Microbial Keratitis Following Penetrating Keratoplasty

Abstract

* PURPOSE: To investigate the prevalence of microbial keratitis, predisposing risk factors and treatment modalities in patients who developed keratitis following penetrating keratoplasty (PK). * PATIENTS AND METHODS: The records of 285 patients who had undergone PK between January 1991 and December 1995 in a tertiary care center were reviewed. Patients who developed postoperative microbial keratitis were evaluated for predisposing risk factors, microbiological etiology, response to broad spectrum antibiotic therapy and subsequent PK. Patients were mainly treated with fortified topical antibiotics with or without repeat PK. * RESULTS: Of the 285 patient records reviewed, microbial keratitis developed in 21 eyes of 21 patients (7.4%). Seventy-one percent of infections occurred within 6 months after grafting. Keratitis initially began from the donor-recipient border in 16 cases (76.2%) and were central or paracentral in 5 patients. Predisposing risk factors included loose or exposed suture (9), suture removal (1), persistent epithelial defect (3), graft failure (3), contact lens wear (1), Stevens-Johnson syndrome (1). Fifteen (71.4%) patients were culture-positive consisting of Streptococcus pneumoniae (7), Staphylococcus aureus (5), Pseudomonas aureginosa (2), and Hemophilus influenzae (1). Forty-three percent of patients were successfully treated with medical therapy only. Seven patients underwent second PK for visual rehabilitation and 4 for tectonic purposes. After medical and surgical therapy, graft clarity was achieved in 17 (81%) of patients. * CONCLUSIONS: The microbial keratitis following PK is a major postoperative problem affecting the long term prognosis. Careful selection of patients, and preoperative and postoperative control of risk factors, may decrease the frequency of this complication. Several factors, including loose or exposed sutures, epithelial defects, ocular surface disorders, and graft failure, may predispose patients to develop microbial keratitis following PK. [Ophthalmic Surg Lasers 1999;30:449-455.]

Post-keratoplasty Infectious Keratitis: Epidemiology, Risk Factors, Management, and Outcomes

“…The incidence of PKIK differs considerably across different countries, with a higher incidence observed in developing countries than developed countries. Depending on the study design, patient cohort and follow-up duration, the incidence of PKIK in developed countries ranges from 0.02 to 7.9% (Table 1) (26,28,29,31,33,(36)(37)(38)(39)(40)(41)(42)(43)(44). The incidence of PKIK in developing countries is less well documented within the literature, with a higher overall incidence of up to 9.2-11.9% (35,45).…”

“…PKIK affects patients of all age groups, with the majority of cases reported in the literature being between the range of 17-95 years (12,26,28,33,34,36,(46)(47)(48)(49)(50). This reflects the varied indications for keratoplasty such as keratoconus, pseudophakic bullous keratopathy, Fuchs endothelial dystrophy and corneal ulceration, scarring, or perforation within the adult population (12,51).…”

“…Furthermore, suture complications increase the risk of graft rejection and failure (42,63). The occurrence rate of PKIK caused by loose or broken sutures is reported to be as high as 71.6% (10,12,25,26,28,36,39,43,49). Four main causes of suture loosening have been described, which include corneal deturgescence, incomplete epithelialisation over the suture material, suture degradation (exacerbated by corneal vascularisation around the sutures), and cheese-wiring (39).…”

“…Ocular surface diseases constitute a significant risk factor for PKIK (following PKP and DALK) due to the poor ocular environment, breakdown of corneal epithelium, and reduced tear film quantity and quality (including its antimicrobial compounds) (81). Causes include dry eye disease (22.2-28.2%), blepharitis (23.8-43.6%), persistent epithelial defect or neurotrophic keratopathy (14.3-77.8%), trichiasis (13.3-39%), and exposure keratopathy (10,28,31,33,35,36,43,(47)(48)(49)62). In addition, the corneal sensation may only return to a normal level after 12 months post-PKP and DALK, and in some cases never fully recover, which renders the cornea more susceptible to epithelial breakdown and infection (82).…”

“…Subsequent medical treatment is then tailored to the clinical progress and microbiological results. Akova et al (36) reported successful medical management in 43% eyes of the 21 eyes with IK following PKP. Vajpayee et al (62) observed a success rate of 74% in resolving PKIK with medical management alone.…”