This phase is heralded by bilateral panuveitis causing blurring of vision. In 70% of VKH cases, the onset of visual blurring is bilaterally contemporaneous; if initially unilateral, the other eye is involved within several days. The process can include bilateral granulomatous anterior uveitis, variable degree of vitritis, thickening of the posterior choroid with elevation of the peripapillary retinal choroidal layer, optic nerve hyperemia and papillitis, and multiple exudative bullous serous retinal detachments.The convalescent phase is characterized by gradual tissue depigmentation of skin with vitiligo and poliosis, sometimes with nummular depigmented scars, as well as alopecia and diffuse fundus depigmentation resulting in a classic orange-red discoloration ("sunset glow fundus") and retinal pigment epithelium clumping and/or migration.The chronic recurrent phase may be marked by repeated bouts of uveitis, but is more commonly a chronic, low-grade, often subclinical, uveitis that may lead to granulomatous anterior inflammation, cataracts, glaucoma, and ocular hypertension. Full-blown recurrences, though, are rare after the acute stage is over. Dysacusia may occur in this phase. Cause
Although sometimes a viral infection, or skin or eye trauma precedes an outbreak, the exact underlying initiator of VKH disease remains unknown. VKH is attributed, however, to aberrant T-cell-mediated immune response directed against self-antigens found on melanocytes. Stimulated by interleukin 23 (IL-23), T helper 17 cells and cytokines, such as interleukin 17, appear to target proteins in the melanocytes. Risk factors
Affected individuals are typically 20 to 50 years old. The female-to-male ratio is 2:1. By definition, affected people have no history of either surgical or accidental ocular trauma.
Causes
Circulatory disorders
Diabetic vasculopathy
Sepsis with peripheral necrosis
Peripheral artery disease which can lead to gangrene
A severe deep vein thrombosis (phlegmasia cerulea dolens) can cause compartment syndrome and gangrene

Neoplasm
Cancerous bone or soft tissue tumors (e.g. osteosarcoma, chondrosarcoma, fibrosarcoma, epithelioid sarcoma, Ewings sarcoma, synovial sarcoma, sacrococcygeal teratoma, liposarcoma), melanoma

Trauma
Severe limb injuries in which the limb cannot be saved or efforts to save the limb fail. Traumatic amputation (an unexpected amputation that occurs at the scene of an accident, where the limb is partially or entirely severed as a direct result of the accident, for example, a finger that is severed from the blade of a table saw)
Amputation in utero (Amniotic band)

Congenital anomalies
Deformities of digits and/or limbs (e.g., proximal femoral focal deficiency, Fibular hemimelia)
Extra digits and/or limbs (e.g., polydactyly)

Infection
Bone infection (osteomyelitis) and/or diabetic foot infections
Gangrene
Trench foot
Necrosis
Meningococcal meningitis
Streptococcus
Vibrio vulnificus
Necrotizing fasciitis
Gas gangrene
Legionella
Influenza A Virus
Animal bites
Sepsis
Bubonic plague

Frostbite
Frostbite is a cold-related injury occurring when an area (typically a limb or other extremity) is exposed to extreme low temperatures, causing the freezing of the skin or other tissues. Its pathophysiology involves the formation of ice crystals upon freezing and blood clots upon thawing, leading to cell damage and cell death. Treatment of severe frostbite may require surgical amputation of the affected tissue or limb; if there is deep injury autoamputation may occur. Athletic performance
Sometimes professional athletes may choose to have a non-essential digit amputated to relieve chronic pain and impaired performance. Australian Rules footballer Daniel Chick elected to have his left ring finger amputated as chronic pain and injury was limiting his performance.