Blepharitis pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sara Mehrsefat, M.D. [2]
Overview
The exact pathogenesis of blepharitis is not fully understood. It is thought that blepharitis is caused by either bacterial colonization (Staphylococcus aureus or Staphylococcus epidermidis) in the eyelids, or Meibomian gland dysfunction. 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.[3]
Demodex folliculorum is an external parasite in hair follicles, sebaceous glands, and meibomian glands. The exact pathogenesis of chronic blepharitis caused by Demodex folliculorum is not fully understood. It is thought that Demodex folliculorum may infest the meibomian and sebaceous glands. Over-proliferation may lead to lid-margin infection causing ocular-surface irritation and symptoms of ocular discomfort such as itching and foreign-body sensation.[4][5]
Associated Conditions
Blepharitis often is associated with systemic diseases, such as:[6][7]
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.[8]
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.[9] 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.[10]
Images
The following are gross images associated with blepharitis.
![Blepharitis [11]](/index.php/File:193px-Blepharitis.JPG)
![Infant with blepharitis [12]](/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.
- ↑ American Academy of Ophthalmology/ eyewiki (2014) http://eyewiki.aao.org/EyeWiki%3AGeneral_disclaimer%7C Accessed on July 14, 2016
- ↑ 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
