Novel Effective Medical Therapy for Acanthamoeba Keratitis.

PURPOSE: To report first clinical use of novel medical treatment for Acanthamoeba keratitis. METHODS: Interventional observational case series. Two patients with Acanthamoeba keratitis were unsuccessfully treated with polihexanide (PHMB) 0.02% and propamidine 0.1% for 6 weeks, then all were shifted in a compassionate use of PHMB 0.08% with novel standardized protocol. The postinterventional follow-up of patients was at least 7 months. RESULTS: PHMB 0.08% eyedrops in a novel standardized protocol improved infection resolution and led to complete healing of the lesion after 4 weeks in the two cases. Corneal opacities and neovascularization decreased slowly, best-corrected visual acuity slightly improved and progressively increased in the further 7 months, and no infection recurrence occurred. CONCLUSIONS: This preliminary report of two cases shows promising response to polihexanide 0.08% lowering drastically the illness duration, with reduced chance of recurrence, and mostly improving patients' quality of life.

Diagnostic utility of in vivo confocal microscopy in Acanthamoeba keratitis following corneal crosslinking.

Acanthamoeba keratitis (AK) is a rare but potentially sight-threatening complication of corneal collagen crosslinking (CXL) for keratoconus. In this report, we describe an early adolescent male who underwent routine CXL for progressive keratoconus in his left eye. Preprocedural left visual acuity (VA) was 6/9. At day 5 postprocedure, multifocal corneal infiltrates were identified. Corneal scrape, bandage contact lens cultures and herpetic and Acanthamoeba PCR were negative. In vivo, confocal microscopy (IVCM) identified Acanthamoeba cysts within the corneal stroma. Intensive amoebicidal therapy was initiated, but recovery was complicated by significant inflammation, resulting in widespread aggressive corneal vascularisation necessitating topical steroids and steroid-sparing agents. At 10 months, his left VA was 6/24. This report emphasises the importance of maintaining a high index of suspicion for AK in cases of post-CXL microbial keratitis and highlights the diagnostic value of IVCM, particularly in culture-negative and PCR-negative cases.

Comparison of therapeutic effects between big-bubble deep anterior lamellar keratoplasty and penetrating keratoplasty for medically unresponsive Acanthamoeba keratitis.

PURPOSE: To compare the outcomes of big-bubble deep anterior lamellar keratoplasty (BB-DALK) and penetrating keratoplasty (PKP) in the management of medically unresponsive Acanthamoeba keratitis (AK). METHODS: This retrospective study included 27 eyes of BB-DALK and 24 eyes of PKP from a tertiary ophthalmology care centre. Glucocorticoid eye drops were subsequently added to the treatment plan 2 months postoperatively based on the evaluation using confocal laser scanning microscopy. The clinical presentations, best-corrected visual acuity (BCVA), postoperative refractive outcomes, graft survival, and Acanthamoeba recurrence were analyzed. RESULTS: The AK patients included in the study were in stage 2 or stage 3, and the percentage of patients in stage 3 was higher in the PKP group (P = 0.003). Clinical presentations were mainly corneal ulcers and ring infiltrates, and endothelial plaques, hypopyon, uveitis and glaucoma were more common in the PKP group (P = 0.007). The BCVA and the graft survival rate showed no statistically significant differences between the two groups at 1 year after surgery. However, 3 years postoperatively, the BCVA of 0.71 ± 0.64 logMAR, the graft survival rate of 89.5%, and the endothelial cell density of 1899 ± 125 cells per square millimeter in the BB-DALK group were significantly better than those of the PKP group (P = 0.010, 0.046, and 0.032, respectively). 3 eyes (11.1%) in the BB-DALK group and 2 eyes (8.3%) in the PKP group experienced Acanthamoeba recurrence, but the rates showed no statistically significant difference between the two groups (P = 1.000). In the PKP group, immune rejection and elevated intraocular pressure were observed in 5 and 6 eyes, respectively. CONCLUSION: Corneal transplantation is recommended for AK patients unresponsive to antiamoebic agents. The visual acuity and graft survival can be maintained after BB-DALK surgery. Acanthamoeba recurrence is not related to the surgical approach performed, whereas complete dissection of the infected corneal stroma and delayed prescribing of glucocorticoid eye drops were important to prevent recurrence.

Use of In Vivo Corneal Confocal Microscopy to Guide Excimer Laser With Adjunctive Mitomycin C for Treatment of Recalcitrant Acanthamoeba Keratitis.

PURPOSE: The aim of this study was to describe 3 cases of recalcitrant Acanthamoeba keratitis (AK) that were successfully treated using in vivo corneal confocal microscopy (IVCM) to guide excimer laser ablation depth with adjunctive mitomycin C 0.02%. METHODS: Three patients diagnosed with AK did not respond to several weeks of intensive topical therapy with antiamoebic agents. The patient underwent phototherapeutic keratectomy with topical mitomycin C 0.02% application. The maximum stromal depth of cysts measured by IVCM was 80 µm, 100 µm, and 240 µm, and the stromal ablation depths were 80 µm, 100 µm, and 100 µm, respectively. RESULTS: In all 3 eyes, AK resolved after a single excimer laser application, and topical treatment was gradually discontinued within 6 weeks afterward. In 1 eye, penetrating corneal transplantation was performed 6 weeks after phototherapeutic keratectomy because of ongoing severe corneal pain. IVCM and histology of the corneal transplant did not reveal any Acanthamoeba cysts within the excised corneal button. No recurrence was observed during the follow-up period of 19 to 34 months. CONCLUSIONS: IVCM-guided phototherapeutic keratectomy with mitomycin C 0.02% seems to be a safe and successful approach for the treatment of AK, especially in cases of resistance to topical treatment. Corneal IVCM should be performed before laser application to measure cyst depth, determine ablation depth, and assess postoperative treatment success.

Clinical outcomes and prognostic factors in Acanthamoeba keratitis.

PURPOSE: To report clinical findings and prognostic factors for visual and morphological outcomes in patients with Acanthamoeba keratitis (AK). METHODS: Single-center, retrospective, longitudinal study of 51 cases of AK diagnosed by real-time polymerase chain reaction (RT-PCR) between March 2010 and October 2022. The primary outcome was the final best corrected visual acuity (BCVA). Poor visual outcome was defined as a final BCVA ≥ 1 logMAR unit, while good visual outcome was defined as a final BCVA < 1 logMAR unit. Eyes from these two groups were compared, regarding demographic and initial clinical variables, anti-Acanthamoeba treatment used, and complications of the disease. Early diagnosis was defined as ≤ 14 days from symptom onset to diagnostic confirmation and initiation of Acanthamoeba medical treatment. Multivariable logistic regression was used to determine predictors of poor visual outcome. RESULTS: A total of 51 eyes from 46 patients diagnosed with AK, all contact lens (CL) wearers, were included in this study. Average follow-up was 39.0 ± 30.2 [total range 14-120] months. Thirty-one eyes (60.8 %) presented good visual outcome, with a lower baseline age (30.5 ± 9.0 vs. 42.3 ± 15.8; p = 0.020), better initial BCVA (0.8 ± 0.7 logMAR units vs. 1.3 ± 0.9 logMAR units; p = 0.047), higher rate of early diagnosis (45.2 % vs. 5.6 %; p = 0.004), and higher rate of therapeutic epithelial debridement (64.5 % vs. 10 %; p < 0.001). 20 eyes (39.2 %) presented poor visual outcome, with 12 eyes undergoing evisceration/enucleation (23.5 %). These 20 eyes presented a higher rate of complications (90 % vs. 61.3 %; p = 0.031). In multivariable analysis, early diagnosis of AK (OR 19.78; 95 % CI 2.07-189.11; p = 0.010) and therapeutic epithelial debridement (OR 19.02; 95 % CI 3.27-110.57; p = 0.001) were associated with a good visual outcome. CONCLUSIONS: In the present study, poor visual outcome was present in 39 % of affected eyes. Early AK diagnosis (≤14 days from symptom onset) and therapeutic epithelial debridement were associated with good final visual outcome.

The Orphan Drug for Acanthamoeba Keratitis (ODAK) Trial: PHMB 0.08% (Polihexanide) and Placebo versus PHMB 0.02% and Propamidine 0.1.

PURPOSE: To compare topical PHMB (polihexanide) 0.02% (0.2 mg/ml)+ propamidine 0.1% (1 mg/ml) with PHMB 0.08% (0.8 mg/ml)+ placebo (PHMB 0.08%) for Acanthamoeba keratitis (AK) treatment. DESIGN: Prospective, randomized, double-masked, active-controlled, multicenter phase 3 study (ClinicalTrials.gov identifier, NCT03274895). PARTICIPANTS: One hundred thirty-five patients treated at 6 European centers. METHODS: Principal inclusion criteria were 12 years of age or older and in vivo confocal microscopy with clinical findings consistent with AK. Also included were participants with concurrent bacterial keratitis who were using topical steroids and antiviral and antifungal drugs before randomization. Principal exclusion criteria were concurrent herpes or fungal keratitis and use of antiamebic therapy (AAT). Patients were randomized 1:1 using a computer-generated block size of 4. This was a superiority trial having a predefined noninferiority margin. The sample size of 130 participants gave approximately 80% power to detect 20-percentage point superiority for PHMB 0.08% for the primary outcome of the medical cure rate (MCR; without surgery or change of AAT) within 12 months, cure defined by clinical criteria 90 days after discontinuing anti-inflammatory agents and AAT. A prespecified multivariable analysis adjusted for baseline imbalances in risk factors affecting outcomes. MAIN OUTCOME MEASURES: The main outcome measure was MCR within 12 months, with secondary outcomes including best-corrected visual acuity and treatment failure rates. Safety outcomes included adverse event rates. RESULTS: One hundred thirty-five participants were randomized, providing 127 in the full-analysis subset (61 receiving PHMB 0.02%+ propamidine and 66 receiving PHMB 0.08%) and 134 in the safety analysis subset. The adjusted MCR within 12 months was 86.6% (unadjusted, 88.5%) for PHMB 0.02%+ propamidine and 86.7% (unadjusted, 84.9%) for PHMB 0.08%; the noninferiority requirement for PHMB 0.08% was met (adjusted difference, 0.1 percentage points; lower one-sided 95% confidence limit, -8.3 percentage points). Secondary outcomes were similar for both treatments and were not analyzed statistically: median best-corrected visual acuity of 20/20 and an overall treatment failure rate of 17 of 127 patients (13.4%), of whom 8 of 127 patients (6.3%) required therapeutic keratoplasty. No serious drug-related adverse events occurred. CONCLUSIONS: PHMB 0.08% monotherapy may be as effective (or at worse only 8 percentage points less effective) as dual therapy with PHMB 0.02%+ propamidine (a widely used therapy) with medical cure rates of more than 86%, when used with the trial treatment delivery protocol in populations with AK with similar disease severity. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Steroids in the Management of Infectious Keratitis.

PURPOSE: To summarize the evidence base on the use of topical corticosteroids for infectious keratitis. METHODS: Narrative review. RESULTS: Infectious keratitis is a painful condition that often results in visually significant corneal stromal scarring, even when antimicrobial therapy is successful. Corticosteroids may reduce inflammation and subsequent scar formation and while relieving the acute ocular pain associated with a corneal ulcer. However, corticosteroids also reduce the host immune response, which could hinder the ability to clear infection. The safety and effectiveness of corticosteroids depends to a large part on the efficacy of the antimicrobials being used to treat the underlying infection. Randomized trials have found that corticosteroids are safe and effective for herpetic keratitis when used with appropriate antiviral therapy, and are safe for bacterial keratitis when used with broad spectrum topical antibiotics. The effectiveness of corticosteroids for bacterial keratitis has not been shown conclusively, although more advanced bacterial corneal ulcers may do better with corticosteroids. No randomized trials have assessed the safety and effectiveness of steroids for fungal or acanthamoeba keratitis. Animal studies suggest corticosteroids may be harmful in fungal keratitis, and observational human studies have found that steroids are harmful for fungal and acanthamoeba keratitis when started prior to anti-amoebics. CONCLUSIONS: Topical corticosteroids, when used as an adjunct to antimicrobial therapy, may be beneficial if the antimicrobial being used can effectively clear or suppress the infection, such as in bacterial and herpetic keratitis. Randomized trials would be helpful to further delineate the role of corticosteroids for infectious keratitis.

Lately Diagnosed Acanthamoeba Keratitis Manifesting as an Intrastromal Corneal Abscess: A Case Report.

ABSTRACT: A 42-year-old female contact lens wearer presented to a local emergency department with a 3-day history of decreased vision and ocular discomfort in her right eye. She was started on topical fluorometholone and oral acyclovir with initial diagnosis of herpes simplex keratitis. After 3 weeks of worsening symptoms, she was diagnosed with bacterial corneal ulcer and treated with levofloxacin eye drops every 2 hr. After 14 days of no improvement, she was referred to our clinic for further workup. Slitlamp examination demonstrated a solitary dense 3×3-mm infiltration involving anterior and central corneal stroma. The overlying epithelium was intact, and there was no subepithelial infiltration, radial perineuritis, keratic precipitates, or anterior chamber reaction. Corneal sensation was normal. Confocal microscopy and corneal biopsy were definitive for Acanthamoeba infection. The patient received polyhexamethylene biguanide 0.02% every 2 hr and oral ketoconazole 200 mg twice a day, which resulted in improvement in her signs and symptoms within 10 days. The medications were gradually tapered off over 5 months per clinical response. At the 9-month follow-up visit, the best-corrected visual acuity was 5/10 with a superficial central stromal scar at slitlamp examination. Acanthamoeba infection should be considered in contact lens wearers who present with intrastromal corneal abscess.

Comparing cytotoxicity and efficacy of miltefosine and standard antimicrobial agents against Acanthamoeba trophozoites and cyst forms: An in vitro study.

Acanthamoeba keratitis (AK) is an eye disease often occurring in contact lens wearers. AK treatment is prolonged and requires multiple drugs, which can lead to adverse effects. Our study aimed to compare the in vitro activities and safety of Miltefosine with that of conventional antimicrobial agents used to treat AK. Acanthamoeba castellanii genotype T4 was obtained from a patient with keratitis and subjected to in vitro susceptibility testing with various antimicrobial agents, including Chlorhexidine (CHX), Pentamidine isethionate (PI)Polyhexamethylene biguanide (PHMB), and Miltefosine to assess their efficacy against Acanthamoeba trophozoites and cyst. The cytotoxicity of the agents was evaluated in Vero cells, and their selectivity indexes (SI) were calculated. Chlorhexidine exhibited the highest amoebicidal activity with the highest selectivity index against the trophozoite and cyst, ranging from 1.17 to 8.35. The selectivity index of PHMB is slightly comparable to Chlorhexidine, exhibiting significant anti-Acanthamoeba activity. On the other hand, Pentamidine isethionate and Miltefosine displayed low SI among the compounds. Pentamidine isethionate was effective at high concentrations, which was toxic. Miltefosine exhibited the lowest cytotoxicity; nevertheless, due to the lowest anti-Acanthamoeba activity presented a low selectivity against the parasite. Further studies on more clinical samples and prolonged incubation time should be done to investigate the effectiveness and toxicity of drugs in both in vitro and in vivo conditions.

Successful Medical and Surgical Management of Recalcitrant Acanthamoeba Keratitis, Scleritis, and Culture-Positive Scleral Abscess.

PURPOSE: The purpose of this study was to describe the management of a case of recurrent scleritis and Acanthamoeba -positive scleral abscess in a patient after the use of miltefosine for recalcitrant Acanthamoeba keratitis. METHODS: This is a case study. RESULTS: In this study, we report a case of advanced Acanthamoeba keratitis with resultant corneal perforation with therapeutic keratoplasty and associated scleritis who later developed a scleral abscess after treatment with oral miltefosine. The scleral abscess was positive for Acanthamoeba cysts and trophozoites, and after treatment for an additional several months, the patient had complete resolution of her disease. CONCLUSIONS: Acanthamoeba scleritis is a rare complication associated with Acanthamoeba keratitis. It has traditionally been treated as an immune reaction and associated inflammation, especially with the use of miltefosine. Management can require a multitude of different approaches, and in this situation, it has been demonstrated that scleritis can be infectious and that conservative management can be effective.

Corneal Culture and Antibiotic Susceptibility Results for Microbial Keratitis in the Mid-Atlantic Region of the United States, 2016 to 2020.

OBJECTIVE: To examine the microbial distribution and antimicrobial susceptibility of culture-positive microbial keratitis at a large tertiary referral center in the mid-Atlantic region of the United States. METHODS: Retrospective review of culture-positive microbial keratitis cases at the Wilmer Eye Institute from 2016 through 2020. RESULTS: Of the 474 culture-positive microbial keratitis cases, most were bacterial (N=450, 94.9%), followed by fungal (N=48, 10.1%) and Acanthamoeba keratitis (N=15, 3.1%). Of the 450 bacterial isolates, 284 (69.5%) were gram-positive organisms, whereas 157 (28.4%) were gram-negative organisms. The most common bacterial species isolated was coagulase-negative Staphylococcus spp (N=154, 24.8%), and the most common gram-negative isolate was Pseudomonas aeruginosa (N=76, 12.3%). Among fungi, the most common isolates were Candida (N=25, 45.4%), whereas Fusarium (N=6, 10.9%) and Aspergillus (N=3, 5.5%) were less common. Of the 217 bacterial isolates tested for erythromycin susceptibility, 121 (55.7%; ∼60% of coagulase-negative staphylococci and corynebacteria tested) showed resistance to erythromycin. CONCLUSIONS: Microbial keratitis in the Baltimore Mid-Atlantic region of the United States is most commonly caused by bacteria, with fungi and acanthamoeba being less common. Gram-positive bacterial infections predominate. Among fungal keratitis cases, Candida species are more commonly encountered than are filamentous species. Use of erythromycin as infection prophylaxis should be reexamined. Findings from our study may guide empiric treatment in this geographic region.

Diagnosis and treatment of Acanthamoeba Keratitis: A scoping review demonstrating unfavorable outcomes.

Acanthamoeba spp. are pathogens that cause Acanthamoeba keratitis (AK), a serious cornea inflammation that can lead to gradual loss of vision, permanent blindness, and keratoplasty. The efficacy of AK treatment depends on the drug's ability to reach the target tissue by escaping the protective eye barrier. No single drug can eradicate the living forms of the amoeba and be non-toxic to the cornea tissue. The treatment aims to eradicate both forms of protozoan life but is hampered by the resistance of the cysts to the most available drugs, leading to prolonged infection and relapses. Drug therapy is currently performed mainly using diamidines and biguanides, as they are more effective against cysts. However, they are cytotoxic to corneal cells. Drugs are applied topically, and hourly. Over time, the frequency of administration decreases, but the treatment time varies from month to years. This study aims to obtain an up-to-date summary of the literature since 2010, allowing us to identify the trends and gaps and address future research involving new alternatives for treating AK. The results were divided into three phases, pre-treatment, empirical treatment, and the treatment after diagnosis confirmation. The drugs prescribed were stratified into antiamoebic, antibiotic, antifungal, antivirals, and steroids. It was possible to observe the transition in drug prescription during three different stages until the diagnosis was confirmed. There were more indications for antibiotic, antifungal, and antiviral drugs in the early stages of the disease. The antiamoebic drugs were only prescribed after exhausting other treatments. This can be directly involved in developing complications and no responsiveness to medical treatment.

The amoebicidal effect of Torreya nucifera extract on Acanthamoeba lugdunensis.

As the number of contact lens users increases, contact lens induced corneal infection is becoming more common. Acanthamoeba keratitis (AK) is a type of those which is caused by Acanthamoeba species, and may cause severe ocular inflammation and visual loss. We evaluated whether Torreya nucifera (T. nucifera) extract has an anti-amoebic effect and studied its mechanism of action on Acanthamoeba lugdunensis (A. lugdunensis). Cell viability was tested using the alamarBlue™ method, and the cell death mechanism was confirmed using the Tali® Apoptosis Kit. The SYTOX® Green assay was performed to check the plasma membrane permeability. The JC-1 dye was used to measure the mitochondrial membrane potential. A CellTiter-Glo® Luminescent Assay was used to measure the adenosine-triphosphate (ATP) level. Morphological changes in the mitochondria were examined by transmission electron microscopy (TEM). Cystic changes and a decrease in cell viability after treatment with T. nucifera were observed. Both apoptotic and necrotic cells were found in the Tali® Apoptosis assay. There was no significant difference in plasma membrane permeability between the control and T. nucifera treated groups. The collapse of the mitochondrial membrane potential and reduced ATP level in A. lugdunensis was confirmed in the groups treated with T. nucifera. Structural damage to the mitochondria was observed on TEM in the groups treated with T. nucifera. T. nucifera showed an anti-amoebic effect on A. lugdunensis, by inducing the loss of mitochondrial membrane potential. Thus, it could be a future therapeutic agent for AK.

Impact of implementation of polymerase chain reaction on diagnosis, treatment, and clinical course of Acanthamoeba keratitis.

PURPOSE: Acanthamoeba keratitis (AK) is a painful and possibly sight-threatening ocular infection. While the correct diagnosis and specific treatment in the early stages significantly improve the prognosis, the disease is often misdiagnosed and in clinical examination confused with other forms of keratitis. Polymerase chain reaction (PCR) for the detection of AK was first introduced in our institution in December 2013 to improve the timely diagnosis of AK. The aim of this study was to assess the impact of implementation of Acanthamoeba PCR on the diagnosis and treatment of the disease in a German tertiary referral center. PATIENTS AND METHODS: Patients treated for Acanthamoeba keratitis between 1st of January 1993 and 31st of December 2021 in the Department of Ophthalmology of the University Hospital Duesseldorf were identified retrospectively via in-house registries. Evaluated parameters include age, sex, initial diagnosis, method of correct diagnosis, duration of symptoms until correct diagnosis, contact lens use, visual acuity, and clinical findings as well as medical and surgical therapy by keratoplasty (pKP). In order to assess the impact of implementation of Acanthamoeba PCR, the cases were divided into two groups (before (pre-PCR group) and after PCR implementation (PCR group). RESULTS: Seventy-five patients with Acanthamoeba keratitis were included (69.3% female, median age 37 years). Eighty-four percent (63/75) of all patients were contact lens wearers. Until PCR was available, 58 patients with Acanthamoeba keratitis were diagnosed either clinically (n = 28), by histology (n = 21), culture (n = 6), or confocal microscopy (n = 2) with a median duration until diagnosis of 68 (18; 109) days. After PCR implementation, in 17 patients, the diagnosis was established with PCR in 94% (n = 16) and median duration until diagnosis was significantly shorter with 15 (10; 30.5) days. A longer duration until correct diagnosis correlated with a worse initial visual acuity (p = 0.0019, r = 0.363). The number of pKP performed was significantly lower in the PCR group (5/17; 29.4%) than in the pre-PCR group (35/58; 60.3%) (p = 0.025). CONCLUSIONS: The choice of diagnostic method and especially the application of PCR have a significant impact on the time to diagnosis and on the clinical findings at the time of confirmation of diagnosis and the need for penetrating keratoplasty. In contact lens-associated keratitis, the first crucial step is to take AK into consideration and perform a PCR test as timely confirmation of diagnosis of AK is imperative to prevent long-term ocular morbidity.

Therapeutic keratoplasty for severe Acanthamoeba keratitis: risk factors, clinical features, and outcomes of postoperative recurrence.

PURPOSE: To investigate the effect of therapeutic keratoplasty (TKP) in patients with severe Acanthamoeba keratitis (AK) and to analyse the clinical features and risk factors for recurrence. METHODS: Clinical data of patients with severe AK treated with lamellar keratoplasty (LK) or penetrating keratoplasty (PK) due to ineffective drug therapy were analysed in this retrospective study. The effects of keratoplasty, clinical features, and risk factors for recurrence were analysed. RESULTS: The cohort comprised of 58 patients (59 eyes). Of these, 36 eyes were treated with PK and 23 were treated with LK. The probabilities of successful globe salvage were 91.7% and 91.3%, respectively. The final visual acuity (VA) was ≥ 20/60 in 14 eyes (38.9%) that underwent PK and 15 eyes (65.2%) that underwent LK. Postoperative recurrence of Acanthamoeba infection was detected in 10 eyes; 6 eyes (16.7%) showed recurrence after PK, and 4 eyes (17.4%) showed recurrence after LK. Recurrence occurred between 3 and 80 days (median, 14.5 days) after the operation. The risk factors for recurrence after LK were topical corticosteroid use before diagnosis (p = 0.040) and hypopyon (p = 0.009), while those after PK were topical corticosteroid use before diagnosis (p = 0.045). Clinical manifestations of postoperative recurrence include greyish-white infiltration of the recipient bed, anterior chamber inflammation, graft oedema, and keratic precipitate. CONCLUSION: TKP is a treatment option for severe AK that responds poorly to antiamoebic therapy (AAT), although Acanthamoeba infection may relapse, and the visual prognosis is guarded. Topical corticosteroid use before AAT and hypopyon is the two risk factors for recurrence.

Utility of In Vivo Confocal Microscopy in Diagnosis of Acanthamoeba Keratitis: A Comparison of Patient Outcomes.

PURPOSE: The aim of this study was to compare outcomes between cases of Acanthamoeba keratitis (AK) diagnosed and treated with or without the use of in vivo confocal microscopy (IVCM). METHODS: We performed a retrospective comparative case series of 26 eyes of 23 patients diagnosed with AK at the Massachusetts Eye and Ear Infirmary over a 5-year period. The characteristics of all identified cases were summarized. We compared the time from presentation to diagnosis of AK (primary outcome), visual acuity, and rates of therapeutic penetrating keratoplasty between eyes diagnosed by culture-only group (n = 8) and by IVCM to diagnose AK (n = 9) and later confirmed by culture (IVCM/C group). RESULTS: The diagnostic delay was significantly longer in the culture only group (25 ± 29 days) compared with the IVCM/C group (3 ± 3 days, P < 0.01). At 6 months, there was a significant difference in best-corrected visual acuity between the culture-only group (1.46 ± 1.07, n = 7) and the IVCM/C group (0.22 ± 0.22, n = 8), after adjusting for initial baseline visual acuity (P = 0.02). Therapeutic penetrating keratoplasty was performed in 50% of culture-only (n = 7) and 11% of IVCM/C group eyes (n = 9), but this was not statistically significant (P = 0.13). CONCLUSIONS: IVCM can expedite the diagnosis of AK, and its use as an adjunct tool in the diagnosis of AK may result in better patient outcomes compared with basing treatment decisions on corneal cultures alone.

Antiamoebic Susceptibility in Acanthamoeba Keratitis: Comparison of Isolates From South India and Northern California.

PURPOSE: Outcomes of Acanthamoeba keratitis are often worse in India than in the United States. The goal of this study was to determine whether antiamoebic susceptibility patterns were different when comparing Acanthamoeba isolates from India with those of the United States. METHODS: Acanthamoeba isolates were obtained from corneal scrapings of 43 patients with infectious keratitis seen at the Francis I. Proctor Foundation (N = 23) and Aravind Eye Hospital (N = 20) from 2008 through 2012 and plated on growth media. A previously described minimum cysticidal concentration (MCC) assay was performed by a single laboratory technician to assess susceptibility to 5 antiamoebic agents for all isolates. Testing was conducted in triplicate, with the median MCC chosen for analyses. RESULTS: The MCC (µg/mL) of polyhexamethylene biguanide was 6.25 [IQR 5.47-12.5] for Aravind isolates and 6.25 [IQR 6.25-9.375] for Proctor isolates ( P = 0.75), corresponding values were 6.25 [IQR 3.125-6.25] and 3.125 [IQR 3.125-9.375] for chlorhexidine ( P = 0.81), 2500 [IQR 2500-5000] and 5000 [IQR 1250-20,000] for voriconazole ( P = 0.25), 15.6 [IQR 15.6-39.0625] and 15.6 [IQR 15.6-31.25] for hexamidine ( P = 0.92), and 15.6 [IQR 7.81-15.6] and 15.6 [IQR 7.81-31.25] for propamidine ( P = 0.42). CONCLUSIONS: This study found no statistically significant differences in antiamoebic susceptibility of Indian versus US samples from Acanthamoeba keratitis clinical isolates. These findings suggest that differences in antiamoebic susceptibility are likely not responsible for differential outcomes in Acanthamoeba keratitis between the 2 locations.