Radial Keratoneuritis Research Articles

Differentiation of acanthamoeba keratitis from other non-acanthamoeba keratitis: Risk factors and clinical features.

Infectious Keratitis is one of the most common ocular emergencies seen by ophthalmologists. Our aim is to identify the risk factors and clinical features of Acanthamoeba Keratitis (AK). This retrospective chart review study was conducted at King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia, and included all the microbial keratitis cases, male and female patients of all ages. The main outcome is the differentiation between various microbial keratitis types. We included 134 consecutive eyes of 126 persons. We had 24 cases of acanthamoeba keratitis, 22 bacterial keratitis, 24 fungal keratitis, 32 herpetic keratitis, and 32 bacterial co-infection. Contact lens wear was found in 33 eyes (24.6%). Among acanthamoeba keratitis patients, 73% were ≤ 39 years of age, and 73% were females (P <0.001). Also, in AK cases, epithelial defect was found in all cases (100%), endothelial plaques were found in 18 eyes (69.2%), 12 cases had radial keratoneuritis (46.2%), and ring infiltrate was found in 53.8% of AK cases. We determined the factors that increase the risk of acanthamoeba infection and the clinical characteristics that help distinguish it from other types of microbial keratitis. Our findings suggest that younger females and patients who wear contact lenses are more likely to develop acanthamoeba keratitis. The occurrence of epitheliopathy, ring infiltrate, radial keratoneuritis, and endothelial plaques indicate the possibility of acanthamoeba infection. Promoting education on wearing contact lenses is essential to reduce the risk of acanthamoeba infection, as it is the most significant risk factor for this infection.

Breaking-Down Barriers: Proposal of Using Cellulose Biosynthesis Inhibitors and Cellulase Enzyme as a Novel Treatment Modality for Vision Threatening Pythium Insidiosum Keratitis.

Pythium insidiosum, an Oomycete, causes severe keratitis that endangers vision. Its clinical, morphological, and microbiological characteristics are often indistinguishable from those of fungal keratitis, earning it the moniker "parafungus". Distinctive clinical hallmarks that set it apart from other forms of keratitis include radial keratoneuritis, tentacles, marginal infiltration, and a propensity for rapid limbal spread. The therapeutic approach to Pythium keratitis (PK) has long been a subject of debate, and topical and systemic antifungals and antibacterials have been tried with limited success. Approximately 80% of these eyes undergo therapeutic keratoplasty to salvage the eye. Hence, there is a need to innovate for alternative and better medical therapy to safeguard these eyes. The resistance of Pythium to standard antifungal treatments can be attributed to the absence of ergosterol in its cell wall. Cell walls of plants and algae have cellulose as an essential constituent. Cellulose imparts strength and structure and acts as the "skeleton" of the plant. Fungal and animal cell walls typically lack cellulose. The cellular architecture of Pythium shares a similarity with plant and algal cells through the incorporation of cellulose within its cell wall structure. Inhibitors targeting cellulose biosynthesis (CBI), such as Indaziflam, Isoxaben, and Quinoxyphen, serve as critical tools for elucidating the pathways of cellulose synthesis. Furthermore, the enzymatic action of cellulase is instrumental for the extraction of proteins and DNA. To circumvent this issue, we hypothesize that CBI's and cellulase enzymes can act on the Pythium cell wall and may effectively treat PK. The available literature supporting the hypothesis and proof of concept has also been discussed. We have also discussed these drugs' molecular mechanism of action on the Pythium cell wall. We also aim to propose how these drugs can be procured and used as a potential medical management option for this devastating entity.

Pearls and Paradigms in the Management of Acanthamoeba Keratitis: A Review

Abstract Acanthamoeba keratitis (AK) generally displays a protracted course with significant morbidity. This is partly due to the fact that it is often misdiagnosed as viral or fungal keratitis. It is associated most with contact lens (CL) wear in developed countries, and exposure to soil or unsanitary water in the developing countries. The textbook description of AK includes the presence of ring infiltration, radial keratoneuritis, and disproportionate pain. Of the patients that presented to our tertiary care center, only 40% had a history of CL use, and 33% had a ring infiltrate. Corneal scraping for microbiological culture on non-nutrient agar serves as the gold standard for diagnosis. Corneal biopsy and confocal microscopy hold diagnostic value in deeper lesions, and polymerase chain reaction and newer molecular techniques are emerging as rapid and effective tools. Biguanides are the drug of choice for AK. But it is important to reconstitute these drugs in correct dosages; otherwise, corneal toxicity can take place. The use of corticosteroids in AK is a matter of debate. We have used corticosteroids in cases with persistent keratitis, severe pain, and extra-corneal manifestations under the cover of amoebicidal therapy. Surgical intervention in the acute phase is reserved for advanced AK with limbus encroachment, perforations, or fulminant corneal abscesses. AK is thus a severe, potentially blinding disease, where a prompt diagnosis ensuring the timely commencement of amoebicidal therapy is an essential component of improving the patient’s prognosis. In this article, we have discussed the presentation, challenges in diagnosis and management, and our experience in managing AK.

Diagnosis and Management of Acanthamoeba Keratitis

Acanthamoeba keratitis (AK) is a vision-threatening corneal infection that most frequently affects contact lens wearers. Severe pain out of proportion to the corneal findings, radial keratoneuritis, and ring infiltration are relatively specific clinical manifestations of AK. The diagnosis of AK is challenging and it is often misdiagnosed because of atypical presentations. The definitive diagnosis of AK requires the presence of Acanthamoeba cysts or trophozoites in corneal lesions, and a high index of clinical suspicion is important for early diagnosis. In this review, we describe the clinical manifestations, including atypical findings, and management of AK.

Bilateral Acanthamoeba keratitis with radial keratoneuritis – utility of AS-OCT in management and treatment

Acanthamoeba keratitis (AK) is a rare but vision-threatening keratitis that is usually unilateral; however, it has been reported to be bilateral with the use of contact lenses or orthokeratology.1 ...

Predisposing Factors, Clinical Presentations, and Outcomes of Contact Lens-Related Pythium Keratitis.

To describe predisposing factors, clinical presentations, and treatment outcomes of contact lens (CL)-related Pythium keratitis. This was an 11-year retrospective study of CL-related Pythium keratitis conducted from 2009 to 2019. Six eyes of 6 patients were identified. Demographics, predisposing factors, CL history, clinical presentation, diagnostic tests, treatments, and outcomes were reviewed. Mean age of the patients was 34 years (SD 16.3 years) with equal proportion between male and female patients. Five of 6 patients (83.3%) used soft CL, whereas 1 patient used rigid gas permeable lens. All patients had a history of water contamination (tap water and water from river and sea). Mean duration from the onset was 7.8 days (range 4-14 days). Mean size of the corneal lesion was 3.33 mm (SD 1.31 mm) in width. The typical feature of tentacle-like lesions radiating in a reticular pattern was observed in all patients. Feathery edge (1 eye), satellite lesions (2 eyes), and radial keratoneuritis (2 eyes) were also found. Every patient received therapeutic penetrating keratoplasty because of failed medical treatments. One patient subsequently underwent enucleation. Globe salvage was achieved in 5 patients (83.33%). Awareness of the history of water contamination, recognition of specific clinical features of Pythium keratitis, and performing surgical treatment are key for achieving globe salvage in patients with CL-related Pythium keratitis.

Mycobacterium haemophilum scleritis: two case reports and review of literature

BackgroundMycobacterium haemophilum is a rare and emerging nontuberculous mycobacteria (NTM). It normally causes localized or disseminated systemic diseases, particularly skin infections and arthritis in severely immunocompromised patients. There have been 5 cases of M. haemophilum ocular infections reported in the literature. Only 1 case presented with scleritis with keratitis. Here, we reported 2 cases of M. haemophilum scleritis. One of them was immunocompetent host and had keratitis with radial keratoneuritis as a presenting sign.Case presentationCase 1: A 52-year-old Thai female with rheumatoid arthritis presented with scleritis. Conjunctival scraping was carried out and the culture result was positive for M. haemophilum. Despite receiving systemic and topical antibiotics, her clinical symptoms and signs worsened. Surgical debridement was performed. After surgery, the lesion was significantly improved and finally turned to conjunctival scarring. Case 2: A 32-year old healthy Thai male without underlying disease presented with nodular scleritis and keratouveitis with multiple radial keratoneuritis. Surgical debridement of the scleral nodule was performed. Initial microbiological investigations were negative. Herpes ocular infections was suspected. Topical antibiotics, oral acyclovir, low-dose topical steroids and systemic steroids were started. The scleral inflammation subsided but later the keratitis relapsed, requiring corneal biopsy. Histopathology of the specimen revealed acid-fast bacteria and M. haemophilum was identified by polymerase chain reaction (PCR) and sequencing. The diagnosis of Mycobacterial keratitis was made. Although using the combination of systemic and topical antibiotics, his clinical status progressively deteriorated. Multiple therapeutic penetrating keratoplasties were required to eradicate the infection. No recurrence was found during the 1-year follow-up in both cases.ConclusionsM. haemophilum can cause scleritis and keratitis, even in immunocompenent host. Radial keraoneuritis is first described in M. haemophilum keratitis. NTM keratitis should be considered in the differential diagnosis of patients with radial keratoneuritis. Increased awareness and early diagnosis using appropriate culture conditions and molecular techniques are important for the proper treatment of this infection. Prompt surgical intervention appears to be vital for successful management of M. haemophilum scleritis and keratitis.

Use of white light in vivo confocal microscopy for the detection of spatial changes in the corneal nerves in cases of early-stage Acanthamoeba keratitis with radial keratoneuritis.

Purpose:Radial keratoneuritis (RK) is a common feature of Acanthamoeba keratitis (AK). In vivo confocal microscopy (IVCM) is noninvasive and provides real-time images for the diagnosis of corneal diseases by allowing the visualization of corneal structures and morphologies of living organisms at the cellular level. Images of AK with RK obtained using commercial white light IVCM devices have not been frequently evaluated. In the present study, a white light IVCM device was used to evaluate the corneal findings and describe spatial changes in the corneal nerves at different depths in cases of early-stage AK with RK.Methods:In this retrospective, observational study, white light IVCM images focused on RK were evaluated for Acanthamoeba cysts/trophozoites, corneal deposits, and altered corneal nerves, with special emphasis on three-dimensional spatial changes in the corneal nerves at different depths.Results:Seventeen eyes of 17 patients exhibiting early-stage AK with RK were included in the study. Acanthamoeba cysts/trophozoites were observed in the corneal epithelium of 13 eyes and stroma of 7 eyes. Alterations in the corneal nerve morphology and density were observed from the basal epithelial layer to the stromal layer in 12 eyes. Acanthamoeba trophozoites were attached to the corneal stromal nerves in five eyes.Conclusion:These findings suggest that white light IVCM can identify consistent corneal findings, particularly spatial changes in the corneal nerves, in cases of early-stage AK with RK.

Refractory atypical corneal lesions with or without extension onto the conjunctiva responding to Acanthamoeba treatment

AbstractPurposeAcanthamoeba keratitis (AK) is a sight‐threatening infection classically linked to contact lens wear. Starting as a non‐specific unilateral epithelial irregularity like punctate or pseudo‐dendritic lesions, AK can evolve to a ring‐shaped stromal infiltrate with risk of corneal melting. Radial keratoneuritis may appear. Diagnosis relies on protozoan identification by culture with direct exam and PCR analysis. Acanthamoeba can also be demonstrated by in vivo confocal microscopy (IVCM). Early phase AK is treated with a combination of topical amoebicides. We report three atypical cases of suspected AK.MethodsRetrospective report of three women with unilateral atypical corneal lesions, two of them extending to the conjunctiva. Slit lamp photographs, corneal oct and confocal microscopy will be presented.ResultsThree patients, two women in their thirties and one in her sixties, consulted for chronic ocular discomfort unsuccessfully treated by topical antibiotics and corticosteroids for months to years. No history of contact lens wear or water exposure was reported. Two had visual acuity (VA) at 20/20 and one a variable VA for 4 years. Slit lamp examination showed an atypical superficial well delimitated linear lesion across cornea and conjunctiva. In all patients, successive examinations had revealed a moving and migrating character of the refractory lesions to topical antibiotics and corticosteroids. All had a rapid response to Polyhexamethylenebiguanide (PHMB) and propamidine (Brolene) and healed without stromal opacification in a few weeks. Although corneal scrapping cultures remained negative, two of them realized an IVCM with signs of AK and all responded rapidly and completely to amoebicide drops supporting the diagnosis of AK.ConclusionsThese cases show a particularly atypical involvement of corneal and conjunctival refractory lesions responding very well to PHMB and Brolene suggesting an AK origin.

Comparison of anterior segment optical coherence tomography findings in acanthamoeba keratitis and herpetic epithelial keratitis.

This study is to investigate the characteristic features of Acanthamoeba keratitis (AK) that differentiating it from herpetic epithelial keratitis (HEK) using anterior segment optical coherence tomography (AS-OCT). Medical records of three eyes of each AK and herpetic keratitis who had AS-OCT examination were reviewed in this study. Slit-lamp biomicroscopy and AS-OCT was performed on the initial visit and on every follow-up visits in all patients. In all three AK cases, reflective bands in the corneal stroma that correspond to the area of radial keratoneuritis were observed. The depth of the reflective bands varied in each case. After AK treatment, slit-lamp biomicroscopy confirmed that radial keratoneuritis had resolved and AS-OCT confirmed that reflective bands in the corneal stroma had also disappeared in all patients. Unlike the AS-OCT results found in AK, highly reflective HEK lesions were observed only in the subepithelial area, not in the stroma. AS-OCT seems to be helpful analyzing the specific depth of the lesion which enables to distinguish AK from HEK.

Acanthamoeba keratitis: An emerging disease among microbial keratitis in the Cap Bon region of Tunisia

IntroductionThe aim of this study was to describe the prevalence of AK among microbial keratitis as well as their clinical features and to compare their risk factors to those of other infectious keratitis, over the last five years in a referral center in the region of Cap Bon, Tunisia, North Africa. MethodsA retrospective review of the charts of 230 patients (230 eyes) diagnosed with presumed infectious keratitis between January 2011 and December 2016 at the department of ophthalmology of the university hospital of Nabeul in Tunisia. After a detailed ocular examination using standard technique, corneal scrapes were performed under aseptic conditions from each ulcer. Plates were incubated at 30 °C and screened daily for Amoeba.The treatment was adjusted according to the results of microbiological findings and the response of initial treatment.The mean follow up was 11.4 months (1 month–26 months). ResultsA total of 230 corneas were scraped. The prevalence of Acanthamoeba keratitis was 6% (14 cases of 230).All cases of Acanthamoeba keratitis with a history of contact lenses were diagnosed thanks to the test of Contact lenses, their cases or their storage solution, while their corneal scrapings were negative. The corneal scraping was positive for Acanthamoeba only in 4 cases of 14.Acanthamoeba was identified more in young patients (92.8%). Significantly, more patients (54 of 74; 73%) with fungal keratitis and Acanthamoeba keratitis (11 of14; 78.6%) were rural population The most cases of Acanthamoeba keratitis (10 of 14; 71.4%) used contact lenses. Ocular injury was identified in 4 cases of 14 AK (28,5%). Coexistent ocular disease was seen in seven cases of 14 (50%). Of the 230 microbial keratitis, an early diagnosis (≤30 days) was done in 200 cases (86.95%), while a late diagnosis (≥30 days) was made in 30 cases (13%). In AK, most cases (11 of 14; 78,5%) were diagnosed with a delay of more than 30 days. Slit-lamp examination showed stromal infiltrate in 12 cases (85,7%), hypopion in 2 cases (14,3%), immunitary ring in 2 cases (14,3%) and radial keratoneuritis in one case (7,1%). ConclusionContact lenses were identified as the main risk factor of Acanthamoeba keratitis in our study. The diagnosis of AK should be considered in case of atypical keratitis especially among CL wearers in the rural regions of CapBon where the rules of hygiene are not respected.

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.

The Relation of Ocular Surface Irregularity and Visual Disturbance in Early Stage Acanthamoeba Keratitis.

To evaluate the relation between ocular surface irregularity and visual disturbance in early stage Acanthamoeba keratitis (AK). Fifteen patients with culture-proven AK underwent routine ophthalmic examinations, including best-corrected visual acuity (BCVA) measurement, slitlamp biomicroscope examination, and corneal fluorescein dye staining test, in both the eyes. We also evaluated the corneal sensitivity with Cochet-Bonnet esthesiometer, tear functions by Schirmer's test, and ocular surface irregularity by corneal topography and compared the results with the contralateral healthy eyes in this study. The mean logarithm of the minimum angle of resolution BCVA (0.71±0.77) was significantly lower in the eyes with AK (P=0.002). Epithelial disorders were present in all eyes, and radial keratoneuritis in 14 eyes (93.3%). The mean corneal sensitivity (39.3±24.1 mm) was significantly lower in eyes with AK compared with the healthy eyes (P=0.005). The mean Schirmer's test value (22.5±12.0 mm) in eyes with AK was significantly higher compared with the healthy eyes (P=0.01). The ocular surface irregularity indices (the surface regularity index, 2.47±0.42; the surface asymmetry index, 3.24±1.31) were significantly higher in eyes with AK compared with contralateral healthy eyes (P<0.0001 and P<0.0001, respectively). The ocular surface disease in AK is associated with decrease in corneal sensitivity and increase in Schirmer's test value and ocular surface irregularity indices. The visual disturbance in AK may owe not only to corneal haze but also to ocular surface irregularity.

In Vivo Imaging of Radial Keratoneuritis in Patients with Acanthamoeba keratitis by Anterior-Segment Optical Coherence Tomography

To investigate in vivo corneal changes of radial keratoneuritis in early-stage Acanthamoeba keratitis (AK) using anterior-segment optical coherence tomography (AS-OCT). Single-center, prospective clinical study. Four eyes (4 patients with a mean age of 28.5 years) with early-stage AK showing radial keratoneuritis were included in this study. Definitive diagnosis was made by confirmation of AK cysts using in vivo confocal microscopy and culture. Anterior-segment OCT examination was performed on the initial visit and at follow-up visits paying special attention to radial keratoneuritis. Selected AS-OCT images of the cornea were evaluated qualitatively for the shape and degree of light reflection of abnormal neurons. With the use of AS-OCT, we successfully obtained high-resolution images of putative radial keratoneuritis in all patients as highly reflective bands or lines in the corneal stroma. The depth and width of the highly reflective bands/lines varied from case to case (anterior stroma to mid-stroma, from 20 to 200 μm). Some lines ran obliquely from the deep peripheral stroma toward the anterior stroma, and some were located at different depths (subepithelial and mid-stroma) and ran relatively parallel to the corneal layers. After appropriate treatment, radial keratoneuritis was resolved by both slit-lamp biomicroscopy and AS-OCT in all patients. High-resolution Fourier-domain AS-OCT provides novel and detailed visual information of radial keratoneuritis in patients with early-stage AK. Visualization of radial keratoneuritis by AS-OCT may be a useful adjunct to the diagnosis and follow-up of early-stage AK.

Non—Contact Lens Use—Related Acanthamoeba Keratitis in Southern Turkey: Evaluation of Risk Factors and Clinical Features

To assess the diagnostic methods, risk factors, and clinical features of Acanthamoeba keratitis cases in patients who do not wear contact lenses. Medical records of 26 consecutive patients with non-contact lens-related Acanthamoeba keratitis, who were followed up at the tertiary eye care center between May 2010 and May 2012, were analyzed. Laboratory, demographic, and clinical findings were evaluated pertaining to the patients. Twenty-six non-contact lens-related Acanthamoeba keratitis cases were included in the study. The main risk factors were trauma (group 1, n = 13 patients) and ocular surface disease (group 2, n = 12 patients). One patient had both of the risk factors mentioned above. Overall test results showed that Acanthamoeba positivity rates were 15.3% for direct microscopy, 46.1% for culture, 92.3% for conventional polymerase chain reaction (PCR), and 100% for real-time PCR. The rates of full-thickness corneal involvement and ring-shaped infiltrations were higher in group 2, whereas superficial keratitis and radial keratoneuritis were higher in group 1. The final visual acuities were significantly better in group 1 than group 2 (p<0.025). This study is the first regional report from Turkey about Acanthamoeba keratitis in non-contact lens users. A majority of cases admitted to a tertiary eye care center were related to trauma or ocular surface disease. Physician suspicion is critically important for the timely diagnosis of these cases. At this point, molecular diagnostic tests (PCR or real-time PCR) seem to support the clinical diagnosis of Acanthamoeba keratitis with the help of fast and reliable results.

A Case ofSerratia MarcescensKeratitis Presenting as Radial Keratoneuritis

A Case of<i>Serratia Marcescens</i>Keratitis Presenting as Radial Keratoneuritis

In Vivo Laser Confocal Microscopy Findings of Radial Keratoneuritis in Patients with Early Stage Acanthamoeba Keratitis

To investigate in vivo corneal changes of keratoneuritis in early stage Acanthamoeba keratitis (AK) using in vivo laser confocal microscopy. Single-center, prospective, clinical study. Thirteen eyes (12 patients; 5 men and 7 women; mean age ± standard deviation, 22.3 ± 4.2 years) with keratoneuritis resulting from early stage AK were included in this study. In vivo laser confocal microscopy was performed, paying special attention to keratoneuritis. Selected confocal images of corneal layers were evaluated qualitatively for shape and degree of light reflection of abnormal cells and deposits. In all patients, Acanthamoeba cysts were observed clearly in the basal epithelial cell layer as highly reflective round particles with a diameter of 10 to 20 μm. Bowman's layer infiltration of Acanthamoeba cysts was observed in only 1 case, and no cases showed stromal or nerve infiltration of Acanthamoeba cysts. In the stroma, all cases showed highly reflective activated keratocytes forming a honeycomb pattern; these changes were significant around the keratoneuritis. Infiltration of inflammatory cells, possibly polymorphonuclear cells, was observed along with keratocyte bodies in all cases. Numerous highly reflective spindle-shaped materials were observed around the keratoneuritis. Most notably, highly reflective patchy lesions were observed around the keratoneuritis in 11 cases (84.6%). Inflammatory cells also were observed in the endothelial cell layer in 4 cases (30.8%). In vivo laser confocal microscopy identified consistent corneal abnormalities around keratoneuritis in early stage AK patients, of which highly reflective patchy lesions may be characteristic of keratoneuritis. Further morphologic studies of corneas with early stage AK in a larger number of patients may elucidate the clinical significance of radial keratoneuritis and may help us to understand the interaction between Acanthamoeba organisms and host corneal cells or nerves.

Treatment of Early Acanthamoeba Keratitis With Alcohol-Assisted Epithelial Debridement

To study the safety and efficacy of treating early-stage Acanthamoeba keratitis (AK) with 20% alcohol-assisted epithelial debridement. Four consecutive patients (2 wearing orthokeratology lenses and 2 wearing soft contact lenses) presented with pseudodendrites, radial keratoneuritis, and epithelial irregularities. Using a technique similar to laser-assisted subepithelial keratomileusis, we performed alcohol-assisted full-thickness debridement of the corneal epithelium and sent portions for smears, histopathologic and ultrastructural examinations, and culture for evidence of Acanthamoeba. Patients were then started on topical propamidine isethionate and 0.02% polyhexamethylene biguanide. Immediately after debridement, minimal underlying anterior stromal infiltrate or haze was seen. Dosages of antiamoebic agents were tapered as corneal defects reepithelialized (in 1-3 weeks) with no evidence of post-debridement corneal infection. At the final follow-up, 1 cornea was transparent and the other 3 corneas had very faint subepithelial haze. Cultures of all epithelial debridement specimens yielded Acanthamoeba trophozoites and cysts, and histopathologic and electron microscopic examinations revealed Acanthamoeba organisms within corneal epithelial layers. Alcohol-assisted epithelial debridement facilitates detachment of the full-thickness corneal epithelial layer in a controlled manner and seems to be effective in the treatment of early-stage AK. Unlike the fragile fragmented specimens obtained by mechanical scraping without alcohol soaking, epithelial sheets detached easily and the architectures were well preserved, permitting histopathologic and ultrastructural examinations. Most importantly, 20% alcohol-assisted epithelial debridement did not prevent culturing of Acanthamoeba from the removed epithelial specimens.

A case of radial keratoneuritis in non-Acanthamoeba keratitis

A case of non-Acanthamoeba keratitis with radial keratoneuritis, which is thought to be pathognomonic for Acanthamoeba keratitis, is reported. A healthy 32-year-old woman with a history of frequent replacement of her contact lenses due to wear was examined at Dokkyo Medical University Koshigaya Hospital (Saitama, Japan) and found to have a slight corneal opacity that was accompanied by radial keratoneuritis. Based on both the patient’s clinical findings and past history, the presence of Acanthamoeba keratitis was highly suspected. However, direct light microscopy of corneal scrapings stained by the Parker ink–potassium hydroxide method only found Acanthamoeba-type material in the specimen collected at her initial visit. In all other specimens collected from the patient, no Acanthamoeba was found either when using the same method or when performing cultures of the surgical debridement of the corneal lesion. In addition, topical antifungal eye drops, systemic antifungal drugs, and surgical debridement were also not effective in this case. Since a precise diagnosis could not be made, the patient was treated with topical 0.1% betamethasone sodium, which ultimately resulted in a dramatic improvement of her corneal inflammation. At 23 days after initiation of topical administration of 0.1% betamethasone sodium, visual acuity was 20/250, with a slight corneal opacity noted at the original site of infection. The outcome of the current case suggests that radial keratoneuritis is not always pathognomonic for Acanthamoeba keratitis.

Radial keratoneuritis as a presenting sign in Acanthamoeba keratitis

The visual outcomes of Acanthamoeba keratitis, a rare cause of corneal infection, can be devastating. This paper reports two contact lens wearers with severe pain and photophobia who presented to the emergency room. Biomicroscopy revealed radial keratoneuritis in both individuals. Tissue culture on a nonnutrient agar plate with Escherichia coli overlay resulted in a heavy growth of Acanthamoeba. The inpatient treatment included 0.02% polyhexamethylene biguanide, chlorhexidine, neomycin/polymyxin B/bacitracin (Neosporin), and oral fluconazole, which successfully controlled the corneal infection and improvement in the best corrected visual acuity in both patients. Infection did not recur during the 12-month follow-up period. Acanthamoeba keratitis can present as radial keratoneuritis, mimicking other common corneal infections resulting in diagnostic and treatment delays. Early diagnosis and prudent treatment of Acanthamoeba keratitis are the keys to restoring vision and avoiding the subsequent need for penetrating keratoplasty.