Symblepharon is a pathologic condition where the bulbar and palpebral conjunctiva form an abnormal adhesion to one another. Most cases of symblepharon are acquired, though it can rarely be congenital, as sometimes seen in cases of cryptophthalmos.  
Symblepharon can be acquired due to a number of inflammatory or traumatic etiologies.
Immune mediated inflammatory conditions include:
- Steven-Johnson Syndrome/Toxic Epidermal Necrolysis
- Ocular cicatricial pemphigoid
- Granulomatosis with Polyangiitis
- Chronic Graft-versus-host disease
- Paraneoplastic Mucous Membrane Pemphigoid
- Lichen Planus
- Recessive Dystrophic Epidermolysis Bullosa
This list is not exhaustive as there are many pathologies that may cause symblepharon. These diseases cause inflammation in the conjunctiva, injuring the epithelium and leading to symblepharon.
Infections from both bacteria and viruses can also cause symblepharon, such as in the case of chronic chlamydial eye infections or Epidemic Keratoconjunctivitis  Trauma to the eye may cause enough damage leading to symblepharon. This can be seen in cases of chemical, particularly alkali, or thermal burns, such as firework injuries. Congenital symblepharon has been documented in cases of cryptophthalmos. 
Epidemiologic data on this condition is not readily available. This condition occurs in a number of contexts, as described above. For each underlying pathology, the prevalence of symblepharon varies. That data is available elsewhere and is outside the scope of this section.
Symblepharon occurs from an abnormal healing process after injury to the conjunctiva. Whatever the inciting injury, the loss of epithelial cells from both the bulbar and palpebral conjunctiva allow an abnormal adhesion to form between the bulbar and palpebral conjunctiva.
The history of symblepharon is variable, depending on the specific underlying etiology. Patients may complain of dry eyes, burning sensation, photophobia, or decreased vision.
Symblepharon has variable severity and tissue involvement. On a physical exam, there may be only small adhesion between the two layers of conjunctiva. In cases like this, there may not lead to significant decrease in ocular motility. However, in more severe cases, the fornix of the eye may become obliterated, cicatricial entropion may form, or there may be permanent lagophthalmos with exposure of the cornea. Obliteration of the fornix can cause insufficient tear reservoir and blinking. This in turn leads to eventual keratinization of the ocular surface. Entropion can cause ocular trauma to the surface of the eye as the eyelashes rub on the outer surface. With greater tissue involvement, decreased extraocular movement may be seen. Depending on the severity, the symblepharon may or may not involve the cornea.
Laboratory studies are not currently used to diagnose symblepharon. However, laboratory studies are often necessary to diagnose the underlying pathology.
Symblepharon is a physical exam finding. When discovered, the specific etiology of the symblepharon must be investigated.
Medical management of symblepharon aims to prevent or decrease symblepharon formation and to treat the underlying pathology. As discussed above, a number of inflammatory conditions can lead to symblepharon. In some cases, utilizing immune modulating therapy to suppress inflammation may improve outcomes, as seen when using Rituximab when treating Severe Refractory Paraneoplastic Mucous Membrane Pemphigoid. Steroids and other immuno-suppressive drugs such as azathioprine, cyclophosphamide, or mycophenolate may also be used. The symptoms of dry eye caused by symblepharon can be managed using preservative free artificial tears and eye lubricants.
Surgery for symblepharon typically involves tissue grafting to the affected areas, and reconstruction of a normal fornix. Surgical techniques including cicatrix lysis and intraoperative mitomycin C (MMC) application are paired with reconstruction using tissue grafts from either oral mucosal transplantation, conjunctival autografting, or amniotic membrane transplantation.  Cultivated limbal stem cell transplantation is another surgical procedure to treat symblepharon that can be used in cases of severe burns. With stem cell transplantation, care must be taken to not transplant during active inflammation.
Symblepharon can lead to a number of complications. The adhesion can encroach on the limbus and grow over the cornea, leading to vision loss. The adhesions can also decrease eye movement, cause diplopia, and prevent the normal functioning of the eyelids through mechanical forces.
Symblepharon has variable severity. In some cases, symblepharon may be mild and cause no symptoms or damage to the eye. Depending on the severity, etiology, and management of the symblepharon, there is a variable prognosis. In some cases, there may be permanent blindness, in others there may be full resolution with good visual outcome.
- ↑ Glossary. In: Riordan-Eva P, Augsburger JJ. eds. Vaughan & Asbury's General Ophthalmology, 19e. McGraw-Hill; Accessed August 03, 2020. https://accessmedicine-mhmedical-com.neomed.idm.oclc.org/content.aspx?bookid=2186§ionid=165520209
- ↑ 2.0 2.1 Murthy R, Gupta H. Novel surgical technique for the management of partial cryptophthalmos. Indian J Ophthalmol. 2014;62(11):1096-1098. doi:10.4103/0301-4738.146754
- ↑ 3.0 3.1 Fung AT, Martin P, Petsoglou C, Kourt G. (2009). Repair of isolated abortive cryptophthalmos with lower eyelid switch flap and amniotic membrane graft. Ophthalmic plastic and reconstructive surgery, 25(2), 158-161. https://doi.org/10.1097/IOP.0b013e31819aaafb
- ↑ 4.0 4.1 Gündüz K, Günalp I. Congenital symblepharon (abortive cryptophthalmos) associated with meningoencephalocele. Ophthalmic Plast Reconstr Surg. 1997;13(2):139-141. doi:10.1097/00002341-199706000-00009
- ↑ 5.0 5.1 5.2 5.3 Li T, Shao Y, Lin Q, Zhang D. Reversed skin graft combining with lip mucosa transplantation in treating recurrent severe symblepharon: A case report. Medicine (Baltimore). 2018;97(35):e12168. doi:10.1097/MD.0000000000012168
- ↑ 6.0 6.1 Catt CJ, Hamilton GM, Fish J, Mireskandari K, Ali A. Ocular Manifestations of Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis in Children. Am J Ophthalmol. 2016;166:68-75. doi:10.1016/j.ajo.2016.03.020
- ↑ Holsclaw DS. Ocular cicatricial pemphigoid. Int Ophthalmol Clin. 1998;38(4):89-106. doi:10.1097/00004397-199803840-00009
- ↑ Kelmenson AT, Oliver SC, Durairaj VD. Sarcoid-induced symblepharon. Indian J Ophthalmol. 2008;56(4):344-345. doi:10.4103/0301-4738.41430
- ↑ Dunne K, Khalid M. A case of Granulomatosis with Polyangiitis presenting with significant ocular cicatricial scarring and symblepharon formation. Am J Ophthalmol Case Rep. 2016;4:11-13. Published 2016 Jul 1. doi:10.1016/j.ajoc.2016.06.010
- ↑ Allan EJ, Flowers ME, Lin MP, Bensinger RE, Martin PJ, Wu MC. Visual acuity and anterior segment findings in chronic graft-versus-host disease. Cornea. 2011;30(12):1392-1397. doi:10.1097/ICO.0b013e31820ce6d0
- ↑ 11.0 11.1 Wittenberg M, Worm M. Severe Refractory Paraneoplastic Mucous Membrane Pemphigoid Successfully Treated With Rituximab. Front Med (Lausanne). 2019;6:8. Published 2019 Jan 29. doi:10.3389/fmed.2019.00008
- ↑ Mohebbi M, Mirghorbani M, Banafshe Afshan A, Towfighi M. Lichen Planus in Ocular Surface: Major Presentations and Treatments. Ocul Immunol Inflamm. 2019;27(6):987-994. doi:10.1080/09273948.2018.1485955
- ↑ Koulisis N, Moysidis SN, Siegel LM, Song JC. Long-Term Follow-Up of Amniotic Membrane Graft for the Treatment of Symblepharon in a Patient With Recessive Dystrophic Epidermolysis Bullosa. Cornea. 2016;35(9):1242-1244. doi:10.1097/ICO.0000000000000861
- ↑ Akkaya S, Ozkurt YB. Persistent Symblepharon in an Infant Following Epidemic Keratoconjunctivitis. Med Hypothesis Discov Innov Ophthalmol. 2016;5(3):74-77.
- ↑ 15.0 15.1 15.2 DeVoe AG. System of Ophthalmology, Diseases of the Outer Eye; part 1: Conjunctiva, part 2: Cornea and Sclera. Arch Ophthalmol. 1965;74(6):884–885. doi:10.1001/archopht.1965.00970040886033
- ↑ 16.0 16.1 Kaufman HE, Thomas EL. Prevention and treatment of symblepharon. Am J Ophthalmol. 1979;88(3 Pt 1):419-423. doi:10.1016/0002-9394(79)90642-1
- ↑ Kheirkhah A, Blanco G, Casas V, Hayashida Y, Raju VK, Tseng SC. Surgical strategies for fornix reconstruction based on symblepharon severity. Am J Ophthalmol. 2008;146(2):266-275. doi:10.1016/j.ajo.2008.03.028
- ↑ Kheirkhah A, Ghaffari R, Kaghazkanani R, Hashemi H, Behrouz MJ, Raju VK. A combined approach of amniotic membrane and oral mucosa transplantation for fornix reconstruction in severe symblepharon. Cornea. 2013;32(2):155-160. doi:10.1097/ICO.0b013e318247983d
- ↑ Cheng J, Zhai H, Wang J, Duan H, Zhou Q. Long-term outcome of allogeneic cultivated limbal epithelial transplantation for symblepharon caused by severe ocular burns. BMC Ophthalmol. 2017;17(1):8. Published 2017 Jan 31. doi:10.1186/s12886-017-0403-9
- Zhang X, M VJ, Qu Y, et al. Dry Eye Management: Targeting the Ocular Surface Microenvironment. Int J Mol Sci. 2017;18(7):1398. Published 2017 Jun 29. doi:10.3390/ijms18071398