Infectious keratitis after penetrating keratoplasty]

PURPOSE: To investigate the prevalence of microbial keratitis, predisposing risk factors, the spectrum of pathogens and the prognosis for graft survival and visual outcome in patients who developed microbial keratitis following penetrating keratoplasty (PK). MATERIAL: and methods: We reviewed 16 cases (15 patients) of microbial keratitis after PK. In all cases, corneal scrapings were obtained and microbiologically analyzed. Efficacy of treatment was evaluated by anatomical (clarity of graft) and visual recovery. RESULTS: Principal indications for PK were pseudophakic bullous keratopathy (50%) and microbial keratitis in the previous graft (25%). Sixty-three per cent of infections occurred within 1 year of PK. Principal predisposing risk factors were suture-related problems (44%) and microbial keratitis in the previous graft (25%). All of the scrapings were positive according to the microbiological evaluation with gram-positive cocci (64%), gram-positive rods (12%), fungi (18%), and Acanthamoeba (6%). We found 1 case of polymicrobial infection. Best visual and anatomical results were observed in nonadvanced cases and/or these treated early. After medical and surgical treatments, 8 patients (50%) had a clear graft and 10 patients (63%) had visual acuity less than 20/200. CONCLUSION: Postoperative control of risk factors and early recognition of infectious complications may decrease the incidence of severe microbial keratitis after PK.     

Microbial keratitis following corneal transplantation

PURPOSE: To determine the predisposing risk factors and analyse the clinical and microbiological profiles of microbial keratitis following corneal transplantation. METHODS: A retrospective analysis was done of hospital records of all patients who presented with microbial keratitis in the corneal graft between July 2000 and June 2005 at the Corneal Unit of Royal Victorian Eye and Ear Hospital, Melbourne, Australia. RESULTS: Eighty-one episodes of infection were identified in 62 patients over a 5-year period. Thirteen patients had multiple episodes of infection. The mean age of the patients was 70 +/- 16 years (range: 22-92 years). The median time interval between the graft and infection was 17 months (range: 6 days to 385 months). Twenty-two (35%) episodes of primary infection were related to sutures. The associated predisposing risk factors were failed graft (40%), dry eye (18%), Herpes simplex keratitis (8%), and ocular surface disease (8%). Forty-seven (76%) cases were culture positive for bacteria. Ten cases were positive for Herpes simplex virus (HSV) during presentation. CONCLUSION: Failed graft is a long-term risk factor for graft infection in addition to ocular surface disease and H. simplex keratitis. All the predisposing risk factors increase the risk of recurrent graft infection.     

Microbial keratitis following corneal transplantation

PURPOSE: To study clinical and microbiologic characteristics of corneal infections following penetrating keratoplasty (PK). DESIGN: Retrospective case series. METHODS: Medical records of patients who presented to Duke University Eye Center from January 1, 1999 to July 1, 2005 with microbial keratitis after PK were reviewed. RESULTS: Forty-four corneal graft infections were reviewed. Mean interval between PK and infection was 26.3 months. Associated conditions included broken or loose sutures (10, 22.7%) and topical corticosteroids (34, 77.3%). Staphylococcal (12, 20.7%) and Pseudomonal (7, 12.1%) species were common pathogens, and fungal species accounted for eight (18.2%) infections. Twelve patients (27.3%) had polymicrobial infections. Thirteen patients (29.5%) underwent repeat PK. Mean postinfection visual acuity at last follow-up was 20/400. CONCLUSIONS: Microbial infections within corneal grafts can occur anytime in the postoperative course and are associated with broken sutures and the use of topical corticosteroids. The diversity of pathogenic organisms, antibiotic resistance, and the potential for poor outcomes supports aggressive management of these infections.     

Suture-related complications following keratoplasty: a 5-year retrospective study.

PURPOSE: To study the incidence of suture-related complications following penetrating keratoplasty (PK) and their effect on the success of corneal grafting. METHODS: The records of 332 patients receiving 361 grafts in 1993 and 1994 were reviewed, and suture-related complications were recorded. These complications were divided into five groups: suture erosions, infiltrates at the suture sites, infectious keratitis, loose sutures with imminent wound dehiscence, and wound dehiscence after suture removal. RESULTS: Occurrence rates were suture erosions, 10.8%; infiltrates, 9.4%; infectious keratitis related to sutures, 3.3%; loose sutures with imminent wound separation in need of surgical repair, 8.3%; and wound dehiscence following suture removal, 2.4%. CONCLUSIONS: Suture-related complications frequently occur after PK. Infectious keratitis and wound separations needing surgical repair may lead to loss of best-corrected visual acuity due to scarring, induced allograft reactions, and/or increased astigmatism. Recommendations for post-PK suture management are proposed.     

Risk factors for graft infection in India: a case-control study

AIM: To study the demographic, clinical, and microbiological profile and the risk factors for graft infection following penetrating keratoplasty. METHODS: 50 eyes of 50 consecutive patients with graft infection after an optical penetrating keratoplasty were included as cases; 50 eyes of 50 patients with no graft infection were included as controls. The main variables evaluated in this study included the clinical and microbiological profile, sociodemographic status, suture related problems, persistent epithelial defects, and ocular surface disorders. RESULTS: Cultures were positive in 43 (86%) eyes and Staphylococcus epidermidis (67.4%) was the most common organism isolated. Infection could be resolved with treatment in 37 (74%) eyes. In eight (16%) eyes the graft melted and a repeat penetrating keratoplasty had to be performed. Only 6% of the cases could achieve a best corrected visual acuity of 6/18 or better after resolution of the infection. In multivariate logistic regression analysis persistent epithelial defect (OR (95% CI): 3.0 (1.17 to 8.33)), suture related problems (OR (95% CI): 3.6 (1.39 to 9.25)), and ocular surface disorders (OR (95% CI): 2.4 (0.93 to 6.03)) were found to be statistically significant risk factors for graft infection following an optical penetrating keratoplasty. CONCLUSIONS: Staphylococcus epidermidis is the commonest organism responsible for post-keratoplasty microbial keratitis. Persistent epithelial defects, suture related problems, and ocular surface disorders are the major risk factors predisposing to graft infection.     

Microbial keratitis following lamellar keratoplasty

OBJECTIVE: To determine the predisposing factors, etiologic agents, and clinical and visual outcomes in infectious keratitis following lamellar keratoplasty (LK). METHODS: One hundred thirty-five eyes (135 patients) that had undergone LK were retrospectively analyzed for the occurrence of infectious keratitis following LK. The parameters evaluated were predisposing factors, seasonal variation, indications and type of LK, time interval between LK and infection, site and depth of infection, etiologic organisms, type of treatment, outcome in terms of graft status, secondary surgery, visual acuity, and the donor tissue profile. RESULTS: The incidence of infectious keratitis following LK was 11.11%. The most significant predisposing factor was persistent epithelial defect (3 eyes) and suture abscesses (3 eyes). Most cases occurred between May and August (9/15). Twelve cases developed infection within 2 weeks of surgery (80%). Seven cases (7/15) occurred with onlay grafts, 6 with inlay grafts, and 2 with large-diameter LK. Cultures of corneal scrapings were positive in 11 eyes (73.3%), and the most common isolated organism was coagulase-negative Staphylococcus (CNS). Only 2 eyes responded to medical therapy, and graft sloughing occurred in 9 cases. Six eyes underwent penetrating keratoplasty to either salvage the integrity of globe or for visual rehabilitation of cases where infection resulted in corneal opacity. CONCLUSIONS: Infections after LK may not be amenable to antimicrobial therapy and may necessitate the removal of the graft or a therapeutic penetrating keratoplasty.     

Microbial keratitis complicating penetrating keratoplasty

A retrospective review of 68 consecutive episodes of microbial keratitis complicating 66 penetrating keratoplasties (PKs) showed major risk associations: suture-related problems (50%), contact lens wear (26%), previous herpes simplex infection (15%), graft failure (15%), and persistent epithelial defects (15%). Topical steroid (85%) and antibiotic (59%) usage were common iatrogenic factors. Half the infections occurred more than 1 year after grafting. Bacterial infections involving gram-positive organisms (59%) predominated, except for patients with extended-wear hydrophilic contact lenses, which usually involved gram-negative bacilli. The incidence of fungal infections (6%) was relatively low. Recommendations to minimize microbial keratitis include prompt attention to exposed, broken, or loose sutures, and preventive and therapeutic management of epithelial defects. The inadequacy of low-dose antibiotics in precluding microbial infection in many cases and the propensity to develop infections with resistant organisms suggest that guidelines for using postoperative and prophylactic topical antibiotics require reevaluation.     

穿透性角膜移植排斥反应的临床分析

目的探讨导致穿透性角膜移植术后排斥反应的高危病种及危险因素。方法对86例90眼穿透性角膜移植患者术后排斥反应发生率进行回顾性分析。结果各病种排斥反应发生率不同，角膜溃疡为42．86％(9／21)；粘连性角膜白斑为39．13％(9／23)；单纯性角膜白斑为28．57％(8／28)；角膜变性或营养不良为11．11％(1／9)；先天性角膜白斑为100．00％(1／1)；圆锥角膜5眼及大泡性角膜病变3眼无排斥反应发生。术前角膜新生血管形成、虹膜前粘连、术前高眼压、术后高眼压、无晶状体状态、术式增多、大植片使排斥反应发生率增高。结论高危病种有角膜溃疡、粘连性角膜白斑、单疱病毒性角膜炎及化学伤导致的单纯性角膜白斑。术前角膜新生血管形成，虹膜前粘连，术前、术后高眼压，无晶状体，多术式联合，大植片是排斥反应发生的危险因素。     

Successful management of aniridic ocular surface disease with long-term bandage contact lens wear

PURPOSE: To present an aniridic patient with failed penetrating keratoplasties OU (PK) who underwent successful repeat PK OD, which has remained clear for 4 years with continuous bandage lens (BCL) wear. METHODS: A 73-year-old aniridic woman who had a failed PK complicated by ocular surface disease refused limbal stem cell transplantation and underwent repeat PK in her right eye. The immediate postoperative course was uneventful except for mild irregularity of the graft epithelium. Two months postoperatively, she presented with an epithelial defect along the inferotemporal graft margin adjacent to an exposed, loose interrupted suture. The suture was removed, and although the initial epithelial defect healed, she suffered recurrent episodes of epithelial breakdown and generalized whorl epitheliopathy. A BCL was inserted and rendered prompt healing of the graft epithelium, which has remained smooth and intact for 4 years. RESULTS: The graft remains thin and clear with a smooth and intact epithelial surface beneath the BCL and no signs of limbal stem-cell deficiency. CONCLUSION: Long-term BCL wear provided good corneal transplant surface protection in an aniridic patient with recurrent epithelial breakdown, thereby sparing the need for limbal stem cell transplantation and the use of potentially toxic systemic immunosuppressive therapy. Meticulous follow-up is required to monitor contact lens loss and epithelial breakdown as well as signs of secondary infectious keratitis.     

Surgery-related factors influencing corneal neovascularization after low-risk keratoplasty

PURPOSE: To identify the speed of corneal neovascularization (CNV) after penetrating keratoplasty (PK) and to evaluate the influence of surgery-related factors on postkeratoplasty CNV in keratoconus patients. DESIGN: Prospective, longitudinal, observational, case series study. METHODS: All consecutive primary PKs performed for keratoconus by four experienced surgeons between January 1, 2000 and December 31, 2002 at our department were included (n=66 patients). Standardized corneal photographs taken preoperatively and at 6 weeks, 3, 6, 12, 18, and 24 months postoperatively were evaluated. Limbus suture distance (LSD), limbus graft distance (LGD), inner suture angle (ISA), and maximal extension of CNVs in digitized pictures with 100-fold magnification were measured at each of the 16 suture turning points at every timepoint. RESULTS: Forty-four (67%) out of 66 corneal grafts developed some degree of CNV after PK, most commonly from around the 12 o'clock position. The mean speed of CNV growth was 114 microm/month with the fastest growth occurring during the first six weeks after PK. There was an inverse correlation between CNV and LSD, LGD, and ISA (all P<.001). Ninety percent of all CNVs developed with LSD<406 microm and with LGD<1000 microm. Superior limbal localization between 11 and 1 o'clock is an independent risk factor for postoperative neovascularization, too (P<.001). CONCLUSIONS: Small LSD, small LGD, and narrow stitching with small ISA were identified as potentially modifiable surgical risk factors for CNV after PK. The speed of CNV outgrowth was most pronounced in the first weeks after PK making early postoperative controls for CNV growth and initiation of antiangiogenic treatment important.     

Bacterial keratitis after penetrating keratoplasty

Bacterial keratitis continues to be a serious problem in developing countries. The authors studied 881 patients who had undergone penetrating keratoplasty (total of 947 procedures) from January 1983 to March 1986 at the King Khaled Eye Specialist Hospital, Riyadh, Saudia Arabia. All patients were followed for at least 6 months. Clinical evidence of bacterial keratitis developed in 113 (11.9%) eyes with penetrating keratoplasties in 108 patients. The causative organisms among those patients included: Streptococcus pneumoniae, 29 (26%); Staphylococcus epidermidis, 24 (21%); Pseudomonas aeruginosa, 13 (12%); Staphylococcus aureus, 5 (4%); Hemophilus influenzae, 5 (4%); Moraxella spp, 5 (4%); alpha-hemolytic streptococcus, 5 (4%); and other bacteria, 27 (25%). In addition, postoperative epithelial defects that required hospital admission for treatment developed in 21 (2.2%) patients. Herpetic keratitis developed in three (0.3%) patients and fungal keratitis developed in 1 (0.1%). Statistically significant predisposing risk factors included: trichiasis (P less than 0.0001), epithelial defects (P less than 0.0001), soft contact lens wear (P less than 0.0001), and eroding sutures (P less than 0.0001). The authors believe that the incidence of postoperative bacterial keratitis can be minimized or avoided by appropriate selection of patients for penetrating keratoplasties as well as good preoperative and postoperative management of associated ocular conditions.     

Moraxella keratitis: predisposing factors and clinical review of 95 cases

AIM: To analyse the clinical presentation, identify predisposing risk factors and evaluate the outcome of treatment of Moraxella keratitis. METHODS: A retrospective analysis was carried out of culture-proved cases of Moraxella keratitis from hospital records during a 10-year period (from December 1995 to November 2005) at the Corneal Unit of the Royal Victorian Eye and Ear Hospital, Melbourne, Australia. RESULTS: 95 episodes of Moraxella keratitis were identified in 92 patients. 3 (3.2%) patients had recurrent keratitis. The mean age of the patients was 70 (range 17-93) years. Multiple predisposing factors were identified in 23 (24%) eyes, including corneal graft (n = 15), previous herpes keratitis (n = 15) and eye lid diseases (n = 15). Adjunctive procedures were carried out in 42 eyes. These included botulinum toxin injection (n = 17), tarsorraphy (n = 12), penetrating keratoplasty (n = 8), enucleation (n = 3), tissue adhesive and bandage contact lens (n = 4), and conjunctival flap (n = 5). Polymicrobial infection was present in 17 eyes. Final visual acuity was counting finger or less in 25 (26%) eyes. CONCLUSIONS: Local ocular predisposing factors play a major role in Moraxella keratitis. This infection has a poor visual outcome attributable to both the nature of the infection and the predisposing factors.     

Effect of prophylactic oral acyclovir after penetrating keratoplasty for herpes simplex keratitis

PURPOSE: To determine the effect of routine use of prophylactic oral acyclovir after penetrating keratoplasty (PK) for herpes simplex virus (HSV) keratitis on recurrence, rejection, and graft failure rates. METHODS: Records from 70 consecutive patients who underwent PK for HSV keratitis at the W.K. Kellogg Eye Center between August 1, 1990, and December 31, 2000, were reviewed. Data collected included preoperative disease activity, duration, host vascularity, pre- and postoperative vision, and antiviral use. Particular attention was given to all episodes of HSV recurrence, graft rejection, and failure. RESULTS: Fifty-six patients (80%) were treated with prophylactic oral acyclovir after surgery. This cohort experienced fewer episodes of rejection (P = 0.006) and better overall graft survival (P = 0.04) than those who were not treated with prophylactic oral antivirals. There was no statistically significant difference in recurrence-free survival between the 2 groups (P = 0.22). Cox regression analysis failed to identify any single variable as a statistically significant predictor of recurrence, rejection, or graft failure. CONCLUSIONS: Prophylactic oral acyclovir use after PK for HSV keratitis is associated with decreased episodes of rejection and improved graft survival.     

穿透性角膜移植术后排斥反应的危险因素分析

目的探讨导致穿透性角膜移植术后排斥反应的危险因素。方法对168眼穿透性角膜移植术后排斥反应发生情况进行回顾性分析,总结免疫排斥反应发生的时间、次数,原因以及预后等。结果168眼中发生免疫排斥反应46眼,总发生率27．38％。各病种排斥反应发生率不同,圆锥角膜3．85％（1／26）;角膜内皮营养不良9．09％（1／11）;单纯疱疹性角膜炎29．55％（13／44）;真菌性角膜炎34．48％（20／58）;细菌性角膜炎40％（6／15）;角膜内皮细胞功能失代偿40％（2／5）;热、化学伤33．33％（3／9）。结论免疫排斥反应的发生是角膜移植手术失败的主要原因,其发生的时间与发生率同角膜疾病的种、角膜植片的位置及大小密切相关。     

Indications and outcomes of penetrating keratoplasty in a tertiary hospital in the developing world

Background: To assess the indications for and graft outcomes of penetrating keratoplasty (PK) in a tertiary hospital in China. Design: A retrospective analysis of hospital records of patients, who had undergone PK at the First Affiliated Hospital of Zhejiang University in China over a 10‐year period, was performed. Participants: A total of 203 eyes met the inclusion criteria for this study. Methods: All PKs were performed with a standard technique throughout. Main Outcome Measures: Outcome measures included best corrected visual acuity at last follow‐up, and overall graft survival. Data were assessed by Kaplan–Meier survival methods, univariate analysis and multivariate cox proportional hazards regression modelling. Results: Among 203 eyes included in this study, the most common indications for PK in this study group were corneal scar caused by herpes simplex keratitis (24.1%) and trauma (mechanical and chemical) (21.2%). At the last follow‐up, significantly more patients (35.0%) achieved 20/40 or better after PK compared with preoperation (P < 0.05). Overall, the 2‐year graft survival rate was 79.9 ± 3.6%. In a univariate analysis, gender, indications for PK, type of operative procedure, rejection episode, postoperative glaucoma and postoperative herpetic recurrence were shown to be significantly associated with graft survival. In a multivariate analysis, three independent predictors of graft failure were identified including indications, gender and rejection episode. Conclusions: PK is effectively performed to improve visual function in southeast China. The outcomes of this study concur with other published studies and can be used as prognostic guidelines for any tertiary hospital in developing world.     

Light adaptation and the luminance-response function of the cone electroretinogram

Corneal graft survival in 13 patients (14 eyes) receiving oral acyclovir following corneal transplantation for herpes simplex keratitis was compared to that in nine patients (9 eyes) who underwent penetrating keratoplasty for herpes simplex keratitis without receiving postoperative acyclovir. Mean age, duration of disease, and time of follow-up did not differ in the two groups. There were no recurrences of herpes simplex keratitis in any patient receiving acyclovir during a mean follow-up of 16.5 months compared to a 44% (4/9) recurrence rate in patients without acyclovir during a mean follow-up of 20.6 months (p < 0.01). Graft failure occurred in 14% (2/14) of acyclovir treatment eyes and in 56% (5/9) of the grafts in patients not receiving acyclovir. Long term prophylactic oral acyclovir significantly decreased the recurrence of herpes simplex keratitis and reduced corneal graft failure in patients with a history of recurrent herpes simplex keratitis who underwent corneal transplantation.Abbreviations ACV acyclovir - HSK herpes simplex keratitis - PK penetrating keratoplasty Presented as a paper at The American Academy of Ophthalmology, annual meeting in Anaheim, California 13–17 October 1991.     

Outcomes of Descemet’s stripping endothelial keratoplasty in eyes with failed therapeutic penetrating keratoplasty

Purpose: To report the results of Descemet’s stripping endothelial keratoplasty (DSEK) for failed therapeutic penetrating keratoplasty (PK). Methods: Twenty‐seven eyes of 27 patients undergoing DSEK for failed therapeutic PK were analysed. Results: The mean age of the patients was 36 ± 13.9 years (range: 14–70 years). The median size of the therapeutic graft was 10 mm (inter‐quartile range; IQR 9.5–11 mm). Descemet’s membrane stripping was performed in all eyes. Graft clarity was achieved in 20/27 eyes. Six eyes had primary graft failure, and one had interface keratitis in the early postoperative period. In all eyes with primary graft failure, there was progressive stromal vascularization, which led to haziness in the graft. Late postoperative complications were rejection in four eyes, infection in two eyes, secondary graft failure in one eye and vortex keratopathy in one eye. Graft size was found to be a significant risk factor for graft rejection in this series. At the last follow‐up visit, the best‐corrected visual acuity was ≥20/40 in 5/27 eyes (18.5%), 20/60–20/40 in 12/27 eyes (44.4%), 20/100–20/60 in 3/27 eyes (1.5%) and ≤20/200 in 7/27 eyes (25.9%). Conclusions: Considering the limited success of repeat PK in failed large therapeutic keratoplasty, DSEK is a viable option for visual rehabilitation in these eyes, however; visual acuity may be limited due to sub‐epithelial/stromal or interface scarring.     

Antiviral treatment following penetrating keratoplasty for herpetic keratitis

Purpose

To assess the effect of antiviral treatment on corneal graft survival following penetrating keratoplasty for herpetic keratitis.

Methods

Retrospective cohort study of 454 patients receiving primary penetrating keratoplasties (PKs) for viral infection reported to NHS Blood and Transplant (NHSBT) between April 1999 and June 2005. Follow-up data were available on 403 PKs. Kaplan–Meier survival estimates were used to determine graft survival for the three treatment groups: no medication, topical antiviral, and oral antiviral medication. A Cox regression model was used to investigate the combined effects of all additional factors on graft failure. The model was fitted using all pre-operative factors first and then post-operative factors including type of antiviral medication were included.

Results

Patients who received oral antiviral medication post-operatively had consistently better graft survival than those receiving no medication or only topical medication. Patients receiving oral antivirals were less than a third as likely to have a failed graft at 5 years compared with those on no antiviral medication (relative risk (RR) 0.3, CI: 0.2–0.7, P=0.002). Other factors that were found to influence the risk of graft failure were the presence of deep corneal vascularisation (P=0.009), PK performed for therapeutic reasons (P=0.03), large diameter grafts (P=0.04), and experiencing a rejection episode (P=0.003).

Conclusion

Oral antiviral treatment reduces the risk of graft failure in patients undergoing primary PK for herpetic keratitis and should be routinely used in this group of patients post-operatively unless contra-indicated.     

Corneal ulceration in the elderly in Hyderabad, south India

AIMS: To report demographic, microbiological, therapeutic, anatomical, and visual results of corneal ulceration in the elderly patients seen at a tertiary eye care centre in south India. METHODS: 102 consecutive cases of microbial keratitis in patients 65 years and older were studied. Inclusion criteria were: (i) presence of corneal stromal infiltrate upon slit lamp examination; and (ii) microbiological evaluation of corneal scrapings for suspected microbial keratitis. RESULTS: The principal predisposing factors identified in this study were ocular disease (38.2%), previous ocular surgery in the same eye (29.4%), trauma (17.6%), and severe systemic disease (16.7%). Contact lens wear was associated with only two cases (2.0%). 99 organisms were isolated in cultures of corneal scrapings from 74 (72.5%) of the 102 cases. Staphylococcus epidermidis (31.1%), filamentous fungi (25.7%), and Streptococcus pneumoniae (13.5%) were the most common isolates. 12 eyes (11.8%) required surgery, 15 (14.7%) eventually required evisceration, and nine (9.6%) of the 94 followed patients achieved an unaided vision of 20/60 or better at last follow up. CONCLUSIONS: This work represents the largest recent single centre study on (non-viral) microbial keratitis in the elderly, its management, and outcomes of therapy. While the predisposing factors differ from those of general population, the spectrum of microbes responsible for keratitis in the elderly appears to reflect the local microbial flora rather than a predilection for elderly patients. Delay in diagnosis and systemic conditions associated with advancing age probably contribute to poorer outcome from therapeutic measures.     

Clinical characteristics of microbial keratitis in a university hospital in Taiwan

PURPOSE: To analyze the clinical and microbiological characteristics of microbial keratitis at the National Taiwan University Hospital in the preceding 10 years. DESIGN: Retrospective cross-sectional study. METHODS: Medical records were reviewed for all patients with clinically diagnosed microbial keratitis presenting at the National Taiwan University Hospital from January 1992 to December 2001. Risk factors, microbial isolations, clinical patterns, treatment, and outcomes were analyzed. RESULTS: Microbial keratitis was diagnosed for 476 eyes in 453 patients (220 female and 233 male; mean age, 40.7 years). Pseudomonas species were the most commonly isolated organisms (37.7%), followed by fungi (13.5%), staphylococci (8.4%), nontuberculous mycobacteria (7.9%), streptococci (7.6%), and Acanthamoeba (4.4%). Contact-lens wear was the most common predisposing factor (44.3%). Medical treatment was successful for a total of 344 eyes (72.3%), with 132 eyes (27.7%) requiring surgery. The duration from symptom onset to diagnosis of microbial keratitis was statistically significantly shorter for the cases treated medically than the cases treated surgically (7.70 +/- 14.37 and 20.53 +/- 28.85 days, respectively, p =.000000332). Response to medical treatment was more favorable for bacterial infection (except nontuberculous mycobacterial infection) as compared with fungal or Acanthamoeba infection. A total of 84.4% of pseudomonal keratitis cases were cured by medical treatment, while 85% of nontuberculous mycobacterial keratitis cases eventually required surgical treatment to control the infection. CONCLUSION: Contact-lens related pseudomonal keratitis was the most common form of microbial keratitis in Taiwan. Early diagnosis and prompt treatment are important for successful management of microbial keratitis.