[Diagnostics and treatment of infectious keratitis]

Global research on keratomycosis: New insights from latent Dirichlet allocation and HJ-Biplot-driven knowledge mapping study

BACKGROUND

Keratomycosis is a form of infectious keratitis, an infection of the cornea, which is caused by fungi. This disease is a leading cause of ocular morbidity globally with at least 60 % of the affected individuals becoming monocularly blind.

OBJECTIVE

This bibliometric analysis aimed to comprehensively assess the existing body of literature, providing insights of the evolution of keratomycosis research by identifying key themes and research gaps.

METHODS

This work used the modeling method Latent Dirichlet Allocation (LDA) to identify and interpret scientific information on topics concerning existing categories in a set of documents. The HJ-Biplot method was also used to determine the relationship between the analyzed topics, taking into consideration the years under study.

RESULTS

This bibliometric analysis was performed on a total of 2,599 scientific articles published between 1992 and 2022. The five leading countries with more scientific production and citations on keratomycosis were The United States of America, followed by India, China, United Kingdom and Australia. The top five topics studied were Case Reports and Corneal Infections, which exhibited a decreasing trend; followed by Penetrating Keratoplasty and Corneal Surgery, Ocular Effects of Antifungal Drugs, Gene Expression and Inflammatory Response in the Cornea and Patient Data which have been increasing throughout the years. However Filamentous Fungi and Specific Pathogens, and Antifungal Therapies research has been decreasing in trend.

CONCLUSION

Additional investigation into innovative antifungal drug therapies is crucial for proactively tackling the potential future resistance to antifungal agents in scientific writing.

Clinical Observation of Corneal Endothelial Plaques With Fungal and Bacterial Keratitis by Anterior Segment Optical Coherence Tomography and In Vivo Confocal Microscopy

PURPOSE

Endothelial plaque is an important sign of fungal keratitis and is related to diagnosis, surgical indications, and prognosis. However, bacterial keratitis sometimes involves fibrin formation on the back corneal surface, similar to endothelial plaques. Because corneal infiltration interferes with precise observation of the posterior corneal plaque, distinguishing pathogens with a slitlamp is difficult. We hope to assist clinicians in early diagnosis and timely treatment by observing the connection state of endothelial plaques and the corneal endothelium through anterior segment optical coherence tomography (AS-OCT) and the different forms of endothelial plaques in infectious keratopathy through in vivo confocal microscopy (IVCM).

METHODS

We analyzed 52 patients in the Eye Hospital of the First Affiliated Hospital of Harbin Medical University who were clearly diagnosed with fungal or bacterial keratitis with endothelial plaques. All patients underwent AS-OCT and IVCM on admission.

RESULTS

According to the smear, IVCM, or fungal and bacterial culture results, the patients were diagnosed with fungal (28 patients) or bacterial keratitis (24 patients). AS-OCT in 25 patients diagnosed with fungal keratitis revealed that the corneal endothelium-endothelial plaque boundary was unclear and wavy, and 24 patients had unclear cell boundaries and a large number of compactly distributed inflammatory cells in the endothelial layer according to IVCM. AS-OCT in 23 patients diagnosed with bacterial keratitis revealed clear corneal endothelium-endothelial plaque boundaries, and insufficient endothelial cell boundaries with a large number of visible and scattered inflammatory cell structures were observed through IVCM in 22 patients.

CONCLUSIONS

Corneal endothelial plaque detection by AS-OCT and IVCM can be used for early diagnosis of infectious keratitis.

Applications of medicinal chemistry for drug discovery against Acanthamoeba infections

Acanthamoeba is a genus of free-living amoebae, pervasively found in the environment. Most of its pathogenic species are the causative agent of sight-threatening Acanthamoeba keratitis and fatal granulomatous amoebic encephalitis. Despite the advancements in the field of chemotherapy, treating Acanthamoeba infections is still challenging due to incomplete knowledge of the complicated pathophysiology. In case of infection, the treatment regimen for the patients is often ineffective due to delayed diagnosis, poor specificity, and side-effects. Besides the resistance of Acanthamoeba cysts to most of the drugs, the recurrence of infection further complicates the recovery. Thus, it is necessary to develop an effective treatment which can eradicate these rare, but serious infections. Based on various computational and in vitro studies, it has been established that the synthetic scaffolds such as heterocyclic compounds may act as potential drug leads for the development of antiamoebic drugs. In this review, we report different classes of synthetic compounds especially heterocyclic compounds which have shown promising results against Acanthamoeba. Moreover, the antiamoebic activities of synthetic compounds with their possible mode of actions against Acanthamoeba, have been summarized and discussed in this review.

Bilateral Limbal Stem Cell Alterations in Patients With Unilateral Herpes Simplex Keratitis and Herpes Zoster Ophthalmicus as Shown by In Vivo Confocal Microscopy

Purpose

The purpose of this study was to investigate the limbal changes in the palisades of Vogt (POV) in patients with herpes simplex keratitis (HSK) and herpes zoster ophthalmicus (HZO) with the application of in vivo confocal microscopy (IVCM).

Methods

We enrolled 35 eyes of 35 consecutive patients with HSK and 4 patients with HZO in this observational study. Thirty-five participants were also recruited from a healthy population as the control group. All subjects were examined by IVCM in addition to routine slit-lamp biomicroscopy. The IVCM images of the corneal basal epithelial cells, corneal nerve, and the corneoscleral limbus were acquired and then were analyzed semiquantitatively.

Results

The rate of absent and atypical POV was significantly higher in the affected eyes of patients with HSK than in the contralateral eyes and eyes of controls (88.57% vs. 65.71% vs. 17.14%, P < 0.01). In the HZO group, the rate of absent and atypical POV was 100% in the affected eyes and 50% in the contralateral eyes. When compared to the contralateral unaffected eyes and control eyes, the average density of the central basal epithelial cells and the sub-basal nerve plexus density and the total number of nerves in the central area of the affected eyes were significantly lower in the HSK group (1541 ± 704.4 vs. 2510 ± 746.8 vs. 3650 ± 746.1 cells/mm², P < 0.0001). Spearman's rank correlation showed that the presence of absent and atypical POV had a significant negative correlation with central corneal basal epithelial cells (r_s = −0.44979, P < 0.0001), the density of total nerves (r_s = −0.49742, P < 0.0001), and the total nerve numbers (r_s = −0.48437, P < 0.0001). A significant positive correlation was established between the presence of absent and atypical POV and HSK severity in affected eyes in the superior, inferior, nasal, and temporal quadrants (r_s = 0.68940, r_s = 0.78715, r_s = 0.65591, and r_s = 0.75481, respectively, P < 0.0001) and the contralateral eyes (r_s = 0.51636, r_s = 0.36207, r_s = 0.36990, r_s = 0.51241, correspondingly, P < 0.0001).

Conclusions

Both eyes of patients with unilateral HSK and HZO demonstrated a profound and significant loss of limbal stem cells, which may explain the fact that HSK and HZO are risk factors for limbal stem cell deficiency (LSCD) in both eyes. The loss of LSCs was strongly correlated with the sub-basal nerve plexus and central basal epithelial cell alterations as shown by IVCM.

The management of microbial keratitis within Uganda's primary health system: a situational analysis

Background: Microbial keratitis (MK) frequently leads to sight-loss, especially when the infection is severe and/or appropriate treatment is delayed. The primary health system as an entry point plays a central role in facilitating and directing patient access to appropriate care. The purpose of this study was to describe the capacity of primary health centres in Uganda in managing MK. Methods: We carried out a rigorous assessment of primary health centres and mid-cadre training schools in South Western Uganda. Through interviews, checklists and a picture quiz, we assessed capacity and knowledge of MK management. In addition, we interviewed the heads of all the mid-cadre training schools to determine the level of eye health training provided in their curricula. Results: In total, 163 health facilities and 16 training schools were enrolled. Of the health facilities, only 6% had an Ophthalmic Clinical Officer. Only 12% of the health workers could make a diagnosis of MK based on the clinical signs in the picture quiz. Although 35% of the facilities had a microscope, none reported doing corneal scraping. None of the facilities had a stock of the recommended first line treatment options for MK (ciprofloxacin and natamycin eye drops). Among the training schools, 15/16 had an eye health component in the curriculum. However, the majority (56%) of tutors had no formal expertise in eye health. In 14/16 schools, students spent an average of two weeks in an eye unit. Conclusions: Knowledge among health workers and capacity of health facilities in diagnosis and management of MK was low. Training for eye health within mid-cadre training schools was inadequate. More is needed to close these gaps in training and capacity.