【摘要】
目的：评价自体结膜角巩膜缘移植术治疗原发性翼状胬肉的有效性。
方法：原发性翼状胬肉患者15例（15眼），接受自体结膜角巩膜缘移植术。切除翼状胬肉后，植片的角膜缘部分与翼状胬肉切除处的角膜缘对位缝合，植片的上皮面向上。纤维血管组织在原翼状胬肉区遮盖角膜1mm以上定为复发。
结果：随访平均8mo，所有的患者既无一例复发也无并发症发生。
结论：单纯翼状胬肉切除联合自体结膜角巩膜缘移植是一种治疗原发性翼状胬肉安全有效的手术方法。
【关键词】 结膜角巩膜缘自体移植；原发性翼状胬肉；角巩膜缘干细胞移植；结膜移植
AbstractAIM: To investigate the efficiency of limbal conjunctival autografting technique in patients with primary pterygium. METHODS: Fifteen eyes of 15 patients with primary pterygium underwent surgery for the removal of pterygium with limbal conjunctival autograft. After the pterygium excision, the limbal portion of the graft was oriented and sutured to the limbus at the recipient bed with the epithelial surface upside. Recurrence was defined as fibrovascular tissue of more than 1mm over the cornea in the area of previous pterygium excision.
RESULTS: With mean followup period of 8 months, neither recurrences nor serious complications were recorded among our patients.CONCLUSION: Simple excision followed by limbalconjunctival autograft transplantation is a safe and very effective way of treating primary pterygium.
KEYWORDS; limbalconjunctival autograft transplantation;
primary pterygium; limbal stem cell graft; conjunctival graft
INTRODUCTION
Pterygium is a fibrovascular, wingshaped encroachment of conjunctiva on to the cornea. Ultraviolet lightinduced damage to the limbal stem cell barrier, withsubsequent conjunctivalization of the cornea, is the currently accepted etiology[12]. Pterygium is a worldwide condition with a "pterygium belt" between the latitudes 30° north and south of the equator[3]. Simple excision carries a high recurrence rate ranging from 24%89%[4]. The addition of mitomycin C (MMC) of various concentrations has been reported to be effective in preventing recurrence[58]. However, MMC may result in devastating complications such as scleral necrosis and microbial infections[911].
Another alternative adjunct is conjunctival graft (CG)[1214]. The limbal epithelium acts as a junctional barrier to conjunctival overgrowth and pterygium is considered to represent a "local limbal deficiency"[15]. The inclusion of limbal epithelium in conjunctival graft would restore the barrier function of the limbus. Recent studies have reported the effectiveness of limbal conjunctival autograft transplantation (LCAUT) in the prevention of pterygial recurrence [1619]. We therefore set out to conduct a prospective study to assess the effectiveness of this procedure among the patients with primary pterygium.
SUBJECTS AND METHODS
Patients In a prospective study from April 2005 to December 2006, 15 eyes of 15 patients with primary pterygium were assigned to undergo excision of pterygium followed by LCAUT in Farabi Eye Hospital, Tehran, Iran. All patients with primary pterygium (without any previous surgery), with size of the pterygium over the cornea more than 2mm, and presence of patients symptoms due to pterygium such as ocular discomfort or cosmesis were included in our study. Patients with previous ocular surgery for any causes such as glaucoma and cataract surgery, secondary pterygium due to ocular trauma such as chemical burn, and pseudopterygia were excluded from our study.
The study was done in accordance with the Declaration of Helsinki. Before the surgery informed consents were taken from all of the patients. All of the surgeries were performed by one surgeon.
Surgical Procedure The surgical technique was similar in all cases. Peribulbar anesthesia with 20g/L lidocaine and 2.5g/L bupivacaine (2/1) was applied to our patients. The excision consisted of the detachment of pterygium head and dissection of the pterygium body from the overlying conjunctiva.
Subconjunctival pterygial tissue was excised to achieve as clear a margin as possible. The abnormal corneal epithelium and the superficial fibrovascular scar tissue were stripped off by blunt dissection. The calibrated diamond knife was set to 100μm (an allowance of 50μm was made for the lack of epithelium) and a bed, corresponding in dimensions to the donor explants, was fashioned at the recipient site.
The donor tissue consisted of corneallimbalconjunctival explants that were harvested from the superior limbus of the same or fellow eye. Autograft contained 0.5mm of the clear cornea and 2mm of adjacent bulbar conjunctiva. The length of the autograft was equal to the excised limbus at the pterygium site. A front running double edged calibrated diamond knife was set to 150μm. The knife was used to make a circumferential corneal incision, parallel to the limbus, and two radial incisions, extending from either end of the circumferential incision to the limbus. An angled bevelled blade was used to (lamellar) dissect the 150μm of corneal tissue and the dissection was extended to include the limbal tissue and emerge beyond the limbus under the conjunctiva. Two millimetres of conjunctiva, attached to the corneal limbal explants along the limbal border, was then excised. The donor tissue was then sutured onto the recipient eye with two interrupted 100 nylon sutures at the corneal margin and two along the scleral edge of the explant.
Postoperative treatment consisted of topical chloramphenicol and betamethasone eyedrops, four times daily for the first 2 weeks. Steroids were then tapered rapidly. Frequent artificial tears were also used.
All patients were followed daily or twice daily until corneal epithelialization was completed at 1 week, 1, 3, 6 months. Recurrence was defined as fibrovascular tissue of more than 1mm over the cornea in the area of previous pterygium excision.
RESULTS
From April 2005 to December 2006, 15 eyes of 15 patients with primary pterygium were assigned to undergo excision of pterygium followed by LCAUT. The demographic and clinical details are summarized as follows. The mean age of 15 patients (8 males, 7 females) was 45.6 years (range: 2959 years). All patients had primary pterygium. Nine right eyes and six left eyes were involved. Average extension length across the limbus was 3.3mm (range: 1.7 4.3mm). The size of the limbalconjunctival autograft varied from 1.5 to 3 oclock hours. The mean size of LCAUT was 5.36mm (range: 5 6mm). The mean postoperative followup was 8 months (range: 612 months).
In this series of patients the mean followup time was 8 months. No intraoperative complications occurred.
Postoperatively, the limbal grafts started epithelial outgrowths within the first 2 days and the whole corneal surface was completely epithelialized within 10 days in all cases. There was no infection, limbal graft failure, or slipping of tissue. The epithelium was stable, without recurrence of epithelial defects, transparent, and smooth. There was no corneal neovascularization. No scleral thinning, necrosis, or any other visually significant complications were encountered in our patients. Recurrence of pterygium was not seen in our patients.
In the donor eyes there were no intraoperative complications, refractive changes, chronic inflammation, persistent epithelial defects, or corneal neovascularization.
DISCUSSION
Limbal deficiency, or loss of corneal stem cells, is associated with conjunctivalization of the corneal surface, primary and recurrent pterygium, recurrent and persistent epithelial defects, chronic inflammation, scarring, and ulceration of the cornea. Early methods of reconstruction of the ocular surface included conjunctival transplantation and keratoepithelioplasty. Conjunctival transplantation was based on the theory of transdifferentiation of conjunctival epithelium into cornealike epithelium[2022]. However, we now know that conjunctival epithelial transdifferentiation (that is, a morphological, biochemical, and physiological transformation of conjunctival epithelium into corneal epithelium) does not occur[23,24], and conjunctival transplantation to reconstruct the corneal surface in patients with corneal stem cell deficiency has been abandoned. Keratoepithelioplasty was proposed by Thoft[25] as another alternative to reconstruct the ocular surface in patients with corneal stem cell deficiency. In this technique lenticules of peripheral corneal epithelium with superficial stroma were grafted. Subsequently, the technique was modified to include limbal tissue, acknowledging the importance of stem cell transplantation in these conditions, for a successful long term outcome[25,26]. Limbal transplantation, as proposed by Kenyon and Tseng[27], is probably the best current option for ocular surface reconstruction in patients with total corneal stem cell deficiency.
Localized corneal stem cell dysfunction because of loss of limbal barrier against conjunctival invasion has been proposed as a pathogenic factor in pterygium growth and recurrence. Multiple surgical approaches have been used to treat pterygia as simple excision results in severe fibrous tissue regrowth. To treat this disorder both suppression of subconjunctival fibrosis and reconstruction of the limbal barrier are important.
Intraoperative or postoperative antifibrotic agents have been used to reduce the probability of recurrence of pterygium[2830]. Autologous limbal transplantation and amniotic membrane transplantation (AMT) have been proposed as a valid option in recurrent cases[3134]. In this study, pterygium excision supplemented with LCAUT appeared to be successful after midterm followup.
Limbal autografts have been used in treating monocular chemical or thermal burn, aniridia, conjunctival squamous cell carcinoma, recurrent or advanced pterygia, and contact lens associated ocular surface abnormality[6,27,3537]. Limbal autografts have been used successfully to correct limbal dysfunction, acting as a barrier against conjunctival invasion of the cornea and supplying stem cells of the corneal epithelium. In treating chemical burns and other traumatic conditions, the limbal grafts are obtained from the unaffected eye. This type of limbal transplantation does not weaken total limbal function; instead it transfers healthy limbus to the affected area. Some authors believe that a limbal graft need not necessarily cover the entire area of excision[31]. Use of small limbal grafts may lessen concerns about adverse postoperative consequences in the donor area. Simultaneous limbal autograft transplantation may not be necessary in less severe cases; however, a recent study reported that amniotic membrane transplantation alone resulted in further recurrence in 37.5% of eyes treated for recurrent pterygium[38].
Our study included 15 eyes of 15 patiens with primary pterygium and all of them were treated with primary excision and LCAUT. No recurrence occurred in our cases. No major complication, intraoperatively or postoperatively, was seen in our study. Shimazaki et al[31]. reported 7.4% recurrence with this procedure in patients with pterygium. In another report by Kilic and Gurler[39] recurrence rate was 7%. It seems that recurrence rate with this technique to be between zero and 10%[1618,4045]. Although many treatment approaches have been proposed for treatment of primary pterygia such as primary excision with bare sclera, excision and conjunctival graft, excision and AMT, excision and applying mitomycin C, but recurrence rate with some of these modalities are high, and on the other hand some have devastating complications such as scleral perforation and necrosis, secondary glaucoma, corneal perforation, cataract formation, iritis and irreversible damage to stem cells[29,42,46].
In conclusion, after reviewing other studies concerning LCAUT and our study finding, it seems that LCAUT is a safe and very effective procedure in the treatment of primary pterygium. Although this technique primarily has been used as a modality in treatment of recurrent pterygia, but we recommended it in primary cases without any previous surgery to decrease recurrence and also in decrease need for second procedure in recurrent cases.
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