Blepharitis pathophysiology: Difference between revisions
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==Pathophysiology== | ==Pathophysiology== | ||
===Anterior blepharitis=== | ===Pathogenesis=== | ||
====Anterior blepharitis==== | |||
The exact pathogenesis of anterior blepharitis is unknown, but suspected to be multifactorial. | The exact pathogenesis of anterior blepharitis is unknown, but suspected to be multifactorial. | ||
In most blepharitis cases, the eyelids are colonized with [[bacteria]], usually ''[[Staphylococcus aureus]]'', ''[[Corynebacteria]]'', or ''[[Staphylococcus epidermidis]]''. [[Bacterial lipase]] changes [[meibomian gland]] secretions, increasing cholesterol concentration and creating an environment that promotes bacterial growth and [[proliferation]]. Bacterial toxins, mattering, and [[enzymes]] can also create [[inflammation]]. | In most blepharitis cases, the eyelids are colonized with [[bacteria]], usually ''[[Staphylococcus aureus]]'', ''[[Corynebacteria]]'', or ''[[Staphylococcus epidermidis]]''. [[Bacterial lipase]] changes [[meibomian gland]] secretions, increasing cholesterol concentration and creating an environment that promotes bacterial growth and [[proliferation]]. Bacterial toxins, mattering, and [[enzymes]] can also create [[inflammation]]. | ||
[[Allergic response]] to bacterial antigens, mostly staphylococcal antigens, may also cause blepharitis. | [[Allergic response]] to bacterial antigens, mostly staphylococcal antigens, may also cause blepharitis. | ||
===Posterior blepharitis=== | ====Posterior blepharitis==== | ||
Posterior blepharitis is often associated with skin condition, such as [[rosacea]]. Rosacea is associated with plugging and [[hypertrophy]] of the [[sebaceous glands]]. Since the meibomian glands are modified [[sebaceous glands]]. Meibomian gland dysfunction is characterized by functional abnormalities of the[[ meibomian glands]] and altered secretion of meibum. The altered meibomian gland secretions result in an impaired lipid layer of the tear film and instability of the tear film. The abnormal secretions also have a direct toxic effect on the ocular surface. Additionally, the altered lipid composition provides an environment that promotes bacterial growth. | Posterior blepharitis is often associated with skin condition, such as [[rosacea]]. Rosacea is associated with plugging and [[hypertrophy]] of the [[sebaceous glands]]. Since the meibomian glands are modified [[sebaceous glands]]. Meibomian gland dysfunction is characterized by functional abnormalities of the[[ meibomian glands]] and altered secretion of meibum. The altered meibomian gland secretions result in an impaired lipid layer of the tear film and instability of the tear film. The abnormal secretions also have a direct toxic effect on the ocular surface. Additionally, the altered lipid composition provides an environment that promotes bacterial growth. | ||
Demodex folliculorum small parasitic mites that live in [[hair follicles]], [[sebaceous glands]], and [[meibomian glands]] may caused or contributed to chronic blepharitis. This theory is still controversial. Demodex infestation has been implicated in [[rosacea]]. | Demodex folliculorum small parasitic mites that live in [[hair follicles]], [[sebaceous glands]], and [[meibomian glands]] may caused or contributed to chronic blepharitis. This theory is still controversial. Demodex infestation has been implicated in [[rosacea]]. | ||
==Associated Conditions== | ===Associated Conditions=== | ||
Blepharitis often is associated with [[systemic diseases]], such as: | Blepharitis often is associated with [[systemic diseases]], such as: | ||
*[[Rosacea]] | *[[Rosacea]] | ||
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*[[Chalazion]] | *[[Chalazion]] | ||
*[[Trichiasis]] | *[[Trichiasis]] | ||
==Gross Pathology== | ===Gross Pathology=== | ||
On [[gross pathology]], lid margin swelling, misdirection of lashes, loss of lashes, oily or [[greasy deposits]] on lid margins, crusting of anterior lid margin, lid margin [[hyperaemia]], and conjunctival hyperaemia are characteristic findings of blepharitis. | On [[gross pathology]], lid margin swelling, misdirection of lashes, loss of lashes, oily or [[greasy deposits]] on lid margins, crusting of anterior lid margin, lid margin [[hyperaemia]], and conjunctival hyperaemia are characteristic findings of blepharitis. | ||
==Microscopic Pathology== | ===Microscopic Pathology=== | ||
On microscopic histopathological analysis, [[hyperkeratinization]] of the meibomian gland [[ductal epithelium]], superficial [[stromal infiltrate]], and [[neovascularization]] and dilation of existing blood vessels (chronic blepharitis) are characteristic findings of blepharitis. | On microscopic histopathological analysis, [[hyperkeratinization]] of the meibomian gland [[ductal epithelium]], superficial [[stromal infiltrate]], and [[neovascularization]] and dilation of existing blood vessels (chronic blepharitis) are characteristic findings of blepharitis. | ||
On microscopic evaluation, Demodex mites may reveal on epilated eyelashes of patient with chronic blepharitis. | On microscopic evaluation, Demodex mites may reveal on epilated eyelashes of patient with chronic blepharitis. | ||
==Images== | ===Images=== | ||
The following are gross images associated with blepharitis. | The following are gross images associated with blepharitis. | ||
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{{Reflist|2}} | {{Reflist|2}} | ||
[[Category:Infectious disease]] | |||
[[Category:Ophthalmology]] | |||
[[Category:Immunology]] | |||
[[Category:Primary care]] | [[Category:Primary care]] | ||
{{WH}} | {{WH}} | ||
{{WS}} | {{WS}} | ||
Revision as of 15:13, 12 July 2016
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Blepharitis Microchapters | |
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Diagnosis | |
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Treatment | |
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Case Studies | |
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Blepharitis pathophysiology On the Web | |
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American Roentgen Ray Society Images of Blepharitis pathophysiology | |
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Risk calculators and risk factors for Blepharitis pathophysiology | |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Sara Mehrsefat, M.D. [2]
Overview
Blepharitis is caused by an overgrowth of the bacteria that is normally found on the skin. It is usually due to seborrheic dermatitis or a bacterial infection. Both may occur at the same time. Allergies and lice that affects the eyelashes may also cause blepharitis, although these causes are less common. People who have blepharitis have too much oil being produced by the glands near the eyelid. This allows bacteria normally found on the skin to overgrow.
Pathophysiology
Pathogenesis
Anterior blepharitis
The exact pathogenesis of anterior blepharitis is unknown, but suspected to be multifactorial. In most blepharitis cases, the eyelids are colonized with bacteria, usually Staphylococcus aureus, Corynebacteria, or Staphylococcus epidermidis. Bacterial lipase changes meibomian gland secretions, increasing cholesterol concentration and creating an environment that promotes bacterial growth and proliferation. Bacterial toxins, mattering, and enzymes can also create inflammation. Allergic response to bacterial antigens, mostly staphylococcal antigens, may also cause blepharitis.
Posterior blepharitis
Posterior blepharitis is often associated with skin condition, such as rosacea. Rosacea is associated with plugging and hypertrophy of the sebaceous glands. Since the meibomian glands are modified sebaceous glands. Meibomian gland dysfunction is characterized by functional abnormalities of themeibomian glands and altered secretion of meibum. The altered meibomian gland secretions result in an impaired lipid layer of the tear film and instability of the tear film. The abnormal secretions also have a direct toxic effect on the ocular surface. Additionally, the altered lipid composition provides an environment that promotes bacterial growth. Demodex folliculorum small parasitic mites that live in hair follicles, sebaceous glands, and meibomian glands may caused or contributed to chronic blepharitis. This theory is still controversial. Demodex infestation has been implicated in rosacea.
Associated Conditions
Blepharitis often is associated with systemic diseases, such as:
Blepharitis also is associated with ocular diseases, such as:
Gross Pathology
On gross pathology, lid margin swelling, misdirection of lashes, loss of lashes, oily or greasy deposits on lid margins, crusting of anterior lid margin, lid margin hyperaemia, and conjunctival hyperaemia are characteristic findings of blepharitis.
Microscopic Pathology
On microscopic histopathological analysis, hyperkeratinization of the meibomian gland ductal epithelium, superficial stromal infiltrate, and neovascularization and dilation of existing blood vessels (chronic blepharitis) are characteristic findings of blepharitis. On microscopic evaluation, Demodex mites may reveal on epilated eyelashes of patient with chronic blepharitis.
Images
The following are gross images associated with blepharitis.
![Blepharitis [1]](/index.php/File:193px-Blepharitis.JPG)
![Infant with blepharitis [2]](/index.php/File:218px-Infant_with_blepharitis_on_the_right_side.jpg)
