite for trichromacy. An alteration of any of these three cone opsins can lead to colorblindness. Anomalous Trichromacy, when all three cones are functional, but one or more is altered in its spectral sensitivity. Dichromacy, when one of the cones is non-functional and one of the red-green or blue-yellow opponent channels are fully disabled. Cone Monochromacy, when two of the cones are non-functional and both chromatic opponent channels are disabled.