biology

Vogt–Koyanagi–Harada disease

Vogt–Koyanagi–Harada disease is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Vogt–Koyanagi–Harada disease rather than just read about it. In short: Vogt–Koyanagi–Harada disease (VKH) is a multisystem disease of presumed autoimmune cause that affects melanin-pigmented tissues. The most significant manifestation is bilateral, diffuse uveitis, which affects the eyes.

Key takeaways

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Reference excerpt

Vogt–Koyanagi–Harada disease (VKH) is a multisystem disease of presumed autoimmune cause that affects melanin-pigmented tissues. The most significant manifestation is bilateral, diffuse uveitis, which affects the eyes. VKH may variably also involve the inner ear, with effects on hearing, the skin, and the meninges of the central nervous system.

Signs and symptoms

Overview

The disease is characterised by bilateral diffuse uveitis, with pain, redness and blurring of vision. The eye symptoms may be accompanied by a varying constellation of systemic symptoms, such as auditory (tinnitus, vertigo, and hypoacusis), neurological (meningismus, with malaise, fever, headache, nausea, abdominal pain, stiffness of the neck and back, or a combination of these factors; meningitis, CSF pleocytosis, cranial nerve palsies, hemiparesis, transverse myelitis and ciliary ganglionitis), and cutaneous manifestations, including poliosis, vitiligo, and alopecia. The vitiligo often is found at the sacral region.

Phases The sequence of clinical events in VKH is divided into four phases - prodromal, acute uveitic, convalescent, and chronic recurrent. The prodromal phase may have no symptoms, or may mimic a nonspecific viral infection, marked by flu-like symptoms that typically last for a few days. Fever, headache, nausea, meningismus, dysacusia (discomfort caused by loud noises or a distortion in the quality of the sounds being heard), tinnitus, and/or vertigo may occur. Eye symptoms can include orbital pain, photophobia, and tearing. The skin and hair may be sensitive to touch. Cranial nerve palsies and optic neuritis are uncommon. The acute uveitic phase occurs a few days later and typically lasts for several weeks. 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. VKH is more common in Asians, Latinos, Middle Easterners, American Indians, and Mexican Mestizos; it is much less common in Caucasians and in Blacks from sub-Saharan Africa. VKH is associated with a variety of genetic polymorphisms that relate to immune function. For example, it has been associated with human leukocyte antigens (HLA) HLA-DR4 and DRB1/DQA1, copy-number variations of complement component 4, a variant IL-23R locus and with various other non-HLA genes. HLA-DRB1*0405 in particular appears to play an important susceptibility role.

Diagnosis If tested in the prodromal phase, cerebrospinal fluid pleocytosis is found in more than 80% of cases, with mainly lymphocytes. This pleocytosis resolves in about 8 weeks even if chronic uveitis persists. Functional tests may include electroretinogram and visual field testing. Diagnostic confirmation and an estimation of disease severity may involve imaging tests such as retinography, fluorescein or indocyanine green angiography, optical coherence tomography and ultrasound. For example, indocyanine green angiography may detect continuing choroidal inflammation in the eyes without clinical symptoms or signs. Ocular MRI may be helpful and auditory symptoms should undergo audiologic testing. Histopathology findings from eye and skin are discussed by Walton. The diagnosis of VKH is based on the clinical presentation; the diagnostic differential is extensive, and includes sympathetic ophthalmia, sarcoidosis, primary intraocular B-cell lymphoma, posterior scleritis, uveal effusion syndrome, tuberculosis, syphilis, and multifocal choroidopathy syndromes.

Types Based on the presence of extraocular findings, such as neurological, auditory, and integumentary manifestations, the "revised diagnostic criteria" of 2001 classify the disease as complete (eyes along with both neurological and skin), incomplete (eyes along with either neurological or skin), or probable (eyes without either neurological or skin) . By definition, for research homogeneity purposes, the two exclusion criteria are previous ocular penetrating trauma or surgery, and other concomitant ocular disease similar to VKH disease.

Management The acute uveitis phase of VKH is usually responsive to high-dose oral corticosteroids; parenteral administration is usually not required. However, ocular complications may require a subtenon or intravitreous injection of corticosteroids or bevacizumab. In refractory situations, other immunosuppressives such as cyclosporine, or tacrolimus, antimetabolites (azathioprine, mycophenolate mofetil or methotrexate), or biological agents such as intravenous immunoglobulins (IVIG) or infliximab may be needed.

… excerpt ends here. Continue reading the full article.

Illustrations

Vogt–Koyanagi–Harada disease illustration

Worked examples

Example 1 — a first encounter with Vogt–Koyanagi–Harada disease

Start with the simplest possible case. Write down what Vogt–Koyanagi–Harada disease claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Vogt–Koyanagi–Harada disease before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Vogt–Koyanagi–Harada disease ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Vogt–Koyanagi–Harada disease

In research: Vogt–Koyanagi–Harada disease appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Vogt–Koyanagi–Harada disease in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Vogt–Koyanagi–Harada disease is common in secondary-school and first-year university syllabi. It links to neighbouring topics Autoimmune diseases, Autoinflammatory syndromes, Disturbances of human pigmentation, so understanding it makes those chapters shorter.
In everyday life: Look for Vogt–Koyanagi–Harada disease outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Vogt–Koyanagi–Harada disease in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Vogt–Koyanagi–Harada disease means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
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Frequently asked questions

What is Vogt–Koyanagi–Harada disease in simple terms?

Why does Vogt–Koyanagi–Harada disease matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Vogt–Koyanagi–Harada disease?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Vogt–Koyanagi–Harada disease.