Blepharitis pathophysiology: Difference between revisions
No edit summary |
No edit summary |
||
| Line 12: | Line 12: | ||
====Anterior blepharitis==== | ====Anterior blepharitis==== | ||
The exact pathogenesis of anterior blepharitis is not fully understood. | The exact pathogenesis of anterior blepharitis is not fully understood. | ||
It is thought that blepharitis is caused by bacterial colonization (''[[Staphylococcus aureus]]'' or ''[[Staphylococcus epidermidis]]'') in the eyelids. Further, following bacterial colonization, [[bacterial lipase]] changes [[meibomian gland]] secretions, increasing cholesterol concentration and creating an environment that promotes bacterial growth | It is thought that blepharitis is caused by bacterial colonization (''[[Staphylococcus aureus]]'' or ''[[Staphylococcus epidermidis]]'') in the eyelids. Further, following bacterial colonization, [[bacterial lipase]] changes [[meibomian gland]] secretions, increasing cholesterol concentration and creating an environment that promotes bacterial growth. It is thought that bacterial toxins and [[enzymes]] may also create [[inflammation]]. | ||
[[Allergic response]] to bacterial antigens, mostly staphylococcal | [[Allergic response]] to bacterial [[antigens]], mostly staphylococcal antigens, may also cause blepharitis.<ref name="pmid24055901">{{cite journal| author=Bunya VY, Brainard DH, Daniel E, Massaro-Giordano M, Nyberg W, Windsor EA et al.| title=Assessment of signs of anterior blepharitis using standardized color photographs. | journal=Cornea | year= 2013 | volume= 32 | issue= 11 | pages= 1475-82 | pmid=24055901 | doi=10.1097/ICO.0b013e3182a02e0e | pmc=3947496 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=24055901 }} </ref><ref name="pmid3957566">{{cite journal| author=Dougherty JM, McCulley JP| title=Bacterial lipases and chronic blepharitis. | journal=Invest Ophthalmol Vis Sci | year= 1986 | volume= 27 | issue= 4 | pages= 486-91 | pmid=3957566 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=3957566 }} </ref> | ||
====Posterior blepharitis==== | ====Posterior blepharitis==== | ||
The exact pathogenesis of posterior blepharitis is not fully understood. It is thought that posterior blepharitis is the result of [[Meibomian gland]] dysfunction. | The exact pathogenesis of posterior blepharitis is not fully understood. It is thought that posterior blepharitis is the result of [[Meibomian gland]] dysfunction. | ||
Posterior blepharitis is often associated with skin condition, such as [[rosacea]], | Posterior blepharitis is often associated with skin condition, such as [[rosacea]], which is associated with [[sebaceous glands]] abnormalities (meibomian glands are modified [[sebaceous glands]]). Meibomian gland dysfunction is characterized by functional abnormalities of the [[meibomian glands]] and altered secretion of meibum. It is thought that the altered meibomian gland secretions may result in an impaired lipid layer of the tear film and instability of the tear film. The abnormal secretions may also cause a direct toxic effect on the ocular surface. Additionally, the altered lipid composition may provide an environment that affect bacterial growth. | ||
''Demodex folliculorum'' small parasitic mites that | |||
The exact pathogenesis of ''Demodex folliculorum'' (small parasitic mites that lives in [[hair follicles]], [[sebaceous glands]], and [[meibomian glands]]) is not fully understood. It is thought that ''Demodex folliculorum'' may cause or contribute to chronic blepharitis. Additionally, Demodex infestation has been implicated in [[rosacea]].<ref name="pmid25371637">{{cite journal| author=Bhandari V, Reddy JK| title=Blepharitis: always remember demodex. | journal=Middle East Afr J Ophthalmol | year= 2014 | volume= 21 | issue= 4 | pages= 317-20 | pmid=25371637 | doi=10.4103/0974-9233.142268 | pmc=4219223 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=25371637 }} </ref><ref name="pmid15774912">{{cite journal| author=Viswalingam M, Rauz S, Morlet N, Dart JK| title=Blepharokeratoconjunctivitis in children: diagnosis and treatment. | journal=Br J Ophthalmol | year= 2005 | volume= 89 | issue= 4 | pages= 400-3 | pmid=15774912 | doi=10.1136/bjo.2004.052134 | pmc=1772603 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15774912 }} </ref> | |||
===Associated Conditions=== | ===Associated Conditions=== | ||
Revision as of 18:46, 14 July 2016
|
Blepharitis Microchapters | |
|
Diagnosis | |
|---|---|
|
Treatment | |
|
Case Studies | |
|
Blepharitis pathophysiology On the Web | |
|
American Roentgen Ray Society Images of Blepharitis pathophysiology | |
|
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.[1][2]
Pathophysiology
Pathogenesis
Anterior blepharitis
The exact pathogenesis of anterior blepharitis is not fully understood. It is thought that blepharitis is caused by bacterial colonization (Staphylococcus aureus or Staphylococcus epidermidis) in the eyelids. Further, following bacterial colonization, bacterial lipase changes meibomian gland secretions, increasing cholesterol concentration and creating an environment that promotes bacterial growth. It is thought that bacterial toxins and enzymes may also create inflammation. Allergic response to bacterial antigens, mostly staphylococcal antigens, may also cause blepharitis.[1][2]
Posterior blepharitis
The exact pathogenesis of posterior blepharitis is not fully understood. It is thought that posterior blepharitis is the result of Meibomian gland dysfunction. Posterior blepharitis is often associated with skin condition, such as rosacea, which is associated with sebaceous glands abnormalities (meibomian glands are modified sebaceous glands). Meibomian gland dysfunction is characterized by functional abnormalities of the meibomian glands and altered secretion of meibum. It is thought that the altered meibomian gland secretions may result in an impaired lipid layer of the tear film and instability of the tear film. The abnormal secretions may also cause a direct toxic effect on the ocular surface. Additionally, the altered lipid composition may provide an environment that affect bacterial growth.
The exact pathogenesis of Demodex folliculorum (small parasitic mites that lives in hair follicles, sebaceous glands, and meibomian glands) is not fully understood. It is thought that Demodex folliculorum may cause or contribute to chronic blepharitis. Additionally, Demodex infestation has been implicated in rosacea.[3][4]
Associated Conditions
Blepharitis often is associated with systemic diseases, such as:[5][6]
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.[7]
Microscopic Pathology
On microscopic histopathological analysis, hyperkeratinization of the meibomian gland ductal epithelium, perivascular lymphohistocytosis, mononuclear cellular infiltrates, and spongiosis in eyelids (superfeicial dermis) are characteristic findings of seborrheic blepharitis.[8] On microscopic histopathological analysis, nongranulomatous inflammation with neutrophils, acanthosis, or parakeratosis are characteristic findings of staphylococcal blepharitis. On microscopic evaluation, Demodex mites may reveal on epilated eyelashes of patient with chronic blepharitis.[9]
Images
The following are gross images associated with blepharitis.
![Blepharitis [10]](/index.php/File:193px-Blepharitis.JPG)
![Infant with blepharitis [11]](/index.php/File:218px-Infant_with_blepharitis_on_the_right_side.jpg)
References
- ↑ 1.0 1.1 Bunya VY, Brainard DH, Daniel E, Massaro-Giordano M, Nyberg W, Windsor EA; et al. (2013). "Assessment of signs of anterior blepharitis using standardized color photographs". Cornea. 32 (11): 1475–82. doi:10.1097/ICO.0b013e3182a02e0e. PMC 3947496. PMID 24055901.
- ↑ 2.0 2.1 Dougherty JM, McCulley JP (1986). "Bacterial lipases and chronic blepharitis". Invest Ophthalmol Vis Sci. 27 (4): 486–91. PMID 3957566.
- ↑ Bhandari V, Reddy JK (2014). "Blepharitis: always remember demodex". Middle East Afr J Ophthalmol. 21 (4): 317–20. doi:10.4103/0974-9233.142268. PMC 4219223. PMID 25371637.
- ↑ Viswalingam M, Rauz S, Morlet N, Dart JK (2005). "Blepharokeratoconjunctivitis in children: diagnosis and treatment". Br J Ophthalmol. 89 (4): 400–3. doi:10.1136/bjo.2004.052134. PMC 1772603. PMID 15774912.
- ↑ McCulley JP, Dougherty JM (1985). "Blepharitis associated with acne rosacea and seborrheic dermatitis". Int Ophthalmol Clin. 25 (1): 159–72. PMID 3156100.
- ↑ Nemet AY, Vinker S, Kaiserman I (2011). "Associated morbidity of blepharitis". Ophthalmology. 118 (6): 1062–8. doi:10.1016/j.ophtha.2010.10.015. PMID 21276617.
- ↑ Benitez-Del-Castillo JM (2012). "How to promote and preserve eyelid health". Clin Ophthalmol. 6: 1689–98. doi:10.2147/OPTH.S33133. PMC 3484726. PMID 23118519.
- ↑ THYGESON P, VAUGHAN DG (1954). "Seborrheic blepharitis". Trans Am Ophthalmol Soc. 52: 173–88. PMC 1312591. PMID 13274422.
- ↑ Seal D, Ficker L, Ramakrishnan M, Wright P (1990). "Role of staphylococcal toxin production in blepharitis". Ophthalmology. 97 (12): 1684–8. PMID 2087299.
- ↑ Wikipedia (2016) https://en.wikipedia.org/wiki/Blepharitis#/media/File:Infant_with_blepharitis_on_the_right_side.jpg%7C Accessed on July 12, 2016
- ↑ Wikipedia (2016) https://en.wikipedia.org/wiki/Blepharitis#/media/File:Infant_with_blepharitis_on_the_right_side.jpg%7C Accessed on July 12, 2016
