Int Ophthalmol DOI 10.1007/s10792-015-0076-4
ORIGINAL PAPER
A comparative study of different concentrations of topical bevacizumab on the recurrence rate of excised primary pterygium: a short-term follow-up study Qader Motarjemizadeh . Naser Samadi Aidenloo . Siamak Sepehri
Received: 16 January 2015 / Accepted: 23 April 2015 Ó Springer Science+Business Media Dordrecht 2015
Abstract The present study was undertaken to compare the pterygium recurrence rates after treatment with two different concentrations of topical bevacizumab in those who had undergone a primary pterygium excision. The 90 patients who underwent pterygium excision were enrolled in this prospective, placebo-controlled double-blinded interventional case series. The participants were randomly categorized into 3 groups each consisting of 30 subjects. 24 h after surgery, Group II and Group III received a total of 5 and 10 mg/mL dose of topical bevacizumab, respectively; whereas patients in Group I were administered only a placebo starting a day after surgery. Participants were instructed to instill their topical medicines 4 times a day for 1 week. The patients were examined for pterygium recurrence and complications at postoperative 1, 7, and 14 days as well as each month during the following year. Pterygia recurred in 14 patients (46.7 %) in Group I and in 4 patients (13.3 %) in Group II. No recurrence was observed in Group III during the follow-up period. The Kaplan–Meier survival analysis disclosed a significantly better outcome for those who had been treated with 10 mg/mL concentrations of bevacizumab (Mantel–Cox log rank analysis, P \ 0.001). The mean recurrence time was not significantly different between Group I and Group Q. Motarjemizadeh N. S. Aidenloo (&) S. Sepehri Department of Ophthalmology, Medical University of Urmia, 57147-83734 Urmia, Iran e-mail: [email protected]
II. No ocular or systemic complication developed till the end of follow-up. Thus, 10 mg/mL concentration of topical bevacizumab was more efficacious than 5 mg/mL dose in preventing pterygium recurrence. Keywords Pterygium Recurrence Bevacizumab Bare sclera Iran Introduction Pterygium (from the Greek word pterygos, ‘‘little wing’’) is the encroachment of a wing-shaped fibrovascular tissue from the bulbar conjunctiva onto the cornea [1]. This lesion usually grows from the nasal side in the interpalpebral fissure [2] with a prevalence of 2 % in temperate regions and up to 20 % in tropical parts of the world [3]. However, multiple theories have been postulated for the pathogenesis behind pterygium formation, including ultraviolet and infrared exposition, immunological mechanisms, viral infections, neoplasm, dystrophy, limbal stem cell deficiency, and contact lens use [4]; the precise cause of this disorder has not been fully understood yet. But it is clear that fibrovascular proliferation has a very important role in the development of pterygium [5]. Histologically, pterygium is composed of an atrophic conjunctival epithelium and a highly developed vascular neoformation network comprising arterioles, venules, and a great number of capillaries, all of which are observed on a body of hypertrophic and elastotic connective tissue [5].
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Several active angiogenic and epithelial growth factors such as connective tissue growth factor (CTGF), fibroblast growth factor (FGF), plateletderived growth factor (PDGF), heparin-binding epidermal growth factor (HB-EGF), tumor necrosis factor-alpha (TNF-a), transforming growth factor beta (TGF-b), and vascular endothelial growth factor (VEGF) have been shown to be drastically increased in pterygium tissue [6]. However, the most crucial molecule among these factors is VEGF which has been considered as the main target by many antiangiogenic therapies [7]. Indeed, VEGF is the most selective mitogen for endothelial cells [8] and in the presence of this factor, endothelial cells proliferate, migrate, and eventually differentiate into blood vessels [5]. Multiple members of the VEGF family are found in human, including VEGF-A, VEGF-B, VEGF-C, VEGF-D, and placental growth factor (PlGF) [8]. Meanwhile, VEGF-A is the most prominent member of this family, specifically with regard to pathologic angiogenesis [9]. According to the potential role of VEGF in neovascularization, several anti-VEGF therapies have been developed to retard the progression of pterygium [10]. One of them is a 149 kDa full length, humanized, monoclonal antibody called ‘‘Bevacizumab’’ (AvastinÒ). All human VEGF-A isoforms are recognized and neutralized by this antibody [11]. Since, VEGF-A binds to both VEGF receptors (VEGFR1 and VEGFR2) on the surface of endothelial cells, bevacizumab inhibits pterygium growth and induces its regression [12]. In fact, various investigations have shown that intravitreal or topical administration of bevacizumab resulted in increased vessel regression, improved visual acuity, and decreased central retinal thickness [13–15]. To avoid functional abnormalities of vision or discomfort, pterygium is usually removed surgically (simple excision or bare sclera), particularly when it grows to such an extent that covers the pupil. But due to the high rate of pterygium recurrence which is the most unfavorable complication of surgery, excision-based methods are accompanied with graft managements (e.g., conjunctival auto-grafting or amniotic membrane transplantation) [16]. Moreover, post-operatively application of mitomycin C, 5-flurouracil, and b-irradiation are among the methods which have been suggested to improve the outcomes of simple pterygium excision [17]. In this short-term follow-up study, we compared
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the efficacy of two different doses of topical bevacizumab as adjunctive therapy in inhibiting the pterygium recurrence after bare sclera resection.
Methods Study population 90 patients with primary active pterygium were recruited to this multiple-dosing, placebo-controlled, double-blinded interventional case series at Imam Khomeini hospital (A major university hospital in Urmia, Iran), between April 2011 and September 2013. Investigation protocol underwent technical and ethical review and was approved by Human Ethics Committee at the Medical University of Urmia. All subjects were informed about the study’s objectives and informed consent was obtained from all individual participants included in the study. The study was performed in accordance with the Declaration of Helsinki and subsequent revisions. Endocrine glands dysfunction, cardiovascular diseases, autoimmune diseases, diabetes mellitus, administration of other topical medications for pterygium, prior ocular trauma, evidence of other ocular diseases except for refraction errors, and previous conjunctival or scleral surgery were all considered as exclusion criteria. Pregnant and lactating patients and those with recurrent pterygia were also excluded from the investigation. Case’s systolic/diastolic blood pressures were measured at the time of enrollment and subjects who had measures more than 140/90 mmHg or who were using antihypertensive medications were considered as hypertensive. Demographic characteristics, medical, surgical, and ocular history of participants were extracted from their medical records. Patients underwent a complete ophthalmological evaluation, which included detailed slit lamp examination, fundus examinations, and tonometry. A specialist (N. SA) determined all pterygia’ horizontal lengths by measuring the distance from the limbus to the apex of the lesion on the cornea by slit lamp technique. Surgical procedure and topical administration of bevacizumab A pre-surgery evaluation including slit lamp examination and indirect ophthalmoscopy and tonometry was
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performed for each patient. To reduce inter-surgeon bias, all operations were performed by the same surgeon (Q. M) according to D’Ombrain’s bare sclera technique [18]. Briefly, pterygium head was avulsed off the cornea as its body was dissected from the underlying sclera. Thereafter, pterygium tissue detached from the limbal region using beaver blade or corneal burr. Tenon’s layer was removed thoroughly in an area much greater than the pterygium body, but episcleral vessels and the healthy conjunctiva were left intact. Post-operatively, patients were randomly categorized into 3 groups each consisting of 30 subjects. 24 h after surgery, Group II (G2) and Group III (G3) received a total of 5 and 10 mg/mL dose of topical bevacizumab (AvastinÒ, Genentech/Roche, San Fransisco, USA), respectively; whereas patients in Group I (G1) were administered only a placebo starting a day after surgery. Participants were instructed to instill their topical medicines 4 times a day for 1 week. Additionally, all patients also received an eye drop of chloramphenicol 4 times a day for 5 days in combination with betamethasone, six times daily, for 3 days, and then 4 times daily for 2 weeks. All subjects were examined on Days 1, 7, 14, and 30, and monthly for 1 year. All post-operation measurements were performed in a blinded fashion to minimize sampling bias. Participants were also masked as to which agent each patient received. Pterygium recurrence was diagnosed if new vessels or fibrovascular connective tissues were observed beyond the corneal limbus. Statistical analysis All statistical analyses were carried out using the Statistical Package for the Social Sciences (SPSS ver. 17). Two-sided P values less than 0.05 was considered statistically significant for all analyses. Fisher’s exact test was used to compare qualitative variables whereas Mann–Whitney U test and Kruskal–Wallis one-way analysis of variance were utilized to compare intergroup continuous parameters. Spearman’s rank correlation analysis was performed to evaluate the relationship between the pterygium length and the recurrence time. Recurrence-free survival time was calculated by Kaplan–Meier survival analysis with the Mantel–Cox log rank test. The significance of patient age, pterygium length, sun exposure time, and number of dry eyes as conventional risk factors of pterygium
recurrence were determined using the Cox proportional hazard model in Group II. A logistic regression model was also fitted to examine the independent impact of 5 mg/mL concentration of topical bevacizumab on the pterygium recurrence.
Results This study was conducted on 90 eyes of 90 patients, randomly distributed in 3 groups each with 30 subjects. Altogether, 44 men (Aged 28–55 years; mean 39.59 ± 7.34) and 46 women (aged 29–52; mean 40.34 ± 6.29) were included to the study all of who underwent surgery to have their pterygia removed. The clinical and demographic characteristics of the participants are shown in Table 1. No statistically significant differences were observed between the 3 groups in terms of sex, age, laterality, preoperatively sun exposure time, anatomical position of pterygium (temporal vs. nasal), hypertension, dry eye, intraocular pressure, and pterygium length. By grouping pterygia according to their lengths, 4 distinct categories were created, including those with no extension on cornea (Grade I), pterygia with less than 1 mm extension on cornea (Grade II), lesions with 1–2 mm extension on cornea (Grade III), and finally those with more than 2 mm extension on cornea (Grade IV). A same insignificant result was also obtained when the number of pterygia existing in each category was compared between the studied groups (Group I, II, and III) (Table 1). Table 2 shows demographic and clinical data of patients with recurrent pterygium 12 months after surgery. Pterygia recurred in 14 subjects in Group I and 4 patients in Group II (Fisher’s exact test, P = 0.01). No recurrence was observed in Group III during the follow-up period. Mean recurrence time was 5.57 ± 3.06 months (range 2–12 months) in Group I and 5.50 ± 2.08 months (range 3–8 months) in Group II (Mann–Whitney U test, P = 0.878). Mean length of recurrent pterygia was statistically higher in Group I (5.04 ± 0.54 mm) compared to Group II (5.13 ± 1.25 mm; Mann–Whitney U test, P = 0.505). No statistically significant difference was determined between subjects with recurrence existing in Group I and patients with recurrence existing in Group II in terms of age, laterality, anatomical position of pterygium (temporal vs. nasal), hypertension, number of dry eyes, daily sun exposure, pterygium length, and
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Int Ophthalmol Table 1 Pre-operatively demographic characteristics of participants G1 (n = 30) (Placebo)
G2 (n = 30) (5 mg/mL bevacizumab)
G3 (n = 30) (10 mg/mL bevacizumab)
P value
Age (years), mean ± SD
40.97 ± 7.34
39.90 ± 7.07
39.03 ± 6.79
0.702
Sex, n (Male/Female)
17/13
16/14
11/19
0.273
Eye, n (Right/Left)
19/11
16/14
17/13
0.802
Temporal/Nasal, n
13/17
18/12
17/13
0.498
Hypertension, n (%)
4 (13.3)
8 (26.7)
5 (16.7)
0.493
Dry eyes (n)
3 (10)
3 (10)
2 (6.7)
1.000
Intraocular pressure (mmHg), mean ± SD
16.45 ± 3.00
14.87 ± 3.20
17 ± 3.30
0.836
\4 h
18 (60)
16 (53.3)
14 (46.7)
0.626
4–8 h
9 (30)
12 (40)
9 (30)
0.750
[8 h Daily sun exposure (hours), mean ± SD
3 (10) 3.63 ± 2.76
2 (6.7) 3.90 ± 2.48
7 (23.3) 5.10 ± 3.47
0.218 0.234
2 (6.7)
3 (10)
3 (10)
1.000
Sun exposure, n (%)
Pterygium length, n (%) No Extension on cornea (Grade I) Extension on cornea \1 mm (Grade II)
18 (60)
13 (43.3)
10 (33.3)
0.137
Extension on cornea = 1–2 mm (Grade III)
8 (26.7)
9 (30)
10 (33.3)
0.957
Extension cornea [2 mm (Grade IV)
2 (6.7)
5 (16.7)
7 (23.3)
0.210
Pterygium length, mean ± SD
5.16 ± 0.90
5.20 ± 1.07
5.40 ± 1.15
0.467
Table 2 Demographic and clinical data of patients with recurrent pterygium 12 months after surgery
Age (years), mean ± SD
Pterygium recurrence in G1 (n = 14)
Pterygium recurrence in G2 (n = 4)
P value
43.43 ± 6.17
37.33 ± 4.73
0.165
Sex, n (Male/Female)
4/10
4/0
0.023
Eye, n (Right/Left)
8/6
2/2
1.000 1.000
Temporal/Nasal, n
6/8
2/2
Hypertension, n (%)
3 (21.4)
1 (25)
1.000
Dry eyes, n (%)
2 (14.3)
2 (50)
0.197 0.869
Intraocular pressure (mmHg), mean ± SD
16.5 ± 3.3
16 ± 3.8
Daily sun exposure (hours), mean ± SD
5.07 ± 3.38
6 ± 3.60
0.703
Length of primary pterygia, mean ± SD
5.04 ± 0.54
5.33 ± 1.44
0.859
intraocular pressure (Table 2). However, the sex distribution was different in those suffering from pterygium recurrence between Group I and Group II (28.6 vs. 100 %, respectively, P = 0.027). Neither of the demographic characteristics was significantly different between patients with and without recurrence.
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The Kaplan–Meier analysis showed a significantly higher survival rate for those who received the higher dose of bevacizumab (10 mg/mL, Group III) (Fig. 1, Mantel–Cox log rank test, Chi square = 22.92, P \ 0.001). A significantly higher survival rate was also observed for Group III when the Kaplan–Meier
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analysis was achieved only between patients treated with 5 and 10 mg/mL concentrations of bevacizumab (Fig. 1, Mantel–Cox log rank test, Chi square = 4.22, P = 0.04). No patient experienced pterygium recurrence during the first postoperative month. Indeed, the recurrence-free rates after 3, 6, and 9 months were as follows, respectively: 83.3, 66.7, and 63.3 % in Group I and 96.7, 90.0, and 86.7 % in Group II (Fig. 1). Because no recurrence developed in Group III, a proportional hazard analysis was performed exclusively for Group II. The Cox hazard model method did not reveal any significant contribution of age, dry eyes, pterygium length, and daily sun exposure to the recurrence (Table 3). Spearman’s rank correlation analysis did not find any significant difference between pterygium length and recurrence time in Group I (r = -0.191, P = 0.512), in Group II (r = 0.258, P = 0.742), and in all cases with recurrence (r = -0.095, P = 0.708). In order to evaluate the impact of topical administration of bevacizumab on pterygium recurrence, a logistic regression analysis with forward conditional strategy was conducted between subjects who developed recurrent pterygia in Group I and Group II. According to the result, subjects who had received
Fig. 1 Kaplan–Meier survival curves showing the cumulative success probability (lack of recurrence) after pterygium surgery among 3 groups, Group I (placebo), Group II (5 mg/mL bevacizumab), and Group III (10 mg/mL bevacizumab)
placebo were about 5 times more likely to suffer from pterygium recurrence than patients who had been treated by 5 mg/mL concentration of topical bevacizumab (b coefficient = 1.738, Standard error = 0.65, OR = 5.69, CI: 1.59–20.33, P value = 0.007). The difference remained statistically significant even after controlling for the conventional risk factors of pterygium recurrence such as sex, daily sun exposure, pterygium length, age, and dry eyes. There were no systemic or local complications associated with the topical bevacizumab therapy during the follow-up in the current study.
Discussion Surgery has been considered as a main treatment for primary pterygium by most of corneal specialists [19]; however, recent investigations show that recurrence rates range from 15 to 75 % following bare sclera resection [6]. In this manner, numerous substances, with varying degrees of success, have been recommended to decrease the chance of recurrence. Among them, bevacizumab along with mitomycin C is regarded as a prominent postoperative adjuvant therapy for pterygium. Apart from pterygium, bevacizumab has also been used to treat a variety of other ophthalmic disorders, including central retinal vein occlusion [20], diabetic retinopathy [21], neovascular age-related macular degeneration [22], neovascular glaucoma [23], and corneal neovascularization [24]. Subconjunctival injection, intravitreal injection, and topical administration are three main routes which have been used in these treatments to deliver bevacizumab to the target tissue. The subconjunctival or intravitreal injections provide depots from which systemic absorption may occur. Indeed, several systemic complications such as gastrointestinal perforation, hypertension, arteriolar hemorrhage, impaired wound healing, bleeding, endophthalmitis, and arterial thromboembolic events have been reported so far following the subconjunctival or intravitreal injections [9, 25]. Moreover, multiple injections are cumbersome and increase the ocular risks and patients’ discomfort. Therefore, it has been suggested that topical instillation is the best route of bevacizumab administration because it provides not only safety and efficacy but also practicality [9]. However, the optimal dose of bevacizumab and the frequency of topical
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Int Ophthalmol Table 3 Adjusted hazard ratios and 95 % confidence intervals for the contribution of risk factors to the pterygium recurrence in Group II
Variable
Adjusted HR (95 % CI)
P value
Age
0.882 (0.740–1.052)
0.161
Dry eyes
2.829 (0.294–27.210)
0.368
Pterygium length (Pre-operational)
0.926 (0.377–2.274)
0.866
Sun exposure time
1.479 (0.931–2.350)
0.097
administration for pterygium adjuvant therapy have not yet been determined. Although there are multiple studies investigating the efficacy of intravitreal or subconjunctival injections of bevacizumab for the treatment of pterygium in the literature, a few researchers have examined the impact of bevacizumab eye drops (per se or as an adjuvant agent) on primary or recurrent pterygia so far [13–15, 17, 26, 27]. In a case study, Wu et al. [15] examined the efficacy of topical formulation of bevacizumab (25 mg/mL) in a patient with impending recurrent pterygium who had undergone a primary pterygium excision 2 months before. Four times a day administration of bevacizumab eye drops for 3 weeks contributed to a critical regression of limbal conjunctival neovascularization with no evidence of pterygium recurrence. In another study, Leippi et al. [13] evaluated the impact of topical administration of bevacizumab (25 mg/mL) on the rate of pterygium recurrence in 5 eyes from 4 patients. Examined eyes were treated 2 to 8 times per day for 5–24 weeks by bevacizumab eye drops as an adjunctive therapy after pterygium excision and conjunctival autograft. Patients were investigated over a follow-up period ranging from 3 to 14 months. An early recurrence with corneal vascularisation and superficial punctate keratopathy was reported in only 1 eye. In order to analyze the ability of bevacizumab to inhibit corneal neovascularization, Fallah et al. [17] studied 54 patients with impending recurrent pterygium who had undergone bare sclera surgery and application of mitomycin. Participants were subdivided in this prospective clinical trial into two groups (A and B) each consisting 26 subjects. Cases in group A received bevacizumab eye drops (5 mg/mL) twice a day and betamethasone four times daily for 1 week, whereas patients in group B received betamethasone alone four times daily for 1 week. The mean progression of fibrovascular tissue extension in the first group was significantly less than that in the second group
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(P \ 0.01) after 3 months. In a similar investigation, Ozgurhan et al. [14] enrolled 44 patients in a prospective and interventional study. All patients had undergone recurrent pterygium excision with conjunctival autograft transplantation 1 month before the study began. After dividing the patients into bevacizumabreceived group (5 mg/mL, 4 times daily for 2 months) and artificial tear-received group (4 times daily for 2 months), the clinical outcomes of topical bevacizumab were evaluated as adjunctive to the surgical excision. Although no statistically significant differences were observed between these 2 groups in terms of pterygium recurrence rate, corneal neovascularization was significantly higher in subjects who had received artificial tear compared with patients who had received topical bevacizumab (P \ 0.03). Sudhalkar et al. [27] accomplished 23 primary pterygium excisions with rotational conjunctival autograft and applied a 30 day postoperative regimen included antibiotic eye drops (moxifloxacin), preservative-free artificial tears (carboxymethyl cellulose 1 %, four times a day), and topical bevacizumab (1.25 mg/ml, 4 drops a day) to operated eyes. No recurrence was observed till the end of follow-up period (mean time: 34.25 ± 2.4 months). In a case–control study, Karalezli et al. [26] evaluated the effect of topical bevacizumab administration on postoperative pterygium recurrence in 88 eyes that had undergone pterygium excision with limbal-conjunctival autograft transplantation. The control group (46 eyes) received topical dexamethasone 0.1 % and tobramycin 0.3 % for 4 weeks, whereas the case group (42 eyes), in addition to the mentioned steroid and antibiotic treatments, also received a 5 mg/mL dose of topical bevacizumab (4 times daily for 1 month). The investigated groups were statistically similar in terms of recurrence rate over the follow-up period (ranged 24–52 months). Controversial results also have emerged from the subconjunctival injection of bevacizumab. In an offlabel; interventional case series, Alhammami et al.
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[28] treated 20 eyes of patients with recurrent pterygium. All participants received subconjunctival injection of bevacizumab (0.2 ml/2.5 mg) following the injection of 0.2 ml lidocain 2 % in subconjunctival area of pterygium body. There was a significant reduction (P \ 0.05) in the mean surface area of pterygia at different time intervals (1, 3, and 6 months after injection) in the mentioned study. Moreover, Nava-Castan˜eda et al. [29] investigated the efficacy of subconjunctival bevacizumab application as an adjuvant therapy for primary pterygium in a clinicalrandomized trial. Forty-nine patients with primary pterygium were divided into three sub-groups after pterygium excision and a conjunctival autograft. In Group 1 (16 subjects), bevacizumab (2.5 mg/0.1 ml) was injected subconjunctivally adjacent to the site of pterygium separation inside the healthy conjunctiva once after surgery. Those who were in Group 2 (17 subjects) received two injections: one (2.5 mg/0.1 ml) immediately after surgery, and the second (with a same dose) 15 days after surgery. In the third group (the control group with 16 subjects), surgery was performed without bevacizumab application. At the end of follow-up period (1 year) pterygium recurrences were observed only in the third group (P \ 0.04). On the other hand, there are also studies that find no advantage for subconjunctival injection of bevacizumab. Felipe et al. [30] studied 15 patients with primary and recurrent pterygium in an off-label, multiple-dosing, interventional case series. Investigated volunteers received subconjunctival bevacizumab (1.25 mg) every 2 weeks for 10 weeks. Injections were applied to the subconjunctival area of the body of the pterygium and the size of the pterygium (measured by surface area in cm2) was recorded from baseline to 16 weeks postinjection. Their results showed that the mean surface area of the pterygia was statistically similar at all intervals (P [ 0.05). Additionally, Khoshniat et al. [31] achieved a prospective case– control study that included 98 patients with recurrent pterygium. In this investigation, participants had been divided into two groups, a control group with 50 subjects and a case group with 48 individuals. The control group received a single injection of 0.1 ml of bevacizumab via a tuberculin syringe subconjunctivally around the pterygium, whereas the other group (case group) received 0.1 ml of normal saline. All participants were followed in regular 48 h intervals, weekly, up to 1 month and then monthly up to
6 months after injection. No significant difference was observed in the size of pterygium between the investigated groups during the follow-up. These controversial results could be mainly attributed to the tremendous variations which are seen among the reviewed investigations, such as the different criteria used for pterygium recurrence by various investigators, ethnic differences between the studied populations, the extend of major risk factor interference in each study. But it is more probable that the discrepancy observed between various researches lies generally on the differences in the following factors: duration of administration, frequency of instillation/injection, and the concentration of the applied bevacizumab. Our short-term follow-up study clearly shows a dose–response relationship between the different concentrations of bevacizumab eye drops and pterygium recurrence. This is consistent with some other studies investigating the relationship between different doses of bevacizumab and corneal neovascularization [32]. However, there are also findings that failed to establish a significant difference in the rate of pterygium recurrence between various concentrations of subconjunctival bevacizumab injections [33]. To the best of our knowledge, this is the first study which aimed to compare the rate of postoperative pterygium recurrence after treatment with two different topical bevacizumab doses. Our findings support the hypothesis that the bevacizumab eye drops might be useful as an adjunctive therapy in prevention of pterygium recurrence after pterygium excision. In fact, the risk of recurrence decreased more than five times in subjects treated with 5 mg/mL concentration of bevacizumab compared with placebo-received individuals. Pterygia recurred in 4 of the 60 eyes received bevacizumab eye drops, all in the low-dose group (Group II). Neither recurrence was observed in Group III during the follow-up period. Therefore, we have concluded that 10 mg/mL concentration of topical bevacizumab was a more effective dose for adjuvant pterygium therapy than 5 mg/mL dose. VEGF is a crucial cytokine in the wound-healing response and it has been believed that application of anti-VEGF agents such as bevacizumab immediately after bare sclera surgery could inhibit cell proliferation, angiogenesis, wound contraction, and epithelialization [14]. Nevertheless, there was no major case of scleral necrosis, conjunctival cyst, sub-tenon
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granuloma, Symplepharon, epithelial irregularities, or any other complications with bare sclera technique in this investigation. Total recurrence rate was 46.7 % in Group I after 12 months. This was compatible with some previous studies [34]. On the other hand, pterygium recurrence was noted in 13.3 % of subjects who were in Group II. This rate of recurrence was higher than two other investigations in which a same dose of topical bevacizumab (5 mg/ mL) had been administered post-operatively [14, 26]. However, in these studies, the authors used topical bevacizumab eye drops for a longer time than our investigation (1 month in Karalezli et al. [26] and 2 months in Ozgurhan et al. [14] compared to the 1 week in our study). Furthermore, both investigations utilized pterygium excision with conjunctival autograft transplantation technique which has lower recurrence rate compared to bare sclera resection used in our study [34]. Finally, due to the lack of any pterygium recurrence in subjects treated with higher dose of bevacizumab (10 mg/mL), it is impossible to predict how much the risk of pterygium recurrence is diminished in Group III compared to Group I or II. Longer follow-up trials with larger sample size are needed to respond these kinds of questions and to establish the long-term safety, efficacy, and dosing guidelines for the use of topical bevacizumab as an adjunctive therapy for pterygium recurrence. In conclusion, we believe that topical administration of bevacizumab after pterygium excision is a safe and effective adjunct therapy to prevent the recurrence of pterygium. Moreover, 10 mg/mL concentration of topical bevacizumab is more efficacious than 5 mg/ mL dose in preventing pterygium recurrence.
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Acknowledgments The authors wish to thank all the participants of this study and nursing staff of Imam Khomeini hospital for their valuable cooperation.
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Conflict of interest The authors declare that they have no conflict of interest.
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Ethical standards All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
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ORIGINAL PAPER
A comparative study of different concentrations of topical bevacizumab on the recurrence rate of excised primary pterygium: a short-term follow-up study Qader Motarjemizadeh . Naser Samadi Aidenloo . Siamak Sepehri
Received: 16 January 2015 / Accepted: 23 April 2015 Ó Springer Science+Business Media Dordrecht 2015
Abstract The present study was undertaken to compare the pterygium recurrence rates after treatment with two different concentrations of topical bevacizumab in those who had undergone a primary pterygium excision. The 90 patients who underwent pterygium excision were enrolled in this prospective, placebo-controlled double-blinded interventional case series. The participants were randomly categorized into 3 groups each consisting of 30 subjects. 24 h after surgery, Group II and Group III received a total of 5 and 10 mg/mL dose of topical bevacizumab, respectively; whereas patients in Group I were administered only a placebo starting a day after surgery. Participants were instructed to instill their topical medicines 4 times a day for 1 week. The patients were examined for pterygium recurrence and complications at postoperative 1, 7, and 14 days as well as each month during the following year. Pterygia recurred in 14 patients (46.7 %) in Group I and in 4 patients (13.3 %) in Group II. No recurrence was observed in Group III during the follow-up period. The Kaplan–Meier survival analysis disclosed a significantly better outcome for those who had been treated with 10 mg/mL concentrations of bevacizumab (Mantel–Cox log rank analysis, P \ 0.001). The mean recurrence time was not significantly different between Group I and Group Q. Motarjemizadeh N. S. Aidenloo (&) S. Sepehri Department of Ophthalmology, Medical University of Urmia, 57147-83734 Urmia, Iran e-mail: [email protected]
II. No ocular or systemic complication developed till the end of follow-up. Thus, 10 mg/mL concentration of topical bevacizumab was more efficacious than 5 mg/mL dose in preventing pterygium recurrence. Keywords Pterygium Recurrence Bevacizumab Bare sclera Iran Introduction Pterygium (from the Greek word pterygos, ‘‘little wing’’) is the encroachment of a wing-shaped fibrovascular tissue from the bulbar conjunctiva onto the cornea [1]. This lesion usually grows from the nasal side in the interpalpebral fissure [2] with a prevalence of 2 % in temperate regions and up to 20 % in tropical parts of the world [3]. However, multiple theories have been postulated for the pathogenesis behind pterygium formation, including ultraviolet and infrared exposition, immunological mechanisms, viral infections, neoplasm, dystrophy, limbal stem cell deficiency, and contact lens use [4]; the precise cause of this disorder has not been fully understood yet. But it is clear that fibrovascular proliferation has a very important role in the development of pterygium [5]. Histologically, pterygium is composed of an atrophic conjunctival epithelium and a highly developed vascular neoformation network comprising arterioles, venules, and a great number of capillaries, all of which are observed on a body of hypertrophic and elastotic connective tissue [5].
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Several active angiogenic and epithelial growth factors such as connective tissue growth factor (CTGF), fibroblast growth factor (FGF), plateletderived growth factor (PDGF), heparin-binding epidermal growth factor (HB-EGF), tumor necrosis factor-alpha (TNF-a), transforming growth factor beta (TGF-b), and vascular endothelial growth factor (VEGF) have been shown to be drastically increased in pterygium tissue [6]. However, the most crucial molecule among these factors is VEGF which has been considered as the main target by many antiangiogenic therapies [7]. Indeed, VEGF is the most selective mitogen for endothelial cells [8] and in the presence of this factor, endothelial cells proliferate, migrate, and eventually differentiate into blood vessels [5]. Multiple members of the VEGF family are found in human, including VEGF-A, VEGF-B, VEGF-C, VEGF-D, and placental growth factor (PlGF) [8]. Meanwhile, VEGF-A is the most prominent member of this family, specifically with regard to pathologic angiogenesis [9]. According to the potential role of VEGF in neovascularization, several anti-VEGF therapies have been developed to retard the progression of pterygium [10]. One of them is a 149 kDa full length, humanized, monoclonal antibody called ‘‘Bevacizumab’’ (AvastinÒ). All human VEGF-A isoforms are recognized and neutralized by this antibody [11]. Since, VEGF-A binds to both VEGF receptors (VEGFR1 and VEGFR2) on the surface of endothelial cells, bevacizumab inhibits pterygium growth and induces its regression [12]. In fact, various investigations have shown that intravitreal or topical administration of bevacizumab resulted in increased vessel regression, improved visual acuity, and decreased central retinal thickness [13–15]. To avoid functional abnormalities of vision or discomfort, pterygium is usually removed surgically (simple excision or bare sclera), particularly when it grows to such an extent that covers the pupil. But due to the high rate of pterygium recurrence which is the most unfavorable complication of surgery, excision-based methods are accompanied with graft managements (e.g., conjunctival auto-grafting or amniotic membrane transplantation) [16]. Moreover, post-operatively application of mitomycin C, 5-flurouracil, and b-irradiation are among the methods which have been suggested to improve the outcomes of simple pterygium excision [17]. In this short-term follow-up study, we compared
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the efficacy of two different doses of topical bevacizumab as adjunctive therapy in inhibiting the pterygium recurrence after bare sclera resection.
Methods Study population 90 patients with primary active pterygium were recruited to this multiple-dosing, placebo-controlled, double-blinded interventional case series at Imam Khomeini hospital (A major university hospital in Urmia, Iran), between April 2011 and September 2013. Investigation protocol underwent technical and ethical review and was approved by Human Ethics Committee at the Medical University of Urmia. All subjects were informed about the study’s objectives and informed consent was obtained from all individual participants included in the study. The study was performed in accordance with the Declaration of Helsinki and subsequent revisions. Endocrine glands dysfunction, cardiovascular diseases, autoimmune diseases, diabetes mellitus, administration of other topical medications for pterygium, prior ocular trauma, evidence of other ocular diseases except for refraction errors, and previous conjunctival or scleral surgery were all considered as exclusion criteria. Pregnant and lactating patients and those with recurrent pterygia were also excluded from the investigation. Case’s systolic/diastolic blood pressures were measured at the time of enrollment and subjects who had measures more than 140/90 mmHg or who were using antihypertensive medications were considered as hypertensive. Demographic characteristics, medical, surgical, and ocular history of participants were extracted from their medical records. Patients underwent a complete ophthalmological evaluation, which included detailed slit lamp examination, fundus examinations, and tonometry. A specialist (N. SA) determined all pterygia’ horizontal lengths by measuring the distance from the limbus to the apex of the lesion on the cornea by slit lamp technique. Surgical procedure and topical administration of bevacizumab A pre-surgery evaluation including slit lamp examination and indirect ophthalmoscopy and tonometry was
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performed for each patient. To reduce inter-surgeon bias, all operations were performed by the same surgeon (Q. M) according to D’Ombrain’s bare sclera technique [18]. Briefly, pterygium head was avulsed off the cornea as its body was dissected from the underlying sclera. Thereafter, pterygium tissue detached from the limbal region using beaver blade or corneal burr. Tenon’s layer was removed thoroughly in an area much greater than the pterygium body, but episcleral vessels and the healthy conjunctiva were left intact. Post-operatively, patients were randomly categorized into 3 groups each consisting of 30 subjects. 24 h after surgery, Group II (G2) and Group III (G3) received a total of 5 and 10 mg/mL dose of topical bevacizumab (AvastinÒ, Genentech/Roche, San Fransisco, USA), respectively; whereas patients in Group I (G1) were administered only a placebo starting a day after surgery. Participants were instructed to instill their topical medicines 4 times a day for 1 week. Additionally, all patients also received an eye drop of chloramphenicol 4 times a day for 5 days in combination with betamethasone, six times daily, for 3 days, and then 4 times daily for 2 weeks. All subjects were examined on Days 1, 7, 14, and 30, and monthly for 1 year. All post-operation measurements were performed in a blinded fashion to minimize sampling bias. Participants were also masked as to which agent each patient received. Pterygium recurrence was diagnosed if new vessels or fibrovascular connective tissues were observed beyond the corneal limbus. Statistical analysis All statistical analyses were carried out using the Statistical Package for the Social Sciences (SPSS ver. 17). Two-sided P values less than 0.05 was considered statistically significant for all analyses. Fisher’s exact test was used to compare qualitative variables whereas Mann–Whitney U test and Kruskal–Wallis one-way analysis of variance were utilized to compare intergroup continuous parameters. Spearman’s rank correlation analysis was performed to evaluate the relationship between the pterygium length and the recurrence time. Recurrence-free survival time was calculated by Kaplan–Meier survival analysis with the Mantel–Cox log rank test. The significance of patient age, pterygium length, sun exposure time, and number of dry eyes as conventional risk factors of pterygium
recurrence were determined using the Cox proportional hazard model in Group II. A logistic regression model was also fitted to examine the independent impact of 5 mg/mL concentration of topical bevacizumab on the pterygium recurrence.
Results This study was conducted on 90 eyes of 90 patients, randomly distributed in 3 groups each with 30 subjects. Altogether, 44 men (Aged 28–55 years; mean 39.59 ± 7.34) and 46 women (aged 29–52; mean 40.34 ± 6.29) were included to the study all of who underwent surgery to have their pterygia removed. The clinical and demographic characteristics of the participants are shown in Table 1. No statistically significant differences were observed between the 3 groups in terms of sex, age, laterality, preoperatively sun exposure time, anatomical position of pterygium (temporal vs. nasal), hypertension, dry eye, intraocular pressure, and pterygium length. By grouping pterygia according to their lengths, 4 distinct categories were created, including those with no extension on cornea (Grade I), pterygia with less than 1 mm extension on cornea (Grade II), lesions with 1–2 mm extension on cornea (Grade III), and finally those with more than 2 mm extension on cornea (Grade IV). A same insignificant result was also obtained when the number of pterygia existing in each category was compared between the studied groups (Group I, II, and III) (Table 1). Table 2 shows demographic and clinical data of patients with recurrent pterygium 12 months after surgery. Pterygia recurred in 14 subjects in Group I and 4 patients in Group II (Fisher’s exact test, P = 0.01). No recurrence was observed in Group III during the follow-up period. Mean recurrence time was 5.57 ± 3.06 months (range 2–12 months) in Group I and 5.50 ± 2.08 months (range 3–8 months) in Group II (Mann–Whitney U test, P = 0.878). Mean length of recurrent pterygia was statistically higher in Group I (5.04 ± 0.54 mm) compared to Group II (5.13 ± 1.25 mm; Mann–Whitney U test, P = 0.505). No statistically significant difference was determined between subjects with recurrence existing in Group I and patients with recurrence existing in Group II in terms of age, laterality, anatomical position of pterygium (temporal vs. nasal), hypertension, number of dry eyes, daily sun exposure, pterygium length, and
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Int Ophthalmol Table 1 Pre-operatively demographic characteristics of participants G1 (n = 30) (Placebo)
G2 (n = 30) (5 mg/mL bevacizumab)
G3 (n = 30) (10 mg/mL bevacizumab)
P value
Age (years), mean ± SD
40.97 ± 7.34
39.90 ± 7.07
39.03 ± 6.79
0.702
Sex, n (Male/Female)
17/13
16/14
11/19
0.273
Eye, n (Right/Left)
19/11
16/14
17/13
0.802
Temporal/Nasal, n
13/17
18/12
17/13
0.498
Hypertension, n (%)
4 (13.3)
8 (26.7)
5 (16.7)
0.493
Dry eyes (n)
3 (10)
3 (10)
2 (6.7)
1.000
Intraocular pressure (mmHg), mean ± SD
16.45 ± 3.00
14.87 ± 3.20
17 ± 3.30
0.836
\4 h
18 (60)
16 (53.3)
14 (46.7)
0.626
4–8 h
9 (30)
12 (40)
9 (30)
0.750
[8 h Daily sun exposure (hours), mean ± SD
3 (10) 3.63 ± 2.76
2 (6.7) 3.90 ± 2.48
7 (23.3) 5.10 ± 3.47
0.218 0.234
2 (6.7)
3 (10)
3 (10)
1.000
Sun exposure, n (%)
Pterygium length, n (%) No Extension on cornea (Grade I) Extension on cornea \1 mm (Grade II)
18 (60)
13 (43.3)
10 (33.3)
0.137
Extension on cornea = 1–2 mm (Grade III)
8 (26.7)
9 (30)
10 (33.3)
0.957
Extension cornea [2 mm (Grade IV)
2 (6.7)
5 (16.7)
7 (23.3)
0.210
Pterygium length, mean ± SD
5.16 ± 0.90
5.20 ± 1.07
5.40 ± 1.15
0.467
Table 2 Demographic and clinical data of patients with recurrent pterygium 12 months after surgery
Age (years), mean ± SD
Pterygium recurrence in G1 (n = 14)
Pterygium recurrence in G2 (n = 4)
P value
43.43 ± 6.17
37.33 ± 4.73
0.165
Sex, n (Male/Female)
4/10
4/0
0.023
Eye, n (Right/Left)
8/6
2/2
1.000 1.000
Temporal/Nasal, n
6/8
2/2
Hypertension, n (%)
3 (21.4)
1 (25)
1.000
Dry eyes, n (%)
2 (14.3)
2 (50)
0.197 0.869
Intraocular pressure (mmHg), mean ± SD
16.5 ± 3.3
16 ± 3.8
Daily sun exposure (hours), mean ± SD
5.07 ± 3.38
6 ± 3.60
0.703
Length of primary pterygia, mean ± SD
5.04 ± 0.54
5.33 ± 1.44
0.859
intraocular pressure (Table 2). However, the sex distribution was different in those suffering from pterygium recurrence between Group I and Group II (28.6 vs. 100 %, respectively, P = 0.027). Neither of the demographic characteristics was significantly different between patients with and without recurrence.
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The Kaplan–Meier analysis showed a significantly higher survival rate for those who received the higher dose of bevacizumab (10 mg/mL, Group III) (Fig. 1, Mantel–Cox log rank test, Chi square = 22.92, P \ 0.001). A significantly higher survival rate was also observed for Group III when the Kaplan–Meier
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analysis was achieved only between patients treated with 5 and 10 mg/mL concentrations of bevacizumab (Fig. 1, Mantel–Cox log rank test, Chi square = 4.22, P = 0.04). No patient experienced pterygium recurrence during the first postoperative month. Indeed, the recurrence-free rates after 3, 6, and 9 months were as follows, respectively: 83.3, 66.7, and 63.3 % in Group I and 96.7, 90.0, and 86.7 % in Group II (Fig. 1). Because no recurrence developed in Group III, a proportional hazard analysis was performed exclusively for Group II. The Cox hazard model method did not reveal any significant contribution of age, dry eyes, pterygium length, and daily sun exposure to the recurrence (Table 3). Spearman’s rank correlation analysis did not find any significant difference between pterygium length and recurrence time in Group I (r = -0.191, P = 0.512), in Group II (r = 0.258, P = 0.742), and in all cases with recurrence (r = -0.095, P = 0.708). In order to evaluate the impact of topical administration of bevacizumab on pterygium recurrence, a logistic regression analysis with forward conditional strategy was conducted between subjects who developed recurrent pterygia in Group I and Group II. According to the result, subjects who had received
Fig. 1 Kaplan–Meier survival curves showing the cumulative success probability (lack of recurrence) after pterygium surgery among 3 groups, Group I (placebo), Group II (5 mg/mL bevacizumab), and Group III (10 mg/mL bevacizumab)
placebo were about 5 times more likely to suffer from pterygium recurrence than patients who had been treated by 5 mg/mL concentration of topical bevacizumab (b coefficient = 1.738, Standard error = 0.65, OR = 5.69, CI: 1.59–20.33, P value = 0.007). The difference remained statistically significant even after controlling for the conventional risk factors of pterygium recurrence such as sex, daily sun exposure, pterygium length, age, and dry eyes. There were no systemic or local complications associated with the topical bevacizumab therapy during the follow-up in the current study.
Discussion Surgery has been considered as a main treatment for primary pterygium by most of corneal specialists [19]; however, recent investigations show that recurrence rates range from 15 to 75 % following bare sclera resection [6]. In this manner, numerous substances, with varying degrees of success, have been recommended to decrease the chance of recurrence. Among them, bevacizumab along with mitomycin C is regarded as a prominent postoperative adjuvant therapy for pterygium. Apart from pterygium, bevacizumab has also been used to treat a variety of other ophthalmic disorders, including central retinal vein occlusion [20], diabetic retinopathy [21], neovascular age-related macular degeneration [22], neovascular glaucoma [23], and corneal neovascularization [24]. Subconjunctival injection, intravitreal injection, and topical administration are three main routes which have been used in these treatments to deliver bevacizumab to the target tissue. The subconjunctival or intravitreal injections provide depots from which systemic absorption may occur. Indeed, several systemic complications such as gastrointestinal perforation, hypertension, arteriolar hemorrhage, impaired wound healing, bleeding, endophthalmitis, and arterial thromboembolic events have been reported so far following the subconjunctival or intravitreal injections [9, 25]. Moreover, multiple injections are cumbersome and increase the ocular risks and patients’ discomfort. Therefore, it has been suggested that topical instillation is the best route of bevacizumab administration because it provides not only safety and efficacy but also practicality [9]. However, the optimal dose of bevacizumab and the frequency of topical
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Int Ophthalmol Table 3 Adjusted hazard ratios and 95 % confidence intervals for the contribution of risk factors to the pterygium recurrence in Group II
Variable
Adjusted HR (95 % CI)
P value
Age
0.882 (0.740–1.052)
0.161
Dry eyes
2.829 (0.294–27.210)
0.368
Pterygium length (Pre-operational)
0.926 (0.377–2.274)
0.866
Sun exposure time
1.479 (0.931–2.350)
0.097
administration for pterygium adjuvant therapy have not yet been determined. Although there are multiple studies investigating the efficacy of intravitreal or subconjunctival injections of bevacizumab for the treatment of pterygium in the literature, a few researchers have examined the impact of bevacizumab eye drops (per se or as an adjuvant agent) on primary or recurrent pterygia so far [13–15, 17, 26, 27]. In a case study, Wu et al. [15] examined the efficacy of topical formulation of bevacizumab (25 mg/mL) in a patient with impending recurrent pterygium who had undergone a primary pterygium excision 2 months before. Four times a day administration of bevacizumab eye drops for 3 weeks contributed to a critical regression of limbal conjunctival neovascularization with no evidence of pterygium recurrence. In another study, Leippi et al. [13] evaluated the impact of topical administration of bevacizumab (25 mg/mL) on the rate of pterygium recurrence in 5 eyes from 4 patients. Examined eyes were treated 2 to 8 times per day for 5–24 weeks by bevacizumab eye drops as an adjunctive therapy after pterygium excision and conjunctival autograft. Patients were investigated over a follow-up period ranging from 3 to 14 months. An early recurrence with corneal vascularisation and superficial punctate keratopathy was reported in only 1 eye. In order to analyze the ability of bevacizumab to inhibit corneal neovascularization, Fallah et al. [17] studied 54 patients with impending recurrent pterygium who had undergone bare sclera surgery and application of mitomycin. Participants were subdivided in this prospective clinical trial into two groups (A and B) each consisting 26 subjects. Cases in group A received bevacizumab eye drops (5 mg/mL) twice a day and betamethasone four times daily for 1 week, whereas patients in group B received betamethasone alone four times daily for 1 week. The mean progression of fibrovascular tissue extension in the first group was significantly less than that in the second group
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(P \ 0.01) after 3 months. In a similar investigation, Ozgurhan et al. [14] enrolled 44 patients in a prospective and interventional study. All patients had undergone recurrent pterygium excision with conjunctival autograft transplantation 1 month before the study began. After dividing the patients into bevacizumabreceived group (5 mg/mL, 4 times daily for 2 months) and artificial tear-received group (4 times daily for 2 months), the clinical outcomes of topical bevacizumab were evaluated as adjunctive to the surgical excision. Although no statistically significant differences were observed between these 2 groups in terms of pterygium recurrence rate, corneal neovascularization was significantly higher in subjects who had received artificial tear compared with patients who had received topical bevacizumab (P \ 0.03). Sudhalkar et al. [27] accomplished 23 primary pterygium excisions with rotational conjunctival autograft and applied a 30 day postoperative regimen included antibiotic eye drops (moxifloxacin), preservative-free artificial tears (carboxymethyl cellulose 1 %, four times a day), and topical bevacizumab (1.25 mg/ml, 4 drops a day) to operated eyes. No recurrence was observed till the end of follow-up period (mean time: 34.25 ± 2.4 months). In a case–control study, Karalezli et al. [26] evaluated the effect of topical bevacizumab administration on postoperative pterygium recurrence in 88 eyes that had undergone pterygium excision with limbal-conjunctival autograft transplantation. The control group (46 eyes) received topical dexamethasone 0.1 % and tobramycin 0.3 % for 4 weeks, whereas the case group (42 eyes), in addition to the mentioned steroid and antibiotic treatments, also received a 5 mg/mL dose of topical bevacizumab (4 times daily for 1 month). The investigated groups were statistically similar in terms of recurrence rate over the follow-up period (ranged 24–52 months). Controversial results also have emerged from the subconjunctival injection of bevacizumab. In an offlabel; interventional case series, Alhammami et al.
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[28] treated 20 eyes of patients with recurrent pterygium. All participants received subconjunctival injection of bevacizumab (0.2 ml/2.5 mg) following the injection of 0.2 ml lidocain 2 % in subconjunctival area of pterygium body. There was a significant reduction (P \ 0.05) in the mean surface area of pterygia at different time intervals (1, 3, and 6 months after injection) in the mentioned study. Moreover, Nava-Castan˜eda et al. [29] investigated the efficacy of subconjunctival bevacizumab application as an adjuvant therapy for primary pterygium in a clinicalrandomized trial. Forty-nine patients with primary pterygium were divided into three sub-groups after pterygium excision and a conjunctival autograft. In Group 1 (16 subjects), bevacizumab (2.5 mg/0.1 ml) was injected subconjunctivally adjacent to the site of pterygium separation inside the healthy conjunctiva once after surgery. Those who were in Group 2 (17 subjects) received two injections: one (2.5 mg/0.1 ml) immediately after surgery, and the second (with a same dose) 15 days after surgery. In the third group (the control group with 16 subjects), surgery was performed without bevacizumab application. At the end of follow-up period (1 year) pterygium recurrences were observed only in the third group (P \ 0.04). On the other hand, there are also studies that find no advantage for subconjunctival injection of bevacizumab. Felipe et al. [30] studied 15 patients with primary and recurrent pterygium in an off-label, multiple-dosing, interventional case series. Investigated volunteers received subconjunctival bevacizumab (1.25 mg) every 2 weeks for 10 weeks. Injections were applied to the subconjunctival area of the body of the pterygium and the size of the pterygium (measured by surface area in cm2) was recorded from baseline to 16 weeks postinjection. Their results showed that the mean surface area of the pterygia was statistically similar at all intervals (P [ 0.05). Additionally, Khoshniat et al. [31] achieved a prospective case– control study that included 98 patients with recurrent pterygium. In this investigation, participants had been divided into two groups, a control group with 50 subjects and a case group with 48 individuals. The control group received a single injection of 0.1 ml of bevacizumab via a tuberculin syringe subconjunctivally around the pterygium, whereas the other group (case group) received 0.1 ml of normal saline. All participants were followed in regular 48 h intervals, weekly, up to 1 month and then monthly up to
6 months after injection. No significant difference was observed in the size of pterygium between the investigated groups during the follow-up. These controversial results could be mainly attributed to the tremendous variations which are seen among the reviewed investigations, such as the different criteria used for pterygium recurrence by various investigators, ethnic differences between the studied populations, the extend of major risk factor interference in each study. But it is more probable that the discrepancy observed between various researches lies generally on the differences in the following factors: duration of administration, frequency of instillation/injection, and the concentration of the applied bevacizumab. Our short-term follow-up study clearly shows a dose–response relationship between the different concentrations of bevacizumab eye drops and pterygium recurrence. This is consistent with some other studies investigating the relationship between different doses of bevacizumab and corneal neovascularization [32]. However, there are also findings that failed to establish a significant difference in the rate of pterygium recurrence between various concentrations of subconjunctival bevacizumab injections [33]. To the best of our knowledge, this is the first study which aimed to compare the rate of postoperative pterygium recurrence after treatment with two different topical bevacizumab doses. Our findings support the hypothesis that the bevacizumab eye drops might be useful as an adjunctive therapy in prevention of pterygium recurrence after pterygium excision. In fact, the risk of recurrence decreased more than five times in subjects treated with 5 mg/mL concentration of bevacizumab compared with placebo-received individuals. Pterygia recurred in 4 of the 60 eyes received bevacizumab eye drops, all in the low-dose group (Group II). Neither recurrence was observed in Group III during the follow-up period. Therefore, we have concluded that 10 mg/mL concentration of topical bevacizumab was a more effective dose for adjuvant pterygium therapy than 5 mg/mL dose. VEGF is a crucial cytokine in the wound-healing response and it has been believed that application of anti-VEGF agents such as bevacizumab immediately after bare sclera surgery could inhibit cell proliferation, angiogenesis, wound contraction, and epithelialization [14]. Nevertheless, there was no major case of scleral necrosis, conjunctival cyst, sub-tenon
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granuloma, Symplepharon, epithelial irregularities, or any other complications with bare sclera technique in this investigation. Total recurrence rate was 46.7 % in Group I after 12 months. This was compatible with some previous studies [34]. On the other hand, pterygium recurrence was noted in 13.3 % of subjects who were in Group II. This rate of recurrence was higher than two other investigations in which a same dose of topical bevacizumab (5 mg/ mL) had been administered post-operatively [14, 26]. However, in these studies, the authors used topical bevacizumab eye drops for a longer time than our investigation (1 month in Karalezli et al. [26] and 2 months in Ozgurhan et al. [14] compared to the 1 week in our study). Furthermore, both investigations utilized pterygium excision with conjunctival autograft transplantation technique which has lower recurrence rate compared to bare sclera resection used in our study [34]. Finally, due to the lack of any pterygium recurrence in subjects treated with higher dose of bevacizumab (10 mg/mL), it is impossible to predict how much the risk of pterygium recurrence is diminished in Group III compared to Group I or II. Longer follow-up trials with larger sample size are needed to respond these kinds of questions and to establish the long-term safety, efficacy, and dosing guidelines for the use of topical bevacizumab as an adjunctive therapy for pterygium recurrence. In conclusion, we believe that topical administration of bevacizumab after pterygium excision is a safe and effective adjunct therapy to prevent the recurrence of pterygium. Moreover, 10 mg/mL concentration of topical bevacizumab is more efficacious than 5 mg/ mL dose in preventing pterygium recurrence.
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Acknowledgments The authors wish to thank all the participants of this study and nursing staff of Imam Khomeini hospital for their valuable cooperation.
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Conflict of interest The authors declare that they have no conflict of interest.
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Ethical standards All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
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