Autologous Blood vs Fibrin Glue in Pterygium Excision

CLINICAL SCIENCE
Autologous Blood Versus Fibrin Glue in Pterygium Excision
With Conjunctival Autograft Surgery
Gaayathri Nadarajah, MBBS,* Vanitha Hema Ratnalingam, MD(USM), MSurg(UKM),†
and Hazlita Mohd Isa, MBChb, MS(Ophthal), AM(Mal), PhD‡
Purpose: To evaluate graft stability and recurrence rate between fibrin
glue and autologous blood in pterygium conjunctival autograft surgery.
Methods: A prospective, randomized, single-blinded clinical trial
to assess the efficacy of autologous blood in place of fibrin glue in
pterygium surgery. A total of 120 eyes of 111 patients were
randomized according to pterygium morphology, to undergo pterygium surgery with autografting using either autologous blood or
fibrin glue. All patients were operated by a single surgeon; 58 eyes
were operated using fibrin glue and 62 eyes had a conjunctival
autograft with autologous blood. Patients were seen on postoperative
day 1, 1 week, 1 month, 6 months, and 1 year after surgery. Graft
stability and pterygium recurrence were graded by an independent
observer who was masked to the method of treatment.
Results: All 120 eyes completed the 1-year follow-up. Graft loss
was seen only in the autologous blood group. Of the 62 eyes in this
group, a total of 15 (24.2%) grafts dislodged. Recurrence was
calculated after excluding grafts that were dislodged. Of the 105
patients, there were a total of 7 recurrences, 2 (3.4%) from the fibrin
adhesive method and 5 (10.6%) from the autologous blood method.
This was not statistically significant (P = 0.238).
Conclusions: Autologous blood does not exhibit similar graft
stability seen with fibrin glue. Although the recurrence rate may not
be significant, careful patient selection and a standard method needs
to be laid out before the use of this method is widely accepted.
Key Words: pterygium, autologous blood, recurrence, graft stability
(Cornea 2017;36:452–456)
O
ver the years, a wide range of modalities of treatment
has emerged in the world of pterygium surgery, from
beta-irradiation to sutureless surgeries with fibrin glue. These
Received for publication August 7, 2016; revision received October 3, 2016;
accepted October 21, 2016. Published online ahead of print December 8,
2016.
From the *Ophthalmology Department, Pusat Perubatan Universiti Kebangsaan
Malaysia, Cheras, Kuala Lumpur, Malaysia; †Ophthalmology Department,
Hospital Sungai Buloh, Selangor, Malaysia; and ‡Ophthalmology Department, PPUKM, Cheras, Kuala Lumpur, Malaysia.
The authors have no funding or conflicts of interest to disclose.
Reprints: Hazlita Mohd Isa, MBChb, MS(Ophthal), AM(Mal), PhD,
Consultant Ophthalmologist and Senior Lecturer, Pusat Perubatan Universiti Kebangsaan Malaysia, Jalan Yaakob Latif, Bandar Tun Razak,
Cheras, 56000 Kuala Lumpur, Malaysia (e-mail: [email protected]).
Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.
452
| www.corneajrnl.com
methods primarily aim at curtailing the undesired complication of recurrence. Of these methods, fibrin glue has proven to
champion over other methods in both recurrence rates and
patient comfort.1
However, because fibrin glue is fractionated from
pooled human plasma, it has been reported to be associated
with a very small risk of transmission of certain diseases and
hypersensitivity reaction.2 Furthermore, fibrin glue is costly
in certain countries, equating and sometimes more expensive
than that of an intraocular lens. Unfortunately, the majority of
the patients who would benefit from this technique belong to
a lower socioeconomic stratum, hence limiting the application
of this method to an advantaged few.
To overcome both concerns mentioned above, a handful
of studies have emerged over these last few years comparing
the efficacy of autologous blood with fibrin glue. The latest
study is by Kurian et al3 that demonstrated autologous blood
to be as adherent as fibrin glue with comparably low
recurrence rates. Nevertheless, most reports illustrating the
benefits of autologous blood for pterygium surgery are singlearm studies, have a small sample size, or lack proper
randomization technique.4,5
Many landmark studies have proven that the morphology of pterygium is instrumental in predicting recurrence of
pterygium.6 None of the above studies randomized the
patients according to the pterygium morphology. This study
not only is comparable in terms of the sample size but also
has taken the morphology of pterygium into consideration
during randomization.
METHODOLOGY
A prospective randomized single-blind clinical trial
was conducted at 2 tertiary centers in Kuala Lumpur
between November 2014 and August 2015, after receiving
ethical approval by the Research Ethics Committee of the
National University of Malaysia. Patients with pterygium
who attended the ophthalmology clinic and fulfilled the
inclusion criteria were recruited into the study, after providing written informed consent.
The sample size was determined by the standard sample
size calculation formula, with an 80% power for demonstrating reduction in the current recurrence rate of pterygium
surgery by 15%. The recurrence rate was determined after
extensive research on the current available studies.
Patients were examined under the slit lamp and had
their pterygium graded by a single preoperative investigator,
Cornea ! Volume 36, Number 4, April 2017
Copyright ! 2017 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
Cornea ! Volume 36, Number 4, April 2017
Autologous Blood Versus Fibrin Glue
following a grading system devised by Tan et al. Patients who
had bilateral pterygium had each eye randomized separately
according to the grade of pterygium. Pterygium was graded
by a single preoperative investigator into 3 categories based
on fleshiness of pterygium and visibility of the underlying
episcleral vessels, which could predict the likelihood of
recurrence, T1 being least likely to recur and T3 having the
highest possibility to recur (Table 1).
Patients were then stratified according to their pterygium morphology by a single preoperative investigator. Every
20 patients in the subcategory were then randomized into
either the autologous blood or fibrin glue method by a blockpermuted sampling with differing block sizes of 4 and 6, by
the same preoperative investigator. The outcome of this
randomization was not revealed to the masked independent
observer, designated to grade recurrence.
conjunctiva was dissected carefully without swelling it up
with subconjunctival anesthesia, as it may lead to dissection
in the wrong plane. Once a thin Tenon-free graft with a fair
limbal rim was obtained, it was oriented correspondingly on
the cornea adjacent to the wound.
Preoperative Assessment
Conjunctival Autograft With
Autologous Blood
Before surgery, all patients underwent Snellen visual
acuity documentation, intraocular pressure assessment, slitlamp biomicroscopy, and fundus examination. Refraction and
keratometry assessment was done whenever required, and the
size of all pterygium was documented after measuring at the
slit lamp and photographed.
All surgeries were performed by the same surgeon to
ensure consistency in the technique and time allocated for
graft adherence. Topical proparacaine 0.5% was instilled into
the eye to be operated. The surgical field was cleaned with
povidone–iodine 5%, the area draped, and a lid speculum
inserted into the eye. Subconjunctival lidocaine was injected
into the head of pterygium at the start of surgery.
Intraoperative Steps
The head of pterygium was dissected from the cornea
toward the limbus using a Took knife. A maximum of 5 mm
of the body of pterygium was excised (measured with
a Vernier caliper), and the surrounding Tenon tissue was
removed as much as possible, with care taken not to damage
the underlying recti. Hemostasis was secured by applying
pressure with only a cotton bud. Cautery was not used.
Residual fibrous tissue on the cornea was removed with
a Colibri or Beaver blade.
The area of bare sclera was measured with a Vernier
caliper, and a corresponding 1-mm oversized graft was
harvested from the superior bulbar conjunctiva. The bulbar
Conjunctival Autograft With Fibrin Adhesive
The thrombin and fibrinogen components prepared at
the start of surgery were drawn into 2 separate 1-mL syringes.
One drop of the thrombin component followed by a drop of
the protein solution was placed on the scleral bed.2 The graft
was slid over the bare sclera, ensuring epithelium side up and
the limbal edge toward the cornea. The graft was then pressed
gently, edges crimpled together, and left to dry for 1 to
2 minutes before removing the lid speculum.
A homogenous blood film was allowed to form on the
scleral bed. In cases in which the blood film was exceptionally thin or clot formation was premature, a fresh blood film
was created by purposefully pricking the scleral capillaries
with a 20-G needle. The graft was then slid over the bare
sclera, taking into consideration the orientation of the graft at
all times, pressed gently and left for a minimum of 7 minutes,
using the normal clotting time of 4 to 10 minutes as a guide.
The graft was left on for another few minutes, in cases in
which the graft was still found to be mobile after this time.
The edges of the graft were also crimpled together.
For all cases, the graft was checked and confirmed to be
intact after removal of the lid speculum. Dexamethasone/
polymyxin B ointment (Maxitrol) was applied into the eye,
and the eye was double-padded until review the next day.
Follow-up
All patients were reviewed by the same investigator at
postoperative day 1, 1-month, 6-month, and 1-year follow-up.
Graft stability was assessed on post operative day 1. Grafts
were noted on whether they were intact or not and documented
together with anterior segment photographs. Fluorescein staining of the eye was performed to assess the area of bare sclera
exposed in cases of partial or total dislodgement of the graft.
Grades 1 to 3 were considered partial dislodgment, whereas
grade 4 was considered total dislodgement (Table 2). After
TABLE 1. Classification of Pterygium Morphology
TABLE 2. Graft Stability Assessment
Grade
Graft Stability
Grade T1 (atrophic)
Grade T2 (intermediate)
Grade T3 (fleshy)
Description
Episcleral vessels underlying the body of
pterygium were unobscured and clearly
distinguished
Episcleral vessels not indistinctly seen or partially
obscured
Episcleral vessels underlying the body of
pterygium were totally obscured
Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.
Grade 1
Grade 2
Grade 3
Grade 4
An area of fluorescein staining less than or equivalent to
1/4th of the area of bare sclera
An area of fluorescein staining more than 1/4th but less
than or equivalent to 1/2 of the area of bare sclera
An area of fluorescein staining more than 1/2 but less
than or equivalent to 3/4 of the area of bare sclera
Graft completely dislodged from the area of bare sclera
www.corneajrnl.com |
453
Copyright ! 2017 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
Nadarajah et al
Cornea ! Volume 36, Number 4, April 2017
assessment, all patients were administered Maxitrol eyedrops
every 2 hours for a week, 4 times a day for 3 weeks, and twice
a day for another 2 weeks. Chloramphenicol ointment was
prescribed at night for the whole 6 weeks.
Complete or total graft dislodgement (grade 4 graft
stability) was assessed at day 1 up to the 1-week postoperative
period, using a slit lamp and photography. At 1 month, 6
months, and 1 year, patients were assessed for recurrence, and
anterior segment photographs were taken at each visit. Recurrence was defined as true recurrence with fibrovascular tissue
invading the cornea.7 These photographs were evaluated by
a single independent observer who was masked to the randomization method and hence the method used for each patient.
Statistical Analysis
The data were tabulated and analyzed using SPSS for
Windows version 20. The data were analyzed for graft
stability, and the recurrence rate between both methods was
analyzed using the x2 test and Fisher exact test.
RESULTS
Patient Characteristics
Analysis was performed on 120 eyes of 111 patients
who completed the 1-year follow-up. The demographic data
of the patients in the study are summarized in Table 3. Of the
total 111 patients who were recruited, 62 were male and 49
were female. This difference was not found to have any
significance (P = 1). The mean age in the fibrin adhesive
group was 62.3 6 1.7 years and 53.6 6 1.8 years in the
autologous blood group. Although these values were found to
be statistically significant (P = 0.006), it was not relevant
because we did not randomize patients according to age in
this study. The race distribution was as follows: 57.7% of the
study population was Malay, 34.2% Chinese, 5.4% Indian,
and 2.7% were other races. There were no significance of the
racial distribution between both methods (Malay, P = 0.18;
Chinese, P = 0.43; Indian and other races, P = 1) (Table 3).
In the fibrin adhesive method, there were 13 (10.8%)
patients in the T1 grade, 31 (25.8%) in T2 grade, and 14
(11.7%) in the T3 grade. Similar numbers were seen in the
autologous blood method, 14 (11.7%), 30 (25%), and 18 (15%),
in grades T1, T2, and T3, respectively. As randomization was
done meticulously, there was no significant difference in the
TABLE 3. Patient Characteristics
Characteristics Fibrin Glue, n (%) Autologous Blood, n (%)
Sex
Male
Female
Race
Malay
Chinese
Indian
Others
454
Total
30 (27)
23 (20.7)
32 (28.8)
26 (23.4)
62 (55.9)
49 (44.1)
25
23
3
2
39
15
3
1
64
38
6
3
(22.5)
(20.7)
(2.7)
(1.8)
| www.corneajrnl.com
(35.1)
(13.5)
(2.7)
(0.9)
(57.7)
(34.2)
(5.4)
(2.7)
number of patients seen between both methods in all the three
grades (Table 4).
Graft Dislodgement
Partial dislodgement was seen in both fibrin glue (n = 1,
1.7%) and autologous blood groups (n = 6, 9.7%). This result
was not found to be statistically significant (P = 0.116).
In the fibrin group, partial dislodgement of the graft was
seen in 1 case in grade 3 pterygium (T3). However, in the
autologous blood group, graft instability was seen in all 3
grades; 1 in T1, and 3 in T2 and T3 each. Nevertheless, there
were no significant differences between both methods in the T3
grade (P = 0.62). On analyzing all the 3 grades in the autologous
blood group, we also found that these differences were not
statistically significant (P = 0.42), as shown in Table 4.
In contrast, complete graft dislodgement (grade 4 graft
stability) was seen only in the autologous blood method, and
occurred in all three grades (Table 4). Of the 15 (24.2%)
grafts that completely dislodged within the first postoperative
week, 3 (21.4%) were seen in T1, 6 (20%) in T2, and 6
(33.3%) in T3. This rate of dislodgement between the groups
however was not statistically significant.
Recurrence
Recurrence was calculated after excluding all grafts that
were dislodged. Of the 105 patients, there were a total of 7
recurrences, 2 (3.4%) from the fibrin adhesive method and 5
(10.6%) from the autologous blood method. However, there
was no statistical significance seen in recurrence between
these two methods (P = 0.238). In both methods, recurrence
was seen only in the T3 grade, as depicted in Table 4.
It is worth noting that recurrence was documented as
early as the 1-month postoperative period. Two of the 5
recurrences in the autologous blood group were seen at 1
month but none was seen in the fibrin adhesive group. At the
6-month postoperative period, 3 recurrences were seen in the
autologous blood group (4.8%), and 1 (1.7%) recurrence was
detected in the fibrin adhesive group. Nevertheless, these
numbers were also not statistically significant (P = 0.327).
Postoperative Complications
A total of 3 patients developed a Tenon granuloma at the
1-month postoperative period in the autologous blood group.
Two of them were excised with no recurrence thereafter, and
the other resolved with topical application of Maxitrol ointment for a week. The conjunctival autograft of one patient was
inadvertently placed epithelium side down and graft necrosis
was noted at 1-week follow-up. The conjunctival autograft
was reharvested from inferior bulbar conjunctiva, and no
recurrence was seen thereafter. The esthetic value of surgery
done with autologous blood is comparable to that of Tisseel
glue, as shown in Figures 1 and 2.
DISCUSSION
Pterygium is a very common condition faced by
ophthalmologists in Malaysia and neighboring countries,
because it is more commonly seen in countries close to the
Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.
Copyright ! 2017 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
Cornea ! Volume 36, Number 4, April 2017
Autologous Blood Versus Fibrin Glue
TABLE 4. Number of Patients, Partial and Complete Dislodgement, and Recurrence at 1 Year in All 3 Grades Between Both Methods
Grade 1
Characteristics
Number of patients
Partial dislodgement
Complete dislodgement
Recurrence at 1 yr
Grade 2
Grade 3
Fibrin Glue
Autologous Blood
Fibrin Glue
Autologous Blood
Fibrin Glue
Autologous Blood
13
0
0
0
14
1
3
0
31
0
0
0
30
3
6
0
14
1
0
2
18
3
6
5
equator.8 Although it is easy to diagnose and treat,
recurrence is a persistent problem and can cause visionthreatening complications.
There are countless studies and trials that have postulated that recurrence is multifactorial. Although surgery is the
treatment for this condition, it may be a double-edged sword.
A few studies have proven that inflammation during the
postoperative period causes proliferation of not only vascular
cells and fibroblasts but also subconjunctival fibroblast tissue,
and overexpression of matrix metalloproteinases may result in
invasive pterygium.9
The most reliable predictor of recurrence is still the
morphology of pterygium. As seen in many studies, thick
fleshy pterygia are more likely to recur in contrast to their
atrophic counterparts.10 This could also be the reason why
recurrence is more likely to occur in younger age groups as
they tend to have thicker pterygium at presentation.
We found that of the 111 patients who were recruited in
this study, 55.9% were male and 44.1% were female. This is
consistent with the majority of the existing studies, as males
are exposed to more outdoor activities than females are.
Regarding the ethnic distribution, the bulk of our patients
were Malays (57.7%), undeviating from the racial distribution
in Klang Valley, where the study was conducted. As
mentioned earlier, there was no statistical significance in
sex and racial distribution between both groups.
In this study, we found that the majority of the patients
were aged between 50 and 60 years, with the fibrin glue group
having an older mean age of 62.3 6 1.7 years and the
autologous blood group having a younger age range with
a mean of 53.6 6 1.8 years. Age was not considered in the
process of randomization, as many studies have undisputedly
proven that pterygium prevalence increases with age, with the
majority occurring above age 40, as seen in our immediate
FIGURE 1. Day 1 (left) and 6 months (right) postoperative
period appearance of pterygium excision and a conjunctival
autograft with autologous blood.
Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.
neighbors, Singapore (12.3% Malays and 6.9% Chinese),11,12
Sumatera (16.8%),13 and Meiktila, Myanmar (19.6%).14 Our
study area encompasses largely an urban area and a small area
at the fringe of a rural district, which probably accounts for
a smaller number of younger patients, who mostly work in
offices, in contrast to the older subjects who are still involved
in agricultural work under the sun.
In terms of the pterygium grade, the majority of the
patients had the intermediate grade T2 (50.8%), 22.5% were
of the atrophic variety, and 26.7% belong to the fleshy grade
T3. These numbers are similar to those of a study in the same
geographical region.15
Partial dislodgement occurred when the graft was still
stuck to the bulbar conjunctiva but variable amounts of bare
sclera were exposed. A total of 8 grafts were reported to have
partial dislodgement, 1 (1.7%) in the fibrin glue method and 7
(11.3%) in the autologous blood method. No complications
were seen in one patient in the fibrin glue method; but in the
autologous blood method, 2 patients developed a Tenon
granuloma and another developed recurrence. As autologous
blood contains more naturally occurring growth factors, this
could be the reason for more complications due to an
exacerbated fibrovascular response.
In contrast, complete dislodgment was seen only in the
autologous blood method, a total of 15 (24.2%) grafts were
completely dislodged within the first postoperative week. No
grafts in the fibrin glue group dislodged. It is unlikely that
autologous blood is not as adhesive as fibrin adhesive. In fact,
fibrin glue simply mimics the last few stages of the
coagulation cascade that concludes with formation of a stable
fibrin clot.2 Our numbers were comparable to the dislodgement rate in a similar study.5
There were a few shortcomings encountered during the
autologous blood method in which it was difficult to control
the amount of subgraft blood. When more blood oozes,
a larger clot is expected to form beneath the graft, the
contraction of which will probably cause dislodgement of the
graft. Hence, it is recommended that another study be
conducted to gauge the appropriate amount of blood to cover
the scleral bed before sliding over the graft, with a suitable
technique to achieve this.
The duration to leave the graft to adhere on the scleral
bed is based on the normal clotting time of 4 to 10 minutes.
The minimum duration of 7 minutes used in this study fell in
this range and seemed to allow for sufficient graft adhesion. A
further few minutes was allocated in cases in which the graft
was still mobile after 7 minutes. Hence, we believe that this
technique may be a little more time consuming than
www.corneajrnl.com |
455
Copyright ! 2017 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
Nadarajah et al
Cornea ! Volume 36, Number 4, April 2017
FIGURE 2. Day 1 (left) and 6-month
(right) postoperative period appearance of pterygium excision and
a conjunctival autograft with fibrin
glue.
a conjunctival autograft with fibrin glue that ensured graft
adherence within 2 to 3 minutes. Fibrin glue may be a more
feasible method in centers with a large number of patients
with pterygium.
The recurrence rate at 1 year after excluding patients
whose grafts were completely dislodged was more in the
autologous blood group, 5 (10.6%), compared with 2 (3.4%)
in the fibrin adhesive group. Nevertheless, these were not
found to be statistically significant. The recurrence occurred
only in patients with the fleshy morphology of pterygium (T3)
in both methods. The recurrence rate found in this study is
comparable to that of similar studies performed previously.3–5
This is consistent with virtually all existing studies that
emphasize the risk of recurrence to be associated with a more
severe morphology of pterygium.6 Recurrence was noted as
early as 1 month in the autologous blood group, possibly due
to more growth factors present in fresh blood, in contrast to
that found in the fractionated plasma of Tisseel glue.
From this trial, although autologous blood seems to be
a promising new technique in pterygium excision with
conjunctival autograft surgery, more careful patient selection
is warranted to prevent aggressive recurrence. Autologous
blood is likely to be more beneficial in older patients with
more atrophic pterygium, compared with other age groups
and pterygium morphologies. Fibrin adhesive therefore
still remains the mainstay for pterygium surgery until a more
comprehensive recommendation on the use of autologous
blood emerges.
REFERENCES
1. Koranyi G, Seregard S, Kopp ED. Cut and paste: a no suture, small
incision approach to pterygium surgery. Br J Ophthalmol. 2004;88:
911–914.
456
| www.corneajrnl.com
2. Panda A, Kumar S, Kumar A, et al. Fibrin glue in ophthalmology. Indian
J Ophthalmol. 2009;57:371.
3. Kurian A, Reghunadhan I, Nair KG. Autologous blood versus fibrin glue
for conjunctival autograft adherence in sutureless pterygium surgery:
a randomized controlled trial. Br J Ophthalmol. 2014;99:464–470.
4. Sirisha G, Jyothi S. Autologous blood for conjunctival autograft fixation
in pterygium surgery. Indian J Appl Res. 2016;6:328–330.
5. Boucher S, Conlon R, Teja S, et al. Fibrin glue versus autologous blood
for conjunctival autograft fixation in pterygium surgery. Can J
Ophthalmol. 2015;50:269–272.
6. Tan DT, Chee SP, Dear KB, et al. Effect of pterygium morphology on
pterygium recurrence in a controlled trial comparing conjunctival
autografting with bare sclera excision. Arch Ophthalmol. 1997;115:
1235–1240.
7. Prabhasawat P, Barton K, Burkett G, et al. Comparison of conjunctival
autografts, amniotic membrane grafts, and primary closure for pterygium
excision. Ophthalmology. 1997;104:974–985.
8. Jap A, Chan C, Lim L, et al. Conjunctival rotation autograft for
pterygium: an alternative to conjunctival autografting. Ophthalmology.
1999;106:67–71.
9. Solomon A, Pires RT, Tseng SC. Amniotic membrane transplantation
after extensive removal of primary and recurrent pterygia. Ophthalmology.
2001;108:449–460.
10. Shimazaki J, Kosaka K, Shimmura S, et al. Amniotic membrane
transplantation with conjunctival autograft for recurrent pterygium.
Ophthalmology. 2003;110:119–124.
11. Wong TY, Foster PJ, Johnson GJ, et al. The prevalence and risk factors
for pterygium in an adult Chinese population in Singapore: the Tanjong
Pagar survey. Am J Ophthalmol. 2001;131:176–183.
12. Cajucom-Uy H, Tong L, Wong TY, et al. The prevalence of and risk
factors for pterygium in an urban Malay population: the Singapore Malay
Eye Study (SiMES). Br J Ophthalmol. 2010;94:977–981.
13. Gazzard G, Saw SM, Farook M, et al. Pterygium in Indonesia: prevalence,
severity and risk factors. Br J Ophthalmol. 2002;86:1341–1346.
14. Durkin SR, Abhary S, Newland HS, et al. The prevalence, severity and
risk factors for pterygium in central Myanmar: the Meiktila Eye Study.
Br J Ophthalmol. 2008;92:25–29.
15. Ratnalingam V, Eu AL, Ng GL, et al. Fibrin adhesive is better than
sutures in pterygium surgery. Cornea. 2010;29:485–489.
Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.
Copyright ! 2017 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.