Journal of Pediatric Ophthalmology and Strabismus

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Short Subjects 

Limbal Stem Cell Transplantation with Amniotic Membrane for the Treatment of Uniocular Chemical Burn in Children

Silay Canturk, MD; Yonca Akova, MD; Veysi Oner, MD

Abstract

This study evaluated the outcome of corneal surface reconstruction with conjunctival limbal autograft and amniotic membrane transplantation in two children with unilateral ocular chemical burn who underwent surgery. Visual acuity improved from counting fingers at face to 20/60 in one patient and from counting fingers at 30 cm to 20/100 in the other. Both patients received simultaneous symblepharon lysis and regained deep fornices. When used in combination with amniotic membrane, conjunctival autograft allows correction of cicatricial abnormalities and early restoration of corneal surface integrity. Intervention within 6 months is desirable for rehabilitation of vision in the amblyogenic period.

Abstract

This study evaluated the outcome of corneal surface reconstruction with conjunctival limbal autograft and amniotic membrane transplantation in two children with unilateral ocular chemical burn who underwent surgery. Visual acuity improved from counting fingers at face to 20/60 in one patient and from counting fingers at 30 cm to 20/100 in the other. Both patients received simultaneous symblepharon lysis and regained deep fornices. When used in combination with amniotic membrane, conjunctival autograft allows correction of cicatricial abnormalities and early restoration of corneal surface integrity. Intervention within 6 months is desirable for rehabilitation of vision in the amblyogenic period.

From Baskent University School of Medicine, Department of Ophthalmology, Ankara, Turkey.

The authors have no financial or proprietary interest in the materials presented herein.

Address correspondence to Silay Canturk, MD, Baskent University School of Medicine, Department of Ophthalmology, Dadaloglu Mah. 39 Sk. No. 6, Adana, Yuregir, Turkey 01250.

Received: January 08, 2008
Accepted: April 29, 2008
Posted Online: May 21, 2010

Introduction

Chemical burn of the eye is potentially a blinding injury that can destroy limbal epithelial stem cells and secondarily lead to limbal cell deficiency. The chemically injured corneal surface, lacking its regenerating source of epithelial stem cells, heals through ingrowth of conjunctival epithelial cells. This conjunctivalization of the cornea is invariably associated with destruction of the basement membrane, occurrence of superficial vascularization, chronic inflammation, and persistent epithelial defects. Chemical injury may also damage the conjunctival epithelial cells and goblet cells, causing a severe dry eye state with keratinization and symblepharon formation. The cornea may lose its clarity as a result of opacification caused by the chemical burn or invasion by the vascularized conjunctiva. Unilateral loss of vision as a result of unilateral corneal opacification in a visually immature child may also have deleterious consequences, such as amblyopia, loss of fixation, and strabismus.

The goal of treatment should be early restoration of corneal clarity with corneal phenotypic differentiation. In a unilateral injury, treatment with autologous transplantation of limbal tissue as sectors from the fellow eye and replacement of the chemically injured corneal limbus is possible. This technique was initially described by Kenyon and Tseng,1 who obtained successful results in their largest series of adults who underwent conjunctival limbal autograft. There is limited literature on the clinical outcome of this treatment in the pediatric age group.

Favorable results have been observed when human amniotic membrane has been used in conjunction with limbal cell transplantation in ocular chemical burns.2 The amniotic membrane consists of a thick basement membrane that promotes epithelial migration and adhesion. It also contains an avascular stromal matrix, which is considered the component responsible for reducing inflammation, fibrosis, and neovascularization. Successful use of amniotic membrane transplantation in children with other ocular surface disorders, such as epidermolysis bullosa, laryngeo-oculocutaneous syndrome, and measles keratitis, has been reported.3,4 Other reports have described its use in children for the treatment of vernal corneal ulcers and Stevens–Johnson syndrome, but there is little information in the literature about its use in restoring the pediatric ocular surface in combination with autologous limbal stem cell transplantation after ocular chemical burns.5,6

This article describes the treatment of two children with severe unilateral chemical burns caused by a cement splash to the ocular surface.

Case Reports

Surgical Method

The study was approved by the medical ethics committee of Baskent University School of Medicine, Ankara, Turkey. Informed consent was obtained for both patients.

Human amniotic membrane was prepared and preserved by the method proposed by Kim and Tseng.7 The human placenta was harvested at the time of cesarean section after oral consent was obtained from the donors, who had negative results on serologic tests for hepatitis B and C virus, syphilis, and human immunodeficiency virus. Conjunctival epithelium with fibrous tissue covering the cornea was removed up to 3 to 4 mm posterior to the limbus. Bulbar conjunctiva was dissected at the site of symblepharon, and a corneal fibrovascular pannus was removed. Limbal tissue was prepared from the healthy eye. The limbal area was exposed from the 2-o’clock position and the 10-o’clock position, and lamellar dissection of 0.5 mm of corneal limbus and 10.0 mm of adjacent conjunctiva was performed with a surgical blade.

The conjunctival limbal graft was cut into two pieces and transferred to the 12-o’clock and 6-o’clock positions of the affected eye. Then 10-0 nylon was used to suture the limbal tissue and conjunctiva. The amniotic membrane was secured over the limbal transplant and bulbar conjunctiva with the epithelium side up, using 8-0 Vicryl (Ethicon, Somerville, NJ) sutures. The 10-0 nylon sutures and nonabsorbed Vicryl sutures were removed 1 month after surgery under intravenous sedation.

Case 1

A 5-year-old boy was referred for treatment of corneal opacity and limbal stem cell deficiency in October 2004. Five months earlier, he had a cement splash to the left eye and underwent amniotic membrane transplantation at a local hospital. On examination, visual acuity was 20/20 in the right eye (Allen figures) and counting fingers at 30 cm in the left eye. There was symblepharon formation superiorly in the left eye and conjunctivalization of the temporal and central cornea (Fig. 1). Details of the iris were not visible temporally and centrally. The nasal limbus was preserved and the cornea was clear for less than 5 clock hours nasally. There was poor opening of the eyelids because of superotemporal symblepharon formation. A fibrovascular pannus was removed with superficial keratectomy and symblepharon lysis. Autologous limbal cell transplantation with amniotic membrane transplantation was performed.

Case 1, Showing (A) Anterior Corneal Scarring, (B) Symblepharon Formation in the Superior Fornix (black Arrow) and (C) Conjunctivalization of the Cornea (white Arrow). (D–F) Postoperative Day 4 After Autologous Limbal Conjunctival Transplantation with Amniotic Membrane. (D) Limbal Conjunctival Autograph and Amniotic Membrane with Transplantation of the Inferior Fornix Were Performed. (E) Fibrovascular Pannus Was Removed Temporally. (F) Symblepharon Lysis with Limbal Conjunctival Autograph and Amniotic Membrane Transplantation Superiorly Was Achieved. The Reconstructed Ocular Surface 10 Months After Surgery, Showing (G) Mild Anterior Corneal Haze and (H) Persistent Temporal Corneal Vascularization for 2 Clock Hours (black Arrow). (I) Small Temporal Pseudopterygium Is Observed After the Ocular Surface Is Stabilized.

Figure 1. Case 1, Showing (A) Anterior Corneal Scarring, (B) Symblepharon Formation in the Superior Fornix (black Arrow) and (C) Conjunctivalization of the Cornea (white Arrow). (D–F) Postoperative Day 4 After Autologous Limbal Conjunctival Transplantation with Amniotic Membrane. (D) Limbal Conjunctival Autograph and Amniotic Membrane with Transplantation of the Inferior Fornix Were Performed. (E) Fibrovascular Pannus Was Removed Temporally. (F) Symblepharon Lysis with Limbal Conjunctival Autograph and Amniotic Membrane Transplantation Superiorly Was Achieved. The Reconstructed Ocular Surface 10 Months After Surgery, Showing (G) Mild Anterior Corneal Haze and (H) Persistent Temporal Corneal Vascularization for 2 Clock Hours (black Arrow). (I) Small Temporal Pseudopterygium Is Observed After the Ocular Surface Is Stabilized.

After surgery, the left eye was treated with topical ofloxacin four times daily, preservative-free dexamethasone every 3 hours, and preservative-free lubricants every 3 hours. The right eye was treated with topical ofloxacin four times daily and dexamethasone four times daily for 2 weeks. The use of drops in the left eye was tapered over 2 months. Treatment with preservative-free lubricants four times daily and dexamethasone once daily was continued for an additional 4 months. Visual acuity improved to 20/100 in the left eye with Allen figures. Part-time patching for 3 months did not improve visual acuity, and patching was discontinued. The patient was able to open the left eye comfortably, and the superior fornix of the left eye was well formed. The corneal surface was healthy, with superficial scarring and temporal vascularization at the site of the original symblepharon.

Case 2

A 6-year-old girl had a severe chemical burn of the left eye after a cement splash that occurred while she was playing in a construction area. She was referred for evaluation after irrigation of the conjunctival fornices. On examination, a total corneal epithelial defect was present and 180° of limbal whitening in the left eye was observed. The cornea was hazy, and details of the iris were obscure. Cement particles were visible in the superior fornix. Intraocular pressure was normal. Further irrigation with saline and removal of cement particles was performed under intravenous sedation. Prednisolone phosphate 1% drops every 2 hours, tobramycin ointment four times daily, and cyclopentolate 1% three times daily were prescribed.

Two days later, examination showed epithelial cells in the 12-o’clock to the 3-o’clock positions in the peripheral cornea. The dose of steroids was tapered, antibiotic treatment was continued, and the epithelial defect was closed in 6 weeks. Visual acuity remained 20/400 in the left eye. A corneal pannus at the 10-o’clock position developed, and a 300° peripheral corneal neovascularization was evident. Symblepharon formation was seen in the inferior and superior fornix (Fig. 2).

Case 2, Showing (A) Inferior Temporal and Superior Nasal Symblepharon Formation (white Arrow). (B) A Limbal Fibrovascular Pannus for 4 Clock Hours (black Arrow) Is Seen in the Nasal Limbus and Corneal Conjunctivalization Is Observed. (C) the Fornix Is Shortened Superiorly. (D–F) One Week Postoperatively, Amniotic Membrane Is Seen over the Denuded Cornea. (E) Cicatricial Tissue Is Removed. Conjunctival Limbal Autographs Are Placed (D) Inferiorly and (F) Superiorly. (G) Two Months Postoperatively, the Reconstructed Corneal Surface Is Seen. Healthy Tissue Is Observed (H) Nasally, and (I) Superiorly. (I) Deepened Fornix Is Achieved Superiorly.

Figure 2. Case 2, Showing (A) Inferior Temporal and Superior Nasal Symblepharon Formation (white Arrow). (B) A Limbal Fibrovascular Pannus for 4 Clock Hours (black Arrow) Is Seen in the Nasal Limbus and Corneal Conjunctivalization Is Observed. (C) the Fornix Is Shortened Superiorly. (D–F) One Week Postoperatively, Amniotic Membrane Is Seen over the Denuded Cornea. (E) Cicatricial Tissue Is Removed. Conjunctival Limbal Autographs Are Placed (D) Inferiorly and (F) Superiorly. (G) Two Months Postoperatively, the Reconstructed Corneal Surface Is Seen. Healthy Tissue Is Observed (H) Nasally, and (I) Superiorly. (I) Deepened Fornix Is Achieved Superiorly.

Three months later, in October 2004, the patient underwent autologous stem cell transplantation, amniotic membrane transplantation, and symblepharon lysis. The fibrovascular pannus was removed, with superficial keratectomy performed at the same time. After surgery, preservative-free dexamethasone every 2 hours, ofloxacin every 2 hours, and preservative-free lubricants were prescribed for 2 weeks and tapered over 2 months. Visual acuity at the last visit was 20/20 in the right eye (Snellen) uncorrected and 20/50 in the left eye with correction of −0.50 +2.00 × 15. There was good opening of the eye, with deep fornices. Mild anterior stromal haze was present in the cornea. Vision did not improve with a trial of rigid contact lenses. Part-time patching (6 hours per day with 2 hours of close work) was performed with good compliance for 3 months and was discontinued when no improvement was observed. Vision remained stable during a follow-up period of 24 months after surgery.

Discussion

Severe ocular chemical burn usually produces loss of corneal clarity, limbal dysfunction, and sub-conjunctival inflammation and fibrosis.8 The treatment of this complicated injury includes reconstruction of the corneal and conjunctival epithelium to restore the ocular surface. Limbal stem cell transplantation is the only procedure currently known that would promote proper healing of the corneal epithelium in limbal stem cell deficiency secondary to ocular chemical burns.

Both of the patients described in this report received limbal transplantation in the late repair phase of the injury, after corneal epithelization was completed, albeit with vascularized conjunctival epithelium. Case 1 received topical steroids, antibiotics, and lubricants for 4 months and case 2 received the same for 5 months. Case 1 had also received amniotic membrane in the acute phase of injury, but this treatment was not sufficient to prevent conjunctivalization as a result of severe limbal dysfunction. Case 2 received good care right after the onset of surgery, with no improvement in outcome. Limbal stem cell transplantation was necessary to restore the ocular surface. The procedure may carry a higher risk of failure compared with a quiet eye. Amniotic membrane transplantation as a form of bandage is useful in reducing inflammation in the acute phase of injury and preparing for limbal transplant in a severe limbal stem cell deficiency state.

The current results are comparable to the larger series of adult patients who underwent autologous limbal stem cell transplantation for unilateral chemical burn.2,8 Gomes et al.2 reported an 83% success rate in a group of six patients who received conjunctival limbal autograft with amniotic membrane transplantation because of unilateral chemical burn. Shimazaki et al.8 reported a 100% success rate.

Dua et al.9 recently reclassified chemical burns to take into account the extent of limbal involvement in clock hours and the percentage of conjunctival involvement. Grading of six levels of injury was defined as the number of clock hours of limbal involvement. In grade 3 to 6 injury, amniotic membrane transplantation is required to encourage epithelization of the cornea.9 Both of the current patients met the criteria for grade 4, with 6 clock hours of limbal involvement in case 1 and 9 clock hours of limbal injury in case 2. Grade 4 injuries are severe, and there is substantial perilimbal ischemia. Treatment requires transplantation of epithelium in the form of limbal stem cells and conjunctiva. The prognosis is good to guarded with the current ocular reconstruction techniques, but poor when total limbal involvement occurs. Unilateral burn and partial limbal involvement, enabling use of the healthy eye as a tissue source, also were good prognostic factors in the two patients reported.

The use of amniotic membrane helped the epithelization of denuded cornea and provided a suitable environment for the transplanted limbal cells. The amniotic membrane was completely absorbed within 3 weeks after surgery. Thickening and persistence of amniotic membrane has been reported in a human immunodeficiency virus–positive child. Altered immune status is believed to be the likely cause.3

Of the two current patients, case 2 had a better visual outcome than case 1, despite successful reconstruction of the ocular surfaces by limbal cell transplantation and amniotic membrane transplantation. This was due to the presence of corneal stromal scar. Cement contains calcium hydroxide; an alkali agent also reacts with corneal proteoglycan and glycosaminoglycan chains, causing damage to the corneal stroma. This scarring may necessitate a subsequent penetrating keratoplasty or a deep lamellar keratoplasty, preferably some time after the ocular surface has been stabilized after limbal cell transplantation. The combined procedures of autologous limbal stem cell transplantation and penetrating keratoplasty or deep lamellar keratoplasty are not advocated because they may invoke an increased wound healing response and may lead to death of transplanted stem cells.10

Early rehabilitation of vision in the immature visual system is necessary when a unilateral chemical injury occurs and compromises the clarity of the cornea. Both of the current patients were in the amblyogenic age group, and the corneal surface was reconstructed with stem cell autograft transplantation. In one patient, visual acuity improved from 20/400 to 20/50, and in the other, it improved from counting fingers at 1 meter to 20/100 after surgery. Neither patient showed loss of fixation or strabismus during the follow-up period of 24 months. Both patients healed with partial corneal opacity, and both were in the amblyogenic age group. Part-time patching was attempted in both patients; however, no improvement was observed. However, the final vision achieved was in concordance with the amount of scar present in the corneal stroma. Amblyopia can coexist with partial corneal opacities, and a trial of patching should always be performed in the amblyogenic age group to prevent amblyopia from compounding the vision loss caused by corneal opacity.11

The authors presented two patients with successful ocular surface reconstruction for severe chemical burn in children using amniotic membrane and limbal autograft transplantation. Vision improved considerably in both patients, and the ocular surface was stabilized. This technique is useful in children with severe ocular chemical burns. However, scarred corneal stroma may limit the vision potential achieved after surgery. Subsequent penetrating keratoplasty or deep lamellar keratoplasty may be indicated in such cases.

References

  1. Kenyon KR, Tseng SC. Limbal autograft transplantation for ocular surface disorders. Ophthalmology. 1989;96:709–722.
  2. Gomes JA, dos Santos MS, Cunha MC, et al. Amniotic membrane transplantation for partial and total limbal stem cell deficiency secondary to chemical burn. Ophthalmology. 2003;110:466–473. doi:10.1016/S0161-6420(02)01888-2 [CrossRef]
  3. Goyal R, Jones SM, Espinosa M, et al. Amniotic membrane transplantation in children with symblepharon and massive pannus. Arch Ophthalmol. 2006;124:1435–1441. doi:10.1001/archopht.124.10.1435 [CrossRef]
  4. Altan-Yaycioglu R, Akova YA, Oto S. Amniotic membrane transplantation for the treatment of symblepharon in a patient with recessive dystrophic epidermolysis bullosa. Cornea. 2006;25:971–973. doi:10.1097/01.ico.0000225708.70135.d0 [CrossRef]
  5. Tsubota K, Shimazaki J. Surgical treatment of children blinded by Stevens-Johnson syndrome. Am J Ophthalmol. 1999;128:573–581. doi:10.1016/S0002-9394(99)00224-X [CrossRef]
  6. Sridhar MS, Sangwan VS, Bansal AK, Rao GN. Amniotic membrane transplantation in the management of shield ulcers of vernal keratoconjunctivitis. Ophthalmology. 2001;108:1218–1222. doi:10.1016/S0161-6420(01)00622-4 [CrossRef]
  7. Kim JC, Tseng SCG. Transplantation of preserved human amniotic membrane for ocular surface reconstruction in severely damaged rabbit corneas. Cornea. 1995;14:473–484. doi:10.1097/00003226-199509000-00006 [CrossRef]
  8. Shimazaki J, Yang HY, Tsubota K. Amniotic membrane transplantation for ocular surface reconstruction in patients with chemical and thermal burns. Ophthalmology. 1997;104:2068–2076.
  9. Dua HS, King AJ, Joseph A. A new classification of ocular surface burns. Br J Ophthalmol. 2001;85:1379–1383. doi:10.1136/bjo.85.11.1379 [CrossRef]
  10. Solomon A, Ellies P, Anderson D, et al. Long-term outcome of keratolimbal allograft with or without penetrating keratoplasty for total limbal cell deficiency. Ophthalmology. 2002;109:1159–1166. doi:10.1016/S0161-6420(02)00960-0 [CrossRef]
  11. Bradford GM, Kutschke PJ, Scott WE. Results of amblyopia therapy in eyes with unilateral structural abnormalities. Ophthalmology. 1992;99:1616–1621.
Authors

From Baskent University School of Medicine, Department of Ophthalmology, Ankara, Turkey.

The authors have no financial or proprietary interest in the materials presented herein.

Address correspondence to Silay Canturk, MD, Baskent University School of Medicine, Department of Ophthalmology, Dadaloglu Mah. 39 Sk. No. 6, Adana, Yuregir, Turkey 01250.

10.3928/01913913-20100324-10

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