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Purpose: To determine risk factors and clinical signs that may differentiate between bacterial, fungal, and acanthamoeba keratitis among patients presenting with presumed infectious keratitis., Design: Hospital-based cross-sectional study., Methods: We examined the medical records of 115 patients with laboratory-proven bacterial keratitis, 115 patients with laboratory-proven fungal keratitis, and 115 patients with laboratory-proven acanthamoeba keratitis seen at Aravind Eye Hospital, Madurai, India, from 2006-2011. Risk factors and clinical features of the 3 organisms were compared using multinomial logistic regression., Results: Of 95 patients with bacterial keratitis, 103 patients with fungal keratitis, and 93 patients with acanthamoeba keratitis who had medical records available for review, 287 (99%) did not wear contact lenses. Differentiating features were more common for acanthamoeba keratitis than for bacterial or fungal keratitis. Compared to patients with bacterial or fungal keratitis, patients with acanthamoeba keratitis were more likely to be younger and to have a longer duration of symptoms, and to have a ring infiltrate or disease confined to the epithelium., Conclusions: Risk factors and clinical examination findings can be useful for differentiating acanthamoeba keratitis from bacterial and fungal keratitis., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Purpose: To report the use of topical voriconazole 1% (Vfend; Pfizer Inc, New York, New York, USA) ophthalmic solution for Acanthamoeba keratitis (AK) resistant to treatment with chlorhexidine (PerioChip; Dexel Pharma Technologies, Jerusalem, Israel)., Design: Retrospective case series., Methods: Three eyes of 2 patients with culture-proven AK were treated at a tertiary care institution, and their charts were reviewed. Topical voriconazole 1% was instituted as second-line treatment for AK unresponsive to standard treatment with chlorhexidine and hexamidine. Treatment with voriconazole 1% was started at 1-hour intervals. Improvement was assessed and defined by absence of clinical signs of active infection and visual improvement., Results: One patient with unilateral AK and 1 patient with bilateral AK who remained culture-positive for Acanthamoeba despite ongoing treatment with chlorhexidine and hexamidine were treated with voriconazole 1% topical solution as an adjuvant. Both patients were contact lens wearers. Of 3 eyes additionally treated with voriconazole, 2 eyes had clinical resolution of disease. One eye demonstrated recurrent disease after penetrating keratoplasty that resolved after intrastromal injection of voriconazole., Conclusions: We report the use of topical and intrastromal voriconazole in successfully treating AK in cases of chlorhexidine- and hexamidine-resistant Acanthamoeba. Voriconazole may be a promising adjuvant agent in treating AK., (Copyright 2010 Elsevier Inc. All rights reserved.)

Purpose: To describe the current management of Acanthamoeba keratitis (AK)., Design: A perspective based on the literature and author experience., Results: Early diagnosis and appropriate therapy are key to a good prognosis. A provisional diagnosis of AK can be made using the clinical features and confocal microscopy, although a definitive diagnosis requires culture, histology, or identification of Acanthamoeba deoxyribonucleic acid by polymerase chain reaction. Routine use of tissue diagnosis is recommended, particularly for patients unresponsive to treatment for AK. Topical biguanides are the only effective therapy for the resistant encysted form of the organism in vitro, if not always in vivo. None of the other drugs that have been used meet the requirements of consistent cysticidal activity and may have no therapeutic role. The use of topical steroids is controversial, but probably beneficial, for the management of severe corneal inflammatory complications that have not responded to topical biguanides alone. The scleritis associated with AK is rarely associated with extracorneal invasion and usually responds to systemic anti-inflammatory treatment combined with topical biguanides. Therapeutic keratoplasty retains a role for therapy of some severe complications of AK but not for initial treatment. With modern management, 90% of patients can expect to retain visual acuity of 6/12 or better and fewer than 2% become blind, although treatment may take 6 months or more., Conclusions: Better understanding of the pathogenesis of the extracorneal complications, the availability of polymerase chain reaction for tissue diagnosis, and effective licensed topical anti-amoebics would substantially benefit patients with AK.

Purpose: To describe an outbreak of Acanthamoeba keratitis (AK) cases among contact lens wearers., Design: Retrospective cohort study., Methods: Patients with AK were included. Relevant demographic and clinical data were obtained from case records, and patients were interviewed using a standardized questionnaire. Contact lens practices, including type of contact lens and solution used, were noted. In addition, clinical features at presentation, management, and clinical outcomes were recorded., Results: Forty-two patients (affecting 43 eyes) treated between 2000 and 2007 were included. Diagnosis was made by microbiologic culture in 35 cases and by microbiologic and histologic analysis in 2 cases, whereas the remainder were diagnosed based on clinical features and response to treatment. There was a gradual increase in cases since 2005, with a sharp increase in 2007, when 8 local patients were treated. Of 30 patients where contact lens solution data were available, 18 reported using a Complete brand Multipurpose solution (Advanced Medical Optics, Santa Ana, California, USA) before the infection. Among resident cases treated since February 2006, 7 (63%) of 11 patients used a Complete brand solution. Suboptimal hygiene practices were found in all patients interviewed. Fifteen patients required corneal grafting, with 11 undergoing therapeutic deep lamellar keratoplasty (DLK), 2 undergoing optical penetrating keratoplasty (PK), 1 undergoing optical DLK, and 1 undergoing therapeutic PK. The remainder were treated successfully medically with combination antiamebic therapy. The average duration of therapy was 116.2 days (range, 15 to 283 days). Of patients with radial keratoneuritis with or without epithelial disease, 83.3% achieved final vision of 20/40 or better, whereas this was achieved in 41.7% of those with ring infiltrate. Twenty-five percent of patients with ring infiltrate had final visual acuity of counting fingers or worse, whereas no patient with keratoneuritis and epithelial disease had final vision worse than counting fingers., Conclusions: There was an increase in the number of contact lens users with AK seen in the major eye departments of Singapore. Most of our patients also reported using a Complete brand Multipurpose solution before infection, and this parallels a similar outbreak in the United States. Increasing severity of infection was associated with worse visual outcome.

Purpose: To determine the prevalence and characteristics of binocular involvement among patients with Acanthamoeba keratitis., Design: Retrospective case series., Methods: Risk factors and outcomes of bilateral infection were explored among consecutive cases of Acanthamoeba keratitis diagnosed at a single institution from 1997 through mid 2007., Results: Fifty eyes were confirmed to have Acanthamoeba keratitis by microbiologic or histopathologic testing; two-thirds occurred during a regional outbreak beginning in 2004. Five (11%) of 45 patients had infection of both eyes, including three with concurrent involvement and two with successive disease of the contralateral cornea. Three binocularly infected patients used soft contact lenses, and two wore rigid gas-permeable lenses. Nine of 10 eyes achieved visual acuity of 20/30 or better after antiamebic therapy., Conclusions: Bilateral Acanthamoeba keratitis is an infectious complication of contact lens wear. With laboratory confirmation, vision often can be restored with medical therapy.

Purpose: To investigate Acanthamoeba keratitis (AK) risk factors. Diagnosis of AK, a rare but serious corneal infection, has recently increased significantly at the University of Illinois at Chicago (UIC) Cornea Service., Design: Retrospective case-control study., Methods: settings: University, tertiary care hospital. patients: Fifty-five AK cases with contact lens use were diagnosed between May 1, 2003 and September 15, 2006. Clinic-matched controls with contact lens use were recruited. Subjects completed surveys targeting lens hygiene, contact lens solution use, and water exposure. main outcome measure: Acanthamoeba keratitis., Results: Thirty-nine (73.6%) cases and 113 (65.3%) controls participated; 38 cases had complete contact lens data. Thirty-five of 38 cases (92.1%) and 47 of 100 controls (47.0%) used soft lenses. Analysis was performed on 30 cases and 39 controls with matched pairs with soft lens use. Exclusive use of Advance Medical Optics (AMO) Complete MoisturePlus Multi-Purpose Solution was independently associated with AK in multivariable analysis (55.2% vs 10.5%; odds ratio [OR], 16.67; 95% confidence interval [CI] 2.11 to 162.63; P = .008). However, 38.8% of cases reported no use of AMO Complete MoisturePlus Multi-Purpose Solution either alone or in combination with other solutions. Although not statistically significant, additional hygiene-related variables (solution "reuse," lack of "rubbing," and showering with lenses) suggest a pattern of risk., Conclusions: AMO Complete MoisturePlus Multi-Purpose Solution use is independently associated with AK among soft contact lens users. However, it does not explain all cases, suggesting additional factors. Further research into environmental risk factors and hygiene practices is warranted, especially considering this is the second outbreak of an atypical, contact lens-related infection.

Acanthamoeba keratitis is a sight-threatening infection of the ocular surface that is produced by several free-living amebae of the genus Acanthamoeba. Infection is usually initiated by Acanthamoeba-contaminated contact lenses and produces exquisite pain and ulceration of the ocular surface. The pathophysiology of this infection involves an intricate series of sequential events that includes the production of several pathogenic proteases that degrade basement membranes and induce cytolysis and apoptosis of the cellular elements of the cornea, culminating in dissolution of the collagenous corneal stroma. Targeting such proteases could lead to the development of vaccines that target the disease process rather than the pathogen itself.

Purpose: To present four cases of Acanthamoeba keratitis as a complication of orthokeratology., Design: Observational case report., Methods: Four patients with Acanthamoeba keratitis had histories of overnight orthokeratology lens wear of 6 months to 2 years., Results: Three cases were diagnosed with Acanthamoeba keratitis by corneal scraping and one by confocal microscopy examination. The patients were treated with chlorhexidine, metronidazole, and neomycin sulfate, resulting in a rapid resolution of ocular inflammation., Conclusion: Overnight wear of orthokeratology lenses may induce Acanthamoeba keratitis.

Purpose: To report live, active trophozoites in an eye with Acanthamoeba keratitis that resembled Acanthamoeba polyphagia in the anterior chamber fluid obtained by transcorneal tap., Method: After prediagnostic therapy had failed, we performed cryosurgery to break the corneal cell walls and treated the patient with oral fluconazole., Results: The condition resolved after 8 weeks of oral fluconazole therapy. Residual leukoma was treated by corneal graft., Conclusion: Live, motile Acanthamoeba can be isolated from an anterior chamber tap; combination therapy with oral fluconazole after corneal cryosurgery may be effective.

Purpose: To describe a case of Acanthamoeba infection of the cornea after radial and astigmatic keratotomy., Methods: A 29-year-old man developed ulcerative keratitis in the right eye 6 weeks after uncomplicated radial and astigmatic keratotomy., Results: Three sets of corneal cultures for bacteria and fungi were negative. Culture on non-nutrient agar grew Acanthamoeba organisms. Clinical improvement occurred after topical antiamebic therapy was instituted., Conclusions: Incisional keratotomy may predispose the cornea to delayed-onset infectious keratitis. Acanthamoeba should be considered as a possible cause of infection and should be cultured for in refractory cases.

Purpose: Tandem scanning confocal microscopy was performed on two patients with Acanthamoeba keratitis to provide images detailing characteristic findings of the disease. Although tandem scanning confocal microscopy of Acanthamoeba has been described in previous reports, Acanthamoeba keratitis has not been fully characterized with this instrument. In vivo confocal micrographs showed the double-walled structure of the Acanthamoeba cyst and associated radial keratoneuritis (perineuritis)., Methods: We reviewed the records of two patients with a clinical diagnosis of Acanthamoeba keratitis, one with culture-proven Acanthamoeba and the other with a suspected Acanthamoeba infection. Slit-lamp biomicroscopy and in vivo tandem scanning confocal microscopy were performed. The images obtained were compared with images from patients without corneal disease., Results: High-contrast round bodies suggestive of Acanthamoeba cysts, as previously described, and irregular forms suggestive of Acanthamoeba trophozoites were found by tandem scanning confocal microscopy. Additionally, we showed conclusively that under certain circumstances (that is, corneal scarring) tandem scanning confocal microscopy can resolve the double-walled structure of the Acanthamoeba ectocyst surrounding the endocyst. Furthermore, radial keratoneuritis was demonstrated, consisting of an irregularly swollen nerve fiber with probable amoebic infiltration., Conclusions: Confocal microscopy can be a useful, noninvasive imaging technique helpful in the study, diagnosis, and treatment of Acanthamoeba keratitis.

Purpose: A sharp increase of Acanthamoeba keratitis from two cases per year to 30 cases per year at our institution prompted this study to determine whether there was a change in the clinical characteristics, basic epidemiology, and outcome of this disease., Methods: We reviewed all cases of Acanthamoeba keratitis diagnosed at the University of Iowa Hospitals and Clinics from mid-1993 through 1994., Results: We screened 217 patients with keratitis by tandem scanning confocal microscopy and suspected Acanthamoeba in 51 patients. Diagnosis was confirmed by cytology in 43 patients (48 eyes). There were no positive cultures. Patients examined within four weeks of onset of symptoms were younger (mean age, 32.6 +/- 15.4 years) and wore contact lenses (11 of 18 patients), and infrequently herpes simplex keratitis (four of 18 patients) was diagnosed. Patients examined after four weeks were older (mean age, 54.0 +/- 19.5 years), infrequently wore contact lenses (six of 25 patients), and often had herpes simplex keratitis (12 of 25 patients)., Conclusions: Corneal examination with tandem scanning confocal microscopy was associated with a marked increase in the detection of Acanthamoeba, strongly suggesting that the disease is more prevalent than suspected. Acanthamoeba may account for many cases of clinically presumed herpes simplex keratitis, the leading cause of corneal blindness in the United States. Acanthamoeba should be considered in the differential diagnosis of any unexplained keratitis, even those of short duration.

Purpose/methods: Eight years after eight-incision radial keratotomy, a corneal ulcer developed around the inferotemporal incision in an otherwise healthy 39-year-old man. There was no history of corneal trauma or contact lens wear., Results/conclusions: Both Fusarium and Acanthamoeba organisms were eventually isolated from the ulcer. A therapeutic keratoplasty was performed. Inferotemporal incisions may be predisposed to epithelial breakdown and infection many years after radial keratotomy.

We treated a healthy soft contact lens wearer who developed Acanthamoeba sclerokeratitis in the left eye. The patient had severe pain and ring-shaped subepithelial infiltrates. The keratitis progressed and scleral nodules developed despite aggressive treatment with topical clotrimazole, dibromopropamidine isethionate, and corticosteroids. Corneal transplantation and cryotherapy were performed. The corneal button demonstrated Acanthamoeba cysts. Cultures of biopsy specimens taken from two different scleral nodules at two separate times were positive for Acanthamoeba. The disease progressed despite a second corneal graft and the addition of polyhexamethylene biguanide eyedrops. Enucleation of the left eye was required. Histopathologic examination of the specimen documented an Acanthamoeba cyst associated with a granulomatous inflammatory response deep in the sclera. Acanthamoeba scleritis may be associated with a poor prognosis, even with intensive medical and surgical treatment.

We treated three patients who had Acanthamoeba keratitis with oral itraconazole, a new antifungal agent, topical miconazole, and surgical débridement of the lesion. In these patients, healing and regression of the keratitis began six or seven days after initiation of oral itraconazole and miconazole 0.1% eyedrops (every hour during the day). The clinical signs of corneal infection disappeared after nine weeks in Patient 1, after five weeks in Patient 2, and after eight weeks in Patient 3. Visual acuities improved markedly from hand motions to 20/30 in Patient 1, from counting fingers to 20/16 in Patient 2, and from hand motions to 20/40 in Patient 3. In these patients, no systemic or topical signs of toxicity or adverse reactions were noted during the course of treatment.

Contact lens-related Acanthamoeba keratitis has been associated with the use of soft contact lenses and homemade saline solutions. We studied the adherence of Acanthamoeba to unworn extended-wear soft contact lenses on a human corneal isolate of Acanthamoeba castellanii suspended in normal saline (cysts, 6.3 x 10(5)/ml; trophozoites, 3.6 x 10(5)/ml). Unworn hydrogel contact lenses (polymacon, water content 38.6%; 50 lenses, 400 lens segments) were exposed to A. castellanii cysts or trophozoites with or without stirring. After exposure for zero to seven hours, soft contact lenses were or were not washed, and the A. castellanii adherence was determined with a standardized light-microscopy technique (40 fields, ten lens segments for each count) and with scanning electron microscopy. Both cysts and trophozoites adhered to the unworn soft contact lenses. Trophozoites showed acanthopodia, lobopodia, and filopodia. This study indicates that both A. castellanii cysts and trophozoites can firmly adhere to unworn soft contact lens. Such adherence may play a role in the pathogenesis of soft contact lens-related Acanthamoeba keratitis.