11-0 Mersilene as Running Suture for Penetrating Keratoplasty Beatrice E. Frueh, M . D . , Stuart I. Brown, M . D . , a n d S a n d y T. Feldman, M . D .
We evaluated astigmatic results and complications of the combined suturing technique in penetrating keratoplasty by using 11-0 Mersilene as a running suture. Twenty-seven grafts were studied for a follow-up that ranged between ten and 46 months (mean, 27.2 months). During the study, complications included three graft failures, one instance of inadvertent breakage of the running suture, one instance of one suture bite cutting through the recipient cornea, and suture microabscesses in two eyes. Keratometric astigmatism was 2.5 ± 2.1 diopters at six months, was 2.4 ± 2.3 diopters at 12 months, and was 2.5 ± 2.0 diopters at 24 months. Our data indicate that 11-0 Mersilene is suitable for the running suture in corneal transplants in the combined technique. Spontaneous suture dissolution did not occur throughout the follow-up period. The use of a less biodegradable suture enables the maintenance of low levels of astigmatism for longer periods when compared with a previous study that used 11-0 nylon suture.
1 OSTOPERATIVE ASTIGMATISM is a common com plication after penetrating keratoplasty. 18 Sev eral intraoperative factors can contribute to postkeratoplasty astigmatism, such as sutur ing technique,4"12 donor-recipient malapposition, 1314 or trephination technique. 15 · 16 In the
Accepted for publication Sept. 16, 1992. From the Department of Ophthalmology, University of California at San Diego, La Jolla, California. This study was supported in part by an unrestricted grant from Research to Prevent Blindness, Inc., New York, New York; the Swiss Science Foundation, Bern, Switzer land (Dr. Frueh); and National Institutes of Health Physician Scientist Award AG 000353 (Dr. Feldman). Reprint requests to Sandy T. Feldman, M.D., Universi ty of California at San Diego (0946), Shiley Eye Center, 9500 Gilman Dr., La Jolla, CA 92093-0946.
postoperative course, two different approaches are possible. The first technique is to remove all the sutures at a given time postoperatively10·17,18,· the second is to influence astigmatism by selec tively removing interrupted sutures in the pres ence of a running suture4"711 or by adjusting a single running suture. 91219 The major disadvan tage of the first method is that dramatic and unpredictable changes in astigmatism occur frequently after removal of all the sutures, even years postoperatively. 17 ' 28 ' 20 Conversely, not re moving the sutures in corneal transplants car ries the risk of complications associated with exposed sutures,21"24 as well as astigmatic chang es after spontaneous dissolution. 7 In a previous study, 7 we described spontane ous breakage of the 11-0 nylon suture in the combined suture technique in nine of 21 eyes (43%) between 13 and 70 months postopera tively, which resulted in a marked increase in astigmatism. 7 Because of this high rate of disso lution, we investigated the use of a less biode gradable and nonhydrolyzable suture, 11-0 Mersilene, 25 as a running suture in the com bined suturetechnique for penetrating kerato plasty. We evaluated the long-term astigmatic results and complications in a group of 27 corneal transplants with a running 11-0 Mer silene suture.
Material and Methods Between February 1987 and November 1989, 102 penetrating keratoplasties were performed by one of us (S.I.B.) at our institution. Seventytwo eyes were omitted from this study because they were considered ineligible for the com bined suturing technique because of extensive vascularization (45 eyes), perforation (two eyes), or congenital opacification (25 eyes). Three eyes were excluded because of loss to follow-up between six and seven months post operatively.
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The surgical technique was similar in all 27 eyes in this study and was previously de scribed. 6 In brief, the donor cornea was cut with a 7.7-mm disposable hand-held trephine and placed in a 7.5-mm recipient bed. Twelve inter rupted 10-0 nylon sutures were then placed and a running 11-0 Mersilene suture was sutured with 16 bites. All knots of all sutures were buried. Important aspects of suturing Mer silene included making certain that no visible particulate matter was attached to the suture and that the suture was tied with enough ten sion to approximate tissue but not so tightly that the suture would cut through the host tissue. Selective removal of interrupted sutures was initiated as early as six weeks postoperatively in the steepest meridian on the basis of central keratometric readings if the astigma tism was more than 2.5 diopters. Additional interrupted sutures were removed only if loos ening, breakage, or vascularization occurred. The continuous suture was left in place. Postoperative data were collected on a stand ardized form until September 1991 by an inde pendent observer. After an additional surgical procedure, keratometric readings were still re corded, but were not included in the analysis. Data were analyzed with regard to age, gender, preoperative diagnosis, graft clarity, kerato metric astigmatism, and best-corrected visual acuity. The nonparametric, Kaplan-Meier survival analysis method 26 was used to predict the risk of suture disruption with time after penetrating keratoplasty. The survival analysis of Mersilene sutures was compared with that for the 11-0 nylon sutures of our previous study 7 by the Mantel-Haenszel chi-square test.27
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tiation of selective suture removal). Keratomet ric astigmatism was further diminished to 2.9 ± 2.3 diopters at three months, 2.5 ± 2 . 1 diopters at six months, 2.4 ± 2.3 diopters at 12 months, 2.9 ± 1.8 diopters at 18 months, and 2.5 ± 2 diopters at 24 months (Fig. 1). Refractive astig matism was 2.0 ± 1 . 2 diopters at six months and 1.9 ± 1 . 3 diopters at 12 months, respective ly. There was no correlation between age at surgery and postoperative astigmatism (r = .0004). There was no difference in astigmatism between the diagnostic groups. The best-corrected visual acuity was 20/40 or better in 18 of 27 eyes (67%) at six months, in 14 of 26 eyes (54%) at one year, and in 12 of 18 eyes (67%) at two years (Fig. 2). Excluding patients with known extracorneal disease (agerelated macular degeneration [two eyes], severe glaucoma [one eye], and dense cataract [two eyes]), 18 of 25 eyes (72%) had 20/40 or better visual acuity at six months, 14 of 22 eyes (64%) had 20/40 or better visual acuity at one year, and 12 of 16 eyes (75%) had 20/40 or better visual acuity at two years. Kaplan-Meier survival analysis from the time of penetrating keratoplasty to the breakage of the running 11-0 Mersilene suture showed that 100% of the Mersilene sutures remained intact throughout the study. During this study, three grafts failed despite intensive medical treatment; one of those had reduced transparency caused by recurrent her pes simplex keratitis. One graft developed band keratopathy after cryotherapy because of un-
Results The preoperative diagnoses of the 27 eyes studied included bullous keratopathy (ten eyes), failed grafts (six eyes), Fuchs' corneal dystrophy (four eyes), keratoconus (three eyes), and other (four eyes). The mean age of the patients at the time of surgery was 63.4 ± 19.1 years (mean ±. standard deviation). Twelve pa tients were men and 15 were women. The mean follow-up was 27.2 months and ranged be tween ten and 46 months. The mean keratometric astigmatism was 5.5 ± 3.3 (mean ± standard error of the mean) diopters one month postoperatively (before ini
Time (Months) Fig. 1 (Frueh, Brown, and Feldman). Keratometric astigmatism (mean ± standard error of the mean) at varying times after penetrating keratoplasty.
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Fig. 2 (Frueh, Brown, and Feldman). Number of eyes having best-corrected visual acuity in one of three ranges: better than or equal to 20/40, 20/50 to 20/100, and worse than 20/200. The number of eyes included in the analysis were 27, 26, and 18 at six, 12, and 24 months, respectively.
Si
S20/200
20/100-20/50
>20/40
Visual Acuity
controlled glaucoma. In one case, the Mersilene running suture was removed at 24 months be cause of inadvertent breakage while attempting to remove an adjacent interrupted suture. Thereafter the astigmatism increased by 0.75 diopter, but calculated by vectorial analysis there was a change of 6.75 diopters. No patient developed severe vascularization or loosening of the Mersilene suture. Microabscesses along the Mersilene suture were noted in two eyes during the first postoperative week. These mi croabscesses were subepithelial and were open ed with forceps. They did not recur afterward. In one graft, one bite of the running suture cut through the recipient cornea two years after penetrating keratoplasty, but did not cause complications. None of the eyes required surgi
cal correction of corneal astigmatism. Uncom plicated cataract extraction was performed on three eyes at 12 months (two eyes) and 21 months (one eye) after penetrating keratoplas ty. One patient died during this study (after more than 32 months).
Discussion We analyzed the postkeratoplasty astigma tism and longer-term complications of the com bined technique by using 11-0 Mersilene as a running suture. By selectively removing inter rupted sutures in the steep axis, the keratomet ric astigmatism was 2.9 ± 2.3 diopters at three
TABLE 1 MEAN POSTOPERATIVE KERATOMETRIC ASTIGMATISM IN PREVIOUS STUDIES
PREADJUSTMENT OR PRESUTURE REMOVAL INVESTIGATORS 4
Binder Musch and associates10* McNeill and Wessels9
Lin and associates'9
SUTURING METHOD
Combined Double running Combined Control (single running) Adjusted single running Single running Double running
POSTOPERATIVE ASTIGMATISM (DIOPTERS) 3MOS
6MOS
12MOS
3.6 3.00 3.00 4.71
3.3 4.00 2.50
5.50
4.1 3.50 4.00 4.80
5.32
2.87
3.23
6.7 5.9
1.9 5.5
(DIOPTERS)
7.5
z
*ln this study, results represent median keratometric astigmatism, not the mean.
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months postoperatively, 2.5 ± 2 . 1 diopters at six months postoperatively, and 2.4 ± 2.3 diop ters at 12 months postoperatively. These results are comparable to previously reported data af ter penetrating keratoplasty in which the com bined suturing technique, double running su ture, or the single adjustment technique was used (Table l). 4910 · 1219 in one eye, the Mersilene suture had to be removed because of iatrogenic breakage 24 months postoperatively, and in another eye, one bite cut through the recipient cornea, but without consequence. Best-correct ed visual acuity in our study was similar to other studies that used the combined technique with running nylon or double running sutures (range, 11 to 13 months postoperatively) (Table 2). I 0 U Significant vascularization was not in duced in any eye. Microabscess formation with in the first postoperative week along the run ning Mersilene suture was observed in two eyes. These abscesses were opened with jeweler forceps at postoperative slit-lamp examination and did not recur. These abscesses were sterile. In an animal study, Holland and associates 28 found more corneal inflammation by using Mersilene or Prolene sutures, compared with nylon and stainless steel. To date, we have not found such inflammation. We believe that the low rate of inflammation observed with Mer silene sutures in this study was the result of the careful avoidance of foreign-body adherence to the suture at the time of surgery, as well as the use of this technique in eyes without vascular ization. Our data support the study of Bertram and associates, 29 in which no marked differences in the tissue- or suture-related complications were found when a running 11-0 Mersilene suture was compared to a running 11-0 nylon suture in the combined suturing technique. The same study showed that Mersilene was unsuit able for interrupted sutures or as a single running suture in the adjustment technique. Because of its inelasticity, postoperative ma nipulation of Mersilene caused notably more cutting through the cornea than nylon. Intraoperatively, Mersilene is less flexible, and misjudgment of the tension resulted in too tight or too loose interrupted sutures. At four years of follow-up, 100% of the Mer silene sutures remained intact, as compared with our previous study in which only 27.6% of nylon sutures remained intact. 7 Comparison of the Kaplan-Meier curves previously reported for nylon with that for Mersilene in our study, shows statistically significant (P = .015) differ-
TABLE2 POSTOPERATIVE VISUAL ACUITY IN PREVIOUS STUDIES
SUTURE INVESTIGATORS
TECHNIQUE 0
Musch and associates' Double running Combined Combined Stainer, Perl,1' and Binder No exclusions Extracorneal disease
NO. OF EYES (%) WITH 20/40 OR BETTER VISUAL ACUITY AT 12 MOS
38/54 (70.4) 25/54 (46.3) 20/34 (59) 18/27(67)
ences as calculated by the Mantel-Haenszel approach. 27 Because of the lack of spontaneous breakage of 11-0 Mersilene during this study, Mersilene may be superior to nylon for the running 11-0 suture in the combined technique. Nevertheless, because of the previous studies of Holland and associates 28 and Bertram and associates 29 on Mersilene, we advise the use of Mersilene in the combined suture technique only in nonvascularized, noninflamed eyes. With any sutures, but especially with Mer silene, too tight or too superficial intraopera tive suture adjustment may cause postoperative cutting of the Mersilene through the recipient or donor cornea and too loose suture adjust ment will cause the problems associated with exposed sutures. 2124 Our data suggest that the stability of 11-0 Mersilene is superior to 11-0 nylon suture as the running suture in the combined technique; however, longer follow-up is needed to assess if 11-0 Mersilene will degrade later in the postop erative course. The combined suturing tech nique has a value in the management of astig matism after penetrating keratoplasty, as long as the running suture does not degrade and break.
References 1. Samples, J. R., and Binder, P. S.: Visual acuity, refractive error, and astigmatism following corneal transplantation for pseudophakic bullous keratopathy. Ophthalmology 92:1554, 1985. 2. Swinger, C. A.: Postoperative astigmatism. Surv. Ophthalmol. 31:219, 1987. 3. Perlman, E. M.: An analysis and interpretation of refractive errors after penetrating keratoplasty. Ophthalmology 88:39, 1981.
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4. Binder, P. S.: Selective suture removal can re duce postkeratoplasty astigmatism. Ophthalmology 92:1412, 1985. 5. Binder, P. S.: The effect of suture removal on postkeratoplasty astigmatism. Am. J. Ophthalmol. 105:637, 1988. 6. Feldman, S. T., and Brown, S. I.: Reduction of astigmatism after keratoplasty. Am. J. Ophthalmol. 103:477, 1987. 7. Frueh, B. E., Feldman, S. T., Feldman, R. M., Sossi, N. P., Frucht-Pery, J., and Brown, S. I.: Run ning nylon suture dissolution after penetrating kera toplasty. Am. J. Ophthalmol. 113:406, 1992. 8. McNeill, J. I., and Kaufman, H. E.: A double running suture technique for keratoplasty. Earlier visual rehabilitation. Ophthalmic Surg. 8:58, 1977. 9. McNeill, J. I., and Wessels, I. F.: Adjustment of a single continuous suture to control astigmatism after penetrating keratoplasty. Refract. Corneal Surg. 5:216, 1989. 10. Musch, D. C , Meyer, R. F., Sugar, A., and Soong, H. K.: Corneal astigmatism after penetrating keratoplasty. The role of suture technique. Ophthal mology 96:698, 1989. 11. Stainer, G. A., Perl, T., and Binder, P. S.: Con trolled reduction of postkeratoplasty astigmatism. Ophthalmology 89:668, 1982. 12. Van Meter, W. S., Gussler, J. R., Soloman, K. D., and Wood, T. O.: Postkeratoplasty astigmatism control. Single continuous suture adjustment versus selective interrupted suture removal. Ophthalmolo gy 98:177, 1991. 13. Perl, T„ Charlton, K. H., and Binder, P. S.: Disparate diameter grafting. Astigmatism, intraocu lar pressure, and visual acuity. Ophthalmology 88:774, 1981. 14. Troutman, R. C , Swinger, C. A., and Belmont, S.: Selective positioning of the donor cornea in pene trating keratoplasty for keratoconus. Postoperative astigmatism. Cornea 3:135, 1984. 15. Cohen, K. L., Holman, R. E., Tripoli, N. K., and Küpper, L. L.: Effect of trephine tilt on corneal button dimensions. Am. J. Ophthalmol. 101:722, 1986. 16. Insler, M. S., Cooper, H. D., and Caldwell, D. R.: Final surgical results with a suction trephine. Ophthalmic Surg. 18:23, 1987. 17. Mader, T. H., Yuan, R., Wilson, L. A., and Waring, G. O. Ill: Changes in keratometric astigma tism following suture removal more than one year
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after penetrating keratoplasty. ARVO abstracts. Sup plement to Invest. Ophthalmol. Vis. Sci. Philadel phia, J. B. Lippincott, 1990, p. 574. 18. Musch, D. C , Meyer, R. F., and Sugar, A.: The effect of removing running sutures on astigmatism after penetrating keratoplasty. Arch Ophthalmol. 106:488, 1988. 19. Lin, D. T. C , Wilson, S. E., Reidy, J. T., Klyce, S. D., McDonald, M. B., Kaufman, H. E., and McNeill, J. I.: An adjustable single running suture technique to reduce postkeratoplasty astigmatism. A preliminary report. Ophthalmology 97:934, 1990. 20. Lin, D. T. C , Wilson, S. E., and Reidy, J. I.: Topographic changes that occur with 10-0 nylon suture removal following keratoplasty. Refract. Cor neal Surg. 6:21, 1990. 21. Confino, J., and Brown, S. I.: Bacterial endophthalmitis associated with exposed monofilament su tures following corneal transplantation. Am. J. Oph thalmol. 99:111, 1985. 22. Nirankari, V. S., Karesh, J. W., and Richards, R. D.: Complications of exposed monofilament su tures. Am. J. Ophthalmol. 95:515, 1983. 23. Shahinian, L., and Brown, S. I.: Postoperative complications with protruding monofilament nylon sutures. Am. J. Ophthalmol. 83:546, 1977. 24. Sugar, A., and Meyer, R. F.: Giant papillary conjunctivitis after keratoplasty. Am. J. Ophthalmol. 91:239, 1981. 25. Cravy, T. V.: Long-term corneal astigmatism related to selected elastic, monofilament, nonabsorbable sutures. J. Cataract Refract. Surg. 15:61, 1988. 26. Kaplan, E. L., and Meier, P.: Nonparametric estimation from incomplete observations. J. Am. Stat. Assoc. 53:457, 1958. 27. Mantel, N., and Haenszel, W.: Statistical as pects of the analysis of data from retrospective stud ies of disease. J. Nati. Cancer Inst. 22:719, 1959. 28. Holland, E. J., Tchah, H„ Dobler, A. A., Chan, C , Mizener, M. W., Pearlstein, E. S., and Zabel, R. W.: A comparison of suture types in the stimula tion of corneal inflammation. ARVO abstracts. Sup plement to Invest. Ophthalmol. Vis. Sci. Philadel phia, J. B. Lippincott, 1990, p. 270. 29. Bertram, B. A., Drews, C , Gemmili, M., Guell, J., Murad, M., and Waring, G. O.: Inadequacy of a polyester (Mersilene) suture for the reduction of astigmatism after penetrating keratoplasty. Trans. Am. Ophthalmol. Soc. 88:237, 1990.
We evaluated astigmatic results and complications of the combined suturing technique in penetrating keratoplasty by using 11-0 Mersilene as a running suture. Twenty-seven grafts were studied for a follow-up that ranged between ten and 46 months (mean, 27.2 months). During the study, complications included three graft failures, one instance of inadvertent breakage of the running suture, one instance of one suture bite cutting through the recipient cornea, and suture microabscesses in two eyes. Keratometric astigmatism was 2.5 ± 2.1 diopters at six months, was 2.4 ± 2.3 diopters at 12 months, and was 2.5 ± 2.0 diopters at 24 months. Our data indicate that 11-0 Mersilene is suitable for the running suture in corneal transplants in the combined technique. Spontaneous suture dissolution did not occur throughout the follow-up period. The use of a less biodegradable suture enables the maintenance of low levels of astigmatism for longer periods when compared with a previous study that used 11-0 nylon suture.
1 OSTOPERATIVE ASTIGMATISM is a common com plication after penetrating keratoplasty. 18 Sev eral intraoperative factors can contribute to postkeratoplasty astigmatism, such as sutur ing technique,4"12 donor-recipient malapposition, 1314 or trephination technique. 15 · 16 In the
Accepted for publication Sept. 16, 1992. From the Department of Ophthalmology, University of California at San Diego, La Jolla, California. This study was supported in part by an unrestricted grant from Research to Prevent Blindness, Inc., New York, New York; the Swiss Science Foundation, Bern, Switzer land (Dr. Frueh); and National Institutes of Health Physician Scientist Award AG 000353 (Dr. Feldman). Reprint requests to Sandy T. Feldman, M.D., Universi ty of California at San Diego (0946), Shiley Eye Center, 9500 Gilman Dr., La Jolla, CA 92093-0946.
postoperative course, two different approaches are possible. The first technique is to remove all the sutures at a given time postoperatively10·17,18,· the second is to influence astigmatism by selec tively removing interrupted sutures in the pres ence of a running suture4"711 or by adjusting a single running suture. 91219 The major disadvan tage of the first method is that dramatic and unpredictable changes in astigmatism occur frequently after removal of all the sutures, even years postoperatively. 17 ' 28 ' 20 Conversely, not re moving the sutures in corneal transplants car ries the risk of complications associated with exposed sutures,21"24 as well as astigmatic chang es after spontaneous dissolution. 7 In a previous study, 7 we described spontane ous breakage of the 11-0 nylon suture in the combined suture technique in nine of 21 eyes (43%) between 13 and 70 months postopera tively, which resulted in a marked increase in astigmatism. 7 Because of this high rate of disso lution, we investigated the use of a less biode gradable and nonhydrolyzable suture, 11-0 Mersilene, 25 as a running suture in the com bined suturetechnique for penetrating kerato plasty. We evaluated the long-term astigmatic results and complications in a group of 27 corneal transplants with a running 11-0 Mer silene suture.
Material and Methods Between February 1987 and November 1989, 102 penetrating keratoplasties were performed by one of us (S.I.B.) at our institution. Seventytwo eyes were omitted from this study because they were considered ineligible for the com bined suturing technique because of extensive vascularization (45 eyes), perforation (two eyes), or congenital opacification (25 eyes). Three eyes were excluded because of loss to follow-up between six and seven months post operatively.
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The surgical technique was similar in all 27 eyes in this study and was previously de scribed. 6 In brief, the donor cornea was cut with a 7.7-mm disposable hand-held trephine and placed in a 7.5-mm recipient bed. Twelve inter rupted 10-0 nylon sutures were then placed and a running 11-0 Mersilene suture was sutured with 16 bites. All knots of all sutures were buried. Important aspects of suturing Mer silene included making certain that no visible particulate matter was attached to the suture and that the suture was tied with enough ten sion to approximate tissue but not so tightly that the suture would cut through the host tissue. Selective removal of interrupted sutures was initiated as early as six weeks postoperatively in the steepest meridian on the basis of central keratometric readings if the astigma tism was more than 2.5 diopters. Additional interrupted sutures were removed only if loos ening, breakage, or vascularization occurred. The continuous suture was left in place. Postoperative data were collected on a stand ardized form until September 1991 by an inde pendent observer. After an additional surgical procedure, keratometric readings were still re corded, but were not included in the analysis. Data were analyzed with regard to age, gender, preoperative diagnosis, graft clarity, kerato metric astigmatism, and best-corrected visual acuity. The nonparametric, Kaplan-Meier survival analysis method 26 was used to predict the risk of suture disruption with time after penetrating keratoplasty. The survival analysis of Mersilene sutures was compared with that for the 11-0 nylon sutures of our previous study 7 by the Mantel-Haenszel chi-square test.27
December, 1992
tiation of selective suture removal). Keratomet ric astigmatism was further diminished to 2.9 ± 2.3 diopters at three months, 2.5 ± 2 . 1 diopters at six months, 2.4 ± 2.3 diopters at 12 months, 2.9 ± 1.8 diopters at 18 months, and 2.5 ± 2 diopters at 24 months (Fig. 1). Refractive astig matism was 2.0 ± 1 . 2 diopters at six months and 1.9 ± 1 . 3 diopters at 12 months, respective ly. There was no correlation between age at surgery and postoperative astigmatism (r = .0004). There was no difference in astigmatism between the diagnostic groups. The best-corrected visual acuity was 20/40 or better in 18 of 27 eyes (67%) at six months, in 14 of 26 eyes (54%) at one year, and in 12 of 18 eyes (67%) at two years (Fig. 2). Excluding patients with known extracorneal disease (agerelated macular degeneration [two eyes], severe glaucoma [one eye], and dense cataract [two eyes]), 18 of 25 eyes (72%) had 20/40 or better visual acuity at six months, 14 of 22 eyes (64%) had 20/40 or better visual acuity at one year, and 12 of 16 eyes (75%) had 20/40 or better visual acuity at two years. Kaplan-Meier survival analysis from the time of penetrating keratoplasty to the breakage of the running 11-0 Mersilene suture showed that 100% of the Mersilene sutures remained intact throughout the study. During this study, three grafts failed despite intensive medical treatment; one of those had reduced transparency caused by recurrent her pes simplex keratitis. One graft developed band keratopathy after cryotherapy because of un-
Results The preoperative diagnoses of the 27 eyes studied included bullous keratopathy (ten eyes), failed grafts (six eyes), Fuchs' corneal dystrophy (four eyes), keratoconus (three eyes), and other (four eyes). The mean age of the patients at the time of surgery was 63.4 ± 19.1 years (mean ±. standard deviation). Twelve pa tients were men and 15 were women. The mean follow-up was 27.2 months and ranged be tween ten and 46 months. The mean keratometric astigmatism was 5.5 ± 3.3 (mean ± standard error of the mean) diopters one month postoperatively (before ini
Time (Months) Fig. 1 (Frueh, Brown, and Feldman). Keratometric astigmatism (mean ± standard error of the mean) at varying times after penetrating keratoplasty.
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Fig. 2 (Frueh, Brown, and Feldman). Number of eyes having best-corrected visual acuity in one of three ranges: better than or equal to 20/40, 20/50 to 20/100, and worse than 20/200. The number of eyes included in the analysis were 27, 26, and 18 at six, 12, and 24 months, respectively.
Si
S20/200
20/100-20/50
>20/40
Visual Acuity
controlled glaucoma. In one case, the Mersilene running suture was removed at 24 months be cause of inadvertent breakage while attempting to remove an adjacent interrupted suture. Thereafter the astigmatism increased by 0.75 diopter, but calculated by vectorial analysis there was a change of 6.75 diopters. No patient developed severe vascularization or loosening of the Mersilene suture. Microabscesses along the Mersilene suture were noted in two eyes during the first postoperative week. These mi croabscesses were subepithelial and were open ed with forceps. They did not recur afterward. In one graft, one bite of the running suture cut through the recipient cornea two years after penetrating keratoplasty, but did not cause complications. None of the eyes required surgi
cal correction of corneal astigmatism. Uncom plicated cataract extraction was performed on three eyes at 12 months (two eyes) and 21 months (one eye) after penetrating keratoplas ty. One patient died during this study (after more than 32 months).
Discussion We analyzed the postkeratoplasty astigma tism and longer-term complications of the com bined technique by using 11-0 Mersilene as a running suture. By selectively removing inter rupted sutures in the steep axis, the keratomet ric astigmatism was 2.9 ± 2.3 diopters at three
TABLE 1 MEAN POSTOPERATIVE KERATOMETRIC ASTIGMATISM IN PREVIOUS STUDIES
PREADJUSTMENT OR PRESUTURE REMOVAL INVESTIGATORS 4
Binder Musch and associates10* McNeill and Wessels9
Lin and associates'9
SUTURING METHOD
Combined Double running Combined Control (single running) Adjusted single running Single running Double running
POSTOPERATIVE ASTIGMATISM (DIOPTERS) 3MOS
6MOS
12MOS
3.6 3.00 3.00 4.71
3.3 4.00 2.50
5.50
4.1 3.50 4.00 4.80
5.32
2.87
3.23
6.7 5.9
1.9 5.5
(DIOPTERS)
7.5
z
*ln this study, results represent median keratometric astigmatism, not the mean.
—
—
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AMERICAN JOURNAL OF OPHTHALMOLOGY
months postoperatively, 2.5 ± 2 . 1 diopters at six months postoperatively, and 2.4 ± 2.3 diop ters at 12 months postoperatively. These results are comparable to previously reported data af ter penetrating keratoplasty in which the com bined suturing technique, double running su ture, or the single adjustment technique was used (Table l). 4910 · 1219 in one eye, the Mersilene suture had to be removed because of iatrogenic breakage 24 months postoperatively, and in another eye, one bite cut through the recipient cornea, but without consequence. Best-correct ed visual acuity in our study was similar to other studies that used the combined technique with running nylon or double running sutures (range, 11 to 13 months postoperatively) (Table 2). I 0 U Significant vascularization was not in duced in any eye. Microabscess formation with in the first postoperative week along the run ning Mersilene suture was observed in two eyes. These abscesses were opened with jeweler forceps at postoperative slit-lamp examination and did not recur. These abscesses were sterile. In an animal study, Holland and associates 28 found more corneal inflammation by using Mersilene or Prolene sutures, compared with nylon and stainless steel. To date, we have not found such inflammation. We believe that the low rate of inflammation observed with Mer silene sutures in this study was the result of the careful avoidance of foreign-body adherence to the suture at the time of surgery, as well as the use of this technique in eyes without vascular ization. Our data support the study of Bertram and associates, 29 in which no marked differences in the tissue- or suture-related complications were found when a running 11-0 Mersilene suture was compared to a running 11-0 nylon suture in the combined suturing technique. The same study showed that Mersilene was unsuit able for interrupted sutures or as a single running suture in the adjustment technique. Because of its inelasticity, postoperative ma nipulation of Mersilene caused notably more cutting through the cornea than nylon. Intraoperatively, Mersilene is less flexible, and misjudgment of the tension resulted in too tight or too loose interrupted sutures. At four years of follow-up, 100% of the Mer silene sutures remained intact, as compared with our previous study in which only 27.6% of nylon sutures remained intact. 7 Comparison of the Kaplan-Meier curves previously reported for nylon with that for Mersilene in our study, shows statistically significant (P = .015) differ-
TABLE2 POSTOPERATIVE VISUAL ACUITY IN PREVIOUS STUDIES
SUTURE INVESTIGATORS
TECHNIQUE 0
Musch and associates' Double running Combined Combined Stainer, Perl,1' and Binder No exclusions Extracorneal disease
NO. OF EYES (%) WITH 20/40 OR BETTER VISUAL ACUITY AT 12 MOS
38/54 (70.4) 25/54 (46.3) 20/34 (59) 18/27(67)
ences as calculated by the Mantel-Haenszel approach. 27 Because of the lack of spontaneous breakage of 11-0 Mersilene during this study, Mersilene may be superior to nylon for the running 11-0 suture in the combined technique. Nevertheless, because of the previous studies of Holland and associates 28 and Bertram and associates 29 on Mersilene, we advise the use of Mersilene in the combined suture technique only in nonvascularized, noninflamed eyes. With any sutures, but especially with Mer silene, too tight or too superficial intraopera tive suture adjustment may cause postoperative cutting of the Mersilene through the recipient or donor cornea and too loose suture adjust ment will cause the problems associated with exposed sutures. 2124 Our data suggest that the stability of 11-0 Mersilene is superior to 11-0 nylon suture as the running suture in the combined technique; however, longer follow-up is needed to assess if 11-0 Mersilene will degrade later in the postop erative course. The combined suturing tech nique has a value in the management of astig matism after penetrating keratoplasty, as long as the running suture does not degrade and break.
References 1. Samples, J. R., and Binder, P. S.: Visual acuity, refractive error, and astigmatism following corneal transplantation for pseudophakic bullous keratopathy. Ophthalmology 92:1554, 1985. 2. Swinger, C. A.: Postoperative astigmatism. Surv. Ophthalmol. 31:219, 1987. 3. Perlman, E. M.: An analysis and interpretation of refractive errors after penetrating keratoplasty. Ophthalmology 88:39, 1981.
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Mersilene Running Suture for Penetrating Keratoplasty
4. Binder, P. S.: Selective suture removal can re duce postkeratoplasty astigmatism. Ophthalmology 92:1412, 1985. 5. Binder, P. S.: The effect of suture removal on postkeratoplasty astigmatism. Am. J. Ophthalmol. 105:637, 1988. 6. Feldman, S. T., and Brown, S. I.: Reduction of astigmatism after keratoplasty. Am. J. Ophthalmol. 103:477, 1987. 7. Frueh, B. E., Feldman, S. T., Feldman, R. M., Sossi, N. P., Frucht-Pery, J., and Brown, S. I.: Run ning nylon suture dissolution after penetrating kera toplasty. Am. J. Ophthalmol. 113:406, 1992. 8. McNeill, J. I., and Kaufman, H. E.: A double running suture technique for keratoplasty. Earlier visual rehabilitation. Ophthalmic Surg. 8:58, 1977. 9. McNeill, J. I., and Wessels, I. F.: Adjustment of a single continuous suture to control astigmatism after penetrating keratoplasty. Refract. Corneal Surg. 5:216, 1989. 10. Musch, D. C , Meyer, R. F., Sugar, A., and Soong, H. K.: Corneal astigmatism after penetrating keratoplasty. The role of suture technique. Ophthal mology 96:698, 1989. 11. Stainer, G. A., Perl, T., and Binder, P. S.: Con trolled reduction of postkeratoplasty astigmatism. Ophthalmology 89:668, 1982. 12. Van Meter, W. S., Gussler, J. R., Soloman, K. D., and Wood, T. O.: Postkeratoplasty astigmatism control. Single continuous suture adjustment versus selective interrupted suture removal. Ophthalmolo gy 98:177, 1991. 13. Perl, T„ Charlton, K. H., and Binder, P. S.: Disparate diameter grafting. Astigmatism, intraocu lar pressure, and visual acuity. Ophthalmology 88:774, 1981. 14. Troutman, R. C , Swinger, C. A., and Belmont, S.: Selective positioning of the donor cornea in pene trating keratoplasty for keratoconus. Postoperative astigmatism. Cornea 3:135, 1984. 15. Cohen, K. L., Holman, R. E., Tripoli, N. K., and Küpper, L. L.: Effect of trephine tilt on corneal button dimensions. Am. J. Ophthalmol. 101:722, 1986. 16. Insler, M. S., Cooper, H. D., and Caldwell, D. R.: Final surgical results with a suction trephine. Ophthalmic Surg. 18:23, 1987. 17. Mader, T. H., Yuan, R., Wilson, L. A., and Waring, G. O. Ill: Changes in keratometric astigma tism following suture removal more than one year
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after penetrating keratoplasty. ARVO abstracts. Sup plement to Invest. Ophthalmol. Vis. Sci. Philadel phia, J. B. Lippincott, 1990, p. 574. 18. Musch, D. C , Meyer, R. F., and Sugar, A.: The effect of removing running sutures on astigmatism after penetrating keratoplasty. Arch Ophthalmol. 106:488, 1988. 19. Lin, D. T. C , Wilson, S. E., Reidy, J. T., Klyce, S. D., McDonald, M. B., Kaufman, H. E., and McNeill, J. I.: An adjustable single running suture technique to reduce postkeratoplasty astigmatism. A preliminary report. Ophthalmology 97:934, 1990. 20. Lin, D. T. C , Wilson, S. E., and Reidy, J. I.: Topographic changes that occur with 10-0 nylon suture removal following keratoplasty. Refract. Cor neal Surg. 6:21, 1990. 21. Confino, J., and Brown, S. I.: Bacterial endophthalmitis associated with exposed monofilament su tures following corneal transplantation. Am. J. Oph thalmol. 99:111, 1985. 22. Nirankari, V. S., Karesh, J. W., and Richards, R. D.: Complications of exposed monofilament su tures. Am. J. Ophthalmol. 95:515, 1983. 23. Shahinian, L., and Brown, S. I.: Postoperative complications with protruding monofilament nylon sutures. Am. J. Ophthalmol. 83:546, 1977. 24. Sugar, A., and Meyer, R. F.: Giant papillary conjunctivitis after keratoplasty. Am. J. Ophthalmol. 91:239, 1981. 25. Cravy, T. V.: Long-term corneal astigmatism related to selected elastic, monofilament, nonabsorbable sutures. J. Cataract Refract. Surg. 15:61, 1988. 26. Kaplan, E. L., and Meier, P.: Nonparametric estimation from incomplete observations. J. Am. Stat. Assoc. 53:457, 1958. 27. Mantel, N., and Haenszel, W.: Statistical as pects of the analysis of data from retrospective stud ies of disease. J. Nati. Cancer Inst. 22:719, 1959. 28. Holland, E. J., Tchah, H„ Dobler, A. A., Chan, C , Mizener, M. W., Pearlstein, E. S., and Zabel, R. W.: A comparison of suture types in the stimula tion of corneal inflammation. ARVO abstracts. Sup plement to Invest. Ophthalmol. Vis. Sci. Philadel phia, J. B. Lippincott, 1990, p. 270. 29. Bertram, B. A., Drews, C , Gemmili, M., Guell, J., Murad, M., and Waring, G. O.: Inadequacy of a polyester (Mersilene) suture for the reduction of astigmatism after penetrating keratoplasty. Trans. Am. Ophthalmol. Soc. 88:237, 1990.
