Symblepharon is the formation of scar-tissue adhesions between the inner lining of the eyelid and the surface of the eyeball, two structures that normally glide freely against each other. These adhesions can restrict eye movement, distort the eyelids, dry out the eye, and, when severe, threaten vision entirely. Despite being well recognized clinically, the molecular processes behind the condition remain poorly understood, and no treatment has proven reliably durable for every patient.1PubMed Central. Molecular mechanisms and treatments for ocular symblephara
What Happens Inside the Eye
The conjunctiva is a thin, transparent membrane that covers the white of the eye (the bulbar conjunctiva) and lines the inside of the eyelids (the palpebral conjunctiva). Between these two surfaces sits a pocket called the fornix, which allows the lids to open, close, and slide smoothly over the globe. Under normal conditions, these surfaces never stick to each other. In symblepharon, however, scar tissue bridges the gap. The fornix shrinks or disappears, and the lid and eyeball become physically tethered together.
The scarring behind symblepharon is a form of conjunctival fibrosis. After injury or chronic inflammation, the body’s wound-healing machinery goes into overdrive. Fibroblasts in the conjunctiva begin producing large amounts of collagen and other structural proteins. Research using animal and human tissue has shown that specific collagen types, particularly type VIII and type I, are upregulated in post-surgical conjunctival scar tissue, and that their expression is driven by signaling molecules like TGFβ2.2PubMed Central. Upregulation of distinct collagen transcripts in post-surgery scar tissue: a study of conjunctival fibrosis These collagens appear to localize within fibrous structures and around the cells that wrap blood vessels, suggesting the scarring process is tightly linked to new blood vessel formation in the healing tissue.3Disease Models & Mechanisms. Upregulation of distinct collagen transcripts in post-surgery scar tissue: a study of conjunctival fibrosis
What makes symblepharon especially frustrating to treat is that this fibrotic cascade can be self-sustaining. Once inflammation triggers collagen overproduction, the resulting scar tissue can perpetuate more inflammation, which lays down more scar. Breaking that cycle is the central challenge of treatment.
Common Causes
Symblepharon rarely appears out of nowhere. It is almost always the downstream consequence of something that damages the conjunctival surface badly enough to trigger aggressive scarring. The most common culprits fall into a few categories.
Chemical burns, particularly alkali burns, are among the most frequent causes. Alkaline substances penetrate tissue quickly and cause deep, ongoing damage even after the initial exposure is washed away. The resulting inflammation in the conjunctival fornix can produce adhesions within days to weeks. Acid burns can also cause symblepharon, though they tend to cause less penetrating injury. Patients with total limbal stem cell deficiency from chemical burns sometimes require multiple reconstructive surgeries to address the resulting adhesions.4BMJ Case Reports. Multiple conjunctival autografts from the contralateral eye for management of recurrent symblepharon in eyes with unilateral chemical burn
Stevens-Johnson syndrome (SJS) is another major cause. SJS is a severe, often drug-triggered immune reaction that blisters the skin and mucous membranes, including those of the eye. In the acute phase, the conjunctiva becomes inflamed and the surface epithelium is lost. Even after the skin lesions heal, chronic inflammation can lead to ongoing scarring of the conjunctiva, eventually resulting in symblepharon, fused eyelids, and keratinization of the eye’s surface.5PubMed Central. Symblepharon as Ocular Manifestation Post Stevens-Johnson Syndrome: A Rare Case
Ocular cicatricial pemphigoid (OCP) is an autoimmune condition in which the body’s immune system attacks the conjunctiva. Over time, this leads to progressive scarring, dry eye, shrinkage of the fornix, and inward-turning eyelids with misdirected lashes (trichiasis).6PubMed Central. Ocular cicatricial pemphigoid Unlike chemical burns, which cause a single catastrophic injury, OCP produces slow, relentless damage that may go unnoticed for years. By the time symblepharon is visible, significant tissue destruction has already occurred.
Prior eye surgery and radiation therapy are additional risk factors. Any procedure that disrupts the conjunctival surface, from pterygium removal to tumor excision, can leave behind a wound that heals with adhesions instead of smooth re-epithelialization.
Recognizing the Signs
The symptoms of symblepharon depend on how extensive the adhesions are and where they form. A small band of scar tissue in the lower fornix might cause only mild discomfort or tearing. But as adhesions become more extensive, the consequences escalate. The condition is characterized by tear film abnormalities, reduced numbers of the goblet cells that produce the mucus layer of tears, restricted eyelid movement, and limited eye movement that can cause double vision. Entropion (the eyelid turning inward), trichiasis (lashes rubbing against the cornea), and lagophthalmos (inability to fully close the lids) are all recognized complications.7PubMed Central. Management of Painful Blind Eye with Bilateral Symblepharon: A Case Report – Section: Introduction
Diagnosis is generally straightforward for an ophthalmologist. Pulling the lower lid away from the globe and asking the patient to look up will reveal adhesion bands bridging the fornix. In severe cases, the fornix is completely obliterated and the lid is virtually fused to the eyeball. More subtle cases may require careful slit-lamp examination and documentation over time, particularly when autoimmune disease is suspected, since progressive shortening of the fornix can be slow.
Grading systems exist to classify severity, ranging from minor bands that leave the fornix mostly intact to complete obliteration of the conjunctival pocket. These grades help guide surgical planning, since mild adhesions may respond to simpler procedures, while severe cases demand more complex reconstruction with tissue grafting.
Surgical Treatment Options
Surgery is the primary treatment for established symblepharon, because once scar tissue has formed, it does not resolve on its own. The basic principle is the same across techniques: the adhesions are carefully divided, the lid is freed from the globe, and the raw surfaces left behind are covered with some kind of tissue graft to prevent the scar from forming again. Where the approaches differ is in what material is used to resurface the defect.
Amniotic Membrane Transplantation
Amniotic membrane, harvested from donated placental tissue, has become one of the most widely used biological grafts in ocular surface reconstruction. The membrane acts as a scaffold for new cell growth and has well-documented anti-inflammatory properties. In one evaluation of amniotic membrane transplantation for symblepharon, complete surface healing was achieved in all patients, though about 30% developed some degree of new scarring during follow-up.8Eye. Evaluation of the outcome of amniotic membrane transplantation for ocular surface reconstruction in symblepharon In children with symblepharon and extensive corneal scarring, amniotic membrane transplantation restored the ocular surface and improved comfort in all treated patients, with visual improvement in several eyes.9PubMed. Amniotic membrane transplantation in children with symblepharon and massive pannus
A thicker version of the membrane graft has also been tried. While this “super-thick” amniotic membrane prevented primary symblepharon formation on the initial ocular surface, secondary adhesions formed in a subset of patients who needed further treatment afterward.10PubMed. Super-Thick Amniotic Membrane Graft for Ocular Surface Reconstruction Recurrence remains the main limitation of amniotic membrane grafts, particularly in severe or inflammatory cases.
Oral Mucosa Autograft
When amniotic membrane alone is insufficient, surgeons often turn to tissue from the patient’s own mouth. The inner lining of the lip or cheek is biologically similar to the conjunctiva: it is moist, thin, and designed to function on a sliding surface. After the adhesions are released, this mucosal tissue is harvested, trimmed, and sutured into the conjunctival defect. In one series, oral mucosa grafts sutured directly to the sclera after symblepharon release showed no recurrence at three years, with good cosmetic and anatomical outcomes in all seven patients.11American Journal of Ophthalmology Case Reports. Long-term follow up of oral mucosa autograft sutured to the sclera in severe symblepharon
The mouth donor site heals on its own and can typically be closed with direct sutures. In one case involving a large adhesion from a burn scar, the lower lip inner mucosa provided enough tissue to fully cover the defect left after releasing the scar.12PubMed Central. Optimizing Surgical Correction of Symblepharon Secondary to Lower Eyelid Burn Scar One practical advantage of oral mucosa is that it is the patient’s own tissue, so there is no risk of immune rejection.
Conjunctival Autograft and Combined Approaches
When one eye is affected and the other is healthy, conjunctival tissue can be harvested from the unaffected eye and transplanted to the damaged one. This approach has the appeal of using tissue that is biologically identical to what was lost. In patients with extensive, recurrent symblepharon from chemical burns, multiple conjunctival autografts from the contralateral eye corrected the adhesions without complications at the donor site.13BMJ Case Reports. Multiple conjunctival autografts from the contralateral eye for management of recurrent symblepharon in eyes with unilateral chemical burn
For the most severe cases, surgeons often combine multiple techniques. A graded strategy based on severity has shown that adding oral mucosa or conjunctival autograft to the reconstruction achieved successful outcomes in the worst grades of symblepharon.14PubMed. Surgical strategies for fornix reconstruction based on symblepharon severity Patients with symblepharon complicated by limbal stem cell deficiency, where the cornea can no longer regenerate its surface, may need limbal tissue transplantation combined with oral mucosal grafting to address both problems simultaneously.15PubMed Central. Clinical Outcomes of Keratolimbal Allograft Transplantation With Oral Mucosal Transplantation for Limbal Stem Cell Deficiency With Symblepharon
Preventing Adhesions and Reducing Recurrence
Because treating established symblepharon is difficult and recurrence rates can be high, there has been substantial interest in preventing adhesions from forming in the first place, especially after acute injuries like chemical burns or during the inflammatory phase of conditions like Stevens-Johnson syndrome.
Symblepharon rings are plastic conformers placed in the fornix to physically keep the eyelid and globe surfaces separated while healing occurs. In acute SJS, a creative variation called the “amnion doughnut” coats a symblepharon ring with amniotic membrane on both sides, so that the membrane contacts both the palpebral and bulbar surfaces simultaneously. This provides an anti-inflammatory effect and serves as both a scaffold for new cell growth and a barrier against adhesion formation.16PubMed Central. The Amnion Doughnut: A Novel Method for Sutureless Fixation of Amniotic Membrane to the Bulbar and Palpebral Conjunctiva in Acute Ocular-Involving Stevens-Johnson Syndrome
Even simpler approaches have shown promise in acute settings. In one case of alkali burn, a gelatin sponge placed against the tarsal side of the upper fornix was kept in place for 11 days while the bulbar conjunctiva healed. No symblepharon formation was observed at six months.17American Journal of Ophthalmology. Preventing symblepharon formation with a gelatin sponge in the eye of a patient with an alkali burn This kind of physical barrier approach works because the adhesions form when two raw, denuded surfaces come into contact during healing. If you keep them apart long enough for each surface to re-epithelialize independently, adhesion is far less likely.
Mitomycin C, a drug that inhibits cell proliferation, has been used as an adjunct both during surgery and as a standalone injection. When applied to exposed sclera during pterygium surgery complicated by symblepharon, it helped prevent recurrence. In one series, patients treated with mitomycin C alongside amniotic membrane and limbal conjunctival autograft recovered full eye movement and deep fornices without recurrence over a mean follow-up of roughly 22 months.18PubMed. Mitomycin C, amniotic membrane transplantation and limbal conjunctival autograft for treating multirecurrent pterygia with symblepharon and motility restriction Subconjunctival injection of mitomycin C has also been tested in patients with ocular cicatricial pemphigoid, where eight out of nine patients showed disease quieting in the treated eye based on serial evaluation of scarring and redness.19PubMed. Subconjunctival mitomycin C for the treatment of ocular cicatricial pemphigoid
The Emotional and Functional Toll
Symblepharon is not just a structural problem. Many patients with severe ocular surface disease and bilateral conjunctival scarring live with chronic pain and significant vision loss. The psychological impact is real: patients with bilateral vision loss from these conditions experience higher rates of anxiety and clinical depression.20PubMed Central. Management of Painful Blind Eye with Bilateral Symblepharon: A Case Report – Section: Discussion For someone whose symblepharon resulted from an accident or an adverse drug reaction, the emotional weight of a potentially preventable outcome can compound the physical burden.
Even in cases where vision can be partially restored, the recovery process is often long and involves multiple surgeries. Each surgery carries its own risk of triggering new scar tissue. Patients with autoimmune causes like OCP face the added challenge of a disease that never fully goes away: even after surgical correction, ongoing systemic immunosuppression is usually necessary to slow the immune attack on the conjunctiva and reduce the chance that adhesions will re-form.
Quality of life considerations increasingly shape treatment decisions. In some cases of painful blind eyes with dense bilateral symblepharon, the goal of surgery shifts from restoring vision to simply managing pain and achieving a comfortable, cosmetically acceptable outcome. A prosthetic shell fitted over a phthisical (shrunken) eye can sometimes improve appearance and comfort when reconstruction is no longer realistic.
Symblepharon in Cats
Humans are not the only species affected. Symblepharon is quite common in cats, particularly kittens, and the cause is almost always feline herpesvirus-1 (FHV-1). When kittens are infected before or shortly after their eyes open, the virus destroys the conjunctival epithelium at a stage when the tissue is still developing. The raw surfaces of the lid and globe fuse together as they heal, sometimes extensively enough to seal the eye nearly shut.21PubMed Central. Ocular manifestations of feline herpesvirus
Feline symblepharon tends to be permanent. Unlike the human version, where surgical techniques have achieved good long-term results in many patients, surgery in cats has a high recurrence rate because the underlying viral infection often reactivates and re-damages the surface. Treatment in veterinary medicine focuses more on managing the consequences, keeping the eye lubricated, controlling secondary infections, and surgically freeing the lid from the cornea only when the adhesion directly blocks the pupil or causes pain. Many cats with mild to moderate symblepharon live comfortably with the condition for years, adapting to reduced peripheral vision or minor ocular discharge.
The feline herpesvirus model has also provided some useful parallels for researchers studying human conjunctival scarring. Both conditions involve epithelial destruction followed by aberrant wound healing, and both produce adhesions that are stubbornly difficult to resolve once established. The virus-driven model in cats has been a natural laboratory for studying how surface healing goes wrong, even though the human causes are more varied.
Why Treatment Remains Difficult
Despite decades of surgical refinement, symblepharon is one of those conditions where the science still has more questions than answers at the molecular level. The broad strokes of wound healing are well known: inflammation triggers fibroblast activation, fibroblasts produce excess collagen, and the collagen matures into dense scar tissue. But the specific signals that distinguish normal conjunctival healing from the runaway scarring that produces adhesions have not been fully mapped out. Research has identified some of the collagen types involved and the role of signaling molecules like TGFβ2 in driving fibroblast activity, yet translating that into a drug that could be applied to the eye to prevent adhesion formation has not happened.22PubMed Central. Molecular mechanisms and treatments for ocular symblephara
This gap between understanding and treatment is why current approaches lean so heavily on mechanical solutions: physical barriers to keep surfaces apart, tissue grafts to cover raw areas, and anti-proliferative drugs to slow scar growth. Each of these works to varying degrees, and combining them improves outcomes, but none addresses the root molecular problem. Cultivated oral mucosal epithelial transplantation, in which a patient’s own mouth cells are grown into a sheet in the lab and then applied to the eye, represents one attempt to push the field forward. In a small series of severe cases with active inflammation, this approach improved persistent surface defects in nearly all treated eyes.23Acta Ophthalmologica. Cultivated oral mucosal epithelial transplantation for persistent epithelial defect in severe ocular surface diseases with acute inflammatory activity Lab-grown tissue opens the door to engineering grafts tailored to an individual patient’s biology, potentially reducing both rejection and recurrence. But these techniques remain specialized and are not yet widely available outside major research centers.