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 Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 16  |  Issue : 3  |  Page : 281-285

Amniotic membrane graft versus conjunctival autograft for the management of primary pterygium


Department of Ophthalmology, Faculty of Medicine, Al-Azhar University, Asyut Branch, Cairo, Egypt

Date of Submission10-Aug-2018
Date of Acceptance10-Feb-2019
Date of Web Publication15-Apr-2019

Correspondence Address:
Ashraf M Gad Elkareem
Department of Ophthalmology, Al-Azhar University Hospital, Assiut, 71524
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/AZMJ.AZMJ_81_18

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  Abstract 


Aim To compare amniotic membrane graft versus conjunctival autograft for the management of primary pterygium.
Design A prospective, randomized study.
Patients and methods Fifty eyes of 50 patients with primary pterygium were prospectively included in this study and were randomized into two groups. Group I included 25 patients who underwent surgical excision and limbal-conjunctival autograft transplantation; group II included 25 patients who underwent surgical excision and human amniotic membrane graft transplantation. Recurrence rate, refractive changes, and complications were evaluated and compared between both groups.
Results Recurrence after surgical excision was observed in eight patients with an overall recurrence rate of 16% (8/50) in both groups. The recurrence was slightly higher in the amniotic membrane group, about 20% (five cases) than the conjunctival autograft group which was about 12% (three cases). The recurrence was higher in the first 3 months postoperatively which was about 62% (5/8) in both groups and increased to about 100% (8/8) at 6 months postoperatively. No recurrence was observed in either group after 6 months. Visual acuity improved in 22 and 23 patients while it remained unchanged in three and two patients in group I and group II, respectively.
Conclusion Conjunctival autograft should be considered as the first choice for pterygium excision even in recurrent pterygia. Amniotic membrane graft can be considered as a first choice for patients with advanced and diffuse conjunctival involvement or for those who probably will need the conjunctiva for glaucoma-filtering procedure in the future.

Keywords: amniotic membrane graft, conjunctival autograft, pterygium excision


How to cite this article:
Gad Elkareem AM, Nooreldin A. Amniotic membrane graft versus conjunctival autograft for the management of primary pterygium. Al-Azhar Assiut Med J 2018;16:281-5

How to cite this URL:
Gad Elkareem AM, Nooreldin A. Amniotic membrane graft versus conjunctival autograft for the management of primary pterygium. Al-Azhar Assiut Med J [serial online] 2018 [cited 2020 Jul 10];16:281-5. Available from: http://www.azmj.eg.net/text.asp?2018/16/3/281/255863




  Introduction Top


Pterygium is a fibrovascular encroachment of the bulbar conjunctiva over the cornea. It is a common ocular problem especially in hot, dusty climates [1]. It has a worldwide prevalence rate ranging from about 0.5–25% being more in tropical areas [2].

Many theories have been developed to explain the development of pterygium, one of this is the exposure to ultraviolet rays [3]. Ultraviolet rays can induce genetic mutations in certain genes as the P53 tumor suppressor gene with its abnormal expression in pterygium epithelial cells. This could suggest that ptergyium is not just a degenerative lesion but could be a result of uncontrolled cell proliferation [4],[5].

The main line of pterygium treatment is surgical excision [6]. There are certain indications for surgical excision of pterygium like impairment of visual acuity by inducing astigmatism or extending into the pupillary area, cosmetic disfigurement, fleshy irritating pterygium, or diplopia through limitation of ocular motility [7],[8].

The main problem after surgical removal of pterygium is the high recurrence rate which ranges from 2 to 40% [9]. Thus several techniques have been developed to overcome the postoperative recurrence, but no one is ideal, including the use of beta irradiation, intraoperative mitomycin C, conjunctival autograft, and amniotic membrane graft [10],[11],[12].

Beta radiation and mitomycin C significantly reduced the recurrence rate, but they carry the risk of complications such as scleral necrosis and melting, cataract, and secondary glaucoma [13],[14].

In this study, we prospectively compared limbal-conjunctival autograft transplantation with human amniotic membrane grafting regarding the recurrence rate of primary pterygium.


  Patients and methods Top


Fifty eyes of 50 patients with primary pterygium were prospectively included in this study between March 2017 and December 2017 and were randomized into two groups. Group I included 25 patients who underwent surgical excision and limbal-conjunctival autograft transplantation; group II included 25 patients who underwent surgical excision and human amniotic membrane graft transplantation.

Patients with systemic diseases such as diabetes mellitus or vascular collagen diseases are excluded. Complete ophthalmic examinations including visual acuity, intraocular pressure, slit lamp biomicroscopy, and fundus examination were performed to exclude certain eye diseases such as cicatricial pemphigoid, glaucoma or keratoconjunctivitis sicca.

The size of the pterygium should be at least 2 mm (2.0–6.0; mean, 3.1 mm) into the cornea. All patients had a minimum follow up of 6 months (6–12 months) at the time of analysis of the data.

The study was carried out in the Ophthalmology Department, Al-Azhar University Hospital, Asyut.

The study was done after the approval of the research and Ethical Committee, School of Medical Sciences, Al-Azhar University, Egypt.

A written informed consent for the procedure was obtained from each patient.

Surgical procedures

Pterygium excision

After draping the patient subpterygium anesthesia with 4% lignocaine containing 1 : 10 000 adrenaline was used for most patients. The head of the pterygium was dissected from the cornea starting 0.5 mm in front of the head toward the sclera using a No 15 Bard-Parker blade, then the pterygium was separated and excised with spring scissors. The subconjunctival Tenon’s tissue was separated from the overlying conjunctiva, undermined, and excised extensively. A bipolar cauterization was done for the bleeders. A rectangular area of bare sclera of about 4–6 mm was created to receive the graft.

Amniotic membrane graft

The bare scleral area was then covered with a sterile human amniotic membrane graft, which was oriented with the basement membrane side up. The amniotic membrane was sutured through the episcleral tissue to the edge of the conjunctiva along the bare sclera border with seven to eight interrupted stitches of 10/0 nylon sutures.

Conjunctival autograft

A conjunctival autograft 0.5 mm larger than the bare sclera was dissected and excised from superotemporal bulbar conjunctiva 3 mm from the limbus. This area was later closed with a continuous suture of 10/0 nylon. The graft was then sutured to bare sclera with interrupted 10/0 nylon suture.

Postoperative medications and follow-up

A mixed antibiotic and steroid eye drops and ointment were prescribed for the patient for 2 weeks. Any irritating sutures were removed after 2 weeks. 0.1% fluorometholone eye drops was given to the patients four times daily and decreased to twice daily for 2 months later. The patients were followed up monthly for 6 months, then every 3 months for 1 year. Any fibrovascular growth invading the cornea seen by slit lamp examination was considered as a recurrence.

Statistical analysis

A descriptive statistic of the study population was made ([Table 1]). The Wilcoxon rank-sum test with continuity correction and Fisher’s exact test were used (P<0.05) to analyze the risk of recurrence.
Table 1 Demographic data of the patients and incidence of recurrence

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  Results Top


The demographic data of the patients in the two groups are shown in [Table 1]. No significant difference was seen in both groups regarding the age (P=0.808), sex (P=0.508), and the size of the pterygia (P=0.620). The mean age was 41.1±12.5 in group I and 40.2±11.8 in group II; the mean size of the pterygia was 2.91±0.71 in group I and 3.01±0.65 in group II.

In our study, we excised the pterygia from 50 eyes of 50 patients including 38 men and 12 women. Recurrence was observed in eight patients with an overall recurrence rate of 16% (8/50).

The recurrence was slightly higher in the amniotic membrane group (about 20%, five cases) than with the conjunctival autograft group (about 12%, three cases).

The recurrence was higher in the first 3 months postoperatively which was about 62% (5/8) in both groups and increased to about 100% (8/8) at 6 months postoperatively. No recurrence was observed in either group after 6 months.

Regardless of age a significant incidence of recurrence was seen among patients below 40 year in the operated group where six patients out of eight had recurrence below 40 years (P=0.002); no significant difference in recurrence rate was found above 40 years. Regarding the sex the recurrence rate was significantly higher in men (about 14%, seven cases) than in women (2%, one case) (P=0.001).

Regarding the refractive state and the visual acuity

The mean pretreatment visual acuity was 0.59±0.23 and 0.57±0.22 in groups I and II, respectively. The visual acuity improved in the postoperative period to 0.86±0.11and 0.92±0.07 in groups I and II, respectively. Visual acuity was improved by one line in six patients in group I, and in two patients in group II, and by two lines in five patients and in seven patients in group I and group II, respectively. Finally, it improved by three lines in 11 patients and 14 patients, while it remained unchanged in three patients and two patients in group I and group II, respectively.

There was a statistically significant improvement in preoperative astigmatism after surgery in both groups with no significant difference between them ([Table 2]).
Table 2 Changes in visual acuity and astigmatism

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Two cases experienced postoperative bacterial keratoconjunctivitis which was treated successfully in 10 days with intensive antimicrobial eye drops and ointment. Postoperative persistent conjunctival hyperemia without recurrence was observed in one case of the conjunctival autograft group in a young male patient of 25 years old which was reduced with topical steroids for 2 weeks. Biogenic granuloma was seen in one case which was excised latter on. No major complications were occurred intraoperatively.


  Discussion Top


Ptrygium is a multifactorial degenerative disease involving both the conjunctiva and the cornea. The main problem with surgical excision is the high recurrence rate. One of the suggested possibilities for the development of pterygium is damage to the limbal stem cells by ultraviolet light and activation of matrix metalloproteinase [4]. Amniotic membrane and conjunctival autograft are probable sources of stem cells.

To reduce the variability among the results of our study each technique was carried out by the same surgeon during the whole study.

The effective surgical technique is the one which prevents recurrences without any complications. The conjunctival autografting technique first used by Kenyon et al. [15] seems to be the one that can achieve this goal.

Depending on the surgeon’s skill and experience, the recurrence rate after conjunctival autograft can range from 2 to 39% [8],[16].

Amniotic membrane transplantation was used effectively to treat patients with partial limbal stem cell deficiency and this improved both the vision and the corneal surface [17],[18].

The thick basement membrane with the vascularized stromal matrix of the amniotic membrane enhances migration and differentiation of epithelial cells, strengthen adhesion of basal epithelial cells, and also inhibits conjunctival fibroblasts proliferation and the extracellular matrix production. All these factors are a probable mechanism by which amniotic membrane transplantation reduces the recurrence of pterygia [19],[20],[21].

Several studies recorded a recurrence rate of 5.3, 3.8, 2.5, 5, and 4.5% after limbal-conjunctival autografting [22],[23],[24],[25],[26] while Wong et al. [27] had a higher recurrence rate (18.2%) after inferior limbal-conjunctival autografting in recurrent pterygia.

The recorded recurrence rate after amniotic membrane transplantation was 15.4% [28], 2% [7]. Amniotic membrane graft and conjunctival autografts seem to be equally effective in the prevention of recurrence of primary pterygium.

In our study, the recurrence with amniotic membrane graft was 20% as compared with 12% in patients treated with conjunctival autograft.

In the present study, the recurrence rate was higher in the first 3 months postoperatively which was about 75% (6/8) in both groups and increased to about 100% (8/8) at 6 months postoperatively and no recurrence was observed in either group after 6 months in our study.

In comparison with other studies, the mean recurrence time was 4.33±0.27 months in the present study which is in line with studies reporting the recurrences 4–6 months after surgery. Moreover, we found no association between recurrence rate and pterygium size, which again is in line with previous studies [29],[30].

The recurrence usually occurs within 4 month to 1 year after surgery and several factors such as surgical trauma, fibroblastic activity induced by postoperative inflammation, and vascular proliferation play an important role in the recurrence of pterygium [9].

When considering the age of the patients regardless of the operated group there was a significant increase in the recurrence rate among younger patients below 40 years, while above 40 years no significant difference in the recurrence rate was found. Regarding the sex the recurrence rate was significantly higher in men (about 14%, seven cases) than in women (2%, one case) (P=0.001). This can be explained by the higher exposure of men to the ultraviolet rays especially in those who worked outdoors in an environment with high surface reflectance of ultraviolet light compared with women who worked most of the time indoors.

Huerva et al. [31] did not find any significant difference between male and female patients, while they found a higher recurrence rate of pterygium among young patients after conjunctival autograft.

The recurrence rates in our study were higher in both groups than those previously reported [19], possibly due to the sunny climates in our country, the dark race of our patients, small amounts of subconjunctival tissue removed, the use of sutures to close the conjunctival or amniotic grafts and drugs given after surgery.

Although this study shows that amniotic membrane grafts are less equivalent than conjunctival autografts in reducing recurrences after pterygium excision, use of amniotic membrane grafts is less tedious and a time-saving procedure; also it saves the conjunctiva for glaucoma surgery if needed in the future and provide a comparable alternative for pterygium surgery.

Pterygia may reduce vision either by direct obscuration of the visual axis or, more commonly, through irregular astigmatism induced either by distortion of the cornea or the axial tear film [32]. Conjunctival grafts heal rapidly and would be unlikely to worsen induced astigmatism [10],[15].

In this study, the mean visual acuity improved postoperatively in both groups with no statistically significant difference between both groups. The value of astigmatism also statistically improved after surgery in both groups with no significant difference between the two groups.

Katırcıoglu and colleagues and others have reported no statistically significant difference between preoperative and postoperative visual acuity in amniotic membrane graft and conjunctival autograft groups [33],[13],[14], which is consistent with the results of the current study.

Our postoperative complications are consistent with the complications reported in other studies [7],[21].


  Conclusion Top


Conjunctival autograft can be used as a first line of treatment for primary or recurrent pterygium. The amniotic membrane graft can be also considered as a first choice for patients with advanced and diffuse conjunctival involvement and for those who probably will need the conjunctiva for glaucoma‐filtering procedure in the future.

Amniotic membrane grafting is a good alternative when compared with conjunctival autograft for pterygium surgery.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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31.
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