Aim: To examine the clinical profile of cases requiring resuturing following penetrating keratoplasty (PKP) at a tertiary care eye hospital.
Methods: The medical records of 947 consecutive patients who had undergone PKP between 1998 and 2006 were reviewed retrospectively and cases that were resutured during this period were analysed. The main parameters studied were indications for PKP, suturing techniques, causes of resuturing, visual acuity outcome and post-resuturing complications.
Results: The incidence of resuturing was 5.4% (51 eyes). The number of cases requiring resuturing was higher in corneal grafts performed for microbial keratitis (12%) than those for keratoconus (10%) and corneal endothelial decompensation (2.5%; p = 0.08). Wound dehiscence was the leading cause for resuturing (43%), followed by loose or broken sutures (37.3%). The most common complications after resuturing were occurrence of microbial keratitis (7.8%) and graft failure (5.9%).
Discussion: Resuturing may have to be performed more commonly for corneal transplantation surgery done for microbial keratitis and keratoconus. The major indications for resuturing are wound dehiscence and loose/broken sutures.
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Corneal wound healing plays an important role in the surgical outcome after penetrating keratoplasty (PKP).1 2 Factors that affect the process of corneal wound healing include the primary cause of corneal transplantation surgery, suitable apposition of the graft–host junction and postoperative use of corticosteroids.2–6 The postoperative course after PKP may be complicated by problems such as loosening of sutures, broken sutures, suture infections, graft infection and wound dehiscence.7 Furthermore, these problems may warrant a resuturing of the corneal graft. In the present study we evaluated the clinical profile and outcome of cases of corneal transplantation that required resuturing.
METHODS AND MATERIALS
Study design and participants
In a retrospective case analysis of 947 consecutive PKP procedures performed from July 1998 to June 2006 at the Royal Victorian Eye and Ear Hospital (Melbourne, Australia), medical records of patients who were admitted for resuturing of the corneal grafts were analysed. The study complied with the Declaration of Helsinki. The main parameters studied were indications for PKP, time from PKP to resuturing, indications for resuturing and visual acuity outcomes.
Surgical technique for PKP
In all cases PKP was performed using a standard surgical technique. The host cut ranged from 7.5 to 8.0 mm in diameter and the graft was oversized by 0.5 mm. The suturing techniques used included either placement of 16 interrupted sutures or 20-bite continuous running sutures using 10-0 monofilament nylon. Additional surgical procedures, such as cataract surgery with/without intraocular lens (IOL) implantation, IOL removal or anterior vitrectomy, were performed whenever indicated. Postoperatively all patients were administered prednisolone sodium phosphate 1% eye drops every 4 h, chloramphenicol 0.5% eye drops four times daily and cycloplegic eye drops. Corticosteroid eye drops were continued in a tapering dose up to a period of 1 year after PKP. Anti-glaucoma medications were added when required. Patients were scheduled for a follow-up visit on the first day after surgery, then 1 and 3 weeks and 1, 3 and 6 months after surgery, and then each year. Selective suture removal, if required for control of astigmatism, was undertaken in all cases 3 months after the primary surgery. In all cases complete suture removal was performed by the end of 1 year of follow-up.
All patients who required resuturing of the corneal graft were admitted to the hospital. The resuturing technique included either replacement or additional application of sutures depending on the clinical presentation.
The postoperative treatment regimen after resuturing was similar to that after the primary corneal transplantation. Patients were re-scheduled for follow-up. At each follow-up, patients underwent a complete ophthalmic examination including assessment of visual acuity and graft status. Any complications during the follow-up period were recorded in all eyes.
Descriptive statistical analysis was performed to characterize the baseline demographic and clinical data of the participants. Differences in proportion were analysed using χ2 statistics. One-way ANOVA was used to investigate the indications for and outcomes of resuturing following corneal grafting. The parameters were analysed using the SPSS statistical software (version 14.0; SPSS Science, Chicago, IL, USA).
Of the 947 cases analysed, resuturing had to be performed in 51 cases (5.4%). Corneal endothelial decompensation (CED) was the most common indication for primary PKP (42.3%), followed by keratoconus (34.6%) (table 1).
The incidence of resuturing was greater in cases operated for microbial keratitis (4/33; 12.1%) and keratoconus (33/328; 10.1%) than for CED (10/401; 2.5%) (p = 0.08). The major indication for PKP was keratoconus in the resutured grafts (33 eyes; 66.7%; p<0.001). The average time between PKP and resuturing was 34.9 (SD 15.9) months (range 0.1–351).
Causes of resuturing
The causes of resuturing were classified according to clinical presentation. Patients presented either with unsatisfactory wound closure, loose or broken sutures, or wound dehiscence. Unsatisfactory wound closure was characterized by wound leak or overriding graft–host junction. The major causes of resuturing were wound dehiscence (43.1%) and loose or broken sutures (37.3%) (table 2).
Of the 22 cases with wound dehiscence, 16 (72.7%) had history of trauma that was in the form of either assault (n = 11) or an accidental fall (n = 5). Post-traumatic wound dehiscence was associated with IOL displacement in three cases and expulsion of IOL in one. Six cases (27.3%) had spontaneous wound dehiscence after suture removal. The primary indication for PKP in these cases was keratoconus (n = 3), microbial keratitis (n = 2) and CED (n = 1). Spontaneous wound dehiscence occurred within a mean time period of 11.5 (SD 5.18) days (range 6–20) after removal of sutures in these cases. The mean duration after primary surgery and spontaneous wound dehiscence was 18.8 (SD 6.99) months (range 15–32).
Resuturing for suture-related problems and unsatisfactory wound closure was undertaken in 25 eyes (49%). Cases operated for keratoconus had a higher incidence of loose sutures and/or broken sutures as well as unsatisfactory wound closure than CED and microbial keratitis (table 3). Resuturing for astigmatism was performed in four cases. The mean astigmatism in these cases was 6.25 (SD 1.32) dioptres (range 5–8).
Of the 51 eyes, 43 eyes required eight sutures or fewer and eight eyes required more than eight sutures. Interrupted sutures were applied in majority of the eyes (90.2%) during resuturing.
The mean average follow-up period post-resuturing was 14.8 (SD 12.6) months (range 0.5–52). Best-corrected visual acuity of 6/18 or better was achieved in 47% eyes at the last follow-up. No change in visual acuity was seen in 70% eyes. In 16% of the eyes, a gain of ⩾1 line (Snellen chart) was observed whereas 14% eyes had a loss of ⩾1 line after corneal suturing of corneal graft. Statistical analysis revealed that none of variables independently altered the visual outcome.
The major complications observed were infection of the graft and graft failure. Graft infection occurred in four eyes (7.8%). The primary indication for corneal transplantation in these cases was microbial keratitis (two eyes), CED (one eye) and keratoconus (one eye).
Three eyes had graft failure (5.9%) during the follow-up period. Of these, corneal transplantation was performed for CED (two eyes) and keratoconus (one eye).
PKP involves creation of a 360° wound and placement of 16–24 sutures, which may remain for 1 year or more. These factors create a permanent weakness in the eyeball making it amenable to a life-long risk of wound-related problems.2 8 Also, in a case of corneal grafting, sutures per se can cause multiple complications.7 9 The occurrence of wound and suture-related problems may require resuturing depending on the time of presentation and severity of such complications.
Although several studies have evaluated the incidence and cause of wound dehiscence after corneal transplantation,2–6 there has not be an analysis of the overall causes of resuturing after corneal transplantation. In a retrospective review of 51 cases, Renucci et al2 analysed the causes, clinical characteristics and treatment of wound dehiscence after PKP. Bullous keratopathy was the main indication for PKP (51%). The majority of the cases had wound dehiscence because of trauma (53%) and suture-related complications (27%).
In another retrospective case series of 30 eyes with corneal grafts that underwent repair of wound dehiscence at the Wills Eye Hospital (Wrightstown, PA, USA), the major indications for PKP were keratoconus (23%) and Fuchs’ endothelial dystrophy (20%). Trauma was the most common cause of wound dehiscence (29 eyes). Das et al10 reviewed 76 cases with wound dehiscence after corneal transplantation. Resuturing for wound dehiscence was performed in 29 eyes. The main causes of wound dehiscence were trauma (19 eyes) and post-suture removal (ten eyes) in this study.
In our study, although CED was the commonest indication for PKP in 947 cases, keratoconus was the overall major indication for PKP among the patients who underwent resuturing. Patients with keratoconus usually belong to a younger age group and therefore may be prone to ocular trauma and possible traumatic wound rupture.2 3 5 6 11
Overall, resuturing was more commonly performed for cases that underwent PKP for microbial keratitis. Cases of PKP performed for microbial keratitis often have severe ocular surface inflammation7 12 and are susceptible to suture-related problems necessitating surgical intervention. This is often seen during the early postoperative period.
A second surgical intervention after corneal grafting can increase the incidence and severity of post-PKP complications by many fold.7 13 In our series 7.8% of eyes had graft infection and 5.9% had graft failure despite successful resuturing.
Our observations show that resuturing of corneal wound after PKP may be required even after a long time after keratoplasty for a variety of reasons, including wound dehiscence, loose/broken sutures and infectious keratitis. Recently, efforts have been made to improve the graft–host wound configuration and strengthen it. These include intrastromal tucking of peripheral flange in PKP14 and achieving a lamellar configuration of the graft–host junction.15 New technologies such as femtosecond laser are being currently evaluated for creation of an optimal wound profile for PKP.16 Mechanical stability of the corneal wound has been shown to be superior with “top-hat” keratoplasty using femtosecond laser compared with traditional keratoplasty.17 18 All these techniques aim to create a stronger corneal wound, thereby reducing the possibility of wound dehiscence. The introduction of a sutureless surgical technique such as Descemet’s stripping automated endothelial keratoplasty (DSAEK) is an addition to the armamentarium of corneal surgeons, potentially nullifying all the post-PKP wound- and suture-related complications in cases requiring corneal transplantation for endothelial decompensation.19 20
Competing interests: None.