|Year : 2019 | Volume
| Issue : 3 | Page : 171-176
Outcomes of preoperative intrapterygial injection of mitomycin C for pterygium excision with and without inferior conjunctival flap
Ved Prakash Gupta, Shekhar Sanghi, Jolly Rohatgi, Upreet Dhaliwal
Department of Ophthalmology, University College of Medical Sciences, G. T. B. Hospital, Delhi, India
|Date of Web Publication||11-Oct-2019|
Dr. Ved Prakash Gupta
Department of Ophthalmology, University College of Medical Sciences, G. T. B. Hospital, Dlishad Garden, Delhi - 110 095
Source of Support: None, Conflict of Interest: None
| Abstract|| |
PURPOSE: This study aimed to report the comparison of recurrence rate and complications of intrapterygial injection of mitomycin C (MMC) 1 month before bare sclera excision of pterygium with and without conjunctival flap from the inferior bulbar conjunctiva.
METHODS: This prospective interventional study enrolled 60 patients of pterygia from November 2010 to June 2012. All eyes received 0.1 ml (0.02%) of intrapterygial MMC injection 1 month preoperatively. Patients were divided into two groups of 30 each: Group 1 – bare scleral excision (BSE) and Group 2 – BSE with conjunctival flap from the inferior bulbar conjunctiva to cover the bare sclera. Chi-square test, Fisher's exact test, and unpaired t-test were used for statistical analysis.
RESULTS: The mean age was 40.6 ± 12.8 years and 36.9 ± 10.9 years in Group 1 and 2, respectively, (P = 0.2329). There were 11 (36.7%) males and 19 (63.3%) females in Group 1 and 7 (23.3%) males and 23 (76.7%) females in Group 2 (P = 0.101). The recurrence rate was 0% in Group 1 and 3.3% (1 eye) in Group 2 (P = 1.00). Postoperatively, scleral whitening occurred in 6 (20%) eyes in Group 1 and none in Group 2 (P = 0.015).
CONCLUSION: Both techniques, BSE alone or with conjunctival flap from the inferior bulbar conjunctiva 1 month after intrapterygial MMC, resulted in negligible (0%–3.3%) recurrence of pterygium. Conjunctival flap significantly reduced (0%) the postoperative complication of scleral whitening. This is the first report of efficacy of conjunctival flap in reducing scleral whitening after intrapterygial MMC.
Keywords: Conjunctival flap, intrapterygial injection, mitomycin C, preoperative, pterygium
|How to cite this article:|
Gupta VP, Sanghi S, Rohatgi J, Dhaliwal U. Outcomes of preoperative intrapterygial injection of mitomycin C for pterygium excision with and without inferior conjunctival flap. Oman J Ophthalmol 2019;12:171-6
|How to cite this URL:|
Gupta VP, Sanghi S, Rohatgi J, Dhaliwal U. Outcomes of preoperative intrapterygial injection of mitomycin C for pterygium excision with and without inferior conjunctival flap. Oman J Ophthalmol [serial online] 2019 [cited 2020 Jul 13];12:171-6. Available from: http://www.ojoonline.org/text.asp?2019/12/3/171/268909
| Introduction|| |
Despite a variety of surgical procedures for the management of pterygium, the recurrence of pterygium remains the most enigmatic postoperative complication of pterygium surgery. Recurrence rates vary with the procedure. Recurrence rate with bare sclera excision varies from 37% to 91%., Therefore, various adjunctive therapies have been used to lower the recurrence rate including conjunctival autograft,, limbal–conjunctival autograft,, topical mitomycin C (MMC),,,,,,,,,,,,,,,, and conjunctival flap., In 1985, Kenyon et al. described pterygium excision with conjunctival autografting as a promising technique with a low recurrence rate of 5.3%, and the procedure became a standard procedure. However, later on, many studies have reported high recurrence rates of 21%–40% even with free conjunctival autografting.,, Even with limbal–conjunctival autograft having stem cells, recurrence rates of 0%–18% were reported.,
The first adjunctive use of MMC in pterygium surgery was reported by Kunitomo and Mori in 1963. MMC has been used along with pterygium surgery in different concentrations and forms, i.e., postoperative drops,,,,,,,,,,, intraoperative application,,,,,, and single-drop instillation at the end of bare sclera excision  to reduce the recurrence rate following pterygium surgery.,,,,,,,,,,,,,,,,, Although the recurrence rate has been reduced after the use of MMC, there are reports of serious vision-threatening complications following MMC application., Rubinfeld et al. reported severe complications such as scleral thinning, corneal edema, secondary glaucoma, corneal perforation, iritis, and cataract formation after postoperative instillation of 0.04% MMC and urged extreme caution while using this agent for the prevention of pterygium recurrence.
In view of the severe complications following the use of MMC and the high recurrence rate of 38%, there was a need to explore a new regime of MMC which could reduce the recurrence rate without causing serious complications. Recently, to decrease the ocular surface exposure to MMC, Donnenfeld et al. reported a new regime of subconjunctival injection of 0.1 ml of 0.015% MMC into the head of pterygium at the limbus as adjunctive therapy 1 month before pterygium excision, with a recurrence rate of 6% without any complication in 36 patients. They concluded that preoperative subconjunctival low-dose MMC therapy 1 month before bare sclera excision of pterygium is a safe and effective treatment for the management of pterygium. Khakshoor et al. injected 0.1 ml of 0.02% MMC subpterygeally along the limbus 1 month before bare sclera excision of pterygium without any recurrence of pterygium. However, it was associated with persistent whitening of sclera and hypovascularity at the site of excision in 5.5% of patients. Whereas, these complications were not observed in conjunctival rotational flap with pterygium excision with intraoperative MMC group.
We hypothesized that covering the bare sclera at the site of pterygium excision with conjunctival flap might prevent this complication of hypovascularity and whitening  without affecting the recurrence rate. This study was, therefore, undertaken to compare the recurrence rate and complications after intrapterygial injection of 0.02% MMC 1 month before bare scleral excision (BSE) of pterygium alone and with adjunctive conjunctival flap. To the best of our PubMed search, this is the first study on preoperative intrapterygial MMC injection 1 month before bare sclera excision of pterygium with conjunctival flap.
| Methods|| |
This was a prospective interventional study which enrolled patients of primary pterygium from November 2010 to June 2012. The study was approved by the institutional ethics committee. The study adhered to the tenets of Declaration of Helsinki. Patients with dry eye, autoimmune disorders such as rheumatoid arthritis, collagen vascular disorders, herpes simplex keratitis, and concurrent active uveitis; pregnant and lactating females; those who reported hypersensitivity to MMC; those who had past ocular surface, adnexal, or intraocular surgery; and contact lens users were excluded from the study.
Patients were allocated into two groups of 30 patients each. Group 1 patients received intrapterygial injection of 0.1 ml of 0.02% MMC 1 month before BSE of pterygium, and Group 2 patients received intrapterygial injection of 0.1 ml of 0.02% MMC 1 month before BSE with conjunctival flap transposed from the inferior bulbar conjunctiva to cover the bare sclera.
Detailed history, general physical examination, systemic examination, and comprehensive ocular evaluation were done before MMC injection and postoperatively periodically including best-corrected visual acuity, extraocular movements, slit-lamp biomicroscopy for pterygium as well as anterior segment evaluation, Goldmann Applanation Tonometry, and fundus examination. Dry eye was ruled out with Schirmer 1 test, basal secretion test, and tear film breakup time.
All surgeries, including intrapterygial injection of MMC, were performed by the same surgeon, under local anesthesia, after prior written informed consent. All odd serial numbers were included in Group 1 and even numbers in Group 2. Intrapterygial injection was given in a minor operation theater. Conjunctiva was anesthetized by instilling two drops of proparacaine 0.5% eye drops. After putting self-retaining wire speculum, pterygium was lifted with Lim's Forceps, and 0.1 ml of freshly prepared 0.02% (0.2 mg/ml) MMC was injected intrapterygially 2 mm away from the corneal limbus using a 26G tuberculin syringe. Conjunctival sac was irrigated with 30 ml normal saline. After injection, patients were advised topical lubricants and moxifloxacin 0.5% eye drops, four times a day. Weekly follow-up was performed.
One month after intrapterygial MMC injection, Group 1 patients underwent BSE, and Group 2 patients underwent BSE with conjunctival flap transposed from the inferior bulbar conjunctiva to cover the bare sclera. Conjunctival flap was performed as follows: adjacent inferior bulbar conjunctiva was marked (7–8 mm × 4–5 mm) with gentian violet, and a thin conjunctival pedicle flap without Tenon's capsule was created with a pedicle at the inferonasal end with the help of Westcott Scissors. No tenonectomy was performed. The flap was then transposed upward to cover the bare sclera. The flap was sutured to the adjoining conjunctiva with 8-0 Vicryl interrupted sutures. No cautery was used in either group. Eye was patched after putting moxifloxacin 0.5% eye ointment. All patients received the same postoperative treatment including topical prednisolone acetate 1% with gatifloxacin 0.3% four times a day and carboxymethyl cellulose 0.5% drops qid for 2–3 weeks. Loteprednol was substituted for prednisolone acetate after 2 weeks. Follow-up examinations were not done by masked observers. The surgeon and assistants were aware of the groups. Follow-up was done on postoperative day 1, weekly for 4 weeks, fortnightly for 3 months, and then every 3 monthly.
At each visit, patients were specifically examined for recurrence and complications of MMC (pain, lacrimation, foreign body sensation, photophobia, dellen formation, persistent corneal epithelial defects, hypovascularity of conjunctiva, scleral whitening and scleral thinning, or ulceration at pterygium resected site) and forniceal shortening. Scleral whitening was graded as follows: Grade I – scleral whitening with few vessels still visible, Grade II – porcelain white sclera with no vessels or capillaries visible, Grade III – whitening with scleral necrosis (scleral gutter or ulcer), and Grade IV – all of the above with uveal exposure. The recurrence was defined as overgrowth of fibrovascular tissue beyond the limbus postoperatively.
Qualitative parameters were compared in both the groups using Chi-square test and Fisher's exact test at 5% level of significance (P < 0.05). Quantitative parameters were compared using unpaired t-test. All statistical analyses were performed with SPSS version 20.0 (SPSS Science Inc., Chicago, Illinois, USA).
| Results|| |
Sixty eyes of 60 patients were enrolled in the study including 30 eyes in each group. The age of patients ranged from 15 years to 65 years (mean: 38.5 ± 12.7 years). The mean age of patients was 40.6 ± 12.8 years and 36.9 ± 10.9 years in Group 1 and 2, respectively (P = 0.2329). There were 11 (36.7%) males and 19 (63.3%) females in Group 1 and 7 (23.3%) males and 23 (76.7%) females in Group 2 (P = 0.101). The right eye was involved in 6 (20%) patients in Group 1 and 16 (53.3%) patients in Group 2, while the left eye was involved in 24 (80%) patients in Group 1 and 14 (46.7%) patients in Group 2 (P = 0.015). All patients had primary nasal pterygium, except one case of temporal pterygium in Group 1. The average corneal involvement was 2.8 ± 1.42 mm and 2.7 ± 0.98 mm in Group 1 and 2, respectively (P = 0.92). After injection of MMC, 48.3% of patients complained of irritative symptoms of pain, foreign body sensation, watering, and photophobia in the MMC-injected eye which disappeared after 1 month; conjunctival congestion was noted in 52 (86.7%) eyes which disappeared by the end of 1 month. Decreased fibrovascularity of pterygia was observed at the end of 1 month in all cases.
No recurrence was observed in Group 1 (100% success rate). Recurrence was observed in 1 (3.33%) case in Group 2 (96.67% success rate). This patient was noted to have pale conjunctival flap at the end of 1 month. The flap sloughed off completely later on. This patient also had constant low-grade pain and inflamed eye and finally developed recurrence at 3 months. The recurrence rate was not statistically significantly different between the two groups (P = 1.00).
Scleral whitening in the bare sclera area was present in 6 (20%) patients in Group 1 [Figure 1], while no such whitening was observed in Group 2 [Figure 2]. The difference was statistically significant (P = 0.015). Scleral whitening was Grade I in 3 (10%) patients, Grade II in 2 (6.7%) patients, and Grade III in 1 (3.3%) patient. None of the patients had Grade IV scleral whitening (choroidal exposure). Conjunctival swab was sterile in all the cases. Management of patients with scleral whitening included stopping topical steroid drops, frequent instillation of topical moxifloxacin 0.5% and lubricant eye drops, oral Vitamin C 500 mg twice a day, and patching of the eye. The scleral whitening showed improvement in all the patients within 12-week period.
|Figure 1: Photograph showing whitening of sclera after bare sclera excision of pterygium 1 month after intrapterygial injection of mitomycin C (Group 1)|
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|Figure 2: Postoperative photograph 12 months after bare sclera excision of pterygium with inferior conjunctival flap 1 month after intrapterygial injection of mitomycin C (Group 2)|
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The follow-up period ranged from 24 months to 51 months, with a mean follow-up period of 26.6 and 26.5 months in Group 1 and 2, respectively.
| Discussion|| |
Subconjunctival MMC before excision of pterygium appears to be a promising new adjunctive therapy in the armamentarium of ophthalmologist with very low recurrence rates of 0%–6%., Experience with this form of MMC administration is still very limited. We investigated the effect of preoperative intrapterygial MMC injection 1 month before bare sclera excision of pterygium with and without conjunctival flap from the inferior bulbar conjunctiva for the treatment of primary pterygia. This is the first study in the literature which has investigated the effect of inferior bulbar conjunctival flap with BSE of pterygium 1 month after intrapterygial injection of 0.1 ml of 0.02% (0.2 mg/ml) MMC in the body of pterygium. The success rate was 100% in Group 1 (no recurrence) and 96.67% in Group 2 (3.33% recurrence). No statistically significant difference was noted between the recurrence rates of the two groups (P = 1.00). Subconjunctival injection of MMC 0.02% (0.1 ml of 0.02% solution) 1 month before BSE is a quick, easy, and safe surgical procedure and is at least as effective as conjunctival rotational flap with intraoperative MMC.
Khakshoor et al. reported no recurrence following BSE 1 month after subpterygeal injection of 0.1 ml of 0.02% MMC during 1-year follow-up, in Group A and 4.3% in those of pterygium excision with rotational flap from the superior conjunctiva and intraoperatively 0.02% MMC for 2 min (Group B). Our study was different compared to the previous study  as in both the groups surgery was performed 1 month after intrapterygial MMC injection and not intraoperative MMC application. Furthermore, conjunctival flap was transposed from the inferior bulbar conjunctiva instead of superior bulbar conjunctiva.
Donnenfeld et al. reported a recurrence rate of 6%, which is higher compared to our study. They did not notice any sclera whitening or wound-healing complications. We believe that this could be due to injection of lesser concentration of MMC (0.1 ml of 0.15 mg/ml) in their study. They claimed a number of advantages of subconjunctival MMC as follows: (1) it allows exact dose delivery, which is equivalent to approximately one drop of 0.2 mg/ml MMC, rather than the inexact and substantially higher dosing with intraoperative sponge delivery; (2) MMC is delivered directly to the activated fibroblasts at the pterygium site where it can work directly on the cells responsible for pterygium recurrence without damaging the epithelial stem cells, which plays no role in pterygia formation or recurrence; (3) it minimizes and titrates exposure of MMC to the ocular surface; (4) it is effective in preventing pterygium recurrence; and (5) it avoids the epithelial and sclera toxicity associated with epithelial and bare sclera delivery of the MMC. Although the technique is simple, quick, and associated with low recurrence, it is a two-stage procedure. Avisar et al. reported no recurrence and no serious complications after 12–23 months of follow-up in 27 patients who underwent combined cataract and pterygium excision with subconjunctival injection of 0.015% MMC 4 weeks before surgery. Another recent study reported a recurrence rate of 4.2% after pterygium excision 1 month after subpterygial injection of 0.015% MMC.
Donnefield et al. waited 1 month after the injection of MMC before performing bare sclera pterygium surgery on the basis of their previous experience with subconjunctival MMC for pemphigoid, in which the eyes became less inflamed at 1 month. To circumvent the disadvantage of waiting for 1 month for the second-stage surgery, recently, investigators have performed excision of pterygium 24 h after subconjunctival injection of MMC with a recurrence rate of 4%–5.7%., However, despite the reduction in waiting period from 1 month to 24 h, it remains a two-stage operation.
Histopathology of recurrent pterygia pretreated with subconjunctival MMC injection 1 month before pterygium excision also showed evidence of an inhibitory effect of MMC on vascular endothelium and stromal fibroblasts. Transmission electron microscopy of excised specimens of pterygium 1 month after subconjunctival injection of 0.1 mL of 0.15 mg/mL MMC demonstrated inhibition of fibrovascular activity in the pterygial stroma, leading to degeneration of the extracellular matrix and nerve axons. The ultrastructural results were consistent with clinical observation of reduced vascularity in the pterygium after MMC injection and verified the effectiveness of subconjunctival MMC 1 month before pterygium excision in decreasing the risk of pterygium recurrence.
It is extremely important to carefully monitor the concentration and dosage of MMC injection, because the subconjunctival injection negates the ability of the tear film to dilute the medication, increasing exposure time to the subconjunctival tissue. Carrasco et al. reported that a patient with dry eye developed scleral ulceration 3 months after the preoperative injection of a higher volume of subconjunctival MMC, pterygium excision, and conjunctival autografting. Thus, even subconjunctival route of administration of MMC should be used with caution, particularly regarding dosage and patient selection.
Khakshoor et al. reported persistent whitening of sclera and hypovascularity at the site of excision in 5.5% of patients of preoperative subpterygial MMC group, while no such whitening was noted in intraoperative MMC with rotational conjunctival flap from the superior bulbar conjunctiva group. In our study, scleral whitening in the bare sclera area was present in 20% of eyes in Group 1, whereas no such whitening developed in Group 2 eyes. The difference in scleral whitening between the two groups was statistically significant (P = 0.015). It seems that intrapterygial injection of MMC results in high concentration of the drug in the pterygial tissue and underlying sclera causing ischemia of episcleral vascular plexus and whitening of sclera and hypovascularity at the site of excision. The concentration of MMC used in our study was similar to Khakshoor et al.'s study, which was higher than other studies (0.020% vs. 0.015%).
MMC is known to cause scleral ischemia. Intrapterygial injection perhaps delivers maximum concentration of MMC near the sclera causing ischemia of episcleral vessels leading to scleral whitening. Conjunctival pedicle flap covered bare sclera in Group 2 and provided vascularity to the covered area and thus appears to prevent whitening of sclera at the pterygium resection site. We believe that the present study strongly supports our hypothesis of covering the bare sclera with conjunctival flap in patients undergoing bare sclera excision 1 month after intrapterygial injection of MMC to prevent scleral whitening. Khakshoor et al. also did not observe this complication with rotational conjunctival flap from the superior bulbar conjunctiva in their Group B; however, they had used intraoperative MMC.
In the past, 0.5 ml of 0.2 mg/ml of MMC has been administered subconjunctivally to experimental animals, glaucoma patients, and patients with ocular cicatricial pemphigoid without any adverse effects., Even a high dose of 1 mg of MMC subconjunctival injection did not cause significant local side effects, except local thinning of the conjunctiva with lack of superficial vessels. The absence of local adverse effects following subconjunctival MMC injection ,, could be explained by the presence of intact conjunctival covering over sclera. Avisar and Weinberger reported that leaving the whole sclera uncovered in pterygium surgery places patients at high risk of complications and recurrence. We preferred conjunctival pedicle flap over free conjunctival autograft as it offered following advantages: (1) feeding of the flap is provided with own vessels, (2) short surgical time based on our past experience, (3) reverse placement of the flap is not seen, (4) it needs fewer sutures, (5) it is less traumatic than autograft technique during conjunctival transport, and (6) the surgery does not require extreme experience. We believe that the conjunctival flap was simple, easier to perform, cosmetically more acceptable, and was highly effective in preventing scleral and conjunctival whitening or hypovascularity in our study. Moreover, reduced recurrence rate of 3.3% was promising compared to the recurrence rates of 7.7% and 33.3% observed after pterygium excision with conjunctival flap transposition from the superior bulbar conjunctiva., The superior bulbar conjunctiva, shielded from solar damage, has been the preferred location for obtaining a conjunctival flap in pterygium surgery. We used conjunctival flap from the inferior bulbar conjunctiva as it avoided manipulation of superior bulbar conjunctiva with inherent risk of scarring, which is undesirable in patients requiring glaucoma filtering surgery in future.
It is, thus, concluded that both techniques, BSE alone or with conjunctival flap from the inferior bulbar conjunctiva 1 month after intrapterygial MMC, resulted in negligible (0%–3.3%) recurrence of pterygium. Conjunctival flap significantly reduced (0%) the postoperative complication of scleral whitening. It is suggested that further studies may be conducted using lower concentration of intrapterygial MMC (0.1 ml of 0.10 mg/ml) 1 month before BSE of pterygium to reduce the incidence of scleral and conjunctival whitening or hypovascularity while retaining its efficacy. The limitations of the study included relatively small sample size compared to similar studies in the literature. Larger studies may be able to better clarify the role of conjunctival flap following intrapterygial MMC injection in cases of primary pterygia.
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[Figure 1], [Figure 2]