Clinical outcomes and prognostic factors associated with acanthamoeba keratitis

Impact of contact lens hygiene risk factors on the prevalence of contact lens-related keratitis in Alexandria-Egypt

BACKGROUND

This study aimed at measuring the effect of contact lens hygiene risk factors on the prevalence of contact lens-related keratitis and identifying the specific risk factors to both microbial and non-microbial keratitis independently.

METHODS

A cross-sectional study was conducted at Alexandria Ophthalmology Hospital from May to October 2023. All contact lens wearers attending the outpatient clinic had undergone face-to-face interviews using a standardized validated questionnaire which included demographic data and contact lenses (CLs) hygiene risk factors. Participants were classified into two groups; normal group and keratitis group. Keratitis group was further subdivided into non-microbial and microbial group.

RESULTS

The study included 245 contact lens wearers; 149 normal cases, 50 (20.4%) contact lens-related non-microbial keratitis (CLNK) cases, and 46 (18.8%) contact lens-related microbial keratitis (CLMK) cases. Sharing contact lenses and eye trauma were significant risk factors for both CLNK (p=0.036), (p=0.001) and CLMK (p=0.003), (p=0.017). CLs wear duration for more than 12 hours was associated with an increased risk of CLNK by about 4 times (p=0.030) and overnight wear of contact lenses increased the risk of CLNK by 2.6 times (p=0.030). Showering or swimming in lenses was identified as a significant risk factor for CLMK (p=0.012), moreover washing lenses with tap water increased the risk of CLMK (p=0.030).

CONCLUSIONS

Poor compliance with contact lenses hygiene rules results in a high prevalence of contact lens-related keratitis. Eye trauma and sharing contact lenses were significant hygiene risk factors for both contact lens-related non-microbial keratitis and contact lens-related microbial keratitis.

Perspectives on the Incidence of Acanthamoeba Keratitis: A Systematic Review and Meta-Analysis

TOPIC

To provide an overview on the incidence of Acanthamoeba keratitis (AK).

CLINICAL RELEVANCE

Although being a sight-threatening cause of infectious keratitis, a comprehensive assessment of the incidence of AK is lacking.

METHODS

Incidence of AK was computed as the number of eyes with AK per health care center, per year (annualized center incidence [ACI]). Two meta-analytical ratios also were calculated: (1) the ratio of eyes with AK to the count of eyes with nonviral microbial keratitis (MK) and (2) the ratio of eyes with AK to the overall population (i.e., the total number of people in a nation or region, as indicated by the authors in each study). Center was defined as the health care facility where the study took place. Actual and projected estimates of the number of eyes with AK in years were calculated multiplying the ratio of eyes with AK to the total population and the corresponding population estimates, sourced from the United Nations Population Prospects.

RESULTS

Overall, 105 articles were included, published between 1987 and 2022. The total number of eyes identified was 91 951, with 5660 eyes affected by AK and 86 291 eyes affected by nonviral MK. The median ACI was 1.9 eyes with AK per health care center per year (95% confidence interval [CI], 1.5-2.6 eyes), with no statistically significant differences among continents. The ratio of eyes with AK to the total number of eyes with MK was 1.52% (95% CI, 1.03%-2.22%), whereas the ratio of eyes with AK in relationship to the entire population was estimated at 2.34 eyes per 1 000 000 people (95% CI, 0.98-5.55 per 1 000 000 people). The projected increase in the numbers of eyes with AK indicated an increase of 18.5% (n = 15 355 eyes with AK) in 2053 and 25.5% (n = 16 253 eyes with AK) in 2073, compared with the baseline of 2023 (n = 12 953 eyes with AK).

DISCUSSION

Acanthamoeba keratitis emerged as a relatively low-incident disorder, and no significant differences in terms of its incidence were found among different continents.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Clinical Profile and Demographic Distribution of Acanthamoeba Keratitis: An Electronic Medical Record-Driven Data Analytics from an Eye Care Network in India

OBJECTIVE

To describe the clinical profile of patients presented with Acanthamoeba keratitis (AK) to a multi-tier ophthalmology hospital network in India.

METHODS

This cross-sectional hospital-based study included 1945339 new patients registering between September 2016 and May 2022. Patients with clinically confirmed diagnosis of AK in one or both eyes were included in the study. All the relevant data were documented using an electronic medical record (EMR) system.

RESULTS

A total of 245 (0.013%) patients were diagnosed with AK and majority were male (62.86%) with unilateral (99.59%) affliction. The most common age group was during the fourth decade of life, 65 (26.53%) patients and predominantly were adults (95.51%). The prevalence of the infection was higher in patients from a lower socioeconomic status (43.27%) from rural geography (52.24%) and in agriculture-related work (28.16%). The most common inciting factor was injury with vegetative matter (8.98%), dust (7.76%) and contact lens wear (4.49%). The majority of the eyes had blindness (20/400 to 20/1200) in 116 (47.15%) eyes with a presenting visual acuity (logMAR) of 2.14 ± 1.04. Among the surgical interventions, therapeutic keratoplasty was performed in 41 (16.67%) eyes, penetrating keratoplasty in 22 (8.94%) eyes, and evisceration in 2 (0.81%) eyes.

CONCLUSION

AK more commonly affects males presenting during the fourth decade of life from lower socio-economic status and is predominantly unilateral. A fourth of the affected eyes underwent keratoplasty and the majority had significant visual impairment at presentation.

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.

Depth, size of infiltrate, and the microbe - The trio that prognosticates the outcome of infective keratitis

PURPOSE

To analyze the influence of infiltrate size, depth, and organism on the outcome of microbial keratitis.

DESIGN

Retrospective comparative study.

METHODS

Medical records of patients with infective keratitis, who reported from January 2015 to December 2019 to a tertiary eye care center, were analyzed. Size and depth of ulcer at presentation were the factors used to group patients, and the influence on the outcome of the organism causing it was analyzed. Grouping was as follows: group A: ulcer size <6 mm/anterior to midstromal infiltrate, group B: ulcer < 6 mm/full-thickness infiltrate, group C: ulcer >6 mm/anterior to midstromal infiltrate, group D: ulcer > 6 mm/full-thickness infiltrate. Patients with viral keratitis or unidentified organism were excluded. Response to treatment and best-corrected visual acuity (BCVA) at the final follow-up were the outcome measures.

RESULTS

In the study, 1117/6276 patients were included, with 60.8% patients in group A. A significant improvement in visual acuity was noted in groups A/B compared to groups C/D. Group A had the best response to medical management, irrespective of the organism. Higher risk for surgery was noted in group C compared to group B, with group A as the reference. Overall resolution with medical treatment was noted in 70% miscellaneous keratitis, 64.8% bacterial keratitis, 64.3% mixed keratitis, 62.5% acanthamoeba keratitis, 52.6% fungal keratitis, and 12.1% Pythium keratitis. Bacteria and acanthamoeba responded better to medical management than fungal keratitis, whereas Pythium had the highest risk for surgery.

CONCLUSION

An interplay between virulence of the organism along with depth and size of the infiltrate determines the outcome of microbial keratitis.

Ultrasensitive and rapid diagnostic tool for detection of Acanthamoeba castellanii

Acanthamoeba keratitis is a devastating infectious disease of the cornea caused by an opportunistic amoeba, Acanthamoeba castellanii. It is poorly recognized, and diagnostic delays can lead to irreversible damage to the vision. The gold standard for diagnosis has been a sample culture that lasts approximately 2 weeks. Nevertheless, the essence of time has led to the need for an accurate and fast technique to detect A. castellanii from a sample. We developed both traditional and quantitative real-time-PCR-based methods to detect A. castellanii in less than 3 hours and with the sensitivity of one amoeba. Diagnostic laboratories can select the best-suited method for their purposes from 2 comparable methods. The correct treatment can be initiated from the emergency room when the diagnosis has been made quickly within a few hours, hence saving the patient from long-term complications.

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.

Acanthamoeba Keratitis Risk Factors for Daily Wear Contact Lens Users: A Case-Control Study

PURPOSE

This study was designed to establish risk factors for the development of Acanthamoeba keratitis (AK) for daily disposable (DD) contact lens (CL) users compared with daily wear (DW) reusable lens users and for risks unique to DD users. This is important because, in many major economies, CL use is the principal cause of microbial keratitis, of which AK accounts for approximately 50% of cases with sight loss. Determining these AK risks informs practitioner advice and consumer behavior.

DESIGN

Case-control study.

PARTICIPANTS

Cases and controls were recruited from an Accident and Emergency Department serving South-East England. Cases were new CL users with AK recruited retrospectively from January 2011 to February 2013 and prospectively thereafter until August 2014. Controls were recruited prospectively from February 2014 to June 2015.

METHODS

Analysis of a self-administered questionnaire.

MAIN OUTCOME MEASURES

Independent risk factors and population attributable risk percentage (PAR%) for AK.

RESULTS

A total of 83 AK cases and 122 controls were recruited; DD use was reported by 20 (24%) cases and 66 (54%) controls. In multivariable analyses adjusted for potential confounders, the odds of AK was higher for DW reusable soft lenses (odds ratio [OR], 3.84; 95% confidence interval [CI], 1.75-8.43) and rigid lenses (OR, 4.56; 95% CI, 1.03-20.19) than for DD lenses. Within the DD-using subset, AK was associated with the following modifiable risk factors: less frequent professional follow-up visits (OR, 10.12; 95% CI, 5.01-20.46); showering in lenses (OR, 3.29, 95% CI, 1.17-9.23); lens reuse (OR, 5.41; 95% CI, 1.55-18.89); and overnight wear (OR, 3.93; 95% CI, 1.15-13.46). The PAR% estimated that 30% to 62% of cases could be prevented by switching from reusable soft lens to DD lens use.

CONCLUSIONS

Acanthamoeba keratitis risks are increased > threefold in DW reusable lens users versus DD lens use. Acanthamoeba keratitis risks for DD lens users can be minimized by adherence to safe use guidelines (no reuse, overnight wear, or contamination by water). Safe CL use can be improved by increasing the prominence of risk avoidance information from manufacturers and regulators. Because AK accounts for half of severe keratitis in CL users, these measures can be expected to have public health benefits.

Novel Drug Delivery Systems to Improve the Treatment of Keratitis

Keratitis is a disease characterized by inflammation of the cornea caused by different pathogens. It can cause serious visual morbidity if not treated quickly. Depending on the pathogen causing keratitis, eye drops containing antibacterial, antifungal, or antiviral agents such as besiloxacin, moxifloxacin, ofloxacin, voriconazol, econazole, fluconazole, and acyclovir are used, and these drops need to be applied frequently due to their low bioavailability. Studies are carried out on formulations with extended residence time in the cornea and increased permeability. These formulations include various new drug delivery systems such as inserts, nanoparticles, liposomes, niosomes, cubosomes, microemulsions, in situ gels, contact lenses, nanostructured lipid carriers, carbon quantum dots, and microneedles. Ex vivo and in vivo studies with these formulations have shown that the residence time of the active substances in the cornea is prolonged, and their ocular bioavailability is increased. In addition, in vivo studies have shown that these formulations successfully treat keratitis. However, it has been observed that fluoroquinolones are used in most of the studies; similar drug delivery systems are generally preferred for antifungal drugs, and studies for viral and acanthameba keratitis are limited. There is a need for new studies on different types of keratitis and different drug active substances. At the same time, proving the efficacy of drug delivery systems, which give promising results in in vivo animal models, with clinical studies is of great importance for progress in the treatment of keratitis.

Overnight orthokeratology-associated Acanthamoeba keratitis at a tertiary referral hospital in Taiwan: A retrospective case-control study

BACKGROUND

Acanthamoeba keratitis (AK) is a vision-threatening disease, usually associated with contact lens (CL) wear. As overnight orthokeratology (OOK) is increasingly used to control myopia, we have found incidence of OOK-associated AK is increasing. This study aimed to investigate the clinical presentation and visual outcomes of OOK-associated AK.

METHODS

Demographic characteristics, clinical features, and treatment outcomes were collected by reviewing the medical charts of CL-associated AK patients (n = 35) diagnosed at Taipei Veterans General Hospital from 2001 to 2016. Cases were OOK-associated AK patients (n = 13), and controls were all other CL-associated AK patients (n = 22). Student t tests and chi-square tests were used to compare cases and controls. Linear regression analyses were used to identify factors associated with the final visual outcome in CL-associated AK.

RESULTS

OOK-associated AK accounted for half of all CL-associated AK after 2010. OOK-associated AK patients and other CL-associated patients had similar best-corrected logarithm of the minimum angle of resolution visual acuity (BCLVA) before treatment (1.10 ± 0.75 vs 1.13 ± 0.76, p = 0.893), but OOK-associated AK patients were younger (17.15 ± 3.21 vs 26.36 ± 12.81 years, p = 0.004), had less severe disease (ring infiltration, 0% vs 31.82%, p = 0.023), and had better post-treatment BCLVA (0.06 ± 0.15 vs 0.51 ± 0.95, p = 0.041). Multiple linear regression analysis showed that better BCLVA after treatment in CL-associated AK was associated with initial presentation without ring infiltration (p = 0.002) but not with OOK use itself (p = 0.793). Twenty-six of 35 CL-associated AK patients had final BCLVA equal to or better than 0.10 (Snellen visual acuity of 6/7.5). All 13 OOK-associated AK cases were treated with chlorhexidine 0.02% ± voriconazole 1% ± oral voriconazole, and 12 of these patients had final BCLVA equal to or better than 0.10.

CONCLUSION

Most CL-associated AK patients had satisfactory visual outcomes. Half of AK at our hospital is OOK-associated since 2010. Early diagnosis and correct treatment may be the reason why OOK-associated AK patients had better vision prognosis.

Incidence and Risk Factors of Ocular Hypertension and Glaucoma in Patients With Acanthamoeba Keratitis

OBJECTIVES

To determine the incidence of ocular hypertension (OHT) and glaucoma in patients with acanthamoeba keratitis (AK) and to outline the risk factors for the development of glaucoma.

METHODS

A retrospective review of patients diagnosed with AK at our institute during the period from 2000 to 2018. The main outcome measures were the incidence of OHT and glaucoma, and risk factors for the development of glaucoma.

RESULTS

Fifty-two eyes diagnosed with AK were included. The incidence of OHT and glaucoma was 51.9% and 32.7%, respectively. The mean duration from disease onset to the first attack of elevated intraocular pressure was 8.4±16.6 months. The use of corticosteroids in the treatment regimen was significantly associated with the development of glaucoma (odds ratio, 3.93; 95% confidence interval, 0.96-16.15; P=0.049). At the last follow-up visit, both patients with glaucoma and nonglaucoma patients had improved visual acuity without a difference in the mean amount of logarithm of the minimum angle of resolution acuity improvement among them (0.56±0.91 vs. 0.67±0.87, P=0.686).

CONCLUSION

Our findings confirm that OHT and glaucoma are frequent complications in AK. Patients treated with a regimen containing corticosteroids are at a higher risk; thus, they should receive close intraocular pressure monitoring.

Acanthamoeba Keratitis in Egypt: Characteristics and Treatment Outcomes

Purpose

To study the predisposing factors, clinical manifestations, and treatment outcome of patients with Acanthamoeba keratitis (AK) at Tanta University’s Ophthalmology Hospital in Tanta, Egypt.

Methods

A retrospective study of 42 patients (44 eyes) with Acanthamoeba keratitis who had medical records available for review over 4 years.

Results

Forty-four eyes of 42 patients were treated for AK over the study period. In 29 eyes (65.8%), AK was related to contact lens wear. Severe ocular pain was the main presenting symptom in 38 eyes (86.3%). The most common ocular signs were radial perineural corneal infiltrates (65.9%), pseudo-dendrites (43.2%), ring infiltrates (45.5%), and diffuse stromal infiltration (59%). Acanthamoeba was detected by culture, smear, and in-vivo confocal microscopy (IVCM) in 25 eyes (56.8%), while in 19 eyes (43.2%) the diagnosis was based solely on the clinical findings. IVCM was effective in detection of Acanthamoeba in cases with early presentation, while culture was more sensitive in late presentation with corneal melting. The mean duration of treatment was 73.3 ± 23.7 days. Surgical intervention in the form of tectonic grafts or amniotic membrane transplant was required in five cases (11.3%) due to progressive corneal thinning and perforation. Seventeen patients (38.6%) had 0.2 or better final best-corrected visual acuity after treatment.

Conclusion

The diagnosis of AK remains a major challenge for most ophthalmologists. Contact lens abuse is the major risk factor. Early diagnosis and appropriate treatment of AK with biocidal agents can improve the final outcome and help avoid surgical intervention. IVCM is an excellent tool for early diagnosis of AK.

Challenges in Acanthamoeba Keratitis: A Review

To review challenges in the diagnosis and management of Acanthamoeba keratitis (AK), along with prognostic factors, in order to help ophthalmologists avoid misdiagnosis, protracted treatment periods, and long-term negative sequelae, with an overarching goal of improving patient outcomes and quality of life, we examined AK studies published between January 1998 and December 2019. All manuscripts describing clinical manifestations, diagnosis, treatment, prognosis, and challenges in short- and long-term management were included. The diagnosis of AK is often challenging. An increased time between symptom onset and the initiation of appropriate therapy is associated with poorer visual outcomes. The timely initiation of standardized antiamoebic therapies improves visual outcomes, decreases the duration of treatment, and reduces the chances of needing surgical intervention. In clinical practice, AK diagnosis is often missed or delayed, leading to poorer final visual outcomes and a negative impact on patient morbidity and quality of life.

Evaluation of Acanthamoeba keratitis cases in a tertiary medical care centre over 21 years

To report on Acanthamoeba keratitis cases in a tertiary university eye-hospital in Graz, Austria, over a 21-year period. Retrospective study. Parameters included demographics, diagnostics, clinical courses, medical therapies, surgical interventions, secondary complications, and best spectacle-corrected visual acuity (BSCVA). Patient records for 44 eyes of 42 patients were analysed; 2 bilateral infections. Mean age at presentation was 31 ± 13 (16-65) years; contact lenses were used in 41 of 44 eyes (93.2%). Symptoms at initial presentation were mainly pain (41/43, 95.3%) and photophobia (16/43, 37.2%). Most frequent morphological findings were stromal infiltrates (30/44, 68.2%). Diagnosis was mainly confirmed by smears (40/42, 95.2%) and polymerase chain reaction (8/42, 19%). Antiamoebic treatment comprised biguanides and diamidines. Penetrating keratoplasty was performed in 10/44 (22.7%) eyes. Median time from symptom onset to initial visit was 2 (0-26) weeks; median follow-up was 30 (2-1008) weeks. BSCVA improved in 23/36 (63.9%) eyes, remained unchanged in 6/36 (16.7%) eyes and deteriorated in 7/36 (19.4%) eyes. Acanthamoeba keratitis predominantly occurs in young contact lens wearers. Diagnosis should be considered in patients with pain and stromal infiltrates. In the majority of cases, BSCVA can be improved. Early diagnosis and adequate treatment should be implemented to prevent complications.

Effectiveness and Safety of Topical Chlorhexidine and Vitamin E TPGS in the Treatment of Acanthamoeba Keratitis: A Survey on 29 Cases

This study aimed to test the effectiveness of a solution of chlorhexidine (CHX) and D-α-tocopheryl polyethylene glycol succinate (Vitamin E TPGS or TPGS) in the treatment of Acanthamoeba keratitis (AK) via a prospective, interventional case series study. Twenty-nine consecutive patients with AK were enrolled. At baseline, best-corrected visual acuity (BCVA), slit lamp examination, confocal microscopy, and polymerase chain reaction (PCR) were performed. Topical therapy with CHX 0.02% and VE-TPGS 0.2% was administered hourly/24 h for the first day, hourly in the daytime for the next three days, and finally, every two hours in the daytime up to one month. BCVA and ocular inflammation were recorded after two weeks, four weeks, and three months from baseline. Mean logMAR BCVA significantly improved at two weeks (0.78) compared to baseline (1.76), remaining stable over time (0.80 at four weeks, 0.77 at three months). Ocular inflammation improved in 14 eyes at 2 weeks, with further slow improvements in all cases. At three months, no patient had signs of corneal inflammation. The presence of corneal scars was first recorded at the two-week follow-up, with an enlargement at the four-week follow-up. At the three-month follow-up, 19 eyes still showed corneal opacities. In conclusion, the tested solution was shown to be effective for the treatment of AK. Furthermore, it might represent a good first-line treatment.

Seasonal patterns of incidence, demographic factors and microbiological profiles of infectious keratitis: the Nottingham Infectious Keratitis Study

PURPOSE

The purpose of this study is to examine the seasonal patterns of incidence, demographic factors and microbiological profiles of infectious keratitis (IK) in Nottingham, UK.

METHODS

A retrospective study of all patients who were diagnosed with IK and underwent corneal scraping during 2008-2019 at a UK tertiary referral centre. Seasonal patterns of incidence (in per 100,000 population-year), demographic factors, culture positivity rate and microbiological profiles of IK were analysed.

RESULTS

A total of 1272 IK cases were included. The overall incidence of IK was highest during summer (37.7, 95% confidence interval (CI): 31.3-44.1), followed by autumn (36.7, 95% CI: 31.0-42.4), winter (36.4, 95% CI: 32.1-40.8) and spring (30.6, 95% CI: 26.8-34.3), though not statistically significant (p = 0.14). The incidence of IK during summer increased significantly over the 12 years of study (r = 0.58, p = 0.049), but the incidence of IK in other seasons remained relatively stable throughout the study period. Significant seasonal variations were observed in patients' age (younger age in summer) and causative organisms, including Pseudomonas aeruginosa (32.9% in summer vs. 14.8% in winter; p < 0.001) and gram-positive bacilli (16.1% in summer vs. 4.7% in winter; p = 0.014).

CONCLUSION

The incidence of IK in Nottingham was similar among four seasons. No temporal trend in the annual incidence of IK was observed, as reported previously, but there was a significant yearly increase in the incidence of IK during summer in Nottingham over the past decade. The association of younger age, P. aeruginosa and gram-positive bacilli infection with summer was likely attributed to contact lens wear, increased outdoor/water activity and warmer temperature conducive for microbial growth.

Personal hygiene risk factors for contact lens-related microbial keratitis

Objective

Microbial keratitis is a sight-threatening complication of contact lens wear, which affects thousands of patients and causes a significant burden on healthcare services. This study aims to identify compliance with contact lens care recommendations and identify personal hygiene risk factors in patients who develop contact lens-related microbial keratitis.

Methods and analysis

A case–control study was conducted at the University Hospital Southampton Eye Casualty from October to December 2015. Two participant groups were recruited: cases were contact lens wearers presenting with microbial keratitis and controls were contact lens wearers without infection. Participants underwent face-to-face interviews to identify lens wear practices, including lens type, hours of wear, personal hygiene and sleeping and showering in lenses. Univariate and multivariate regression models were used to compare groups.

Results

37 cases and 41 controls were identified. Showering in contact lenses was identified as the greatest risk factor (OR, 3.1; 95% CI, 1.2 to 8.5; p=0.03), with showering daily in lenses compared with never, increasing the risk of microbial keratitis by over seven times (OR, 7.1; 95% CI, 2.1 to 24.6; p=0.002). Other risks included sleeping in lenses (OR, 3.1; 95% CI, 1.1 to 8.6; p=0.026), and being aged 25–39 (OR, 6.38; 95% CI, 1.56 to 26.10; p=0.010) and 40–54 (OR, 4.00; 95% CI 0.96 to 16.61; p=0.056).

Conclusion

The greatest personal hygiene risk factor for contact lens-related microbial keratitis was showering while wearing lenses, with an OR of 3.1, which increased to 7.1 if patients showered daily in lenses. The OR for sleeping in lenses was 3.1, and the most at-risk age group was 25–54.

Acanthamoeba Keratitis: Current Status and Urgent Research Priorities

Background:

First discovered in the early 1970s, Acanthamoeba keratitis has remained a major eye infection and presents a significant threat to the public health, especially in developing countries. The aim is to present a timely review of our current understanding of the advances made in this field in a comprehensible manner and includes novel concepts and provides clear directions for immediate research priorities.

Methods:

We undertook a search of bibliographic databases for peer-reviewed research literature and also summarized our published results in this field.

Results:

The present review focuses on novel diagnostic and therapeutic strategies in details which can provide access to management and treatment of Acanthamoeba keratitis. This coupled with the recently available genome sequence information together with high throughput genomics technology and innovative approaches should stimulate interest in the rational design of preventative and therapeutic measures. Current treatment of Acanthamoeba keratitis is problematic and often leads to infection recurrence. Better understanding of diagnosis, pathogenesis, pathophysiology and therapeutic regimens, would lead to novel strategies in treatment and prophylaxis.

Acanthamoeba keratitis therapy: time to cure and visual outcome analysis for different antiamoebic therapies in 227 cases

AIMS

To test the hypothesis that Acanthamoeba keratitis (AK) outcomes differ for different topical antiamoebic therapies (AAT) and to provide the detailed patient outcome data.

METHODS

A retrospective cohort study of 227 patients developing AK between 25 July 1991 and 10 August 2012. Inclusion criteria required a complete record of AAT treatment for both the primary outcome of a medical cure rate at 12 months and the secondary outcome of Snellen visual acuity ≤6/24 and/or surgical intervention. Analysis used multivariable regression to control for differences in baseline disease characteristics for both primary and secondary outcomes with unadjusted analyses for other outcomes. Subjects were categorised for analysis both by the AAT used at baseline and also by mutually exclusive AAT (patients exposed to all the drugs in each group, and no others, for some period). AAT categories were PHMB monotherapy, PHMB+diamidine, PHMB+chlorhexidine+diamidine, diamidine monotherapy and other AAT.

RESULTS

Analysis by baseline AAT showed no notable difference between treatments for both a medical cure at 12 months in 60.79% (138/227) or for a poor outcome in 49.34% (112/227). When AATs were analysed by mutually exclusive groups, PHMB monotherapy provided the best outcomes. These findings are subject to bias requiring careful interpretation. Overall cure rates for the 214 subjects with resolved outcomes were 94.27% (214/227), median time to cure 5 months (IQR 3.25-9.00 months) and range 1-26.24 months.

CONCLUSION

PHMB 0.02% monotherapy for the initial treatment of AK is as effective as biguanide+diamidine combination therapy. Chlorhexidine monotherapy was too infrequent for comparison. The outcome data are the most detailed available.

Therapeutic penetrating keratoplasty for acanthamoeba keratitis: a review of cases, complications and predictive factors

PURPOSE

To review 12 acanthamoeba keratitis (AK) patients who required a therapeutic penetrating keratoplasty (TPK) and determine whether there are factors at the presenting visit that can predict the need for TPK.

MATERIALS AND METHODS

This was a retrospective case series. All diagnosed AK patients between January, 2009 and February, 2016 at Wills Eye Hospital, Philadelphia, PA, USA, were enrolled. Information regarding demographics, disease manifestation, management and complications was collected. Potential predictors for TPK were obtained by comparing TPK cases with those who were treated medically.

RESULTS

Sixty-three eyes from 63 patients were diagnosed with AK. Twelve eyes (19%) required TPK during the course of treatment, and 51 eyes (81%) were treated medically. Reasons for performing TPK included medically non-responsive ulcer in seven eyes (58%), perforated ulcer in three eyes (25%) and significant corneal thinning in two eyes (17%). The most common post-TPK complications included graft failure (75%), cataract (50%) and uncontrolled glaucoma required glaucoma surgery (17%). Reactivation of AK was seen in one (8%) patient. Anti-amoebic treatment beginning after 25 days from the start of AK symptoms [odds ratio (OR) = 7.63; confidence interval (CI) = 1.01-55.33; p = 0.041] and poorer presenting vision (OR = 5.42; CI = 1.91-15.36; p = 0.002) were independent predictors of the need for TPK in multivariate analysis.

CONCLUSION

TPK is a procedure with significant postoperative complications but is required by some patients with AK. Eyes with higher risk for needing TPK can be identified earlier and thus provided more intensive treatment and closer follow-up care.

Acanthamoeba keratitis - Clinical signs, differential diagnosis and treatment

PURPOSE

To summarize actual literature data on clinical signs, differential diagnosis, and treatment of acanthamoeba keratitis.

METHODS

Review of literature.

RESULTS

Clinical signs of acanthamoeba keratitis are in early stages grey-dirty epithelium, pseudodendritiformic epitheliopathy, perineuritis, multifocal stromal infiltrates, ring infiltrate and in later stages scleritis, iris atrophy, anterior synechiae, secondary glaucoma, mature cataract, and chorioretinitis. As conservative treatment, we use up to one year triple-topical therapy (polyhexamethylene-biguanide, propamidine-isethionate, neomycin). In therapy resistant cases, surgical treatment options such as corneal cryotherapy, amniotic membrane transplantation, riboflavin-UVA cross-linking, and penetrating keratoplasty are applied.

CONCLUSION

With early diagnosis and conservative or surgical treatment, acanthamoeba keratitis heals in most cases.

"Therapeutic Penetrating Keratoplasty: A Retrospective Review"

PURPOSE

To report the indications, outcomes, and complications of therapeutic penetrating keratoplasty (Th PK) in patients with corneal perforation and/or nonhealing corneal ulceration.

METHODS

A retrospective review was conducted of 51 eyes of 51 patients undergoing Th PK between January 1, 2006 and April 15, 2016. Data collected included patient demographics, visual acuity (VA), size of the corneal infiltrate and epithelial defect, degree of corneal thinning/perforation, microbiological results, surgical details, and postoperative complications.

RESULTS

The average age at presentation was 56.0 years (range 6-92 years), and most of the patients were females (n=31, 60.8%). Th PK was performed for corneal perforation in 28 eyes (54.9% of cases), nonhealing corneal ulcer in 16 eyes (31.4% of cases), and imminent risk of corneal perforation in 7 eyes (13.7% of cases). Infection was the most common reason for performing a Th PK and was present in 92.3% (47/51) of all cases. Of the infectious cases, the most common etiologies were bacterial (44.7%, 21/47) and fungal (31.9%, 15/47). The most common identifiable risk factor for undergoing a Th PK was a history of contact lens wear, which was seen in 32.7% of patients. Initial anatomic success was achieved in all patients after performing Th PK. Most patients (33/51; 64.7%) had clear grafts at their last follow-up examination. There was an improvement in VA in 70.2% (33/47, where data were available) of the patients at the final postoperative visit compared with the preoperative visit. Average best postoperative VA (1.14±0.88 logarithm of the minimum angle of resolution [LogMAR]; 20/276) was significantly better than the presenting (1.98±0.68 LogMAR; 20/1910) and preoperative (2.18±0.55 LogMAR; 20/3,027) visual acuities (P<0.0001). The most common complication after Th PK was cataract, which was present in 81.8% (27/33) of phakic eyes in which lens status could be assessed, followed by graft failure (47.1%; 24/51), and secondary glaucoma (45.1%; 23/51). Five eyes developed infection in the therapeutic graft, four eyes had persistent corneal epithelial defect at their last follow-up visit, and two eyes underwent evisceration.

CONCLUSIONS

Therapeutic penetrating keratoplasty achieves anatomic success and it is a useful procedure for restoring a stable cornea in cases in which infection fails to heal or when the cornea perforates. Furthermore, Th PK achieves corneal clarity and improves vision in most patients.

Effect of ethanol pretreatment in Acanthamoeba keratitis: a long-term follow-up study

Purpose

The aim of this study was to evaluate the long-term outcomes of ethanol pretreatment in Acanthamoeba keratitis (AK).

Patients and methods

This single-center, retrospective, interventional study included 22 patients (24 eyes) who developed AK and underwent ethanol pretreatment between 2009 and 2015. Samples for smears, polymerase chain reaction, and culture for evidence of Acanthamoeba were collected. After ethanol pretreatment, the patients were treated with corneal epithelial debridement, topical 0.02% polyhexamethylene biguanide, and 0.1% propamidine isethionate. The primary outcomes were a clinically stable ocular surface, complete recovery from corneal infection, and acceptable corneal haze. The secondary outcome measure was improvement in best-corrected visual acuity. Complications and predictors of the visual outcome were also recorded.

Results

Ethanol pretreatment was successful in 20 (83.3%) of the 24 eyes, and no further optical keratoplasty was required. Four eyes required rescue therapeutic keratoplasty because of rapid progression of AK. Patients in whom ethanol pretreatment was successful achieved good final visual outcomes regardless of sex, age, or causative Acanthamoeba species. Patients with worse initial best-corrected visual acuity and rigid gas permeable lens-related AK had better improvement in vision.

Conclusion

Ethanol as a pretreatment for AK is safe and effective. Combined with corneal epithelial debridement, ethanol pretreatment may preclude the need for optical and therapeutic keratoplasty. This technique is suitable for all stages of AK presenting within 3 weeks of symptom onset and achieves favorable results especially in early AK.

Risk factors, demographics and clinical profile of Acanthamoeba keratitis in Melbourne: an 18-year retrospective study

Purpose

To assess incidence, risk factors, presentation and final visual outcome of patients with Acanthamoebakeratitis (AK) treated at the Royal Victorian Eye and Ear Hospital (RVEEH), Melbourne, Australia, over an 18-year period.

Methods

A retrospective review of all cases of AK managed at RVEEH between January 1998 and May 2016 was performed. Data collected included age, gender, affected eye, signs and symptoms, time between symptoms and diagnosis, risk factors, presenting and final visual acuity (VA), investigations, medical treatment, surgical interventions and length of follow-up.

Results

A total of 36 eyes affected by AK in 34 patients were identified. There were 26 cases diagnosed early (<30 days) and 10 were diagnosed late (≥30 days). There were 31 (86.1%) cases associated with contact lens (CL). Signs associated with early AK included epithelial infiltrates, while signs of late AK included uveitis, ring infiltrate, endothelial plaque and corneal thinning (p<0.05). Surgical treatment was required in seven cases (19.4%). There were 29 (80.6%) cases that reported improved VA. Median best corrected final VA was worse in patients with late diagnosis (logarithm of minimal angle of resolution (logMAR) 0.5, IQR: 0.2–0.8), compared with patients with early diagnosis (logMAR 0.0, IQR: 0.0–0.3; p=0.01). Late diagnosis was associated with a prolonged disease period.

Conclusion

AK was an uncommon cause of severe keratitis and was associated commonly with CL. Patients with late diagnosis had worse presenting and final VAs as well as a prolonged disease period, indicating need for early recognition and management.

Rapid resolution of stromal keratitis with the assistance of oral voriconazole in resistant acanthamoeba keratitis

Acanthamoeba keratitis (AK) is an unusual infectious disease of the cornea which sometimes leads to blindness. We report the experience of adding oral voriconazole in conjunction with topical antiacanthamoebic drops to treat refractory AK. A 20-year-old girl experienced a deep stromal keratitis with large epithelial defect in the left eye, suspected as AK. The initial best-corrected visual acuity (BCVA) of the eye was counting finger. She received topical chlorhexidine 0.02% and voriconazole 1% during the first 14 days but in vain. Oral voriconazole was administered and resulted in a rapid regression of the lesion. A total resolution was achieved after 2 weeks of triple combination therapy. The BCVA of the left eye finally achieved 20/20 at 6-month follow-up. Although oral voriconazole was seldom used in treating acute AK, the additional use of oral voriconazole combined with topical antiacanthamoebic drugs may help to achieve a successful treatment effect in refractory stromal AK.

Use of adjunctive topical corticosteroids in bacterial keratitis

PURPOSE OF REVIEW

Topical corticosteroid use in the setting of infectious keratitis has been a controversial issue. The aim of this review is to provide an update on the evidence for use of topical corticosteroids in addition to antibiotics in bacterial keratitis.

RECENT FINDINGS

Judicious use of steroids is postulated to limit the inflammatory component of bacterial keratitis, but can theoretically retard healing. Three small randomized controlled trials and one large-scale trial, the Steroids for Corneal Ulcers Trial, have provided the most recent evidence to address this debate. Adjunctive topical corticosteroids initiated after at least 48 h of antibiotic usage in cases of culture-proven bacterial keratitis appear generally safe in the treatment of bacterial keratitis. They may be beneficial in cases of severe ulcers especially when initiated early in the course of the infection, in non-Nocardia ulcers, and in certain Pseudomonas ulcers.

SUMMARY

Several randomized controlled trials have greatly contributed to our understanding of the controversy over steroid use in the management of bacterial keratitis. Future studies are needed to confirm subgroup analysis findings and define optimal timing, dosage, and the most appropriate treatment populations.

Emerging trends in contact lens-related infections

PURPOSE OF REVIEW

This article reviews the literature on past and recent trends in contact lens-related microbial keratitis from bacterial, fungal, and Acanthamoeba infections.

RECENT FINDINGS

Contact lens wear is the most important risk factor for microbial keratitis. Despite increased use of daily disposable contact lens wear, the incidence of bacterial ulcers related to contact lens wear remains high. Overnight contact lens wear is the leading risk factor in contact lens-related bacterial infections. There may be a trend towards increasing antibiotic resistance of Gram-positive bacteria to fourth-generation fluoroquinolones. The incidence of Acanthamoeba and fungal infections, despite resolution of two outbreaks involving multipurpose solutions, are also on the rise.

SUMMARY

Contact lens-related microbial keratitis is rising and may be associated with more severe, vision threatening, infections.

Seasonal, geographic, and antimicrobial resistance patterns in microbial keratitis: 4-year experience in eastern Pennsylvania

PURPOSE

The aim of this study was to review the demographics, causative organisms, seasonal and geographic variation, and antimicrobial resistance patterns of microbial keratitis at our institution over a 4-year period.

METHODS

Electronic medical records of all patients with microbial keratitis who underwent corneal culturing at a single institution in eastern Pennsylvania between January 1, 2009 and December 31, 2012 were reviewed.

RESULTS

A total of 311 patients representing 323 instances of infectious keratitis were analyzed. The most frequently implicated organisms in contact lens-related infections were Pseudomonas aeruginosa for bacteria and Fusarium species for fungus, compared with Staphylococcus aureus and Candida species in non-contact lens-associated bacterial infections. Bacterial keratitis occurred most frequently in spring and least frequently in winter (P = 0.024). Patients who live in large fringe metro (suburban) areas accounted for the highest proportion of infectious keratitis cases. P. aeruginosa and methicillin-sensitive S. aureus isolates were highly susceptible to fluoroquinolones, whereas 32% of coagulase-negative staphylococcus isolates tested were resistant to moxifloxacin and gatifloxacin, and all methicillin-resistant S. aureus organisms tested were resistant to these 2 fluoroquinolones. No organisms tested were resistant to tobramycin, gentamicin, or vancomycin. No fungal infections tested were resistant to voriconazole.

CONCLUSIONS

Most infectious keratitis occurred in nonwinter months and in patients from suburban counties. Although fluoroquinolones were effective against the most common bacteria, staphylococcal species exhibited a high rate of resistance, representing a therapeutic challenge given the increasing use of fluoroquinolones as first-line monotherapy. No organisms tested were resistant to tobramycin, gentamicin, vancomycin, or voriconazole.

Chlorhexidine Monotherapy with Adjunctive Topical Corticosteroids for Acanthamoeba Keratitis

PURPOSE

To assess the efficacy of chlorhexidine monotherapy for Acanthamoeba keratitis, and to determine the therapeutic outcomes of concomitant topical corticosteroids.

METHODS

In this prospective interventional case series, 31 eyes of 31 patients with Acanthamoeba keratitis (AK) were treated with chlorhexidine 0.02% as monotherapy, from April 2010 to April 2011. The diagnosis of AK was made based on clinical manifestations and positive confocal microscopic (confoscan 3.4, Nidek Co. Ltd., Gamagori, Japan) results. We report the percentage of a favorable clinical response within two weeks of initiating treatment, worsening of the infection while receiving chlorhexidine, recovery of visual acuity (VA), duration of treatment with chlorhexidine and corticosteroids, necessity for addition of other anti-Acanthamoeba agents, presence of corneal scar at the end of the treatment, and need for penetrating keratoplasty (PK).

RESULTS

Two weeks after initiation of chlorhexidine, improvement in signs and symptoms was observed in 26 (83.9%) patients but 3 eyes required the addition of propamidine. After initial improvement in one patient, the infection worsened, necessitating the addition of Polyhexamethylene Biguanide (PHMB) and propamidine. A total of 26 (83.9%) patients received topical corticosteroids with mean duration of 65.8 ± 45.1 days. In 22 (71%) eyes, final visual acuity was ≥0.80. Improved VA occurred in 29 eyes (93.5%). Optical PK was considered in 3 (9.7%) eyes and a corneal scar developed in 8 (25.8%) eyes.

CONCLUSION

Chlorhexidine is effective for monotherapy in AK and could be a good choice for initiating treatment. After the initial response to anti-Acanthamoeba agents, corticosteroids can be used as adjunctive therapy depending on the clinical condition.

Clinical characteristics of Acanthamoeba keratitis infections in 28 states, 2008 to 2011

PURPOSE

The aim was to describe a geographically and clinically diverse sample of cases of Acanthamoeba keratitis (AK) and establish the risk factors for poor outcomes among patients with this disease.

METHODS

We conducted a retrospective, population-based case series of 116 patients with AK identified through a national surveillance network. Data were collected via a medical record review by diagnosing ophthalmologists and by phone interviews with patients. Exact logistic regression modeling was used to determine risk factors for poor visual outcomes.

RESULTS

Among patients with data available on contact lens use, it was found that 93.3% wore contact lenses. The median time from symptom onset to care seeking was 2 days, whereas the median time from symptom onset to diagnosis was 27 days. Keratoplasty was performed in 27 of 81 patients with available outcome data and was more likely in patients >40 years old [odds ratio (OR) 5.25, 95% confidence interval (CI) 1.49-21.92]. When adjusted for age, the risk factors for keratoplasty included the presence of a ring infiltrate (OR 40.00, 95% CI 3.58-447.0) or any sign of stromal invasion (OR 10.48, 95% CI 2.56-55.09). One-third of patients with available data on best-corrected visual acuity had a best-corrected visual acuity <20/200, with the presence of a ring infiltrate as the only significant predictor of this outcome when adjusted for age (aOR 3.45, 95% CI 1.01-12.31).

CONCLUSIONS

AK remains challenging to diagnose. Consequently, patients with advanced disease are more likely to have poor outcomes, particularly if they are older. The increasing awareness of AK among general eye care providers may shorten referral times and potentially improve outcomes.

The impact of topical corticosteroid use before diagnosis on the outcome of Acanthamoeba keratitis

OBJECTIVE

To examine the impact of topical corticosteroid use before the diagnosis of Acanthamoeba keratitis (AK) on final visual outcomes and to determine the prognostic factors predicting poorer outcomes.

DESIGN

Cohort study.

PARTICIPANTS

A total of 209 eyes of 196 patients with retrievable medical records, diagnosed with AK at Moorfields Eye Hospital, London, between January 1991 and April 2012. One eye was randomly excluded from analysis in the 13 cases of bilateral AK.

METHODS

Patient demographic, initial clinical examination findings, and management details were collected. The outcomes of patients treated with topical corticosteroids before diagnosis of AK were compared with those not treated with topical corticosteroids before diagnosis. A multivariable logistic model, optimized for prior corticosteroid use, was used to derive the odds ratios (ORs) of a suboptimal visual outcome.

MAIN OUTCOME MEASURES

Suboptimal visual outcome was defined as final visual acuity (VA) ≤ 20/80, corneal perforation, or need for keratoplasty.

RESULTS

Acanthamoeba keratitis was diagnosed on microbiological culture in 94 eyes (48.0%), on histopathologic examination in 27 eyes (13.8%), on confocal microscopy in 38 eyes (19.4%), and on the basis of a typical clinical course and response to treatment in 37 eyes (18.9%). Final VA and prior corticosteroid use data were available for 174 eyes (88.8%). In multivariable analysis, corticosteroid use before diagnosis was associated with suboptimal visual outcome (OR, 3.90; 95% confidence interval [CI], 1.78-8.55), as were disease stage 3 at presentation (OR, 5.62; 95% CI, 1.59-19.80) and older age (60+ years) at diagnosis (OR, 8.97; 95% CI, 2.13-37.79).

CONCLUSIONS

Corticosteroid use before diagnosis of AK is highly predictive of a poorer visual outcome. This is largely due to the initial misdiagnosis of AK as herpetic keratitis. It is important to include AK in the differential diagnosis of keratitis in all contact lens users with keratitis, particularly before making a diagnosis of herpes keratitis and before the use of topical corticosteroids in the therapy of any indolent keratitis.

Influence of Acanthamoeba genotype on clinical course and outcomes for patients with Acanthamoeba keratitis in Spain

Genotype T4 is by far the most frequent genotype of Acanthamoeba keratitis (AK) and therefore has been considered the most virulent. This study included 14 cases of AK of genotype T4 and three cases of non-T4 genotype. We found that cases of non-T4 genotype had a worse response to medical therapy, greater need for surgical intervention, greater risk of extracorneal involvement, and remarkably poorer final visual outcome than those of T4 genotype, suggesting an association between Acanthamoeba virulence and genotype that requires additional case investigation.

Acanthamoeba, fungal, and bacterial keratitis: a comparison of risk factors and clinical features

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.

[Effectiveness of initial antibiotic therapy for treatment of contact lens-related bacterial keratitis]

BACKGROUND

Contact lens-related microbial keratitis is a cause of potentially sight-threatening corneal opacification. Effective initial antimicrobial therapy is crucial to prevent long-term complications. This investigation was undertaken to test the effectiveness of current routine empirical antibiotic treatment regimens.

METHODS/PATIENTS

All consecutive cases of contact lens-related keratitis presenting in the outpatient clinic of the Department of Ophthalmology at the Medical University of Innsbruck between January 2010 and April 2012 were retrospectively analyzed.

RESULTS

Cultures were positive in 69 out of the 123 cases included in the study. Culture results identified 59.4 % Gram positive strains, 50.7 % Gram negative strains and 7.2 % fungal strains. Mixed infections accounted for 29 % of cases. The combination of an aminoglycoside and a second generation quinolone antibiotic was the most common initial treatment regimen (87.8 %). In vitro this regimen was less effective compared to combinations of moxifloxacin and ciprofloxacin or moxifloxacin and gentamicin.

CONCLUSION

Empirical combined regimens remain an effective treatment of contact lens-related keratitis. Fluoroquinolones proved to be inadequate for monotherapy.

Effect of low concentrations of benzalkonium chloride on acanthamoebal survival and its potential impact on empirical therapy of infectious keratitis

IMPORTANCE

The significant antiacanthamoebal effect of benzalkonium chloride, at or below concentrations used for preservation of common ophthalmic preparations, should be understood both when choosing empiric antibiotic therapy for infectious keratitis and when assessing the persistent rise in Acanthamoeba cases in the United States since 2003.

OBJECTIVE

To characterize the antiacanthamoebal efficacy of low concentrations of benzalkonium chloride (BAK) for drug preservation and therapeutic effect against Acanthamoeba.

DESIGN

Experimental study with a review of the literature.

SETTING

Laboratory.

EXPOSURES

A concentration of 10(4) trophozoites of 3 well-characterized clinical strains of Acanthamoeba were exposed at 0.5, 2.0, 3.5, 5.0, and 6.5 hours to BAK (0.001%, 0.002%, and 0.003%), moxifloxacin hydrochloride (0.5%), and moxifloxacin (0.5%) + BAK (0.001% and 0.003%) with hydrogen peroxide (3%) and amoeba saline controls.

MAIN OUTCOMES AND MEASURES

Amoeba survival was calculated using the most probable number method recorded as log kill values. The relationship of BAK concentration and exposure time as well as the relative effect of BAK and moxifloxacin on acanthamoebal survival were analyzed.

RESULTS

Amoebicidal activity of BAK is both time dependent and concentration dependent in pooled and strain-stratified analyses (P < .001). Moxifloxacin demonstrated no significant independent inhibitory effect or additive effect to BAK efficacy on acanthamoebal survival. The profound antiacanthamoebal effect of BAK, 0.003%, was similar to that of hydrogen peroxide for certain strains.

CONCLUSIONS AND RELEVANCE

Low concentrations of BAK, previously demonstrated to concentrate and persist in ocular surface epithelium, exhibit significant antiacanthamoebal activity in vitro at or below concentrations found in commercially available ophthalmic anti-infectives. The unexplained persistence of the Acanthamoeba keratitis outbreak in the United States, clusters abroad, and clinical studies reporting resolution or modification of Acanthamoeba keratitis without specific antiacanthamoebal therapy suggests that other contributing factors should be considered, including changes in the formulations used for empirical therapy of presumed infectious keratitis occurring in the same period.

Prognostic factors associated with the need for surgical treatments in acanthamoeba keratitis

PURPOSE

The objective of this study was to assess the factors associated with anatomical and visual outcomes in patients presenting with Acanthamoeba keratitis (AK).

METHODS

This is a retrospective noncomparative interventional case series study comprising 44 eyes from 42 patients presenting with AK, treated with topical hexamidine diisethionate and topical polyhexamethylene biguanide, monitored between 2004 and 2008. AK was confirmed by polymerase chain reaction or direct microscopic examination. Correlation between clinical presentation and prognosis was assessed. Anatomical outcome was assessed according to the percentage of eyes requiring at least 1 surgical procedure in addition to topical treatment. Visual outcome was assessed by the best-corrected visual acuity at the end of follow-up.

RESULTS

Polymerase chain reaction results were positive for Acanthamoeba in 40 of the 44 eyes (91%) and in 16 of the 44 eyes (36%) by direct microscopic examination. Confocal microscopy suggested the presence of Acanthamoeba in 12 of 19 eyes (63%). Amniotic membrane transplantation was performed in 8 eyes, penetrating keratoplasty in 4 eyes, and evisceration in 2 eyes. The average follow-up time was 10 months. Surgical treatment was significantly associated (P < 0.05) with time from symptom onset to diagnosis of >30 days, an initial visual acuity of ≤20/200, an infiltrate size of >3 mm, preperforating infiltrates, and corneal neovascularization. The average final visual acuity was 20/48 in eyes that did not require surgical treatment (n = 34) and 20/1702 in eyes that required at least 1 surgical procedure (n = 10; P < 0.0001).

CONCLUSIONS

Late diagnosis, low initial visual acuity, corneal neovascularization, large infiltrates, and preperforated infiltrates were associated with surgical treatment in patients presenting with AK. Surgical intervention was associated with worse visual outcome.

[Delayed course of Acanthamoeba keratitis]

A 35-year-old male presented with corneal ulceration on the left eye with a history of treatment over several months. At the first visit in our department we saw an elliptically shaped ulcerative stromal keratitis with circular peripheral neovascularization. There was organized hypopyon with hyphemia. The best corrected visual acuity (BCVA) was light perception. The patient had used contact lenses for many years. Under the suspicion of herpetic keratitis due to a positive "dendrite" the patient had undergone antiviral therapy for 6 months in a different department. Our diagnosis was Acanthamoeba keratitis. We performed penetrating excimer laser keratoplasty-à-chaud (8.0 × 7.0 mm/8.1 × 7.1 mm) with simultaneous cryotherapy of the mid-peripheral cornea. The topical therapy was polyhexamethylene biguanide, propamidine isoethionate, neomycin and steroids in intervals. A repeat penetrating excimer laser keratoplasty (8.5 × 7.5 mm/8.6 × 7.6 mm) with simultaneous amniotic membrane patch and lateral tarsorrhaphy was performed 2 months later due to melting of the graft with positive Seidel test. After successful surgery of the mature cataract the BCVA was 20/25. In a patient with a positive contact lens history acanthamoeba keratitis should always be considered as a differential diagnosis to herpes simplex keratitis in the early course of the disease.

Bowman's layer encystment in cases of persistent Acanthamoeba keratitis

BACKGROUND

The purpose of this study was to report Acanthamoeba encystment in Bowman's layer in Japanese cases of persistent Acanthamoeba keratitis (AK).

METHODS

Laser confocal microscopic images of the cornea were obtained in vivo from 18 consecutive eyes from 17 confirmed AK patients. Retrospectively, 14 cases treated over 4 months were categorized as a nonpersistent group and three cases that required prolonged therapy for more than 6 months were categorized as a persistent group. Clinical outcomes based on final best-corrected visual acuity were retrospectively analyzed, and selected confocal images were evaluated qualitatively for abnormal findings.

RESULTS

The final best-corrected visual acuity was significantly lower (P < 0.01) for patients in the persistent group compared with that in the nonpersistent group. At the initial visit, in vivo confocal microscopy demonstrated Acanthamoeba cysts exclusively in the epithelial layer in both the nonpersistent group (80%) and the persistent group (100%). At a subsequent follow-up visit, numerous Acanthamoeba cysts were observed in the epithelial cell layer and in Bowman's layer in all patients with persistent AK, but Acanthamoeba cysts were undetectable in all cases with nonpersistent AK tested.

CONCLUSION

Invasion of cysts into Bowman's layer was characteristically observed in patients with persistence of AK. This finding suggests that invasion of Acanthamoeba cysts into Bowman's layer may be a useful predictor for a persistent clinical course.

Assessment of real-time polymerase chain reaction detection of Acanthamoeba and prognosis determinants of Acanthamoeba keratitis

OBJECTIVE

To evaluate the diagnostic value of real-time polymerase chain reaction (PCR) for detecting Acanthamoeba in eyes diagnosed with Acanthamoeba keratitis (AK) by conventional tests. In addition, to determine the preoperative prognosis-determining factors in eyes with AK.

DESIGN

Retrospective, cross-sectional study.

PARTICIPANTS

A total of 104 eyes of 103 patients who were diagnosed with AK or with bacterial or bacteria-associated keratitis (BK) by conventional tests.

METHODS

Twenty-nine eyes with AK and 75 eyes with BK were evaluated for Acanthamoeba and bacterial DNA by real-time PCR. The Acanthamoeba copy numbers, bacterial load, and clinical parameters in the patients with AK were assessed for those significantly associated with poor outcome, that is, final visual acuity of <20/50 or requiring keratoplasty, by logistic regression analysis.

MAIN OUTCOME MEASURES

Acanthamoeba DNA copy number, bacterial DNA copy number, and odds ratio (OR) for poor prognosis.

RESULTS

The detection of amoebic DNA was 50 times more sensitive by real-time PCR than by conventional cyst counting. The Acanthamoeba copy numbers at the first visit (mean: 4.7×10(5)±3.2×10(5) copies) were significantly correlated with the AK stage, and both were significant risk factors for a poor outcome. The Acanthamoeba DNA copy numbers at the first visit and AK stage had a significantly high risk for poor outcome (OR of Acanthamoeba DNA copy per logarithm of copy numbers: 3.48, 95% confidence interval [CI], 1.04-111.63, P<0.05; OR of AK stage: 2.8 per stage increase, 95% CI, 1.07-7.30, P<0.05, after adjustment of age). In the AK cases with poor outcome, the amoebic DNA was not reduced by more than 90% after 1 month of treatment. The weak amoebic reduction was significantly associated with advanced AK stages or previous use of steroids. Bacterial 16S rDNA was detected in 53.6% of the eyes with AK, but it was not associated with any risk for refractoriness.

CONCLUSIONS

Real-time PCR was effective in detecting and managing AK. The Acanthamoeba copy number and AK stage at the first visit were significantly associated with poor outcome.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.