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

Assessing PCR-Positive Acanthamoeba Keratitis-A Retrospective Chart Review

Ophthalmologists' diagnostic and treatment competence in Acanthamoeba keratitis varies widely. This investigator-initiated, retrospective, single-center chart review examined the electronic patient files regarding PCR-positive Acanthamoeba keratitis. We included corneal and contact lens assessments. We further reviewed the patient's medical history, corneal scraping results regarding viral or fungal co-infections, and the duration from symptom onset to final diagnosis. We identified 59 eyes of 52 patients from February 2010 to February 2023, with 31 of 52 (59.6%) being female patients. The median (IQR, range) patient age was 33 (25.3 to 45.5 [13 to 90]) years, and the mean (SD, range) time to diagnosis after symptom onset was 18 (10.5 to 35 [3 to 70]) days. Overall, 7 of 52 (7.7%) patients displayed a bilateral Acanthamoeba infection, and 48 (92.3%) used contact lenses at symptom onset. Regarding other microbiological co-infections, we found virologic PCR testing in 45 of 52 (86.5%) patients, with 3 (6.7%) positive corneal scrapings. Fungal cultures were performed in 49 of 52 (94.2%) patients, with 5 (10.2%) positive corneal scrapings. The medical treatment success rate was 45/46 (97.8%). This study raises awareness of patient education in contact lens handling and screens for further microbial co-infections in suspected Acanthamoeba cases.

The incidence of severe complications in acanthamoeba keratitis: Qualitative and quantitative systematic assessment

Acanthamoeba keratitis (AK) is a rare, sight-threating corneal infection. The disease is challenging to diagnose and treat, and the amoeba can rapidly encyst, persisting in the tissue and causing recurrences. Medical therapy is conventionally considered the first line treatment, but advanced cases could require more invasive treatments like a "chaud" corneal transplant. We review the incidence of severe complications in patients affected by AK. Of 439 reports screened, 158 met our inclusion criteria. Incidence of severe complications was low, with 2.21 % patients developing perforation, 1 % requiring evisceration/enucleation and less than 1 % developing endophthalmitis. Corneal transplantation was required in 16.68 % of the cases. According to our results, and considering the reported incidences of these complications in other infectious keratitis, AK patients have an overall low risk of developing perforation, endophthalmitis, and enucleation/evisceration. Nevertheless, data available in the literature remain poor, and further randomized control trials are needed to confirm our findings.

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

PURPOSE

The aim of this study was to describe 3 cases of recalcitrant Acanthamoeba keratitis (AK) that were successfully treated using in vivo corneal confocal microscopy (IVCM) to guide excimer laser ablation depth with adjunctive mitomycin C 0.02%.

METHODS

Three patients diagnosed with AK did not respond to several weeks of intensive topical therapy with antiamoebic agents. The patient underwent phototherapeutic keratectomy with topical mitomycin C 0.02% application. The maximum stromal depth of cysts measured by IVCM was 80 μm, 100 μm, and 240 μm, and the stromal ablation depths were 80 μm, 100 μm, and 100 μm, respectively.

RESULTS

In all 3 eyes, AK resolved after a single excimer laser application, and topical treatment was gradually discontinued within 6 weeks afterward. In 1 eye, penetrating corneal transplantation was performed 6 weeks after phototherapeutic keratectomy because of ongoing severe corneal pain. IVCM and histology of the corneal transplant did not reveal any Acanthamoeba cysts within the excised corneal button. No recurrence was observed during the follow-up period of 19 to 34 months.

CONCLUSIONS

IVCM-guided phototherapeutic keratectomy with mitomycin C 0.02% seems to be a safe and successful approach for the treatment of AK, especially in cases of resistance to topical treatment. Corneal IVCM should be performed before laser application to measure cyst depth, determine ablation depth, and assess postoperative treatment success.

New Frontiers in Acanthamoeba Keratitis Diagnosis and Management

Acanthamoeba Keratitis (AK) is a severe corneal infection caused by the Acanthamoeba species of protozoa, potentially leading to permanent vision loss. AK requires prompt diagnosis and treatment to mitigate vision impairment. Diagnosing AK is challenging due to overlapping symptoms with other corneal infections, and treatment is made complicated by the organism's dual forms and increasing virulence, and delayed diagnosis. In this review, new approaches in AK diagnostics and treatment within the last 5 years are discussed. The English-language literature on PubMed was reviewed using the search terms "Acanthamoeba keratitis" and "diagnosis" or "treatment" and focused on studies published between 2018 and 2023. Two hundred sixty-five publications were initially identified, of which eighty-seven met inclusion and exclusion criteria. This review highlights the findings of these studies. Notably, advances in PCR-based diagnostics may be clinically implemented in the near future, while antibody-based and machine-learning approaches hold promise for the future. Single-drug topical therapy (0.08% PHMB) may improve drug access and efficacy, while oral medication (i.e., miltefosine) may offer a treatment option for patients with recalcitrant disease.

In-vivo corneal confocal microscopy: Imaging analysis, biological insights and future directions

In-vivo corneal confocal microscopy is a powerful imaging technique which provides clinicians and researcher with the capabilities to observe microstructures at the ocular surfaces in significant detail. In this Mini Review, the optics and image analysis methods with the use of corneal confocal microscopy are discussed. While novel insights of neuroanatomy and biology of the eyes, particularly the ocular surface, have been provided by corneal confocal microscopy, some debatable elements observed using this technique remain and these are explored in this Mini Review. Potential improvements in imaging methodology and instrumentation are also suggested.