Corneal graft survival after therapeutic keratoplasty for Acanthamoeba keratitis

Acanthamoeba keratitis - A review

This is a comprehensive review after a thorough literature search in PubMed-indexed journals, incorporating current information on the pathophysiology, clinical features, diagnosis, medical and surgical therapy, as well as outcomes of Acanthamoeba keratitis (AK). AK is a significant cause of ocular morbidity, and early diagnosis with timely institution of appropriate therapy is the key to obtaining good outcomes. The varied presentations result in frequent misdiagnosis, and co-infections can increase the morbidity of the disease. The first line of therapy continues to be biguanides and diamidines, with surgery as a last resort.

Corneal Transplantation for Infectious Keratitis: A Prospective Dutch Registry Study

PURPOSE

The aim of this study was to analyze real-world practice patterns and graft survival after corneal transplantation for infectious keratitis in the Netherlands.

METHODS

All consecutive keratoplasties for infectious keratitis registered in the Netherlands Organ Transplant Registry were included. Graft survival was analyzed using Kaplan-Meier survival curves with Cox regression to compare the 3 most common pathogens with subgroup analysis for type and reason of transplantation, sex, and graft size. Multivariable analysis was performed using the same explanatory factors.

RESULTS

Between 2007 and 2017, 1111 keratoplasties for infectious keratitis were registered in the Netherlands Organ Transplant Registry. The most common pathogens were viruses (n = 437), bacteria (n = 271), and Acanthamoeba (n = 121). Human leukocyte antigen (HLA) matching did not provide a significant survival benefit, whereas emergency procedures showed worse graft survival [hazard ratio (HR) = 0.40, P = 0.120; HR = 2.73, P < 0.001, respectively]. Graft size >8.5 mm was significantly worse than graft size 8.5 mm (HR = 2.062, P = 0.010). In therapeutic keratoplasty, graft survival was significantly worse for Acanthamoeba than viral keratitis (HR = 2.36, P = 0.008). In the multivariable model, adjusting for graft size, type, and reason for transplantation, viral and bacterial keratitis did not differ significantly in graft survival, and Acanthamoeba showed a significantly worse prognosis (vs. viral keratitis, HR = 2.30, P < 0.001; bacterial keratitis, HR = 2.65, P < 0.001).

CONCLUSIONS

Viral keratitis was the most common indication for transplantation, followed by bacterial and Acanthamoeba keratitis. HLA matching did not offer protection over elective non-HLA-matched procedures, whereas emergency procedures and grafts sized >8.5 mm showed poor survival. In optical keratoplasty, survival is high for all pathogens, whereas in therapeutic keratoplasty Acanthamoeba shows poor outcome.

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.

Rose Bengal Photodynamic Antimicrobial Therapy: A review of the intermediate term clinical and surgical outcomes

PURPOSE

To evaluate the intermediate term clinical outcomes of Rose Bengal Photodynamic Antimicrobial Therapy (RB-PDAT) for infectious keratitis. Secondarily, to evaluate the surgical outcomes of individuals that underwent optical keratoplasty after RB-PDAT.

DESIGN

Retrospective cohort study.

METHODS

Retrospective chart review of 31 eyes from 30 consecutive individuals with infectious keratitis refractory to standard medical therapy who underwent RB-PDAT at the Bascom Palmer Eye Institute between January 2016 and July 2020. Data collected included demographics, risk factors for infectious keratitis, microbiological diagnosis, Best Spectacle-Corrected Visual Acuity (BCVA), clinical outcomes after RB-PDAT and complication rates post-keratoplasty. RB-PDAT was performed as described in previous studies. Graft survival was evaluated using Kaplan Meier curves with log-ranks in individuals that underwent keratoplasty after RB-PDAT.

RESULTS

Mean age of the study population was 53±18.0 years. 70% were female; 53.3% self-identified as non-Hispanic White; 43.3% as Hispanic. Mean follow-up time was 28.0±14.4 months. Risk factors included contact lens use (80.6%), history of infectious keratitis (19.3%), and ocular surface disease (16.1%). Cultures were positive for Acanthamoeba (51.6%), Fusarium (12.9%), and Pseudomonas (6.5%). 22.5% of individuals with Acanthamoeba infection were treated with concomitant Miltefosine. Clinical resolution was achieved in 77.4% of individuals on average 2.72±1.85 months after RB-PDAT with 22.5% requiring therapeutic penetrating keratoplasties and 54.8% subsequently requiring optical penetrating keratoplasties. At 2 years, the overall probability of graft survival was 78.7% and the graft failure rate was 21.3%.

CONCLUSION

RB-PDAT is a potential adjunct therapy for infectious keratitis that may reduce the need for a therapeutic penetrating keratoplasty. Cases that undergo keratoplasty after RB-PDAT may have a higher probability of graft survival at one year postoperatively.

A history of over 40 years of potentially pathogenic free-living amoeba studies in Brazil - a systematic review

Free-living amoeba (FLA) group includes the potentially pathogenic genera Acanthamoeba, Naegleria, Balamuthia, Sappinia, and Vermamoeba, causative agents of human infections (encephalitis, keratitis, and disseminated diseases). In Brazil, the first report on pathogenic FLA was published in the 70s and showed meningoencephalitis caused by Naegleria spp. FLA studies are emerging, but no literature review is available to investigate this trend in Brazil critically. Thus, the present work aims to integrate and discuss these data. Scopus, PubMed, and Web of Science were searched, retrieving studies from 1974 to 2020. The screening process resulted in 178 papers, which were clustered into core and auxiliary classes and sorted into five categories: wet-bench studies, dry-bench studies, clinical reports, environmental identifications, and literature reviews. The papers dating from the last ten years account for 75% (134/178) of the total publications, indicating the FLA topic has gained Brazilian interest. Moreover, 81% (144/178) address Acanthamoeba-related matter, revealing this genus as the most prevalent in all categories. Brazil’s Southeast, South, and Midwest geographic regions accounted for 96% (171/178) of the publications studied in the present work. To the best of our knowledge, this review is the pioneer in summarising the FLA research history in Brazil.

Therapeutic Corneal Transplantation in Acanthamoeba Keratitis: Penetrating Versus Lamellar Keratoplasty

PURPOSE

The purpose of this article was to compare clinical outcomes between therapeutic penetrating keratoplasty (TPK), therapeutic deep anterior lamellar keratoplasty (TDALK), and optical penetrating keratoplasty (OPK) in Acanthamoeba keratitis.

METHODS

A literature search was conducted in online libraries from 1980 to 2021. The primary end points were best-corrected visual acuity (VA), graft survival, and infection recurrence. In addition, we enrolled 35 consecutive patients with AK from our practice evaluating best-corrected VA and high-order aberrations.

RESULTS

A total of 359 AK eyes from 33 published studies were retrieved from 175 publications screened. One hundred sixty-five eyes (73%) that underwent TPK and 39 eyes (84%) treated with TDALK had a clear graft at the last follow-up visit. Only the patients treated with OPK had 82 clear grafts (94%) during the follow-up period. Forty-seven (21%) of TPK patients reached VA ≥20/30, compared with 11 (25%) of TDALK patients and 35 (40%) of OPK patients. Acanthamoeba infection recurrence occurred in 38 eyes (16.8%) that underwent TPK, 9 (19%) that underwent TDALK, and 8 (9.5%) that underwent OPK. In our series, best-corrected visual acuity in nonsurgically treated patients was 1 ± 0.50 logMAR compared with 0 logMAR of surgically treated patients. High-order aberrations were significantly lower in surgically treated eyes after AK resolution, particularly in TDALK when compared with TPK patients. Best-corrected visual acuity was better in TDALK patients compared with TPK patients.

CONCLUSIONS

After AK resolution by 6 to 12 months of medical treatment, OPK seems to be the best surgical choice in patients with AK. If AK could not be eradicated by medical therapy, TDALK may be chosen in the early disease stage and TPK in later stages.

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

Post-keratoplasty infectious keratitis (PKIK) represents a unique clinical entity that often poses significant diagnostic and therapeutic challenges. It carries a high risk of serious complications such as graft rejection and failure, and less commonly endophthalmitis. Topical corticosteroids are often required to reduce the risk of graft rejection but their use in PKIK may act as a double-edged sword, particularly in fungal infection. The increased uptake in lamellar keratoplasty in the recent years has also led to complications such as graft-host interface infectious keratitis (IIK), which is particularly difficult to manage. The reported incidence of PKIK differs considerably across different countries, with a higher incidence observed in developing countries (9.2-11.9%) than developed countries (0.02-7.9%). Common risk factors for PKIK include the use of topical corticosteroids, suture-related problems, ocular surface diseases and previous corneal infection. PKIK after penetrating keratoplasty or (deep) anterior lamellar keratoplasty is most commonly caused by ocular surface commensals, particularly Gramme-positive bacteria, whereas PKIK after endothelial keratoplasty is usually caused by Candida spp. Empirical broad-spectrum antimicrobial treatment is the mainstay of treatment for both PKIK, though surgical interventions are required in medically refractory cases (during the acute phase) and those affected by visually significant scarring (during the late phase). In this paper, we aim to provide a comprehensive overview on PKIK, encompassing the epidemiology, risk factors, causes, management and outcomes, and to propose a treatment algorithm for systematically managing this challenging condition.

Large-Diameter Penetrating Keratoplasties are Mostly Due to Very Severe Infectious Keratitis and Cannot Always Prevent Secondary Enucleation

PURPOSE

To report the indications and outcomes of penetrating keratoplasties with a graft diameter > 8.5 mm in severe corneal diseases at the Department of Ophthalmology at Saarland University Medical Centre.

STUDY DESIGN

Retrospective (6 years), descriptive, and observational.

METHODS

Thirty-five large-diameter penetrating keratoplasties (LDPKPs) in 27 patients (mean age, 62 ± 22 years) were performed from March 2010 to December 2016. The indication for surgery, number of previous corneal transplantations, best-corrected visual acuity (BCVA) before surgery, intraocular pressure, graft status, and BCVA at last follow-up were recorded.

RESULTS

Infectious keratitis represented 83% of the indications (of those, 45% fungal). The mean corneal graft diameter was 10.8 ± 1.7 (min 8.75, max 15.0) mm. Twenty-three eyes (65% absolute) had at least one previous penetrating keratoplasty (mean graft size, 9.2 ± 1.6 mm). The mean pre-surgery BCVA was 1.96 ± 0.23 logMAR. With a mean follow-up period of 20.2 ± 13.4 months, the mean BCVA was 1.57 ± 0.57 logMAR at last follow-up. Overall, 12 grafts (35%) remained clear until the last follow-up, and in 23 grafts (65%), the primary disease recurred, or corneal decompensation developed. Up to the last follow-up, 6 eyes (17%) had to be enucleated.

CONCLUSIONS

In complex cases of infectious keratitis requiring a LDPKP to remove the complete pathology and preserve eye integrity, the visual outcomes are generally expected to be poor, not only because of the well-known risks of LDPKP but also because of the consequences of the infectious disease itself. This knowledge is important for adequate counselling of the patient preoperatively.

Outcome of therapeutic deep anterior lamellar keratoplasty in advanced Acanthamoeba keratitis

Purpose

To report and analyze the outcomes of therapeutic deep anterior lamellar keratoplasty (DALK) in patients with advanced Acanthamoeba keratitis (AK).

Methods

Medical records of microbiologically confirmed AK, underwent DALK from 2004 to 2017, were reviewed and the data related to early and late outcome including complications were retrieved. Outcome of cases with largest diameter of infiltrate ≥8 mm at the time of surgery (advanced keratitis) were analyzed and compared with those with less severe keratitis (infiltrate size less than 8 mm).

Results

Out of 23 patients of AK in whom DALK was performed, ten (43.4%) patients had advanced keratitis. Mean age of these patients was 38.7 ± 8.6 years (range, 25 to 56). Median visual acuity at presentation was 2.78 (IQR, 1.79-3.0) that improved to 1.79 (IQR, 0.70-2.78) postoperatively. Early complications included recurrence of AK in 2 (20%), Descemet's membrane detachment in 5 (50%), and persistent epithelial defect in 3 (30%) cases. Overall, 6 (60%) grafts failed, whereas 4 (40%) patients had clear graft at their last follow-up. Median follow-up of these cases was 5 months (IQR, 1.4-11.4). One graft developed stromal rejection, which resolved with increased dose of corticosteroids. In comparison, DALK performed for less severe keratitis (N = 13) had 1 (7.6%) recurrence and 2 (15.8%) grafts failure (OR, 8.25). The probability of one-year graft survival and eradication of infection was 32% and 74.1%, respectively, in advanced cases compared to 91.6% and 83.9% in less severe cases.

Conclusion

Outcome of DALK in advanced Acanthamoeba keratitis is less favorable compared to those carried out for less severe keratitis cases.

Risk factors influencing survival of acellular porcine corneal stroma in infectious keratitis: a prospective clinical study

Background

A worldwide lack of donor corneas demands the bioengineered corneas be developed as an alternative. The primary objective of the current study was to evaluate the efficacy of acellular porcine corneal stroma (APCS) transplantation in various types of infectious keratitis and identify risk factors that may increase APCS graft failure.

Methods

In this prospective interventional study, 39 patients with progressive infectious keratitis underwent therapeutic lamellar keratoplasty using APCS and were followed up for 12 months. Data collected for analysis included preoperative characteristics, visual acuity, graft survival and complications. Graft survival was evaluated by the Kaplan–Meier method and compared with the log-rank test.

Results

The percentage of eyes that had a visual acuity of 20/40 or better increased from 10.3% preoperatively to 51.2% at 12 months postoperatively. Twelve patients (30.8%) experienced graft failure within the follow-up period. The primary reasons given for graft failure was noninfectious graft melting (n = 5), and the other causes included recurrence of primary infection (n = 4) and extensive graft neovascularization (n = 3). No graft rejection was observed during the follow-up period. A higher relative risk (RR) of graft failure was associated with herpetic keratitis (RR = 8.0, P = 0.046) and graft size larger than 8 mm (RR = 6.5, P < 0.001).

Conclusions

APCS transplantation is an alternative treatment option for eyes with medically unresponsive infectious keratitis. Despite the efficacy of therapeutic lamellar keratoplasty with APCS, to achieve a good prognosis, restriction of surgical indications, careful selection of patients and postoperative management must be emphasized.

Trial registration Prospective Study of Deep Anterior Lamellar Keratoplasty Using Acellular Porcine Cornea, NCT03105466. Registered 31 August 2016, ClinicalTrails.gov

Rose Bengal Photodynamic Antimicrobial Therapy for Patients With Progressive Infectious Keratitis: A Pilot Clinical Study

PURPOSE

To report clinical outcomes of rose bengal photodynamic antimicrobial therapy (RB-PDAT) as an adjunct treatment for severe, progressive infectious keratitis.

DESIGN

Consecutive interventional case series.

METHODS

Patients with progressive infectious keratitis unresponsive to standard medical therapy underwent RB-PDAT at the Bascom Palmer Eye Institute from January 2016 through March 2018. RB-PDAT was performed by applying a solution of rose bengal (0.1% or 0.2% RB in balanced salt solution) to the de-epithelialized cornea for 30 minutes, followed by irradiation with a 6 mW/cm² custom-made green LED source for 15 minutes (5.4 J/cm²).

RESULTS

The current study included 18 patients (7 male and 11 female) ranging from 17 to 83 years old. Acanthamoeba was the most frequent microbe (10/17; 59%), followed by Fusarium spp. (4/17; 24%), Pseudomonas aeruginosa (2/17; 12%), and Curvularia spp. (1/17; 6%); 1 patient had no confirmed microbiologic diagnosis. Main clinical risk factor for keratitis included contact lens wear (79%). The average area of epithelial defect prior to first RB-PDAT was 32 ± 27 mm² and average stromal depth hyperreflectivity measured with anterior segment optical coherence tomography was 269 ± 75 μm. Successful RB-PDAT (avoidance of therapeutic keratoplasty) was achieved in 72% of the cases, with an average time to clinical resolution (decreased pain and inflammation with re-epithelialization and infiltrate resolution) of 46.9 ± 26.4 days after RB-PDAT. Time of follow-up after RB-PDAT was 13.3 ± 5.7 months.

CONCLUSION

RB-PDAT can be considered as an adjunct therapy for cases of severe, progressive infectious keratitis before performing a therapeutic keratoplasty.

Early Penetrating Keratoplasty À Chaud May Improve Outcome in Therapy-Resistant Acanthamoeba Keratitis

INTRODUCTION

Long-standing acanthamoeba keratitis (AK) may result in corneal neovascularization, extension of the infiltrate to the limbus or sclera, broad peripheral synechiae, mature cataract or ischemic posterior segment inflammation. We investigated the impact of early emergency penetrating keratoplasty (PKP) in therapy-resistant cases among the patients of a highly specialized tertiary care center.

METHODS

In this retrospective, observational cohort within a single institution, we collected data on best-corrected visual acuity (BCVA), epithelial wound healing, graft survival and secondary complications of AK patients who underwent PKP. A total of 23 eyes of 23 patients diagnosed with acute, therapy-resistant AK between 2006 and 2015 were enrolled. Postoperative combined topical treatment was tapered for 6-9 months.

RESULTS

Eyes were grouped based on preoperative disease duration as shorter (group 1) or longer (group 2) than the median. The median was 5.3 (0.66-36) months. The BCVA in group 1 (20/44 ± 20/18; 0.32 ± 0.18 logMAR) was significantly better than in group 2 (20/1200 ± 20/1133; 1.28 ± 0.89; logMAR); p = 0.015. Persisting epithelial defects occurred in 5 patients (50%) of group 1 and in 10 patients (77%) of group 2. In 5 eyes (group 2), no epithelial healing could be achieved. After 36 months, graft survival (Kaplan-Meier) was 78% (18 grafts) for all patients (90% in group 1 and 44% in group 2).

CONCLUSION

PKP à chaud within 5.3 months after first symptoms of therapy-resistant AK seems to result in better final BCVA than delayed graft surgery if the disease is resistant to a classical topical triple therapy. In addition, early PKP may have a favorable impact on epithelial healing and graft survival.

FUNDING

We thank the Alexander von Humboldt Foundation for supporting the work of Prof. N. Szentmáry at the Department of Ophthalmology of Saarland University Medical Center in Homburg/Saar, Germany. We thank the University of Saarland for funding the medical writing assistance and the Rapid Service Fees. The funding organisation had no role in the design or conduct of this research.

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.

Interstitial keratitis diagnosis and treatment

Interstitial keratitis is a non-ulcerative, non-suppurative, more or less vascularized inflammation of the corneal stroma. The corneal lesions result from the host response to bacterial, viral (40% of cases) or parasitic antigens, or from an autoimmune response (1% of cases) without active corneal infection. The natural history of the disease is divided into two phases: acute and cicatricial. This type of keratitis is less common than ulcerative bacterial keratitis, but it is a non-negligible cause of visual loss. It is associated with systemic or infectious disease and requires early diagnosis and appropriate treatment to optimize visual prognosis and avoid other complications.

Reduction of Acanthamoeba Cyst Density Associated With Treatment Detected by In Vivo Confocal Microscopy in Acanthamoeba Keratitis

PURPOSE

Acanthamoeba keratitis (AK) is a severe vision-threatening ocular infection that is frequently a diagnostic challenge. Treatment course is lengthy and often not fully effective. Contact lens wear has been recognized as the prime risk factor for AK. In vivo confocal microscopy (IVCM) is a noninvasive imaging modality that allows direct visualization of potential causative pathogens in real time with an established utility in the diagnosis of AK. In this study, we aim to assess the utility of IVCM in monitoring disease progression in contact lens wearers with culture-confirmed keratitis.

METHODS

Fourteen eyes from 11 patients with culture-confirmed AK were included in this retrospective study. IVCM was performed during the patient's initial visit and all follow-up visits. All available confocal sequences were reviewed and graded in a masked fashion. Density of Acanthamoeba cyst infiltration and changes in the cyst density as a percentage of baseline cyst density measured at each patient's initial visit were calculated. A univariate regression analysis was performed to assess the association between treatment and changes in cyst density per month of treatment.

RESULTS

Acanthamoeba cysts were identified by IVCM in all of these culture-confirmed cases of keratitis. Mean cyst density in the central cornea at presentation was 99 ± 64.9 cells per square millimeter (range, 38-255/mm). Cyst density in our study population significantly decreased by approximately 5.3% with each month of antiamebic treatment (P = 0.001; R = 0.41).

CONCLUSIONS

Reduction in Acanthamoeba cyst density with treatment can be monitored by IVCM, which in turn can be used clinically in prognostication and disease monitoring of AK.

Quantitative Analysis of Depth, Distribution, and Density of Cysts in Acanthamoeba Keratitis Using Confocal Microscopy

PURPOSE

To quantify the density, distribution, and depth of invasion of cysts in the corneas of eyes with acanthamoeba keratitis (AK) by in vivo confocal microscopy (IVCM) with a novel scanning pattern.

METHODS

The medical records of patients with AK evaluated at the Doheny Eye Center UCLA between September 2014 and July 2016 were reviewed retrospectively. Patients with clinically diagnosed AK underwent IVCM at various time points during their clinical course. Five corneal locations were scanned at each time point: the central area and 4 standard points on the peripheral cornea corresponding to temporal, nasal, inferior, and superior locations. The IVCM scans were manually graded to quantify the maximum depth of invasion and density of cysts.

RESULTS

Twenty-one eyes of 18 patients with visible cysts on IVCM were included. Mean cyst density at presentation was 214.1 ± 120.2/mm (range: 64-484 cells/mm), and the average cyst depth was 164.3 ± 81.2 μm (range: 17-290 μm). In 17 eyes, the average cyst depth was 139.4 ± 68.6 μm (range: 17-245 μm), mean cyst density was 177.9 ± 99.6/mm, and an average of 1.4 ± 1.3 quadrants was infiltrated at presentation, and reached clinical resolution with medical treatment without surgical intervention. Four eyes that ultimately underwent therapeutic penetrating keratoplasty had cysts in all 4 quadrants and deeper cyst infiltration; the average cyst depth in these corneas was 270.5 ± 17.5 μm (range: 252-290).

CONCLUSIONS

Eyes with AK requiring therapeutic keratoplasty were more likely to have a deeper and more diffuse penetration of cysts in the cornea compared with those resolving with medical treatment.

Results with the Boston Type I keratoprosthesis after Acanthamoeba keratitis

Purpose

To report the outcomes of implantation of the Boston Type I keratoprosthesis in three patients with Acanthamoeba keratitis (AK), a severe infection that can lead to significant visual loss.

Observations

Case series reporting three patients with difficult cases of AK that needed multiple corneal transplantations and glaucoma surgeries. All patients were implanted with the Boston Type I keratoprosthesis device. The main outcomes measure were the visual function and anatomical retention after implantation of the Boston Type I keratoprosthesis. All patients retained the device over the long-term and had good visual function. In one patient a retroprosthetic membrane developed and in another patient an epithelial lip developed over the anterior surface of the keratoprosthesis. The visual acuities range from 20/25 to 20/80 in the implanted eyes.

Conclusions and importance

The Boston Type I keratoprosthesis resulted in good anatomic and functional results after multiple graft failures after AK.

Acanthamoeba in the eye, can the parasite hide even more? Latest developments on the disease

Acanthamoeba spp. is a free living protozoan in the environment, but can cause serious diseases. Acanthamoeba keratitis (AK), a severe and painful eye infection, must be treated as soon as possible to prevent ulceration of the cornea, loss of visual acuity, and eventually blindness or enucleation. Although the disease affects principally contact lens (CLs) wearers, it is recognized nowadays as a cause of keratitis also in non-CLs wearers. Although the number of infections caused by these amoebae is low, AK is an emerging disease presenting an extended number of cases each year worldwide mostly due to the increasing use of CLs, but also to better diagnostic methods and awareness. There are two principal causes that lead to severe outcomes: misdiagnosis or late diagnosis of the causal agent, and lack of a fully effective therapy due to the existence of a highly resistant cyst stage of Acanthamoeba. Recent studies have reported different genotypes that have not been previously associated with this disease. In addition, Acanthamoeba can act as a reservoir for phylogenetically diverse microorganisms. In this regard, recently giant viruses called Pandoravirus have been found within genotypes producing keratitis. What potential risk this poses is not yet known. This review focuses on an overview of the present status and future prospects of this re-emerging pathology, including features of the parasite, epidemiology, clinical aspects, diagnosis, and treatment.

Non-contact lens related Acanthamoeba keratitis

The purpose of the study is to describe epidemiology, clinical features, diagnosis, and treatment of Acanthamoeba keratitis (AK) with special focus on the disease in nonusers of contact lenses (CLs). This study was a perspective based on authors' experience and review of published literature. AK accounts for 2% of microbiology-proven cases of keratitis. Trauma and exposure to contaminated water are the main predisposing factors for the disease. Association with CLs is seen only in small fraction of cases. Contrary to classical description experience in India suggests that out of proportion pain, ring infiltrate, and radial keratoneuritis are seen in less than a third of cases. Majority of cases present with diffuse infiltrate, mimicking herpes simplex or fungal keratitis. The diagnosis can be confirmed by microscopic examination of corneal scraping material and culture on nonnutrient agar with an overlay of Escherichia coli. Confocal microscopy can help diagnosis in patients with deep infiltrate; however, experience with technique and interpretation of images influences its true value. Primary treatment of the infection is biguanides with or without diamidines. Most patients respond to medical treatment. Corticosteroids play an important role in the management and can be used when indicated after due consideration to established protocols. Surgery is rarely needed in patients where definitive management is initiated within 3 weeks of onset of symptoms. Lamellar keratoplasty has been shown to have good outcome in cases needing surgery. Since the clinical features of AK in nonusers of CL are different, it will be important for ophthalmologists to be aware of the scenario wherein to suspect this infection. Medical treatment is successful if the disease is diagnosed early and management is initiated soon.

Associated factors, diagnosis and management of Acanthamoeba keratitis in a referral Center in Southern China

BACKGROUND

To analyse the associated factors, diagnosis, clinical manifestations and therapeutic effects of Acanthamoeba keratitis at a tertiary ophthalmic centre in Southern China.

METHODS

A retrospective clinical study was performed in fifteen patients who were admitted to Zhongshan Ophthalmic Centre (ZOC) from January 2004 to December 2014. The patients' pathogenesis-associated factors were analysed, and preoperative diagnoses were determined using corneal scraping cultures and/or confocal microscopy followed. All diagnoses were confirmed by postoperative pathological examinations. At follow-up, best-corrected visual acuity (BCVA), the recurrence rate and graft transparency were evaluated to assess therapeutic effects.

RESULTS

The main pathogenic factors observed in the fifteen patients were a history of injury or a foreign body entering the eyes (12 cases). In all, Acanthamoeba keratitis was preoperatively diagnosed in 5 cases using corneal scraping cultures or confocal microscopy. Ocular symptoms included redness, photophobia, tearing, and blurred vision. Penetrating keratoplasty was performed in thirteen patients, and postoperative pathological examinations were performed to confirm these diagnoses. The logarithm of the minimum angle of resolution (logMAR) of visual acuity was significantly improved after keratoplasty (p < 0.01). No recurrence was observed, and approximately 90% of the corneal grafts were found to be transparent during the follow-up period.

CONCLUSIONS

Corneal trauma may be the main pathogenic factor that causes Acanthamoeba keratitis in southern China. Corneal scraping combined with confocal microscopy was helpful for achieving a correct diagnosis. Early keratoplasty combined with amoebicidal therapy is an effective treatment strategy in Acanthamoeba keratitis.

[Acanthamoeba keratitis]

Early diagnosis and appropriate therapy are key elements for a good prognosis in Acanthamoeba keratitis (AK). AK should be considered in any case of corneal trauma complicated by exposure to soil or contaminated water, and in all contact lens (CL) wearers. A presumptive diagnosis of AK can be made clinically and with in vivo confocal microscopy, although a definitive diagnosis requires identification of Acanthamoeba on direct scraping, histology, or identification of Acanthamoeba DNA by polymerase chain reaction (PCR). We use cysticidal drugs for treating AK because encysted forms are more resistant than trophozoites to treatment. The treatment protocol used a biguanide (PHMB 0.02% or chlorhexidine 0.02%) and a diamidine (propamidine 0.1% or hexamidine 0.1%). New diagnostic modalities and more specific topical anti-amoebic treatments would substantially benefit patients with AK.

Profile of sight-threatening infectious keratitis: a prospective study

PURPOSE

To prospectively study patients presenting with sight-threatening corneal ulcers with a view to identify the predisposing factors, causative organisms, clinical signs and treatment outcomes.

METHODS

Prospectively, over 3-year period, all cases with serious infective keratitis presenting to Queens Medical Hospital in Nottingham, UK, were recruited. Detailed information on the aetiology, culture results, signs & symptoms, the treatment given and the patient's response was collected and statistically analysed.

RESULTS

One hundred and forty-three eyes of 129 patients were enrolled. Thirty-one patients were managed as out-patients, and 98 were treated as in-patients. The mean duration of admission was 9 ± 13 days but was significantly higher in older patients and in Acanthamoeba keratitis cases. The important risk factors were ocular surface disease (32%), contact lens wear (26%) and previous ocular surgery (20%). Old age, deep infiltration, steroid use and poor initial vision were risk factors for prolonged course of treatment in bacterial keratitis. Corneal scrapings were done in 89% of the cases, but positive results were obtained only in 41.7%. Staphylococcus aureus was the most common isolated bacteria (18.8%). Acanthamoeba and Pseudomonas aeruginosa were the second and third common causative organisms (16.6% and 15%, respectively). Overall, 8.3% needed corneal grafting, which survived in 83.3% and eradicated infection in 100%.

CONCLUSION

Microbial keratitis is an important cause of ocular morbidity. Previous ocular disease is an important predisposing factor. Old age, steroid use and poor presenting visual acuity are important prognostic indicators. Corneal grafting is an effective option for managing recalcitrant corneal infections.

Practice patterns and opinions in the treatment of acanthamoeba keratitis

PURPOSE

Management of acanthamoeba keratitis remains challenging for ophthalmologists. We conducted a survey of members of The Cornea Society to elicit expert opinions on the diagnosis and treatment of acanthamoeba keratitis.

METHODS

An online survey was sent to all subscribers of The Cornea Society via the kera-net listserv. Descriptive statistics were performed.

RESULTS

Eighty-two participants completed the online survey. Of the 82 respondents, 76.8% included the combination of clinical examination and culture in their diagnostic strategy and 43.9% used confocal microscopy. Most respondents (97.6%) had used combination therapy with multiple agents to treat acanthamoeba keratitis at some point in the past, whereas a smaller proportion (47.6%) had ever used monotherapy. Respondents most commonly chose polyhexamethylene biguanide as the ideal choice for monotherapy (51.4%), and dual therapy with a biguanide and diamidine as the ideal choice for combination therapy (37.5%). The majority of respondents (62.2%) reported using topical corticosteroids at least some of the time for acanthamoeba keratitis. Keratoplasty was an option considered by most respondents (75.6%), although most (85.5%) would only perform surgery after medical treatment failure.

CONCLUSIONS

There was a wide range of current practice patterns for the diagnosis and treatment of acanthamoeba keratitis. The lack of sufficiently powered comparative effectiveness studies and clinical trials makes evidence-based decision-making for this disease difficult.

A retrospective study of nine cases of Acanthamoeba keratitis

Purpose

To evaluate the clinical features of Acanthamoeba keratitis in nine patients diagnosed at Dokkyo Medical University Koshigaya Hospital, Saitama, Japan.

Methods

In nine eyes of nine patients, Acanthamoeba keratitis was diagnosed by direct light microscopy of corneal scrapings stained by the Parker ink-potassium hydroxide method between September 2006 and September 2009. Their clinical features and course were studied retrospectively. Antifungal eye drops, systemic antifungal therapy, and surgical debridement of the corneal lesions were performed in all patients.

Results

At presentation, the clinical stage was initial in six cases, transient in one case, and complete in two cases. The patients were all contact lens wearers who had washed their lens storage cases with tap water. After treatment, final visual acuity was improved in six cases, unchanged in one case, and worse in two cases. The patient with the worst final vision (hand motion) had rheumatoid arthritis and was taking oral prednisolone, which led to corneal perforation and prevented adequate debridement from being done.

Conclusion

Acanthamoeba keratitis is closely related to wearing contact lenses and washing the lens storage case with tap water. Although final visual acuity improved after treatment in most patients, insufficient surgical debridement resulted in a poor visual prognosis.

Acanthamoeba keratitis: diagnosis and treatment update 2009

PURPOSE

To describe the current management of Acanthamoeba keratitis (AK).

DESIGN

A perspective based on the literature and author experience.

RESULTS

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

CONCLUSIONS

Better understanding of the pathogenesis of the extracorneal complications, the availability of polymerase chain reaction for tissue diagnosis, and effective licensed topical anti-amoebics would substantially benefit patients with AK.

Differential effects of α-helical and β-hairpin antimicrobial peptides against Acanthamoeba castellanii

In this work we evaluated the ability of different types of antimicrobial peptides to promote permeabilization and growth inhibition of Acanthamoeba castellanii trophozoites, which cause eye keratitis. We used cationic α-helical peptides P5 and P6, corresponding to the N-terminus of the pore-forming protein from Triatoma infestans, a blood-sucking insect, and a β-hairpin amphipathic molecule (gomesin), of the spider Acanthoscurria gomesiana haemocytes. A. castellanii permeabilization was obtained after 1 h incubation with micromolar concentrations of both types of peptides. While permeabilization induced by gomesin increased with longer incubations, P5 permeabilization did not increase with time and occurred at doses that are more toxic for SIRC cells. P5, however, at doses below the critical dose used to kill rabbit corneal cells was quite effective in promoting growth inhibition. Similarly, P5 was more effective when serine protease inhibitor was added simultaneously to the permeabilization assay. High performance chromatography followed by mass spectrometry analysis confirmed that, in contrast to gomesin, P5 is hydrolysed by A. castellanii culture supernatants. We conclude that the use of antimicrobial peptides to treat A. castellanii infections requires the search of more specific peptides that are resistant to proteolysis.