Journal of Refractive Surgery

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Complications of Mersilene Sutures in Penetrating Keratoplasty

Bradley A Bertram, MD; Carolyn Drews-Botsch, PhD; Mary Gemmill, COMT; Jose Guell, MD; Mervat Murad, MD; George O Waring, III, MD, FACS

Abstract

ABSTRACT

BACKGROUND: After penetrating keratoplasty, many corneal surgeons adjust sutures to reduce astigmatism and then leave the sutures in place indefinitely. Nylon sutures can hydrolyze and break years after surgery. In a series of human penetrating keratoplasties, we studied the use of polyester (Mersilene®) sutures that do not hydrolyze.

METHODS: We performed two prospective studies of polyester (Mersilene) sutures in human penetrating keratoplasty done by one surgeon. Study I was a randomized comparison of combined running and interrupted Mersilene and nylon sutures in 45 consecutive eyes. Study Il was a case series of single running Mersilene suture with postoperative adjustment of suture tension to manage astigmatism in 23 consecutive eyes. We evaluated the performance of the suture and the control of astigmatism.

RESULTS: The interrupted running suture study demonstrated that interrupted Mersilene sutures were 5.5 times more likely to have handlingrelated complications than nylon Interrupted sutures (p = .01); in addition, they were three times as likely to have tissue-related complications as nylon (p = .16). The running suture study demonstrated an unacceptable complication rate of 69% when Mersilene was used as a single adjustable running suture. Af 6 months postoperatively, the median refractive astigmatism for the adjustable cases was 3.37 diopters (mean, 4.03 ± 2.37 D). Eyes with significant suture-related complications were 2.85 times more likely to have greater than 4.00 D of refractive astigmatism than were eyes without suture-related complications.

CONCLUSIONS: Mersilene is an undesirable suture for use in penetrating keratoplasty. [Refract Cornea! Surg 1992;8;296-305.)

RÉSUMÉ

INTRODUCTION. Après kératoplastie transfixiante nombreux sont les chirurgiens rompus à cette technique qui tente de réduire l'astigmatisme secondaire par l'ajustement des sutures. Il est reconnu que les sutures en Nylon s'hydrolysent progressivement avec le temps. Nous rapportons sur une série de keratoplasties transfixiantes l'utilisation de sutures en polyester (MersileneR) connues pour leur stabilité.

METHODES. Nous avons conduit deux études prospectives sur l'utilisation des sutures en polyester (Mersilene) dan les greffes de cornee. Des greffes ont éfé réalisées un seul chirurgion. Dans le première étude, nous avons comparé l'utilisation combinée de surjet de points séparés en Mersilène et en Nylon sur 40 yeux consécutifs. Dans l'étude numéro 2, nous avons réalisé un simple surjet en Mersilene avec un ajustement postopératoire de la tension de ces sutures pour améliorer l'astigmatisme sur 23 yeux consécutifs. Nous avons évalué l'efficacité de ces sutures et du contrôle de l'astigmatisme post-opératoire.

Abstract

ABSTRACT

BACKGROUND: After penetrating keratoplasty, many corneal surgeons adjust sutures to reduce astigmatism and then leave the sutures in place indefinitely. Nylon sutures can hydrolyze and break years after surgery. In a series of human penetrating keratoplasties, we studied the use of polyester (Mersilene®) sutures that do not hydrolyze.

METHODS: We performed two prospective studies of polyester (Mersilene) sutures in human penetrating keratoplasty done by one surgeon. Study I was a randomized comparison of combined running and interrupted Mersilene and nylon sutures in 45 consecutive eyes. Study Il was a case series of single running Mersilene suture with postoperative adjustment of suture tension to manage astigmatism in 23 consecutive eyes. We evaluated the performance of the suture and the control of astigmatism.

RESULTS: The interrupted running suture study demonstrated that interrupted Mersilene sutures were 5.5 times more likely to have handlingrelated complications than nylon Interrupted sutures (p = .01); in addition, they were three times as likely to have tissue-related complications as nylon (p = .16). The running suture study demonstrated an unacceptable complication rate of 69% when Mersilene was used as a single adjustable running suture. Af 6 months postoperatively, the median refractive astigmatism for the adjustable cases was 3.37 diopters (mean, 4.03 ± 2.37 D). Eyes with significant suture-related complications were 2.85 times more likely to have greater than 4.00 D of refractive astigmatism than were eyes without suture-related complications.

CONCLUSIONS: Mersilene is an undesirable suture for use in penetrating keratoplasty. [Refract Cornea! Surg 1992;8;296-305.)

RÉSUMÉ

INTRODUCTION. Après kératoplastie transfixiante nombreux sont les chirurgiens rompus à cette technique qui tente de réduire l'astigmatisme secondaire par l'ajustement des sutures. Il est reconnu que les sutures en Nylon s'hydrolysent progressivement avec le temps. Nous rapportons sur une série de keratoplasties transfixiantes l'utilisation de sutures en polyester (MersileneR) connues pour leur stabilité.

METHODES. Nous avons conduit deux études prospectives sur l'utilisation des sutures en polyester (Mersilene) dan les greffes de cornee. Des greffes ont éfé réalisées un seul chirurgion. Dans le première étude, nous avons comparé l'utilisation combinée de surjet de points séparés en Mersilène et en Nylon sur 40 yeux consécutifs. Dans l'étude numéro 2, nous avons réalisé un simple surjet en Mersilene avec un ajustement postopératoire de la tension de ces sutures pour améliorer l'astigmatisme sur 23 yeux consécutifs. Nous avons évalué l'efficacité de ces sutures et du contrôle de l'astigmatisme post-opératoire.

Astigmatism is one of the major contributors to decreased visual acuity after successful penetrating keratoplasty.1,2 Using current techniques, mean astigmatism after penetrating keratoplasty ranges between 2.50 to 4.00 diopters with 45% to 48% of eyes having greater than 3.00 D.3,4 To reduce astigmatism, surgeons have adjusted sutures after penetrating keratoplasty, using both selective removal of the interrupted sutures from the steep semimeridian3"13 and adjustment of tension on a single running suture.14-16

These techniques can reduce astigmatism after penetrating keratoplasty,3"16 but suffer a major disadvantage - the suture must remain in place indefinitely. If the suture biodegrades, it may loosen and be associated with epithelial defects, sterile infiltrates, microbial keratitis, or allograft rejection. If the suture is removed at any time after surgery, large changes in astigmatism may still occur, demonstrating that the wound cannot be "set" independent of the suture tension.3-7,8,14,17'18 The standard material used for suturing keratoplasties is nylon, usually 15 µ (11-0) or 22 µ (10-0) in diameter. Since nylon contains water in its molecular structure, it undergoes hydrolysis during 2 to 3 years after surgery, creating the potential difficulties mentioned above. Two other suture materials are available for corneal surgery, polypropylene (Prolene) and polyester (dacron, Mersilene(®)). These do not hydrolyze and have been used extensively in general surgery, particularly for the permanent attachment of prostheses such as vascular grafts and cardiac valves. The advantage of a nonbiodegradable suture for prolonged retention in the cornea is obvious: once the suture tension is adjusted and reaches an eqtiilibrium in the tissue, it is likely to remain permanently in that position without subsequent changes, providing a safer, more stable long-term postoperative course. Polyester sutures seem to fulfill these criteria.

However, relatively little information about the safety and efficacy of using polyester sutures in penetrating keratoplasty is available. We designed two prospective studies to explore the feasibility of using polyester (Mersilene) sutures in penetrating keratoplasty. The first was a randomized comparison of combined running and interrupted polyester and nylon sutures; we called this the interrupted running suture study. The second was a case series of a single running 10-0 or 11-0 polyester sutures with postoperative adjustment of suture tension; we called this the running suture study. Throughout this article, we use the more familiar trade name, Mersilene, for polyester sutures.

Table

Table 1Surgical Procedures Performed in Two Studies of Mersilene Sutures for Penetrating Keratoplasty

Table 1

Surgical Procedures Performed in Two Studies of Mersilene Sutures for Penetrating Keratoplasty

MATERIALS AND METHODS

All of the cases reported in this article were done by one surgeon (G.O.W.) with assistance from corneal fellows. An informed consent was obtained, according to Emory University School of Medicine standards on human subjects in medical research. Only a single eye from each patient was included in the studies. Eyes entered into each series had avascular corneas. Those with intense vascularization or large focal peripheral traumatic scars were excluded to minimize the effect of asymmetrical healing on the amount of postoperative astigmatism to isolate the effect of the sutures better.

Study of Combined Interrupted With Running Mersilene or Nylon Sutures

The goal of this study was to compare the biocompatibility and behavior of nylon and Mersilene sutures after penetrating keratoplasty. Data on the effect of selectively removing interrupted sutures to reduce astigmatism was an ancillary part of this evaluation.

Patients undergoing penetrating keratoplasty between December, 1987 and July, 1988, were eligible for inclusion in this portion of the study. Just prior to surgery, corneas were randomized to one of two treatment groups. Half of the eyes were sutured with a Mersilene 11-0 running suture; the other half received a running 11-0 nylon suture. Regardless of the treatment group, all eyes also had six nylon and six Mersilene interrupted 10-0 sutures placed at each of the 12 clock hours.

Surgical Technique. All surgery was performed using regional retrobulbar and seventh cranial nerve anesthesia obtained with 0.75% bupivacaine with hyaluronidase. Aphakic and Pseudophakie eyes were stabilized with a scleral support ring sutured to the episclera. The diameter of the recipient bed ranged from 7.5 to 8.0 mm. The donor cornea, which was preserved in either McCarey-Kaufman or Ksol medium, was cut from the endothelial side using a triconcave polycarbonate block (Tanne) and a disposable free-hand trephine or a Hanna suction punch block (Moria-Dugast, SA, Paris, France).19

The diameter of the donor was larger than the recipient by 0.25 mm for phakic and Pseudophakie eyes and by 0.50 mm for aphakic eyes. The host cornea was trephined in one of two methods: 1) with the Hanna suction trephine19 and a diamond knife or 2) with a free-standing disposable Week blade as described by van Rij and Waring20 and corneal scissors. Some eyes had additional surgical procedures such as extracapsular cataract extraction, intraocular lens removal, intraocular lens insertion, gonioplasty, iridoplasty, and anterior vitrectomy (Table 1). Donor buttons were sutured to the host with four interrupted 10-0 nylon sutures in the cardinal positions. Two additional 10-0 nylon sutures were then placed at varying clock hours and six polyester 10-0 sutures at the remaining clock hours. A continuous 11-0 nylon or polyester suture was placed with 12 antitorque bites between the previous 12 interrupted sutures. The surgeon attempted to tie all sutures with equal tension, and any sutures judged too loose or too tight by visual inspection were removed and replaced during surgery. Intraoperative keratoscopy and keratometry were not used. All knots were buried in the recipient cornea. All patients received a subconjunctival injection of dexamethasone (2 mg), gentamicin (20 mg), and cefazolin (100 mg) at the conclusion of surgery.

Table

Table 2Demographic Characteristics of Patients Receiving Penetrating Keratoplasty

Table 2

Demographic Characteristics of Patients Receiving Penetrating Keratoplasty

Postoperative Care. Topical corticosteroids and antibiotics in tapering dosages were used after surgery. Eyes were examined every 2 to 4 weeks after surgery using slit-lamp microscopy, keratometry (Bausch & Lomb), keratography (Nidek), and manifest refraction. Interrupted sutures were selectively removed from the steep semimeridian to reduce astigmatism, as described in previous publications.3,5'6,10·11 The tension on interrupted sutures was not adjusted, but the running sutures were removed if they broke or loosened excessively. The location and reason for removal of all sutures was noted. The presence or absence of the following complications were recorded by the surgeon on a standardized prospective data sheet at each visit: infiltration, infection, broken suture, epithelial defect, neovascularization, allograft reaction, graft failure, tight suture, loose suture, cheesewiring, wound leak, dehiscence, and exposed knot.

Statistical Analysis. Complications arising within 9 months of surgery were analyzed. The risk of complication in Mersilene running sutures was compared with the risk in nylon sutures using a Fisher's exact chi-square. We did not control for potentially confounding factors such as age, sex, or diagnosis because of the small sample size.

The risk of complications in Mersilene interrupted sutures was compared to the risk of complications in nylon interrupted sutures using a McNemar's chisquare. This comparison was made within individuals to avoid confounding as a result of individual susceptibility to complications. The number of nylon and Mersilene sutures affected by complications was also evaluated within individuals using a onesample t-test.

The effect of suture type on the risk of each complication was evaluated individually. Two separate categories of complications were also identified. Infiltration, infection, broken sutures, epithelial defects, neovascularization, and graft failure were considered to be related to the interaction between the suture and the tissue. These complications were combined to form an index called tissue-related complications. Tight sutures, loose sutures, cheesewiring, wound leaks, dehiscence, and exposed knots were assumed to be related to the ease of handling of the suture. These six complications were combined into an index known as handling-related complications.

Study of Single Running Mersilene Sutures

This study was designed to answer two questions: 1) what is the general behavior of running Mersilene in penetrating keratoplasty, and 2) what is the efficacy of postoperative adjustment of running Mersilene in managing postoperative astigmatism? Patients undergoing penetrating keratoplasty between June, 1989 and October, 1989 were eligible for inclusion in this study. Informed consent was obtained.

The astigmatic goal was a refractive astigmatism of less than 3.50 D. Thus, we have defined astigmatic success as less than 3.50 D refractive astigmatism and astigmatic failure as greater than 4.00 D. Those eyes between 3.50 D and 4.00 D inclusive were classified as intermediate successes to better isolate the successes and failures.

Table

Table 3Indications for Penetrating KeratoplastyTable 4incidence of Complications from Running Sutures in Penetrating Keratoplasty

Table 3

Indications for Penetrating Keratoplasty

Table 4

incidence of Complications from Running Sutures in Penetrating Keratoplasty

We have defined significant suture related complications as they relate to astigmatic success or failure as the following: 1) suture breakage, 2) cheesewiring of sutures, 3) extensive suture loosening requiring early removal, and 4) wound slip.

Surgical Technique. The technique was the same as for the interrupted running suture study, with a few exceptions. The recipient bed diameter ranged from 7.75 mm to 9 mm. A Gender motorized microkeratome was used to trephine one eye. The diameter of the donor button was the same as the host opening for keratoconus eyes and .25 mm larger for phakic and Pseudophakie eyes. The donor buttons were sutured at the four cardinal positions with interrupted 10-0 nylon suture on a compound curved needle. A single running 10-0 or 11-0 Mersilene suture was placed in an antitorque or radial fashion with 20 to 24 bites. The cardinal sutures were removed, the intraocular pressure was raised to normal, the running suture was tightened and tied, and the knot was buried in recipient stroma. If a wound leak was present after inflation of the globe, additional 10-0 or 11-0 nylon interrupted sutures were placed. Intraoperative adjustment of sutures to reduce astigmatism was not performed. All sutures were tied to approximate the edges of the wound without producing excessive tissue compression or a "barrel top* configuration to the graft.

Table

Table 5Incidence of Complications From Interrupted Sutures in the Interrupted Running Study (Number of Eyes With One or More Affected Interrupted Sutures)

Table 5

Incidence of Complications From Interrupted Sutures in the Interrupted Running Study (Number of Eyes With One or More Affected Interrupted Sutures)

Postoperative Care. Postoperative care was the same as in the interrupted running suture study with a few exceptions. Interrupted sutures, which were present in some eyes, were removed early in the postoperative course to leave only the running suture.

Adjustment of the running sutures began approximately 1 month after surgery, depending on the patient's follow-up schedule. In some cases, videokeratography was performed (Corneal Modeling System, Computed Anatomy, Ine). The steep semimeridian was located by identifying the axis of the plus cylinder on the refraction, the steep meridian on keratometry, and the semimeridian in which the photokeratography mires were indented or the videokeratography color map was red on the normalized scale. If more than 3.25 D of refractive astigmatism was present, sutures were adjusted as long as the wound was stable clinically. Adjustments were performed at the slit-lamp microscope with topical proparacaine 0.5% anesthesia using a Tennant tying forceps in a manner similar to that described by McNeill and Wessels.14 Suture tension was distributed from the flat toward the steep semi-meridians on a loop-by-loop basis. Topical antibiotic was placed at the conclusion of adjustment. Adjustment was repeated at subsequent visits if the refractive astigmatism was still greater than 3.25 D.

RESULTS

Study of Combined Interrupted With Running Mersilene or Nylon Sutures

Eyes from a total of 51 patients were randomized for inclusion in the study. We report the outcomes in 45 eyes in the first 9 months after surgery. Follow-up information was incomplete on seven eyes because of suture removal by another physician or loss to follow up prior to 9 months. Two eyes had primary graft failure necessitating repeat surgery within 3 months. Twenty of the 45 eyes followed for at least 9 months were randomly assigned to receive Mersilene running sutures and 25 received a nylon running suture. Patients receiving a nylon running suture were demographically similar to those receiving a Mersilene running suture (Table 2).

The reasons for surgery are listed in Table 3. Complications rarely occurred in the polyester or nylon running sutures within 9 months of surgery (Table 4). For example, cheesewiring occurred in 2 of the 25 eyes with a nylon running suture and in 3 of the 20 that received a polyester suture. Broken sutures occurred in five eyes; three that received a nylon suture and two that received a polyester suture. There was no evidence that any complication occurred more or less commonly in polyester sutures than in nylon sutures. The frequency of complications also did not differ between suture types when complications were grouped into those which occurred because of the interaction between the suture and the tissue (tissue-related complications) and those that occurred because of the difficulty of handling the suture during surgery (handlingrelated complications). Twenty-eight percent of complications were tissue-related in the nylon group and 30% in the Mersilene group. Similarly, 16% (nylon) and 20% (Mersilene) of complications were handling-related.

Figure J : Number of suture ad'iustments in patients with single running Mersilene sutures.Figure 2: Patient in single running Mersilene group with (A) loose exposed suture requiring (B) "reefing suture." (C) A cheesewired suture through the donor can also be seen.Figure 3: Patient in single running Mersilene group with (1) neovascularization into the donor, (2) suture infiltrate, and (3) a broken suture.

Figure J : Number of suture ad'iustments in patients with single running Mersilene sutures.

Figure 2: Patient in single running Mersilene group with (A) loose exposed suture requiring (B) "reefing suture." (C) A cheesewired suture through the donor can also be seen.

Figure 3: Patient in single running Mersilene group with (1) neovascularization into the donor, (2) suture infiltrate, and (3) a broken suture.

On the other hand, nylon interrupted sutures appeared to be less prone to complications than polyester sutures. As shown in !able 5, at least one polyester suture had a tissue-related complication in 17 (38%) of the 45 eyes. Tissue-related complications affected at least one nylon suture in 13 (29%) of the 45 eyes. Similarly handling-related complications, particularly tight sutures, also affected polyester sutures more frequently than nylon sutures. For example, at least one of the six polyester sutures was affected by a handling-related complication for 37 of the 45 eyes. Twenty-eight eyes experienced this type of complication in a nylon interrupted suture.

Those eyes with a tissue-related complication associated with a nylon suture tended to have similar complications in polyester sutures; and those without a complication in a nylon suture usually did not have one in a polyester suture. For example, 26 eyes did not have a tissue-related complication in either type of suture and 11 eyes had such complications in both types of suture. This finding suggests that patient characteristics played some role in predicting whether or not complications arose. However, polyester sutures were three times more likely to be affected by tissue-related complications than nylon sutures in those eyes in which only one type of suture was affected (p = .16) (!able 5). Similarly, given that handling-related complications arose in only one type of suture, polyester sutures were 5.5 times more likely to be affected than nylon sutures (p = .01) (Table 5). These findings suggested that there were individuals who were susceptible to complications only in polyester sutures.

Figure 4: Refractive astigmatism 6 months after penetrating keratoplasty In the single running Mersilene group.

Figure 4: Refractive astigmatism 6 months after penetrating keratoplasty In the single running Mersilene group.

Study of Single Running Mersilene Sutures

Twenty-three eyes in 23 patients had an adjustable running Mersilene suture (Tables 2, 3). Twéntytwo of 23 eyes had suture adjustment. One cornea had a persistent epithelial defect which precluded suture manipulation. The first adjustment occurred at a mean of 53 days postoperatively (range, 14 to 161). The average number of adjustments per eye was 2.7 (range, 1 to 6) (Fig 1).

Sixteen (69%) of the 23 eyes suffered complications (Table 4). Loose exposed suture loops appeared in 12 eyes (52%); three of these required "reefing" sutures21 (Fig 2). Three additional eyes had early removal of extensively loosened sutures at 5 to 6 months postoperatively. Suture infiltrates were identified in six eyes (26%), although none was determined to be microbial (Fig 2). Sutures broke in three eyes (13%) (Fig 3). Two of these were 11-0 and one was 10-0; two broke during suture adjustment; one broke spontaneously at a point that had been manipulated two months after a suture adjustment. Three eyes (13%) had a partial thickness wound slip with anterior displacement of the donor; two occurred after extensively loose running sutures were removed early, and one occurred 1 month postoperatively in an eye with an extensively loose suture. One of these was not treated, one was repaired at the slit-lamp microscope with interrupted sutures, and one was repaired in the operating room with wound revision. Neovascularization into the donor occurred in three eyes (13%) (Fig 3). Wound leaks were seen on the 1st postoperative day in three eyes (13%). Two were repaired by redistributing the tension on the suture and one with addition of an interrupted suture. Cheesewiring of the suture through the donor or host occurred in two eyes (9%) (Fig 2). Exposed knots as a result of suture adjustment complicated two eyes.

Infectious crystalline keratopathy, endothelial graft rejection, and a persistent epithelial defect were seen in one eye each, unrelated to the sutures.

At 6 months postoperatively, the median refractive astigmatism was 3.37 D (mean, 4.03 ± 2.37; range, 1.25 to 9.75 D). Twelve eyes (50%) were considered an astigmatic success (less than 3.50 D); 6 eyes (27%) were considered an astigmatic failure (greater than 4.00 D) (Fig 4). Complications from the Mersilene suture reduced the feasibility of the suture manipulating to minimize postoperative astigmatism (Table 4).

Four of the 6 eyes with high residual astigmatism had significant suture-related complications: 2 broken sutures, 1 early removal with wound dehiscence, and 1 cheesewiring. The other 2 eyes with high residual astigmatism did not have significant suture-related complications. One eye had no additional adjustment because maculopathy limited visual acuity. One eye had five suture adjustments with little reduction in corneal astigmatism; this patient had the first adjustment on postoperative day 73 compared to the mean of postoperative day 53. Patients with significant suture-related complications were 2.85 times more likely to have greater than 4.00 D of astigmatism than patients without suture complications.

DISCUSSION

Mersilene Suture for Penetrating Keratoplasty

In these two studies, Mersilene proved to be an unsuitable suture for penetrating keratoplasty because of its high incidence of complications. The interrupted running suture study demonstrated a statistically significant increased incidence of handling-related complications and a trend toward an increased incidence of tissue-related complications in Mersilene interrupted sutures compared to nylon. The running suture study demonstrated an unacceptable rate of complications when Mersilene was used as a single adjustable running suture. Interestingly, the high rate of complications seen in the second study was not apparent when Mersilene was used as a running suture in the first study; presumably because the support of the interrupted sutures prevented these complications.

We think that two properties of Mersilene contributed to its high rate of complications: inelasticity and deformability. The loose exposed suture loops and the cheesewiring that we observed with Mersilene were complications on opposite extremes of the continuum of suture tension. As the early postoperative edema of the wound subsided, the inelastic Mersilene was unable to adapt to the new wound volume, and loops loosened, sometimes eroding through the epithelium. At the other extreme, in areas where the running Mersilene suture was under greater tension, especially after suture adjustment, its inelasticity overcame tissue resistance and the suture cheesewired through both the donor and the host. The stiff Mersilene suture is relatively deformable, and is easily crimped and flattened when it is grasped firmly with tying forceps (Fig 2). We think that this weakens the suture and leads to easier suture breakage. Suture breakage occurred in 3 of 23 eyes (13%) in the running suture study, whereas McNeill and Kaufman12 described no suture breakages out of 205 adjustments in their running nylon suture study, using the same adjustment technique with the Tennant tying forceps.12

Mersilene was also relatively difficult to handle during surgery. It tended to kink during placement and tying, and created knots that were more difficult to bury. Furthermore, Mersilene is dyed a light blue-green color which makes it more difficult to see under the operating microscope than the darker nylon.

The Mersilene suture has been used successfully to close limbal and scleral cataract wounds, with the purported advantage that its lack of elasticity and biodegradability creates a more stable wound with less astigmatism decay after surgery. Although Drews22 found no difference between nylon and Mersilene, Cravy23 demonstrated that Mersilene had less tendency to produce against-the-rule change in astigmatism after cataract surgery. However, there is a large difference between placing a few bites of Mersilene in a scleral wound beneath a conjunctival flap, where loosening of the suture or breakage of the suture will cause little problem and using a Mersilene suture to secure a corneal transplant, where loosening or breakage can be associated with graft complications.

In this study, all sutures were tied in a gentle fashion so as to approximate the wound without creating excessive wound compression and a "barrel top" configuration of the graft. It is possible that tying the Mersilene sutures tighter, especially the isolated running Mersilene suture, might have produced fewer complications of suture loosening as wound edema decreased, although one might expect more cheesewiring under these circumstances. Since Mersilene lacks the elasticity of nylon, we recommend tying it more tightly than nylon if it is used for wound closure.

Adjustment of Running Sutures After Penetrating Keratoplasty

McNeill and Wessels14 reported adjustment at the slit-lamp microscope under keratometric control of eyes with a single 10-0 nylon irinning suture. Van Meter and colleagues15 retrospectively compared the technique of combined running interrupted nylon sutures with selective removal of the interrupters to the technique of adjustment of a single running suture. All three papers preferred the single running technique.

Wood and Nabors16 have reported results of adjustment of a single running nylon suture with opening of the anterior half of the stromal wound in the area of adjustment.

Although we were able to reduce postoperative astigmatism with the adjustment of a single rurming Mersilene suture, the level of success was below that described by McNeill and Wessels,14 Van Meter and colleagues15, and worse than we achieved with a combined running interrupted nylon technique.3,5

Thus, two challenges currently confront the surgeon who wishes to actively adjust astigmatism after penetrating keratoplasty. The first is to perform prospective randomized clinical trials that compare combined running and interrupted sutures using selective removal of interrupted to adjustment of a single running suture with or without stromal wound dehiscence. The second challenge is to develop a biocompatible and clinically effective nonbiodegradable suture that can be adjusted readily and then left in place permanently without complications.

REFERENCES

1. Jensen AD, Maumenee AE. Refractive errors following keratoplasty. Trans Am Ophthalmol Soc. 1974;72:123-131.

2. Troutman RC, Kelly S, Kaye D, Clahane AC. The use and preliminary results of the Troutman surgical keratometer in cataract and corneal surgery. Transactions of the American Academy of Ophthalmology and Otolaryngology. 1977;83:232-238.

3. Pradera I, Ibrahim O, Waring GO. Refractive results of successful penetrating keratoplasty, intraocular lens implantation with selective suture removal. Refract Corneal Surg. 1989;5:231-239.

4. Binder PS. The effect of suture removal on postkeratoplasty astigmatism. Am J Ophthalmol. 1988;105:637-645.

5. Burk LL, Waring GO, Redjaee B, Stulting RD, The effect of selective suture removal on astigmatism following penetrating keratoplasty. Ophthalmic Surg. 1988;19:849-854.

6. Harris DJ, Waring GO, Burk LL. Keratography as a guide to selective suture removal for the reduction of astigmatism after penetrating keratoplasty. Ophthalmology. 1989;96:1597-1607.

7. Steiner GA, Perl T, Binder PS. Controlled reduction of postkeratoplasty astigmatism. Ophthalmology. 1982;89:668676.

8. Binder PS. Selective suture removal can reduce postkeratoplasty astigmatism. Ophthalmology. 1985;92:1412-1416.

9. Feldman ST, Brown SI. Reduction of astigmatism after keratoplasty. Am J Ophthalmol. 1987;103:477-478.

10. Burk LL, Redjaee B, Stulting RD, Waring GO. Changes in astigmatism after removal of individual sutures in penetrating keratoplasty. Invest Ophthalmol Vis Sci. 1986;27(suppl):92.

11. Kozarsky AM, Waring GO. Photokeratoscopy in the management of astigmatism following keratoplasty. Dev Ophthalmol. 1985;11:91-98.

12. McNeill JI, Kaufman HE. A double running suture technique for keratoplasty: earlier visual rehabilitation. Ophthalmic Surg. 1977;8:58-61.

13. Cottingham AJ. Residual astigmatism following keratoplasty. American Academy of Ophthalmology Annual Meeting Program. 1980;118(suppl).

14. McNeill JI, Wessels D?. Adjustment of single continuous suture to control astigmatism after penetrating keratoplasty. Refract Corneal Surg. 1989;5:216-223.

15. Van Meter WS, Gussler JR, Steineman TL, Wood TO. Control of astigmatism following keratoplasty with an adjusted single continuous suture compared to combined running/ interrupted suturing. Invest Ophthalmol Vis Sci. 1990;31(supplX302.

16. Wood TO, Nabors G. Wound revision for postkeratoplasty astigmatism. Invest Ophthalmol Vis Sci. 1990;31(suppl);575.

17. Mader TH, Yuan R, Lynn MJ, et al. Changes in keratometric astigmatism following suture removal more than one year after penetrating keratoplasty. Invest Ophthalmol Vis Sci. 1990;31(suppV>:574.

18. Musch DC, Meyer RF, Sugar A. The effect of removing running sutures on astigmatism after penetrating keratoplasty. Arch Ophthalmol. 1988;106:488-492.

19. Waring GO, Hanna KD. The Hanna suction punch block and trephine system for penetrating keratoplasty. Arch Ophthalmol. 1989;107:1536-1539.

20. van Rij G, Waring GO. Configuration of corneal trephine opening using five different trephines in human donor eyes. Arch Ophthalmol. 1988;106:1228-1223.

21. Kenyon KR, Grene RB. The anchor suture for securing loosened, continuous sutures in penetrating keratoplasty. Refract Corneal Surg. 1989;5:268-270.

22. Drews RC. Astigmatism shift after extracapsular surgery: Mersilene versus nylon. Int Ophthalmol. 1989;13:209-210.

23. Cravy TV. Long-term corneal astigmatism related to selected elastic, monofilament, nonabsorbable sutures. J Cataract Refract Surg. 1989;15:61-69.

Table 1

Surgical Procedures Performed in Two Studies of Mersilene Sutures for Penetrating Keratoplasty

Table 2

Demographic Characteristics of Patients Receiving Penetrating Keratoplasty

Table 3

Indications for Penetrating Keratoplasty

Table 4

incidence of Complications from Running Sutures in Penetrating Keratoplasty

Table 5

Incidence of Complications From Interrupted Sutures in the Interrupted Running Study (Number of Eyes With One or More Affected Interrupted Sutures)

10.3928/1081-597X-19920701-10

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