Diagnostic armamentarium of infectious keratitis: A comprehensive review

Unveiling challenging corneal infections: a comprehensive etiological diagnosis through metagenomic next-generation sequencing (mNGS) of corneal tissue samples

PURPOSE

The objective of this study was to assess the clinical diagnostic value of metagenomic next-generation sequencing (mNGS) in cases of challenging corneal infections using corneal tissue samples.

METHODS

This retrospective study involved 42 patients with corneal infections, where conventional diagnostic techniques failed to identify the causative pathogen. Corneal tissue specimens underwent mNGS, followed by microbial culture for validation. Sensitivity-guided antimicrobial therapy was administered upon identification of the pathogen. The diagnostic and therapeutic efficacy of mNGS was analyzed to evaluate its clinical utility.

RESULTS

A total of 42 patients were included in this study, with mNGS detection results obtained for 38 cases (90.48%). Among them, 30 cases (71.43%) were clinically significant, eight cases (19.05%) had low clinical relevance, and four cases (9.52%) showed no detection. Following corresponding antimicrobial treatment, 30 patients exhibited significant improvement, resulting in a treatment effectiveness of 71.43%. The prognosis of mNGS-positive patients was superior to that of mNGS-negative patients, with statistically significant differences observed (P < 0.001).

CONCLUSIONS

Corneal tissue mNGS facilitated the rapid identification of causative agents in challenging corneal infections with unclear clinical diagnoses. It could be seamlessly integrated with traditional diagnostic methods to guide the diagnosis and treatment of corneal diseases.

Penetrative Ionic Organic Molecular Cage Nanozyme for the Targeted Treatment of Keratomycosis

Keratomycosis, caused by pathogenic fungi, is an intractable blinding eye disease. Corneal penetration is an essential requirement for conventional antifungal medications to address keratomycosis. Due to the distinctive anatomical and physiological structure of the cornea, the therapeutic efficacy is hampered by the inadequate penetration capacity. Despite the emergence of diverse antifungal drug delivery systems and advanced antifungal nanomaterials, it has remained challenging to achieve corneal penetration over the past decade. This study fabricates a penetrative ionic organic molecular cage-based nanozyme (OMCzyme) for treating keratomycosis. The synthesis of OMCzyme involved two steps. Initially, the ionic OMC is synthesized by a [2+3] cycloimination reaction of triformylphloroglucinol and 2,3-diaminopropionic acid. Subsequently, OMCzyme is fabricated by coordination of Fe2⁺ with carboxyl anions and phenolic hydroxyls in the organic cage, and further deposition of silver nanoparticles on the surface of OMC-Fe complex. The as-prepared OMCzyme demonstrates excellent water dispersion, peroxidase-like activity, in vitro and in vivo biocompatibility, and corneal penetration. Notably, the nanozyme displays targeted antifungal activity, effectively combating Fusarium solani with negligible cytotoxicity toward human corneal epithelial cells. The hybrid mimic is further demonstrated to be effective in treating keratomycosis in mice, indicating the potential of OMCzyme for curing fungal infectious diseases.

Baicalein glycymicelle ophthalmic solution: Preparation, in vitro antimicrobial activities, and antimicrobial mechanism evaluations

The purpose of this study was to develop a novel baicalein (BAI) loaded glycymicelle ophthalmic solution with small molecule phytochemical glycyrrhizin as nanocarriers and to explore this solution's potential as an antimicrobial agent against ocular infections. The optimized BAI glycymicelles had a high encapsulation efficiency (98.76 ± 1.25 %), a small particle size (54.38 ± 2.41 nm), a uniform size distribution (polydispersity index = 0.293 ± 0.083), and a zeta potential of -28.3 ± 1.17 mV. The BAI glycymicelle ophthalmic solution exhibited an excellent short-term storage stability. BAI glycymicelles significantly increased the apparent solubility and in vitro release capability of BAI. The BAI glycymicelle ophthalmic solution exhibited no hen's egg-chorioallantoic membrane' irritation and strong in vivo ocular tolerance in rabbits. The BAI glycymicelles noticeably enhanced the in vivo corneal permeation. The BAI glycymicelles also precipitated increased in vitro antioxidant activity and significantly improved in vitro antipathogen activities. Various antimicrobial mechanisms, including the destruction of the bacterial cell wall, damage to the bacterial cell membranes, interruptions to the biofilm structure, and the apoptosis of bacteria, were inflicted on BAI glycymicelles. These findings provided useful knowledge regarding the development of a novel ophthalmic solution and formulation of BAI.

Understanding Acanthamoeba Keratitis: An In-Depth Review of a Sight-Threatening Eye Infection

Acanthamoeba keratitis (AK) is a rare but potentially sight-threatening corneal infection caused by the Acanthamoeba parasite. This microorganism is found ubiquitously in the environment, often in freshwater, soil, and other sources of moisture. Despite its low incidence, AK presents significant challenges due to delayed diagnosis and the complex nature of therapeutic management. Early recognition is crucial to prevent severe ocular complications, including corneal ulceration and vision loss. Diagnostic modalities and treatment strategies may vary greatly depending on the clinical manifestation and the available tools. With the growing reported cases of Acanthamoeba keratitis, it is essential for the ophthalmic community to thoroughly understand this condition for its effective management and improved outcomes. This review provides a comprehensive overview of AK, encompassing its epidemiology, risk factors, pathophysiology, clinical manifestations, diagnosis, and treatment.

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.

Infectious eye disease in the 21st century-an overview

Infectious diseases affecting the eye often cause unilateral or asymmetric visual loss in children and people of working age. This group of conditions includes viral, bacterial, fungal and parasitic diseases, both common and rare presentations which, in aggregate, may account for a significant portion of the global visual burden. Diagnosis is frequently challenging even in specialist centres, and many disease presentations are highly regional. In an age of globalisation, an understanding of the various modes of transmission and the geographic distribution of infections can be instructive to clinicians. The impact of eye infections on global disability is currently not sufficiently captured in global prevalence studies on visual impairment and blindness, which focus on bilateral disease in the over-50s. Moreover, in many cases it is hard to differentiate between infectious and immune-mediated diseases. Since infectious eye diseases can be preventable and frequently affect younger people, we argue that in future prevalence studies they should be considered as a separate category, including estimates of disability-adjusted life years (DALY) as a measure of overall disease burden. Numbers of ocular infections are uniquely affected by outbreaks as well as endemic transmission, and their control frequently relies on collaborative partnerships that go well beyond the remit of ophthalmology, encompassing domains as various as vaccination, antibiotic development, individual healthcare, vector control, mass drug administration, food supplementation, environmental and food hygiene, epidemiological mapping, and many more. Moreover, the anticipated impacts of global warming, conflict, food poverty, urbanisation and environmental degradation are likely to magnify their importance. While remote telemedicine can be a useful aide in the diagnosis of these conditions in resource-poor areas, enhanced global reporting networks and artificial intelligence systems may ultimately be required for disease surveillance and monitoring.

In Vivo Confocal Microscopy Characterization of Candida parapsilosis Keratitis

ABSTRACT

The present clinical case concerns two patients with mycotic keratitis because of Candida parapsilosis in which corneal confocal microscopy presented a characteristic feature of this pathogen. Both described patients used a therapeutic contact lens and administered a therapy with steroid eye drops which are well known predisposing factors for the onset of corneal mycoses. This report can be useful for correctly identifying the pathologic condition and quickly directing the therapy.

Clinical Applications of Anterior Segment Optical Coherence Tomography: An Updated Review

Since its introduction, optical coherence tomography (OCT) has revolutionized the field of ophthalmology and has now become an indispensable, noninvasive tool in daily practice. Most ophthalmologists are familiar with its use in the assessment and monitoring of retinal and optic nerve diseases. However, it also has important applications in the assessment of anterior segment structures, including the cornea, conjunctiva, sclera, anterior chamber, and iris, and has the potential to transform the clinical examination of these structures. In this review, we aim to provide a comprehensive overview of the potential clinical utility of anterior segment OCT (AS-OCT) for a wide range of anterior segment pathologies, such as conjunctival neoplasia, pterygium, scleritis, keratoconus, corneal dystrophies, and infectious/noninfectious keratitis. In addition, the clinical applications of AS-OCT (including epithelial mapping) in preoperative planning and postoperative monitoring for corneal and refractive surgeries are discussed.

Frequency and visual outcomes of herpes simplex keratitis in a Kuwaiti tertiary referral center

Background

Herpes simplex virus (HSV), a cause of many ocular pathologies, may affect the corneal epithelium, stroma, or endothelium, with the epithelium as the most frequently affected location. We aimed to determine the frequency and visual outcomes of HSV keratitis over a 1-year period at Farwaniya Hospital, Kuwait.

Methods

This prospective observational case series included patients diagnosed with HSV keratitis who presented to the outpatient or eye casualty department between September 2022 and September 2023. Full history, demographic profile, detailed ocular and slit-lamp examinations, and visual acuity assessments were recorded prior to and after treatment. Baseline corneal sensation was assessed in the four corneal quadrants using the cotton wisp test.

Results

Of the 227 patients who presented with infectious keratitis, 72 (31.7%) were diagnosed with HSV keratitis. The mean (SD) age was 45.86 (16.06) years, and 48 (66.7%) patients were male. The subtypes of HSV keratitis were endotheliitis in 27 (37.5%) patients, dendritic ulcer in 22 (30.6%), stromal keratitis with ulceration in 9 (12.5%) and without ulceration in 8 (11.1%), and geographic ulcer in 6 (8.3%). The mean baseline best-corrected distance visual acuity (BCDVA) differed significantly between the HSV keratitis subtypes (P < 0.001). Most patients (n = 70, 97.2%) had unilateral eye involvement, were treated within 1 - 2 weeks, and demonstrated improved BCDVA. Despite the improvement in BCDVA in all HSV keratitis subtypes, a significant difference in the median BCDVA remained after treatment (P < 0.001). Pairwise comparisons revealed a significantly better BCDVA after treatment in eyes with dendritic epithelial ulcers than in eyes with HSV stromal keratitis with ulceration (P = 0.003) or geographic epithelial ulcers (P = 0.005). After treatment, corneal haze and neovascularization were detected in 54 (75.0%) and 24 (33.3%) patients, respectively.

Conclusions

We detected a substantial frequency of HSV keratitis in one of the governorates of Kuwait, with endotheliitis as the most common manifestation. Timely standard treatment interventions based on valid guidelines resulted in BCDVA improvement in all subtypes of HSV keratitis in our series, indicating the importance of early treatment. However, the BCDVA in eyes with dendritic epithelial ulcers remained substantially better than that in eyes with geographic epithelial ulcers or HSV stromal keratitis with ulceration, signifying the effect of the initial HSV keratitis subtype on visual outcomes. To our knowledge, this is the first study to highlight the frequency of HSV keratitis in a Kuwaiti hospital, and larger-scale research in this region is needed to further understand and manage the condition.

Metagenomic next-generation sequencing to investigate infectious keratitis by Corynespora cassiicola: a case report

In this report, the case of a 65-year-old immunosuppressed female who presented with recurring redness and irritation in her right eye for 2 months is described. Ocular examination revealed conjunctival congestion, feather-like greyish-white corneal deep stromal infiltrate, white, floccular material sprawling from the anterior chamber angle and hypopyon. The in vivo confocal microscopy (IVCM) instantly confirmed fungal keratitis, and empirical antifungal therapy was thus administered. The patient exhibited therapeutic penetrating keratoplasty, however, due to the progression of infection and the lack of identified pathogens. The fungal isolate was identified as Corynespora cassiicola by metagenomic next-generation sequencing (mNGS) of the host cornea. The patient responded well to intensive conservative therapy and subsequent surgical therapy. To our knowledge, this case represents the first case of C. cassiicola infection from China, highlighting the emergence of a rare fungus that causes keratitis. Furthermore, mNGS has the capability to facilitate prompt identification and timely management of challenging ocular infections that are difficult to diagnose.

Ocular microbial dysbiosis and its linkage with infectious keratitis patients in Northwest China: A cross-sectional study

OBJECTIVES

To evaluate the alteration of ocular surface microbiome of patients with infectious keratitis in northwest of China.

METHODS

The corneal scrapings, eyelid margin and conjunctiva samples were collected from 57 participants, who were divided into bacterial keratitis, fungal keratitis, viral keratitis and control group. The V3-V4 region of bacterial 16S rDNA in each sample was amplified and sequenced on the Illumina HiSeq 2500 sequencing platform, and the differences among different groups were compared bioinformatically.

RESULTS

Significant alterations of the microbiome were observed in alpha-diversity and beta-diversity analysis between the keratitis groups and the control group (p < 0.05). There was no significant differences between eyelid margin and conjunctiva samples in Alpha-Diversity analysis, but a significant difference between eyelid margin and corneal scraping samples in the keratitis group (p < 0.05, independent t-test). The abundances of Bacillus, Megamonas, Acinetobacter, and Rhodococcu were significantly elevated, while the abundance of Staphylococcus was decreased in the keratitis group compared to the control group.

CONCLUSIONS

The abundance of the ocular microbiome in patients with bacterial keratitis, fungal keratitis, or viral keratitis was significantly higher than those in the control group. Keratitis patients may have ecological disorder on ocular surface microbiome compared with controls. We believe that the conjunctiva and eyelid margin microbiome combined analysis can more comprehensively reflect the composition and abundance of ocular surface microbiome.

Updates in Diagnostic Imaging for Infectious Keratitis: A Review

Infectious keratitis (IK) is among the top five leading causes of blindness globally. Early diagnosis is needed to guide appropriate therapy to avoid complications such as vision impairment and blindness. Slit lamp microscopy and culture of corneal scrapes are key to diagnosing IK. Slit lamp photography was transformed when digital cameras and smartphones were invented. The digital camera or smartphone camera sensor's resolution, the resolution of the slit lamp and the focal length of the smartphone camera system are key to a high-quality slit lamp image. Alternative diagnostic tools include imaging, such as optical coherence tomography (OCT) and in vivo confocal microscopy (IVCM). OCT's advantage is its ability to accurately determine the depth and extent of the corneal ulceration, infiltrates and haze, therefore characterizing the severity and progression of the infection. However, OCT is not a preferred choice in the diagnostic tool package for infectious keratitis. Rather, IVCM is a great aid in the diagnosis of fungal and Acanthamoeba keratitis with overall sensitivities of 66-74% and 80-100% and specificity of 78-100% and 84-100%, respectively. Recently, deep learning (DL) models have been shown to be promising aids for the diagnosis of IK via image recognition. Most of the studies that have developed DL models to diagnose the different types of IK have utilised slit lamp photographs. Some studies have used extremely efficient single convolutional neural network algorithms to train their models, and others used ensemble approaches with variable results. Limitations of DL models include the need for large image datasets to train the models, the difficulty in finding special features of the different types of IK, the imbalance of training models, the lack of image protocols and misclassification bias, which need to be overcome to apply these models into real-world settings. Newer artificial intelligence technology that generates synthetic data, such as generative adversarial networks, may assist in overcoming some of these limitations of CNN models.

Accelerated high fluence photoactivated chromophore for infectious keratitis-corneal cross-linking (PACK-CXL) at the slit lamp: a pilot study

Introduction: Photoactivated Chromophore for Infectious Keratitis-Corneal Cross-Linking (PACK-CXL) has garnered substantial interest among researchers and ophthalmologists due to its high promise as a potential treatment for infectious keratitis. The aim of this study is to evaluate the efficacy and safety of high fluence PACK-CXL, using 10.0 J/cm2 (30 mW/cm2, 5 min, and 33 s) at the slit lamp. Methods: This prospective interventional, nonrandomized cohort study included 20 eyes of 20 patients with bacterial, fungal, or mixed origin keratitis who underwent high fluence PACK-CXL treatment as an adjunct therapy to conventional antimicrobial therapy per American Academy of Ophthalmology treatment guidelines. The re-epithelization time was recorded, and corneal endothelial cell density was counted before and after treatment. Results: The average re-epithelization time was 8.2 ± 2.8 days (range 3-14 days). After PACK-CXL treatment, eight patients (40%) were directly discharged, while the remained patients stayed in the hospital for an average of 5.6 ± 3.5 days. No eyes required keratoplasty. Endothelial cell density counts before and after the PACK-CXL procedure were 2,562.1 ± 397.3, and 2,564.8 ± 404.5 cells/mm2, respectively (p = 0.96). Conclusion: although it was not a randomized control trial, we conclude that high fluence PACK-CXL as an adjuvant therapy is safe with no complications observed, and efficient as time to re-epithelization was less than 14 days for all patients and no patients underwent tectonic keratoplasties. Further research is needed to compare it to the current standard of care.

A 7-year review of clinical characteristics, predisposing factors and outcomes of post-keratoplasty infectious keratitis: the Nottingham infectious keratitis study

Background/objectives

Post-keratoplasty infectious keratitis (PKIK) is a unique sight-threatening clinical entity which often poses significant therapeutic challenges. This study aimed to examine the clinical presentation, risk factors, management, and clinical outcomes of PKIK.

Methods

This was a retrospective study of all patients who presented to the Queen's Medical Centre, Nottingham, with PKIK between September 2015 and August 2022 (a 7-year period). Relevant data on types of keratoplasty, clinical presentations, causative microorganisms, management, and outcome were analyzed.

Results

Forty-nine PKIK cases, including four cases of interface infectious keratitis, were identified during the study period. The most common graft indications for PKP, DALK and EK were failed grafts (9, 37.5%), keratoconus (6, 54.5%) and Fuchs endothelial corneal dystrophy (FECD; 8, 57.1%), respectively. Staphylococcus spp. were the most commonly identified organisms (15, 50.0%). Bullous keratopathy (18, 36.7%), ocular surface disease (18, 36.7%), and broken/loose sutures (15, 30.6%) were the most common risk factors. Concurrent use of topical steroids was identified in 25 (51.0%) cases. Of 31 functioning grafts at presentation, 12 (38.7%) grafts failed at final follow-up with 15 (48.4%) patients retaining a CDVA of ≥1.0 logMAR. The overall estimated 5-year survival rate post-PKIK was 55.9% (95% CI, 35.9%-75.9%), with DALK having the highest survival rate [63.6% (95% CI, 28.9%-98.3%)], followed by EK [57.1% (95% CI, 20.4%-93.8%)] and PKP [52.7% (95% CI, 25.1%-80.3%)], though no statistical difference was observed (p=0.48).

Conclusions

PKIK represents an important cause of IK and graft failure. Bullous keratopathy, OSD and suture-related complications are the commonest risk factors, highlighting the potential benefit of prophylactic topical antibiotics (for unhealthy ocular surface) and early suture removal (where possible) in reducing the risk of PKIK. Graft survival may be higher in lamellar keratoplasty following PKIK but larger studies are required to elucidate this observation.

Diagnosis of Acanthamoeba Keratitis: Past, Present and Future

Acanthamoeba keratitis (AK) is a painful and sight-threatening parasitic corneal infection. In recent years, the incidence of AK has increased. Timely and accurate diagnosis is crucial during the management of AK, as delayed diagnosis often results in poor clinical outcomes. Currently, AK diagnosis is primarily achieved through a combination of clinical suspicion, microbiological investigations and corneal imaging. Historically, corneal scraping for microbiological culture has been considered to be the gold standard. Despite its technical ease, accessibility and cost-effectiveness, the long diagnostic turnaround time and variably low sensitivity of microbiological culture limit its use as a sole diagnostic test for AK in clinical practice. In this review, we aim to provide a comprehensive overview of the diagnostic modalities that are currently used to diagnose AK, including microscopy with staining, culture, corneal biopsy, in vivo confocal microscopy, polymerase chain reaction and anterior segment optical coherence tomography. We also highlight emerging techniques, such as next-generation sequencing and artificial intelligence-assisted models, which have the potential to transform the diagnostic landscape of AK.

Diagnostic performance of deep learning in infectious keratitis: a systematic review and meta-analysis protocol

INTRODUCTION

Infectious keratitis (IK) represents the fifth-leading cause of blindness worldwide. A delay in diagnosis is often a major factor in progression to irreversible visual impairment and/or blindness from IK. The diagnostic challenge is further compounded by low microbiological culture yield, long turnaround time, poorly differentiated clinical features and polymicrobial infections. In recent years, deep learning (DL), a subfield of artificial intelligence, has rapidly emerged as a promising tool in assisting automated medical diagnosis, clinical triage and decision-making, and improving workflow efficiency in healthcare services. Recent studies have demonstrated the potential of using DL in assisting the diagnosis of IK, though the accuracy remains to be elucidated. This systematic review and meta-analysis aims to critically examine and compare the performance of various DL models with clinical experts and/or microbiological results (the current 'gold standard') in diagnosing IK, with an aim to inform practice on the clinical applicability and deployment of DL-assisted diagnostic models.

METHODS AND ANALYSIS

This review will consider studies that included application of any DL models to diagnose patients with suspected IK, encompassing bacterial, fungal, protozoal and/or viral origins. We will search various electronic databases, including EMBASE and MEDLINE, and trial registries. There will be no restriction to the language and publication date. Two independent reviewers will assess the titles, abstracts and full-text articles. Extracted data will include details of each primary studies, including title, year of publication, authors, types of DL models used, populations, sample size, decision threshold and diagnostic performance. We will perform meta-analyses for the included primary studies when there are sufficient similarities in outcome reporting.

ETHICS AND DISSEMINATION

No ethical approval is required for this systematic review. We plan to disseminate our findings via presentation/publication in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42022348596.

Nonsurgical Management of Severe Viral Keratitis with Hypopyon and Retrocorneal Plaques: A Case Series

INTRODUCTION

Severe viral keratitis with hypopyon and retrocorneal plaques is easily misdiagnosed as it mimics fungal or bacterial keratitis and is more likely to undergo emergency therapeutic penetrating keratoplasty (TPK) in the presence of active infection, resulting in poor outcomes. This case series offers some important insights for the management strategy of severe viral keratitis.

METHODS

This retrospective case series involved five patients with unilateral severe infectious keratitis with hypopyon over 3 mm and retrocorneal endothelial plaques. Testing for corneal sensation, microscopy, culture, and anterior segment optical coherence tomography (ASOCT) were performed.

RESULTS

At presentation, all five cases had visual acuity of counting fingers (CF) or worse, large centrally located ulcer with clean ulcer surface, hypopyon, and retrocorneal plaques with reduced corneal sensation. ASOCT demonstrated the presence of retrocorneal plaques with clear space between corneal endothelium and plaques. All cases received systemic and topical ganciclovir and topical steroids. Two patients received intravenous immunoglobulin (IVIG) weekly for 2 weeks. Complete resolution was achieved in all cases except one patient who underwent TPK because of diffuse anterior synechiae of the iris, with recurrence of infection after 10 days. The patients who received IVIG showed resolution earlier compared to the other patients.

CONCLUSIONS

Evaluation of characteristics of retrocorneal plaques by ASOCT and reduced corneal sensation are valuable aids in diagnosis of complicated viral keratitis. Conservative medical management may be a viable option even in severe cases. IVIG may have a role in speedy resolution of severe cases, but more research is needed to confirm this.

Changes in corneal higher-order aberrations during treatment for infectious keratitis

This study aimed to quantify the changes in corneal higher-order aberrations (HOAs) before and after treatment for infectious keratitis and verify the correlation between corneal HOAs and visual acuity. Corneal HOAs were analysed using swept-source anterior segment optical coherence tomography (AS-OCT). Ninety-eight eyes of 96 consecutive patients with infectious keratitis treated with topical eye drops were retrospectively evaluated. Corneal HOAs increased with the infection but decreased with infection resolution following antimicrobial treatment. Corneal HOAs became larger as the degree of corneal findings became more severe. The increase in HOAs of the total cornea was correlated with the decrease in visual acuity both before and after treatment (4 mm, ρ = 0.530 and 0.590; 6 mm, ρ = 0.479 and 0.567, respectively; all P < 0.0001). Furthermore, pretreatment HOA (anterior, 6 mm), pretreatment logMAR best spectacle-corrected visual acuity, and age were prognostic factors significantly associated with posttreatment visual acuity (β = 0.31, P = 0.013; β = 0.36, P < 0.0001; and β = 0.35, P = 0.0007, respectively) (adjusted R² = 0.474). These results indicate that corneal HOAs quantified using AS-OCT can be used as an objective index to evaluate corneal optical function during the treatment of infectious keratitis.

Recent Applications of Contact Lenses for Bacterial Corneal Keratitis Therapeutics: A Review

Corneal keratitis is a common but severe infectious disease; without immediate and efficient treatment, it can lead to vision loss within a few days. With the development of antibiotic resistance, novel approaches have been developed to combat corneal keratitis. Contact lenses were initially developed to correct vision. Although silicon hydrogel-based contact lenses protect the cornea from hypoxic stress from overnight wear, wearing contact lenses was reported as an essential cause of corneal keratitis. With the development of technology, contact lenses are integrated with advanced functions, and functionalized contact lenses are used for killing bacteria and preventing infectious corneal keratitis. In this review, we aim to examine the current applications of contact lenses for anti-corneal keratitis.

Photoactivated Chromophore Corneal Collagen Cross-Linking for Infectious Keratitis (PACK-CXL)-A Comprehensive Review of Diagnostic and Prognostic Factors Involved in Therapeutic Indications and Contraindications

Infectious keratitis is a severe infection of the eye, which requires urgent care in order to prevent permanent complications. Typical cases are usually diagnosed clinically, whereas severe cases also require additional tools, such as direct microscopy, corneal cultures, molecular techniques, or ophthalmic imaging. The initial treatment is empirical, based on the suspected etiology, and is later adjusted as needed. It ranges from topical administration of active substances to oral drugs, or to complex surgeries in advanced situations. A novel alternative is represented by Photoactivated Chromophore Corneal Collagen Cross-Linking (PACK-CXL), which is widely known as a minimally invasive therapy for corneal degenerations. The purpose of this review is to identify the main diagnostic and prognostic factors which further outline the indications and contraindications of PACK-CXL in infectious keratitis. Given the predominantly positive outcomes in the medical literature, we ponder whether this is a promising treatment modality, which should be further evaluated in a systematic, evidence-based manner in order to develop a clear treatment protocol for successful future results, especially in carefully selected cases.

A Review on Pathogens and Necessary Diagnostic Work for Bleb-Related Infections (BRIs)

At the present time, as newer techniques and minimally invasive procedures gain popularity among anterior segment surgeons for regulating intraocular pressure, trabeculectomy still has a leading role in glaucoma surgery. Trabeculectomy retains a highly successful and safe profile; however, one of the major complications includes bleb-related infections (BRIs). To date, the most common pathogens remain Gram-positive cocci, but the list of pathogens that have been identified in the literature includes more than 100 microorganisms. Because antibiotic use is more widespread than ever before and our ability to identify pathogens has improved, the pathogen spectrum will broaden in the future and more pathogens causing BRIs will be described as atypical presentations. The scope of this review was to identify all pathogens that have been described to cause bleb-related infections to date, as well as focus on the risk factors, clinical presentation, and various available diagnostic tools used for an appropriate diagnostic workup.

Alginate-Based Composites for Corneal Regeneration: The Optimization of a Biomaterial to Overcome Its Limits

For many years, corneal transplantation has been the first-choice treatment for irreversible damage affecting the anterior part of the eye. However, the low number of cornea donors and cases of graft rejection highlighted the need to replace donor corneas with new biomaterials. Tissue engineering plays a fundamental role in achieving this goal through challenging research into a construct that must reflect all the properties of the cornea that are essential to ensure correct vision. In this review, the anatomy and physiology of the cornea are described to point out the main roles of the corneal layers to be compensated and all the requirements expected from the material to be manufactured. Then, a deep investigation of alginate as a suitable alternative to donor tissue was conducted. Thanks to its adaptability, transparency and low immunogenicity, alginate has emerged as a promising candidate for the realization of bioengineered materials for corneal regeneration. Chemical modifications and the blending of alginate with other functional compounds allow the control of its mechanical, degradation and cell-proliferation features, enabling it to go beyond its limits, improving its functionality in the field of corneal tissue engineering and regenerative medicine.

The use of in vivo confocal microscopy in fungal keratitis - Progress and challenges

Fungal keratitis (FK) is a serious and sight-threatening corneal infection with global reach. The need for prompt diagnosis is paramount, as a delay in initiation of treatment could lead to irreversible vision loss. Current "gold standard" diagnostic methods, namely corneal smear and culture, have limitations due to diagnostic insensitivity and their time-consuming nature. PCR is a newer, complementary method used in the diagnosis of fungal keratitis, whose results are also sample-dependent. In vivo confocal microscopy (IVCM) is a promising complementary diagnostic method of increasing importance as it allows non-invasive real-time direct visualization of potential fungal pathogens and manifesting infection directly in the patient's cornea. In numerous articles and case reports, FK diagnosis by IVCM has been evaluated, and different features, approaches, sensitivity/specificity, and limitations have been noted. Here, we provide an up-to-date, comprehensive review of the current literature and present the authors' combined recommendations for fungal identification in IVCM images, while also looking to the future of FK assessment by IVCM using artificial intelligence methods.

Clinical Characteristics and Outcomes of Fungal Keratitis in the United Kingdom 2011-2020: A 10-Year Study

Fungal keratitis (FK) is a serious ocular infection that often poses significant diagnostic and therapeutic dilemmas. This study aimed to examine the causes, clinical characteristics, outcomes, and prognostic factors of FK in the UK. All culture-positive and culture-negative presumed FK (with complete data) that presented to Queen’s Medical Centre, Nottingham, and the Queen Victoria Hospital, East Grinstead, between 2011 and 2020 were included. We included 117 patients (n = 117 eyes) with FK in this study. The mean age was 59.0 ± 19.6 years (range, 4–92 years) and 51.3% of patients were female. Fifty-three fungal isolates were identified from 52 (44.4%) culture-positive cases, with Candida spp. (33, 62.3%), Fusarium spp. (9, 17.0%), and Aspergillus spp. (5, 9.4%) being the most common organisms. Ocular surface disease (60, 51.3%), prior corneal surgery (44, 37.6%), and systemic immunosuppression (42, 35.9%) were the three most common risk factors. Hospitalisation for intensive treatment was required for 95 (81.2%) patients, with a duration of 18.9 ± 16.3 days. Sixty-six (56.4%) patients required additional surgical interventions for eradicating the infection. Emergency therapeutic/tectonic keratoplasty was performed in 29 (24.8%) cases, though 13 (44.8%) of them failed at final follow-up. The final corrected-distance-visual-acuity (CDVA) was 1.67 ± 1.08 logMAR. Multivariable logistic regression analyses demonstrated increased age, large infiltrate size (>3 mm), and poor presenting CDVA (<1.0 logMAR) as significant negative predictive factors for poor visual outcome (CDVA of <1.0 logMAR) and poor corneal healing (>60 days of healing time or occurrence of corneal perforation requiring emergency keratoplasty; all p < 0.05). In conclusion, FK represents a difficult-to-treat ocular infection that often results in poor visual outcomes, with a high need for surgical interventions. Innovative treatment strategies are urgently required to tackle this unmet need.