Amniotic membrane transplantation for persistent epithelial defects with ulceration

The surgical management of leaking filtering blebs

Leaking blebs may be encountered in the early postoperative period, or months to years after filtering surgery. Early postoperative bleb leaks are most often related to surgical trauma to the conjunctiva and can be avoided by careful surgical technique. Spontaneous late bleb leaks occur more frequently in glaucoma filtering surgery following adjunctive use of antimetabolites and full-thickness procedures. As we endeavor to achieve better long-term success with filtering surgery, antimetabolites have gained increasing popularity. With this change in clinical practice, a higher rate of bleb leaks is being recognized. These leaks may be uncomplicated or may be associated with sight-threatening complications such as endophthalmitis. The plethora of treatment options for bleb leaks described in the literature reflects the widespread nature of this problem. It also reflects the failure of any one particular approach not only to resolve bleb leaks but also to prevent their recurrence. This paper reviews the contemporary surgical management of leaking blebs and formulates a practical approach to their management.

Management of conjunctival cicatrizing diseases and severe ocular surface dysfunction

Physical or chemical injuries, infections, immunologic oculocutaneous disorders, drugs, and various systemic disorders may cause scarring of the conjunctiva and disturbances of the ocular surface. Trichiasis, lid margin malposition, and dry eye may result in persistent ocular irritation. The cornea may be primarily or secondarily involved. If severe, disturbances of the ocular surface may lead to significant visual impairment. Thorough evaluation of patients and of the underlying disease process is required for optimal management. Treatment may be challenging and should be comprehensive, combining medical measures and surgical correction of structural changes. Suppression of exogenous irritants, treatment of dry eye, antiinflammatory therapy, and immunosuppressants are paramount to control the underlying disease and allow optimal surgical results. Surgical correction of trichiasis and lid margin malposition, conjunctival grafting, mucous membrane transplantation, limbal stem cell transplantation, amniotic membrane transplantation, and penetrating keratoplasty help reestablish a physiologic ocular surface. Severe cases may require keratoprosthetics for visual rehabilitation. Corneal ulceration or perforation requires prompt attention to maintain ocular integrity. Special measures should be considered for patients who require cataract or glaucoma surgery.

The role of laminin-5 in TGF alpha/EGF-mediated corneal epithelial cell motility

Transforming growth factor alpha (TGF alpha) and epidermal growth factor (EGF) stimulate corneal epithelial cell wound closure. However, the role of these growth factors in regulating corneal epithelial cell motility on basement membrane proteins such as laminin has not been elucidated. In the present study we demonstrate that in an in vitro model of corneal wound healing, TGF alpha has no deleterious effects on the deposition of the laminin-5 isoform into the extracellular matrix structure underlying epithelial cells resurfacing bare collagenous stroma. In primary culture, a population of corneal epithelial cells are stimulated by TGF alpha or EGF to become highly motile. These cells are associated with an endogenously secreted, and extracellularly deposited, 'trail' of laminin-5. The laminin-5 trail is specifically associated with motile cells, as non-motile corneal epithelium exhibiting numerous cell-cell contacts does not display a similar laminin-5 localization pattern. In contrast to these observations, a preparation of laminin-5 known to promote cell spreading, adhesion, and formation of hemidesmosomes, when presented exogenously to cultured corneal epithelial cells, does not stimulate motility. However, a commercially available preparation of laminin derived from human placenta which does not contain laminin-5 does significantly promote the migration of TGF alpha- or EGF-stimulated corneal epithelial cells. From these results, it is hypothesized that endogenously secreted laminin-5 functions to promote migration in corneal epithelial cells which have been treated with TGF alpha or EGF. Exogenously presented laminin-5 does not function similarly, but functions to promote corneal epithelial cell adhesion.

The use of processed pericardial tissue in anterior ocular segment reconstruction

PURPOSE

To report the use of processed pericardial tissue in reconstructing the anterior ocular segment.

METHOD

Three case reports.

RESULT

Processed pericardial tissue was found to be a helpful adjunct in providing tectonic support and promoting epithelialization in the cases described.

CONCLUSION

Processed pericardial tissue has potential application to a variety of anterior ocular segment conditions.

Transplantation of amniotic membrane and limbal autograft for patients with recurrent pterygium associated with symblepharon

AIM

Treatment of recurrent pterygium associated with symblepharon requires both suppression of fibrosis and reconstruction of limbal barrier. To achieve this, human amniotic membrane was transplanted and limbal autografts performed.

METHODS

Four patients with severe symblepharon resulting from multiple surgeries for pterygium were treated. Human amniotic membrane was obtained at caesarean section and preserved until surgery. After excision of the fibrous tissues, the amniotic membrane was placed on the sclera, and a limbal autograft transplantation was performed using limbal tissues taken from the affected eye.

RESULTS

Recurrence of symblepharon was not observed in any of the patients and significant suppression of the subconjunctival fibrosis was achieved. Ocular movement improved in all cases. Complete remission of pterygium regrowth occurred in three cases, and a slight (about 1 mm) recurrence occurred in one case. The limbal donor site showed the presence of mild depressions without the formation of pseudopterygium.

CONCLUSION

Transplantation of human amniotic membrane with a limbal autograft appears to be a promising surgical treatment for reconstructing the ocular surface in patients with recurrent pterygium associated with symblepharon.

Important concepts for treating ocular surface and tear disorders

PURPOSE

To outline important concepts for treating ocular surface and tear disorders.

METHOD

A review was conducted of recently published findings.

RESULTS

Five concepts were delineated: ocular surface health is ensured by a close relationship between ocular surface epithelia and the preocular tear film; a stable tear film is inherently maintained by external adnexae; the intact protective mechanism is controlled by effective neuroanatomic integration; corneal epithelial stem cells are located at the corneoscleral limbus; and ocular surface epithelial cell function is supported by stromal fibroblasts and matrix.

CONCLUSIONS

These concepts stress that ocular surface epithelia and the preocular tear film function as a unit and, furthermore, that several corneal and external diseases can be categorized as ocular surface and tear disorders. These concepts also help one formulate unified diagnostic and therapeutic strategies for management of these diseases.

Amniotic membrane transplantation for conjunctival surface reconstruction

PURPOSE

To determine whether preserved human amniotic membrane can be used to reconstruct the conjunctival defect created during surgical removal of a large lesion or during symblepharon lysis.

METHODS

Amniotic membrane transplantation was performed in six consecutive patients (seven eyes) during removal of large conjunctival lesions and in nine patients (nine eyes) during removal of conjunctival scars or symblepharon.

RESULTS

During a mean follow-up period +/- SD of 10.9 +/- 9.1 months (range, 2.2 to 34.0 months), 10 patients (11 eyes) showed successful surface reconstruction without recurrence, five patients (five eyes) showed improved visual acuity, and one patient (one eye) showed epithelialization within 3 weeks and resolution of motility restriction. Two patients (two eyes) showed partial success, with surrounding conjunctival inflammation. Three cases (three eyes) failed and exhibited recurrent scarring: one patient had received mitomycin treatment and beta radiation, whereas the transplanted amniotic membrane of the second patient was partially, and of the third patient was completely, dissolved or replaced by the inflamed pseudopterygial tissue. Two patients (two eyes) had epithelial cyst formation.

CONCLUSION

Amniotic membrane transplantation can be considered an alternative substrate for conjunctival surface reconstruction during removal for large tumors, disfiguring scars, or symblepharon, especially for those whose surrounding conjunctival tissue remains relatively normal.