ARTICLE
Corneal Polishing After Pterygium Excision With Motorized Diamond Burr: A Randomized Control Trial Pinto Chikkanayakanahalli Narasimhaiah, M.D., Shikha Gupta, M.D., Sudarshan Khokhar, M.D., Murugesan Vanathi, M.D., Tanuj Dada, M.D., Ravinder M. Pandey, Ph.D., M.D., and Tushar Agarwal, M.D.
Purpose: To evaluate outcomes of motorized diamond burr polishing versus manual polishing after pterygium excision. Setting: Dr. Rajendra Prasad Center for Ophthalmic Sciences, New Delhi. Design: A randomized, interventional observer-masked controlled trial. Methods: Forty consecutive eyes underwent pterygium excision with fibrin, glue-assisted conjunctival autograft. In group 1 (20 eyes), polishing of the corneal bed was done using a crescent blade, and in group 2 (20 eyes), using a motorized diamond burr. Results: There was no difference in the 2 groups with respect to mean age (P=0.08), gender (P=0.3), preoperative uncorrected visual acuity (UCVA) (P=0.45), best spectacle-corrected visual acuity (BCVA) (P=0.52), spherical equivalent (P=0.5), mean astigmatism (P=0.7), tear function tests like tear break-up time, tear film meniscus height, Schirmer I and II (P=0.6, 0.5, 0.7, 0.9 respectively), pterygium dimension (P=0.4), and conjunctival autograft size (P=0.24). Mean intraoperative surgical time was significantly more in group 1 (16.962.85 min) as compared with 12.2561.88 min in group 2 (P=0.0001). Postoperatively, there was a statistically significant reduction in astigmatism and improvement in UCVA, BCVA, spherical equivalent in all eyes. No difference was found in mean epithelial defect healing time, UCVA, BCVA, astigmatism, tear film break-up time, Schirmer I and II, and tear meniscus height at 6 months between 2 groups; however, significantly better UCVA was found in group 2 at 3 months (P=0.04). Surgically induced astigmatism (SIA) was significantly more in group 2 as compared with group 1 at 6 months (P=0.0006). Conclusions: Motorized diamond burr polishing of the corneoscleral bed during primary pterygium excision in comparison with manual polishing requires significantly lesser surgical time with better UCVA, decreased astigmatism, and greater SIA at 6 months, which indicates greater astigmatic correction. Key Words: Conjunctival autograft—Surgeon-induced astigmatism— Motorized diamond burr. (Eye & Contact Lens 2015;41: 268–272)
P
terygium is characterized by a radially oriented fibrovascular lesion, which often grows across the corneal limbus in the interpalpebral zone. Growth of pterygium may require excision if it From the Cornea and Refractive Services (C.N.P., S.G., S.K., M.V., T.D., T.A.), Dr. Rajendra Prasad Center for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India; and Department of Biostatistics (R.M.P.), All India Institute of Medical Sciences, New Delhi, India. The authors have no funding or conflicts of interest to disclose. Address correspondence to Tushar Agarwal, M.D., Dr. Rajendra Prasad Center for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi 110029, India; e-mail: [email protected] Accepted October 13, 2014. DOI: 10.1097/ICL.0000000000000115
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is visually disabling by obstructing the visual axis, or by producing refractive disturbances, or if it produces ocular surface disturbances like dry eyes, irritation, lacrimation, foreign body sensation, recurrent inflammation, motility restriction, and cosmetic disfigurement.1 The removal of pterygium is followed by polishing of the corneoscleral bed to remove any attached remnants of the tissue and to smoothen the irregular surface, which is usually done differently by the surgeons using a crescent blade,2 diamond burr,3 Westcott scissors,4 iris spatula,5 or No. 64 Beaver blade.6 The goal of pterygium surgery is to restore limbal anatomy to prevent recurrences in future. This restoration is enhanced by smoothing of the corneoscleral bed that aids reepithelialization, enhances corneal clarity in the postoperative period, and might influence the final corneal topography. Excision of pterygium by any technique partially reverses some of the topographic and refractive abnormalities induced by the abnormal fibrovascular tissue, by causing reduction in corneal astigmatism and higher-order aberrations, and by producing keratometric steepening along with visual improvement.7,8 Amongst the various techniques performed for pterygium excision and ocular surface reconstruction, conjunctival autografting with fibrin glue is considered the de facto method for the surgical correction of pterygium. Pan et al.9 in their meta-analysis on studies comparing conjunctival autografting with sutures versus fibrin glue reported that although the rate of complications remains the same between the two groups, fibrin glue confers decreased rate of recurrence and is associated with shorter operating time. Studies demonstrate that conjunctival or limbal autograft is more efficacious than amniotic membrane grafting in preventing recurrence for primary pterygium.10 Further, the use of conjunctival or limbal autografts with or without mitomycin C in conjunction with pterygium excision reduces recurrence rates when compared with bare sclera excision.10 However, no study could be found on comparison of outcomes when the different methods of corneal polishing were applied. Hence, we conducted our study to evaluate the outcomes of motorized diamond burr polishing in comparison with manual polishing after pterygium excision on corneal clarity, topography, residual refractive error, and surgeon-induced astigmatism.
MATERIALS AND METHODS We conducted a randomized, controlled observer-masked clinical trial. Ethical clearance was obtained from the Institutional Review Board of All India Institute of Medical Sciences. An informed consent was obtained from the study participants before study entry. Patients who presented with primary pterygium to our tertiary care center from December 2009 till November 2011 were Eye & Contact Lens Volume 41, Number 5, September 2015
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Eye & Contact Lens Volume 41, Number 5, September 2015 enrolled in the study. Consecutive patients with primary nasal pterygium of size greater than or equal to 2 mm, extending onto the cornea and aged older than 18 years, compliant for follow-up, and willing to participate in the trial were included. Forty eyes of 36 patients underwent pterygium excision with fibrin, glue-assisted conjunctival autograft and were randomized by computer-generated simple randomization with respect to polishing of the corneoscleral bed into 2 groups; group 1 was crescent blade–assisted manual polishing and group 2 consisted of polishing with a motorized diamond burr (Alger Brush 2000; Rumex International Corp, Clearwater, FL) with a 3.5-mm round fine tip (Fig. 1). Sample size was calculated using the following formula11 for comparing mean in two groups of equal size: N ¼ 2=d2 · Cp power; where N is the number of subjects required in each group, d is the standardized difference, and Cp, power is a constant defined by the values chosen for the P value and power. According to precalculated table, Cp, power for a power of 95% and P=0.01 is 17.8. Standard deviation (d) was kept at 1.71 as reported by Yilmaz et al.12 after pterygium excision with conjunctival autograft. Based on this formula, the N was 12.19. Hence, 20 eyes were randomized to each group. Comprehensive ocular examination was done by an observer preoperatively and postoperatively (P.C.N.). The parameters studied included uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BCVA), standardized digital slitlamp photography, pterygium dimensions (horizontal extension and vertical extension), tear film tests (tear break-up time [TBUT], Schirmer I and II, tear meniscus height), and videokeratography TMS-2 (Tomey Co, Nagoya, Japan). The graft parameters were assessed by a masked observer (T.D.) using digital slitlamp photographs (Haag-Streit BP 900, Koeniz, Switzerland). These were reassessed postoperatively on days 1, 3, 7 and at 1, 3, and 6 months in each group. A 6-month period for follow-up was chosen to enable the topography and tear film functions to stabilize. Data regarding patient recruitment and follow-up are shown in Figure 1. A 6-month period was chosen based on the observations of Ti et al.,13 that more than or equal to 85% recurrences occurred within the first 6 months after pterygium excision for both primary and recurrent pterygia.
Surgical Technique The surgery was performed by the same surgeon (T.A.). Parts were prepared and draped, wire speculum was placed to expose the surgical area, and topical anesthesia proparacaine (0.5%) and
Corneal Polishing After Pterygium Excision lignocaine jelly (1%) was instilled. In each eye, although the minimally adherent pterygium tissue was peeled off using Lims forceps (Appasamy, Chennai, India), the firmly adherent pterygium was removed by gentle manipulation and the fibrovascular tissue was removed using spring scissors. The bed of the pterygium in group 1 was polished with a crescent blade, whereas in group 2, it was polished with a motorized diamond burr. Excessively bleeding vessels were cauterized using bipolar cautery, as necessary. The conjunctival defect was measured with a surgical caliper. After subconjunctival injection of xylocaine, equivalently sized limbalconjunctival autograft was harvested from the same eye (superotemporal quadrant), and the graft was adhered using fibrin glue at the site of bare sclera with the limbal edge of tissue facing the cornea. Postoperatively, the eye was patched for 24 hr. Patients were prescribed topical moxifloxacin 0.5% (Vigamox; Alcon Laboratories, Fort Worth, TX) thrice per day for 2 weeks, prednisolone acetate 1% (Alcon Laboratories) 4 times per day for 2 weeks (tapered over 1 month to relieve inflammation), and 0.5% carboxymethylcellulose (Refresh tears; Allergan, Irvine, CA) 4 times per day for 3 months (to prevent foreign body sensation). Patients were examined on days 1, 3, and 7 and 1, 3, and 6 months thereafter postoperatively by a masked observer (P.C.N.). Patients with an epithelial defect persisting for more than 7 days were followed up every day till it epithelialized completely. Main outcome measures were postoperative corneal epithelialization rate, tear film analysis (TBUT, tear film meniscus height, Schirmer I and II), videokeratography, graft status (inflammation, stability, subconjuctival hemorrhage),6 and corneal clarity, the last 2 of these were graded by digital slitlamp photography by a masked observer. Corneal clarity was graded as following: Grade 1 meant opacification of the entire area with iris not seen; grade 2 meant visibility of iris hazily through the cornea with pattern not visible; grade 3 meant iris details seen hazily through the cornea; and grade 4 was clear underlying cornea with no residual opacity. Surgically induced astigmatism (SIA) was calculated using “SIA Calculator” version 2.1 (http://www.insighteyeclinic.in/SIA_ calculator.php) based on keratometry readings obtained from videokeratography. Recurrence was defined as at least a growth of 1 mm of fibrovascular tissue onto the cornea.14
Statistical Analysis Data were analyzed using Stata software version 11.0 (Stata Corp, College Station, TX). In case of continuous parameters, t test was applied and the Wilcoxon rank-sum test was applied to compare mean between the two groups. Categorical variables were compared in the two groups using the Fisher exact test. P#0.05 was taken as statistically significant. The Friedman test was applied with multiple comparison by the Wilcoxon signed-rank-sum test in case of intragroup analysis. Statistical analysis was done by a statistician with no knowledge of about any particular procedure being superior.
RESULTS
FIG. 1. The view shows data regarding patient recruitment and follow-up details.
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Forty eyes of 36 patients were included, of which 20 eyes each were randomized to crescent blade polishing and diamond burr polishing groups after pterygium excision. The mean age of the patients in group 1 was 43.8611.3 years and was 37.969.6 years (P=0.08) in group 2; in group 1, 75% were men, whereas group 2 consisted of 60% of men (P=0.3). Baseline characteristics were similar in the 2 groups with respect to preoperative UCVA 269
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Eye & Contact Lens Volume 41, Number 5, September 2015
P. Chikkanayakanahalli Narasimhaiah et al. TABLE 1.
Baseline Characteristics of the Two Groups With Respect to the Analyzed Parameters
Parameter Tested UCVA (logMAR) BCVA (logMAR) SE refraction (D) Astigmatism (D) TBUT (sec) Schirmer I (mm) Schirmer II (mm) Meniscus height (mm) Pterygium dimension Height (mm) Width (mm) Graft dimension Height (mm) Width (mm)
Group 1 (n=20) Mean6SD
Group 2 (n=20) Mean6SD
P
0.4560.24 0.2360.11 1.1660.8 2.3360.89 10.4563.44 23.167.25 21.1565.4 0.2560.08
0.5060.2 0.2460.1 1.3460.66 2.161.06 13.3562.34 23.764.32 21.363.74 0.2760.09
0.46 0.52 0.45 0.74 0.61 0.75 0.92 0.48
3.660.75 4.660.75
3.7560.78 4.660.82
0.54 1
4.660.75 5.560.61
4.960.85 5.1560.58
0.25 0.07
BCVA, best spectacle-corrected visual acuity; SD, standard deviation; SE, spherical equivalent; TBUT, tear break-up time; UCVA, uncorrected visual acuity.
(P=0.45) and BCVA (P=0.52), spherical equivalent (2.3360.89 in group 1 and 2.161.06 in group 2; P=0.5), mean astigmatism (1.1660.8 in group 1 and 1.3460.66 in group 2; P=0.7), tear function tests, such as TBUT, tear film meniscus height, Schirmer I and II (P=0.6, 0.5, 0.7, 0.9, respectively), and pterygium dimension (P=0.4) (Table 1). The size of the conjunctival autograft (both horizontal and vertical diameter) measured intraoperatively was also comparable between the 2 groups (P=0.24) (Table 1). Mean intraoperative surgical time was 16.962.85 min in group 1 as compared with 12.2561.88 min in group 2 (P=0.0001). The mean epithelial defect healing time was 3.661.46 days in group 1, compared with 3.260.39 days in group 2 (P=non-significant; Wilcoxon signed-rank test). Postoperatively at 7 days, 15% of eyes in group 1 experienced an epithelial defect that was seen in 5% in group 2. In one of the eyes of group 2, graft inversion
FIG. 2. group.
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was noted intraoperatively wherein tenon’s capsule was placed upside down, which was corrected by resurgery. Figure 2 depicts the preoperative and postoperative appearance of a representative eye in each group. There was a significant improvement in UCVA (log of minimal angle of resolution) at 6 months in both groups compared with the preoperative value. Difference in UCVA as calculated using the Wilcoxon rank-sum test between the 2 groups was found to be significantly better in group 2 at 3 months (P=0.04); it was insignificant at other times. A statistically significant improvement in BCVA was observed compared with the preoperative level in both groups, which was significantly more in group 2 at 1 week when compared with group 1 (P=0.019). At subsequent follow-ups, no statistical difference could be observed between the 2 groups (P=0.82, 0.33, and 0.45 at 1, 3, and 6 months, respectively). The mean spherical equivalent decreased from baseline level in both groups at each follow-up; however, reduction was more in the diamond burr group at 1 week (P=0.028). No significant difference was elicited at subsequent follow-ups (P=0.062, 1, 0.07 at 1, 3, and 6 months, respectively). Similarly, a statistically significant reduction in mean astigmatism was observed in both groups when compared with preoperative levels; however, at 1 week, the diamond burr group showed a significantly lesser mean astigmatism (1.3561.06 D) in comparison with the crescent group, which demonstrated a mean astigmatism of 2.3361.6 D (P=0.034) (Table 2). At subsequent follow-ups, no difference was observed between the two groups. Surgically induced astigmatism was significantly more in group 2 as compared with group 1 at 6 months (P=0.0006; Table 2). Tear film break-up time, Schirmer I and II, and tear meniscus height showed no difference from preoperative level till 6 months in any of the groups (at 6 months, P=0.12, 0.1, 0.1, 0.09, respectively; Table 2). Similarly, no significant difference in graft grading was obtained between the 2 groups at the end of 6 months (P=1, 1, 0.3 at 1, 3, and 6 months, respectively; Wilcoxon rank-sum test). One eye developed pterygium recurrence in group 1 (P=NS) for which no surgery was requested by the patient.
The view shows preoperative and postoperative appearance after pterygium excision in each
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Eye & Contact Lens Volume 41, Number 5, September 2015 TABLE 2.
Characteristics of the Two Groups With Respect to Each Other at 6 Months
Parameter Tested UCVA (logMAR) BCVA (logMAR) SE refraction (D) Astigmatism (D) TBUT (sec) Schirmer I (mm) Schirmer II (mm) Meniscus height (mm) SIA
Group 1 (n=20) Mean6SD
Group 2 (n=20) Mean6SD
0.22560.20 0.0560.20 0.560.52 1.260.91 17.561.53 28.561.31 24.561.31 0.2560.06
0.13160.17 0.0460.17 0.2760.42 0.8160.69 16.761.62 27.6 62.01 25.662.01 0.21560.04
1.2060.901
1.9561.20
P 0.14 0.45 0.07 0.20 0.12 0.1 0.1 0.09 0.0006
BCVA, best spectacle-corrected visual acuity; SD, standard deviation; SE, spherical equivalent; SIA, surgically induced astigmatism; TBUT, tear break-up time; UCVA, uncorrected visual acuity.
DISCUSSION Surgical excision of pterygium achieves not only better cosmesis, but also alleviates refractive disturbances. Improvement in vision after the surgical removal of pterygium has been found to correspond to a decrease in simulated keratometric astigmatism, refractive spherocylinder,15 central 3-mm topographic corneal irregularity, along with a statistically significant decrease in surface regularity index and surface asymmetry index.16–18 The refractive properties of the cornea continue to change postoperatively for a long period according to Ozdemir and Cinal,19 who observed that keratometric astigmatism, surgically induced corneal astigmatism, and mean total corneal refractive power continue to decrease significantly till 3 months when compared with 2 weeks postoperatively. The root mean square values of higher-order aberrations also experience a significant reduction with time.20,21 This reduction in SIA is directly proportional to the grade and size7,8,12,22 of pterygium, as well as preoperative astigmatism.12 The final outcome also varies according to the surgical technique of excision,7 with the literature suggesting that the bare sclera excision induces greater corneal steepening in contrast to conjunctival autograft technique.12 However, to our knowledge, the effect of corneal polishing by different surgical means on the final visual outcome is not known; hence, the purpose of conducting this study. Our study showed minimal graft inflammation or subconjunctival hemorrhage postoperatively in either group with equivalent graft stability. We did not encounter any case of graft dehiscence in any of our eyes reinforcing that corneal polishing by either means has no effect on ultimate graft adherence. Glue-assisted graft adhesion was chosen over suture-assisted closure in our study because it is associated with lesser discomfort, pain and inflammation,23 equal stability,6 reduced intraoperative time,24 and possibly a lower recurrence rate.9,25,26 Patients with pterygium are known to exhibit a deficient tear function, including a decreased TBUT, an increased tear osmolarity, a low crystallization percentage, and abnormal mucus fern pattern when compared with control eyes,27–30 which is partially restored after pterygium surgery.31 However, no difference in tear film parameters was observed with respect to tear film break-up time, Schirmer, or tear meniscus height between the 2 groups at 6 months. We observed a significant reduction in mean astigmatism and refractive error (spherical equivalent) when compared with the baseline values in both groups irrespective of the method used for © 2015 Contact Lens Association of Ophthalmologists
Corneal Polishing After Pterygium Excision corneal polishing. We also found earlier recovery of UCVA in the diamond burr group as compared with the manual group at 1 week. This could be due to a smoother corneal bed from less surgical trauma, which decreased light scattering and hence resulted in better unaided vision. Later on, corneal healing might have overcome this limitation in group 1 subjects. Our study showed a significant decrease in mean astigmatism from preoperative level in both groups. Although the difference in astigmatism between the 2 groups was significant only at 1 week, SIA was significantly more in group 2 at 6 months. Surgically induced astigmatism means net vector change in astigmatism after any surgical procedure. In usual circumstances, greater SIA is not a desirable outcome. However, in cases with preexisting corneal astigmatism requiring correction, calculation would show a higher SIA in the treatment group, for example, after Limbal relaxing incisions, astigmatic keratotomy, and pterygium excision. The aim then is to achieve lower astigmatism compared with preoperative levels. Greater SIA in group 2 signifies greater reduction in preoperative astigmatism values. It indicates better astigmatic correction and reversal of preoperative astigmatism to some extent. Hence, diamond burr seems to be better than manual polishing with crescent blade regarding final astigmatism achieved. The comparison of other topographic outcomes such as changes in surface regularity and surface symmetry indices would have provided additional information regarding the refractive outcome between the two techniques. Therefore, we concluded that motorized diamond burr polishing of the corneoscleral bed during primary pterygium excision in comparison with manual polishing with crescent blade results in significant reduction in surgical time, earlier recovery of UCVA, and faster reduction in mean astigmatism; however, the 2 techniques are equivalent in the rate of reepithelialization, final BCVA, tear film function parameters, and recurrence rate at 6 months of follow-up. To conclude, advantages of using a diamond burr for polishing of the corneal residual bed include better reduction in astigmatism, little surgical expertise required, no residual corneal scarring, and probably the removal of more abnormal remnant tissue than manual debridement. REFERENCES 1. 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. 2. Hall RC, Logan AJ, Wells AP. Comparison of fibrin glue with sutures for pterygium excision surgery with conjunctival autografts. Clin Experiment Ophthalmol 2009;37:584–589. 3. Ozgurhan EB, Kara N, Yildirim A, et al. Diamond burr superficial keratectomy with mitomycin C for corneal scarring and high corneal astigmatism after pterygium excision. Clin Ophthalmol 2013;7:951–954. 4. Ayala M. Results of pterygium surgery using a biologic adhesive. Cornea 2008;27:663–667. 5. 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. 6. Srinivasan S, Dollin M, McAllum P, et al. Fibrin glue versus sutures for attaching the conjunctival autograft in pterygium surgery: A prospective observer masked clinical trial. Br J Ophthalmol 2009;93:215–218. 7. Bahar I, Loya N, Weinberger D, et al. Effect of pterygium surgery on corneal topography: A prospective study. Cornea 2004;23:113–117. 8. Maheshwari S. Pterygium-induced corneal refractive changes. Indian J Ophthalmol 2007;55:383–386. 9. Pan HW, Zhong JX, Jing CX. Comparison of fibrin glue versus suture for conjunctival autografting in pterygium surgery: A meta-analysis. Ophthalmology 2011;118:1049–1054.
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P. Chikkanayakanahalli Narasimhaiah et al. 10. Kaufman SC, Jacobs DS, Lee WB, et al. Options and adjuvants in surgery for pterygium: A report by the American Academy of Ophthalmology. Ophthalmology 2013;120:201–208. 11. Whitley E, Ball J. Statistics review 4: Sample size calculations. Crit Care 2002;6:335–341. 12. Yilmaz S, Yuksel T, Maden A. Corneal topographic changes after four types of pterygium surgery. J Refract Surg 2008;24:160–165. 13. Ti SE, Chee SP, Dear KB, et al. Analysis of variation in success rates in conjunctival autografting for primary and recurrent pterygium. Br J Ophthalmol 2000;84:385–389. 14. Ang LP, Chua JL, Tan DT. Current concepts and techniques in pterygium treatment. Curr Opin Ophthalmol 2007;18:308–313. 15. Wu PL, Kuo CN, Hsu HL, et al. Effect of pterygium surgery on refractive spherocylinder power and corneal topography. Ophthalmic Surg Lasers Imaging 2009;40:32–37. 16. Errais K, Bouden J, Mili-Boussen I, et al. Effect of pterygium surgery on corneal topography. Eur J Ophthalmol 2008;18:177–181. 17. Tomidokoro A, Miyata K, Sakaguchi Y, et al. Effects of pterygium on corneal spherical power and astigmatism. Ophthalmology 2000;107:1568–1571. 18. Nejima R, Masuda A, Minami K, et al. Topographic changes after excision surgery of primary pterygia and the effect of pterygium size on topograpic restoration. Eye Contact Lens 2015;41:58–63. 19. Ozdemir M, Cinal A. Early and late effects of pterygium surgery on corneal topography. Ophthalmic Surg Lasers Imaging 2005;36:451–456. 20. Gumus K, Topaktas D, Göktas¸ A, et al. The change in ocular higher-order aberrations after pterygium excision with conjunctival autograft: A 1-year prospective clinical trial. Cornea 2012;31:1428–1431.
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Eye & Contact Lens Volume 41, Number 5, September 2015 21. Pesudovs K, Figueiredo FC. Corneal first surface wavefront aberrations before and after pterygium surgery. J Refract Surg 2006;22:921–925. 22. Kheirkhah A, Safi H, Molaei S, et al. Effects of pterygium surgery on front and ack corneal astigmatism. Can J Ophthalmol 2012;47:423–428. 23. Cha DM, Kim KH, Choi HJ, et al. A comparative study of the effect of fibrin glue versus sutures on clinical outcome in patients undergoing pterygium excision and conjunctival autografts. Korean J Ophthalmol 2012;26:407–413. 24. Bahar I, Weinberger D, Gaton DD, et al. Fibrin glue versus vicryl sutures for primary conjunctival closure in pterygium surgery: Long-term results. Curr Eye Res 2007;32:399–405. 25. Ozdamar Y, Mutevelli S, Han U, et al. A comparative study of tissue glue and vicryl suture for closing limbal-conjunctival autografts and histologic evaluation after pterygium excision. Cornea 2008;27:552–558. 26. Karalezli A, Kucukerdonmez C, Akova YA, et al. Fibrin glue versus sutures for conjunctival autografting in pterygium surgery: A prospective comparative study. Br J Ophthalmol 2008;92:1206–1210. 27. Marzeta M, Toczołowski J. Study of mucin layer of tear film in patients with pterygium [in Polish]. Klin Oczna 2003;105:60–62. 28. Bandyopadhyay R, Nag D, Mondal SK, et al. Ocular surface disorder in pterygium: Role of conjunctival impression cytology. Indian J Pathol Microbiol 2010;53:692–695. 29. Balogun MM, Ashaye AO, Ajayi BG, et al. Tear break-up time in eyes with pterygia and pingueculae in Ibadan. West Afr J Med 2005;24:162–166. 30. Chaidaroon W, Pongmoragot N. Basic tear secretion measurement in pterygium. J Med Assoc Thai 2003;86:348–352. 31. Li M, Zhang M, Lin Y, et al. Tear function and goblet cell density after pterygium excision. Eye (Lond) 2007;21:224–228.
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Corneal Polishing After Pterygium Excision With Motorized Diamond Burr: A Randomized Control Trial Pinto Chikkanayakanahalli Narasimhaiah, M.D., Shikha Gupta, M.D., Sudarshan Khokhar, M.D., Murugesan Vanathi, M.D., Tanuj Dada, M.D., Ravinder M. Pandey, Ph.D., M.D., and Tushar Agarwal, M.D.
Purpose: To evaluate outcomes of motorized diamond burr polishing versus manual polishing after pterygium excision. Setting: Dr. Rajendra Prasad Center for Ophthalmic Sciences, New Delhi. Design: A randomized, interventional observer-masked controlled trial. Methods: Forty consecutive eyes underwent pterygium excision with fibrin, glue-assisted conjunctival autograft. In group 1 (20 eyes), polishing of the corneal bed was done using a crescent blade, and in group 2 (20 eyes), using a motorized diamond burr. Results: There was no difference in the 2 groups with respect to mean age (P=0.08), gender (P=0.3), preoperative uncorrected visual acuity (UCVA) (P=0.45), best spectacle-corrected visual acuity (BCVA) (P=0.52), spherical equivalent (P=0.5), mean astigmatism (P=0.7), tear function tests like tear break-up time, tear film meniscus height, Schirmer I and II (P=0.6, 0.5, 0.7, 0.9 respectively), pterygium dimension (P=0.4), and conjunctival autograft size (P=0.24). Mean intraoperative surgical time was significantly more in group 1 (16.962.85 min) as compared with 12.2561.88 min in group 2 (P=0.0001). Postoperatively, there was a statistically significant reduction in astigmatism and improvement in UCVA, BCVA, spherical equivalent in all eyes. No difference was found in mean epithelial defect healing time, UCVA, BCVA, astigmatism, tear film break-up time, Schirmer I and II, and tear meniscus height at 6 months between 2 groups; however, significantly better UCVA was found in group 2 at 3 months (P=0.04). Surgically induced astigmatism (SIA) was significantly more in group 2 as compared with group 1 at 6 months (P=0.0006). Conclusions: Motorized diamond burr polishing of the corneoscleral bed during primary pterygium excision in comparison with manual polishing requires significantly lesser surgical time with better UCVA, decreased astigmatism, and greater SIA at 6 months, which indicates greater astigmatic correction. Key Words: Conjunctival autograft—Surgeon-induced astigmatism— Motorized diamond burr. (Eye & Contact Lens 2015;41: 268–272)
P
terygium is characterized by a radially oriented fibrovascular lesion, which often grows across the corneal limbus in the interpalpebral zone. Growth of pterygium may require excision if it From the Cornea and Refractive Services (C.N.P., S.G., S.K., M.V., T.D., T.A.), Dr. Rajendra Prasad Center for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India; and Department of Biostatistics (R.M.P.), All India Institute of Medical Sciences, New Delhi, India. The authors have no funding or conflicts of interest to disclose. Address correspondence to Tushar Agarwal, M.D., Dr. Rajendra Prasad Center for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi 110029, India; e-mail: [email protected] Accepted October 13, 2014. DOI: 10.1097/ICL.0000000000000115
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is visually disabling by obstructing the visual axis, or by producing refractive disturbances, or if it produces ocular surface disturbances like dry eyes, irritation, lacrimation, foreign body sensation, recurrent inflammation, motility restriction, and cosmetic disfigurement.1 The removal of pterygium is followed by polishing of the corneoscleral bed to remove any attached remnants of the tissue and to smoothen the irregular surface, which is usually done differently by the surgeons using a crescent blade,2 diamond burr,3 Westcott scissors,4 iris spatula,5 or No. 64 Beaver blade.6 The goal of pterygium surgery is to restore limbal anatomy to prevent recurrences in future. This restoration is enhanced by smoothing of the corneoscleral bed that aids reepithelialization, enhances corneal clarity in the postoperative period, and might influence the final corneal topography. Excision of pterygium by any technique partially reverses some of the topographic and refractive abnormalities induced by the abnormal fibrovascular tissue, by causing reduction in corneal astigmatism and higher-order aberrations, and by producing keratometric steepening along with visual improvement.7,8 Amongst the various techniques performed for pterygium excision and ocular surface reconstruction, conjunctival autografting with fibrin glue is considered the de facto method for the surgical correction of pterygium. Pan et al.9 in their meta-analysis on studies comparing conjunctival autografting with sutures versus fibrin glue reported that although the rate of complications remains the same between the two groups, fibrin glue confers decreased rate of recurrence and is associated with shorter operating time. Studies demonstrate that conjunctival or limbal autograft is more efficacious than amniotic membrane grafting in preventing recurrence for primary pterygium.10 Further, the use of conjunctival or limbal autografts with or without mitomycin C in conjunction with pterygium excision reduces recurrence rates when compared with bare sclera excision.10 However, no study could be found on comparison of outcomes when the different methods of corneal polishing were applied. Hence, we conducted our study to evaluate the outcomes of motorized diamond burr polishing in comparison with manual polishing after pterygium excision on corneal clarity, topography, residual refractive error, and surgeon-induced astigmatism.
MATERIALS AND METHODS We conducted a randomized, controlled observer-masked clinical trial. Ethical clearance was obtained from the Institutional Review Board of All India Institute of Medical Sciences. An informed consent was obtained from the study participants before study entry. Patients who presented with primary pterygium to our tertiary care center from December 2009 till November 2011 were Eye & Contact Lens Volume 41, Number 5, September 2015
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Eye & Contact Lens Volume 41, Number 5, September 2015 enrolled in the study. Consecutive patients with primary nasal pterygium of size greater than or equal to 2 mm, extending onto the cornea and aged older than 18 years, compliant for follow-up, and willing to participate in the trial were included. Forty eyes of 36 patients underwent pterygium excision with fibrin, glue-assisted conjunctival autograft and were randomized by computer-generated simple randomization with respect to polishing of the corneoscleral bed into 2 groups; group 1 was crescent blade–assisted manual polishing and group 2 consisted of polishing with a motorized diamond burr (Alger Brush 2000; Rumex International Corp, Clearwater, FL) with a 3.5-mm round fine tip (Fig. 1). Sample size was calculated using the following formula11 for comparing mean in two groups of equal size: N ¼ 2=d2 · Cp power; where N is the number of subjects required in each group, d is the standardized difference, and Cp, power is a constant defined by the values chosen for the P value and power. According to precalculated table, Cp, power for a power of 95% and P=0.01 is 17.8. Standard deviation (d) was kept at 1.71 as reported by Yilmaz et al.12 after pterygium excision with conjunctival autograft. Based on this formula, the N was 12.19. Hence, 20 eyes were randomized to each group. Comprehensive ocular examination was done by an observer preoperatively and postoperatively (P.C.N.). The parameters studied included uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BCVA), standardized digital slitlamp photography, pterygium dimensions (horizontal extension and vertical extension), tear film tests (tear break-up time [TBUT], Schirmer I and II, tear meniscus height), and videokeratography TMS-2 (Tomey Co, Nagoya, Japan). The graft parameters were assessed by a masked observer (T.D.) using digital slitlamp photographs (Haag-Streit BP 900, Koeniz, Switzerland). These were reassessed postoperatively on days 1, 3, 7 and at 1, 3, and 6 months in each group. A 6-month period for follow-up was chosen to enable the topography and tear film functions to stabilize. Data regarding patient recruitment and follow-up are shown in Figure 1. A 6-month period was chosen based on the observations of Ti et al.,13 that more than or equal to 85% recurrences occurred within the first 6 months after pterygium excision for both primary and recurrent pterygia.
Surgical Technique The surgery was performed by the same surgeon (T.A.). Parts were prepared and draped, wire speculum was placed to expose the surgical area, and topical anesthesia proparacaine (0.5%) and
Corneal Polishing After Pterygium Excision lignocaine jelly (1%) was instilled. In each eye, although the minimally adherent pterygium tissue was peeled off using Lims forceps (Appasamy, Chennai, India), the firmly adherent pterygium was removed by gentle manipulation and the fibrovascular tissue was removed using spring scissors. The bed of the pterygium in group 1 was polished with a crescent blade, whereas in group 2, it was polished with a motorized diamond burr. Excessively bleeding vessels were cauterized using bipolar cautery, as necessary. The conjunctival defect was measured with a surgical caliper. After subconjunctival injection of xylocaine, equivalently sized limbalconjunctival autograft was harvested from the same eye (superotemporal quadrant), and the graft was adhered using fibrin glue at the site of bare sclera with the limbal edge of tissue facing the cornea. Postoperatively, the eye was patched for 24 hr. Patients were prescribed topical moxifloxacin 0.5% (Vigamox; Alcon Laboratories, Fort Worth, TX) thrice per day for 2 weeks, prednisolone acetate 1% (Alcon Laboratories) 4 times per day for 2 weeks (tapered over 1 month to relieve inflammation), and 0.5% carboxymethylcellulose (Refresh tears; Allergan, Irvine, CA) 4 times per day for 3 months (to prevent foreign body sensation). Patients were examined on days 1, 3, and 7 and 1, 3, and 6 months thereafter postoperatively by a masked observer (P.C.N.). Patients with an epithelial defect persisting for more than 7 days were followed up every day till it epithelialized completely. Main outcome measures were postoperative corneal epithelialization rate, tear film analysis (TBUT, tear film meniscus height, Schirmer I and II), videokeratography, graft status (inflammation, stability, subconjuctival hemorrhage),6 and corneal clarity, the last 2 of these were graded by digital slitlamp photography by a masked observer. Corneal clarity was graded as following: Grade 1 meant opacification of the entire area with iris not seen; grade 2 meant visibility of iris hazily through the cornea with pattern not visible; grade 3 meant iris details seen hazily through the cornea; and grade 4 was clear underlying cornea with no residual opacity. Surgically induced astigmatism (SIA) was calculated using “SIA Calculator” version 2.1 (http://www.insighteyeclinic.in/SIA_ calculator.php) based on keratometry readings obtained from videokeratography. Recurrence was defined as at least a growth of 1 mm of fibrovascular tissue onto the cornea.14
Statistical Analysis Data were analyzed using Stata software version 11.0 (Stata Corp, College Station, TX). In case of continuous parameters, t test was applied and the Wilcoxon rank-sum test was applied to compare mean between the two groups. Categorical variables were compared in the two groups using the Fisher exact test. P#0.05 was taken as statistically significant. The Friedman test was applied with multiple comparison by the Wilcoxon signed-rank-sum test in case of intragroup analysis. Statistical analysis was done by a statistician with no knowledge of about any particular procedure being superior.
RESULTS
FIG. 1. The view shows data regarding patient recruitment and follow-up details.
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Forty eyes of 36 patients were included, of which 20 eyes each were randomized to crescent blade polishing and diamond burr polishing groups after pterygium excision. The mean age of the patients in group 1 was 43.8611.3 years and was 37.969.6 years (P=0.08) in group 2; in group 1, 75% were men, whereas group 2 consisted of 60% of men (P=0.3). Baseline characteristics were similar in the 2 groups with respect to preoperative UCVA 269
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Eye & Contact Lens Volume 41, Number 5, September 2015
P. Chikkanayakanahalli Narasimhaiah et al. TABLE 1.
Baseline Characteristics of the Two Groups With Respect to the Analyzed Parameters
Parameter Tested UCVA (logMAR) BCVA (logMAR) SE refraction (D) Astigmatism (D) TBUT (sec) Schirmer I (mm) Schirmer II (mm) Meniscus height (mm) Pterygium dimension Height (mm) Width (mm) Graft dimension Height (mm) Width (mm)
Group 1 (n=20) Mean6SD
Group 2 (n=20) Mean6SD
P
0.4560.24 0.2360.11 1.1660.8 2.3360.89 10.4563.44 23.167.25 21.1565.4 0.2560.08
0.5060.2 0.2460.1 1.3460.66 2.161.06 13.3562.34 23.764.32 21.363.74 0.2760.09
0.46 0.52 0.45 0.74 0.61 0.75 0.92 0.48
3.660.75 4.660.75
3.7560.78 4.660.82
0.54 1
4.660.75 5.560.61
4.960.85 5.1560.58
0.25 0.07
BCVA, best spectacle-corrected visual acuity; SD, standard deviation; SE, spherical equivalent; TBUT, tear break-up time; UCVA, uncorrected visual acuity.
(P=0.45) and BCVA (P=0.52), spherical equivalent (2.3360.89 in group 1 and 2.161.06 in group 2; P=0.5), mean astigmatism (1.1660.8 in group 1 and 1.3460.66 in group 2; P=0.7), tear function tests, such as TBUT, tear film meniscus height, Schirmer I and II (P=0.6, 0.5, 0.7, 0.9, respectively), and pterygium dimension (P=0.4) (Table 1). The size of the conjunctival autograft (both horizontal and vertical diameter) measured intraoperatively was also comparable between the 2 groups (P=0.24) (Table 1). Mean intraoperative surgical time was 16.962.85 min in group 1 as compared with 12.2561.88 min in group 2 (P=0.0001). The mean epithelial defect healing time was 3.661.46 days in group 1, compared with 3.260.39 days in group 2 (P=non-significant; Wilcoxon signed-rank test). Postoperatively at 7 days, 15% of eyes in group 1 experienced an epithelial defect that was seen in 5% in group 2. In one of the eyes of group 2, graft inversion
FIG. 2. group.
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was noted intraoperatively wherein tenon’s capsule was placed upside down, which was corrected by resurgery. Figure 2 depicts the preoperative and postoperative appearance of a representative eye in each group. There was a significant improvement in UCVA (log of minimal angle of resolution) at 6 months in both groups compared with the preoperative value. Difference in UCVA as calculated using the Wilcoxon rank-sum test between the 2 groups was found to be significantly better in group 2 at 3 months (P=0.04); it was insignificant at other times. A statistically significant improvement in BCVA was observed compared with the preoperative level in both groups, which was significantly more in group 2 at 1 week when compared with group 1 (P=0.019). At subsequent follow-ups, no statistical difference could be observed between the 2 groups (P=0.82, 0.33, and 0.45 at 1, 3, and 6 months, respectively). The mean spherical equivalent decreased from baseline level in both groups at each follow-up; however, reduction was more in the diamond burr group at 1 week (P=0.028). No significant difference was elicited at subsequent follow-ups (P=0.062, 1, 0.07 at 1, 3, and 6 months, respectively). Similarly, a statistically significant reduction in mean astigmatism was observed in both groups when compared with preoperative levels; however, at 1 week, the diamond burr group showed a significantly lesser mean astigmatism (1.3561.06 D) in comparison with the crescent group, which demonstrated a mean astigmatism of 2.3361.6 D (P=0.034) (Table 2). At subsequent follow-ups, no difference was observed between the two groups. Surgically induced astigmatism was significantly more in group 2 as compared with group 1 at 6 months (P=0.0006; Table 2). Tear film break-up time, Schirmer I and II, and tear meniscus height showed no difference from preoperative level till 6 months in any of the groups (at 6 months, P=0.12, 0.1, 0.1, 0.09, respectively; Table 2). Similarly, no significant difference in graft grading was obtained between the 2 groups at the end of 6 months (P=1, 1, 0.3 at 1, 3, and 6 months, respectively; Wilcoxon rank-sum test). One eye developed pterygium recurrence in group 1 (P=NS) for which no surgery was requested by the patient.
The view shows preoperative and postoperative appearance after pterygium excision in each
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Eye & Contact Lens Volume 41, Number 5, September 2015 TABLE 2.
Characteristics of the Two Groups With Respect to Each Other at 6 Months
Parameter Tested UCVA (logMAR) BCVA (logMAR) SE refraction (D) Astigmatism (D) TBUT (sec) Schirmer I (mm) Schirmer II (mm) Meniscus height (mm) SIA
Group 1 (n=20) Mean6SD
Group 2 (n=20) Mean6SD
0.22560.20 0.0560.20 0.560.52 1.260.91 17.561.53 28.561.31 24.561.31 0.2560.06
0.13160.17 0.0460.17 0.2760.42 0.8160.69 16.761.62 27.6 62.01 25.662.01 0.21560.04
1.2060.901
1.9561.20
P 0.14 0.45 0.07 0.20 0.12 0.1 0.1 0.09 0.0006
BCVA, best spectacle-corrected visual acuity; SD, standard deviation; SE, spherical equivalent; SIA, surgically induced astigmatism; TBUT, tear break-up time; UCVA, uncorrected visual acuity.
DISCUSSION Surgical excision of pterygium achieves not only better cosmesis, but also alleviates refractive disturbances. Improvement in vision after the surgical removal of pterygium has been found to correspond to a decrease in simulated keratometric astigmatism, refractive spherocylinder,15 central 3-mm topographic corneal irregularity, along with a statistically significant decrease in surface regularity index and surface asymmetry index.16–18 The refractive properties of the cornea continue to change postoperatively for a long period according to Ozdemir and Cinal,19 who observed that keratometric astigmatism, surgically induced corneal astigmatism, and mean total corneal refractive power continue to decrease significantly till 3 months when compared with 2 weeks postoperatively. The root mean square values of higher-order aberrations also experience a significant reduction with time.20,21 This reduction in SIA is directly proportional to the grade and size7,8,12,22 of pterygium, as well as preoperative astigmatism.12 The final outcome also varies according to the surgical technique of excision,7 with the literature suggesting that the bare sclera excision induces greater corneal steepening in contrast to conjunctival autograft technique.12 However, to our knowledge, the effect of corneal polishing by different surgical means on the final visual outcome is not known; hence, the purpose of conducting this study. Our study showed minimal graft inflammation or subconjunctival hemorrhage postoperatively in either group with equivalent graft stability. We did not encounter any case of graft dehiscence in any of our eyes reinforcing that corneal polishing by either means has no effect on ultimate graft adherence. Glue-assisted graft adhesion was chosen over suture-assisted closure in our study because it is associated with lesser discomfort, pain and inflammation,23 equal stability,6 reduced intraoperative time,24 and possibly a lower recurrence rate.9,25,26 Patients with pterygium are known to exhibit a deficient tear function, including a decreased TBUT, an increased tear osmolarity, a low crystallization percentage, and abnormal mucus fern pattern when compared with control eyes,27–30 which is partially restored after pterygium surgery.31 However, no difference in tear film parameters was observed with respect to tear film break-up time, Schirmer, or tear meniscus height between the 2 groups at 6 months. We observed a significant reduction in mean astigmatism and refractive error (spherical equivalent) when compared with the baseline values in both groups irrespective of the method used for © 2015 Contact Lens Association of Ophthalmologists
Corneal Polishing After Pterygium Excision corneal polishing. We also found earlier recovery of UCVA in the diamond burr group as compared with the manual group at 1 week. This could be due to a smoother corneal bed from less surgical trauma, which decreased light scattering and hence resulted in better unaided vision. Later on, corneal healing might have overcome this limitation in group 1 subjects. Our study showed a significant decrease in mean astigmatism from preoperative level in both groups. Although the difference in astigmatism between the 2 groups was significant only at 1 week, SIA was significantly more in group 2 at 6 months. Surgically induced astigmatism means net vector change in astigmatism after any surgical procedure. In usual circumstances, greater SIA is not a desirable outcome. However, in cases with preexisting corneal astigmatism requiring correction, calculation would show a higher SIA in the treatment group, for example, after Limbal relaxing incisions, astigmatic keratotomy, and pterygium excision. The aim then is to achieve lower astigmatism compared with preoperative levels. Greater SIA in group 2 signifies greater reduction in preoperative astigmatism values. It indicates better astigmatic correction and reversal of preoperative astigmatism to some extent. Hence, diamond burr seems to be better than manual polishing with crescent blade regarding final astigmatism achieved. The comparison of other topographic outcomes such as changes in surface regularity and surface symmetry indices would have provided additional information regarding the refractive outcome between the two techniques. Therefore, we concluded that motorized diamond burr polishing of the corneoscleral bed during primary pterygium excision in comparison with manual polishing with crescent blade results in significant reduction in surgical time, earlier recovery of UCVA, and faster reduction in mean astigmatism; however, the 2 techniques are equivalent in the rate of reepithelialization, final BCVA, tear film function parameters, and recurrence rate at 6 months of follow-up. To conclude, advantages of using a diamond burr for polishing of the corneal residual bed include better reduction in astigmatism, little surgical expertise required, no residual corneal scarring, and probably the removal of more abnormal remnant tissue than manual debridement. REFERENCES 1. 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. 2. Hall RC, Logan AJ, Wells AP. Comparison of fibrin glue with sutures for pterygium excision surgery with conjunctival autografts. Clin Experiment Ophthalmol 2009;37:584–589. 3. Ozgurhan EB, Kara N, Yildirim A, et al. Diamond burr superficial keratectomy with mitomycin C for corneal scarring and high corneal astigmatism after pterygium excision. Clin Ophthalmol 2013;7:951–954. 4. Ayala M. Results of pterygium surgery using a biologic adhesive. Cornea 2008;27:663–667. 5. 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. 6. Srinivasan S, Dollin M, McAllum P, et al. Fibrin glue versus sutures for attaching the conjunctival autograft in pterygium surgery: A prospective observer masked clinical trial. Br J Ophthalmol 2009;93:215–218. 7. Bahar I, Loya N, Weinberger D, et al. Effect of pterygium surgery on corneal topography: A prospective study. Cornea 2004;23:113–117. 8. Maheshwari S. Pterygium-induced corneal refractive changes. Indian J Ophthalmol 2007;55:383–386. 9. Pan HW, Zhong JX, Jing CX. Comparison of fibrin glue versus suture for conjunctival autografting in pterygium surgery: A meta-analysis. Ophthalmology 2011;118:1049–1054.
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P. Chikkanayakanahalli Narasimhaiah et al. 10. Kaufman SC, Jacobs DS, Lee WB, et al. Options and adjuvants in surgery for pterygium: A report by the American Academy of Ophthalmology. Ophthalmology 2013;120:201–208. 11. Whitley E, Ball J. Statistics review 4: Sample size calculations. Crit Care 2002;6:335–341. 12. Yilmaz S, Yuksel T, Maden A. Corneal topographic changes after four types of pterygium surgery. J Refract Surg 2008;24:160–165. 13. Ti SE, Chee SP, Dear KB, et al. Analysis of variation in success rates in conjunctival autografting for primary and recurrent pterygium. Br J Ophthalmol 2000;84:385–389. 14. Ang LP, Chua JL, Tan DT. Current concepts and techniques in pterygium treatment. Curr Opin Ophthalmol 2007;18:308–313. 15. Wu PL, Kuo CN, Hsu HL, et al. Effect of pterygium surgery on refractive spherocylinder power and corneal topography. Ophthalmic Surg Lasers Imaging 2009;40:32–37. 16. Errais K, Bouden J, Mili-Boussen I, et al. Effect of pterygium surgery on corneal topography. Eur J Ophthalmol 2008;18:177–181. 17. Tomidokoro A, Miyata K, Sakaguchi Y, et al. Effects of pterygium on corneal spherical power and astigmatism. Ophthalmology 2000;107:1568–1571. 18. Nejima R, Masuda A, Minami K, et al. Topographic changes after excision surgery of primary pterygia and the effect of pterygium size on topograpic restoration. Eye Contact Lens 2015;41:58–63. 19. Ozdemir M, Cinal A. Early and late effects of pterygium surgery on corneal topography. Ophthalmic Surg Lasers Imaging 2005;36:451–456. 20. Gumus K, Topaktas D, Göktas¸ A, et al. The change in ocular higher-order aberrations after pterygium excision with conjunctival autograft: A 1-year prospective clinical trial. Cornea 2012;31:1428–1431.
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Eye & Contact Lens Volume 41, Number 5, September 2015 21. Pesudovs K, Figueiredo FC. Corneal first surface wavefront aberrations before and after pterygium surgery. J Refract Surg 2006;22:921–925. 22. Kheirkhah A, Safi H, Molaei S, et al. Effects of pterygium surgery on front and ack corneal astigmatism. Can J Ophthalmol 2012;47:423–428. 23. Cha DM, Kim KH, Choi HJ, et al. A comparative study of the effect of fibrin glue versus sutures on clinical outcome in patients undergoing pterygium excision and conjunctival autografts. Korean J Ophthalmol 2012;26:407–413. 24. Bahar I, Weinberger D, Gaton DD, et al. Fibrin glue versus vicryl sutures for primary conjunctival closure in pterygium surgery: Long-term results. Curr Eye Res 2007;32:399–405. 25. Ozdamar Y, Mutevelli S, Han U, et al. A comparative study of tissue glue and vicryl suture for closing limbal-conjunctival autografts and histologic evaluation after pterygium excision. Cornea 2008;27:552–558. 26. Karalezli A, Kucukerdonmez C, Akova YA, et al. Fibrin glue versus sutures for conjunctival autografting in pterygium surgery: A prospective comparative study. Br J Ophthalmol 2008;92:1206–1210. 27. Marzeta M, Toczołowski J. Study of mucin layer of tear film in patients with pterygium [in Polish]. Klin Oczna 2003;105:60–62. 28. Bandyopadhyay R, Nag D, Mondal SK, et al. Ocular surface disorder in pterygium: Role of conjunctival impression cytology. Indian J Pathol Microbiol 2010;53:692–695. 29. Balogun MM, Ashaye AO, Ajayi BG, et al. Tear break-up time in eyes with pterygia and pingueculae in Ibadan. West Afr J Med 2005;24:162–166. 30. Chaidaroon W, Pongmoragot N. Basic tear secretion measurement in pterygium. J Med Assoc Thai 2003;86:348–352. 31. Li M, Zhang M, Lin Y, et al. Tear function and goblet cell density after pterygium excision. Eye (Lond) 2007;21:224–228.
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