Infectious keratitis after corneal crosslinking: systematic review

Immediate postoperative keratitis caused by Rhizopus species following standard CXL for keratoconus: A case report and literature review

PURPOSE

To report the first case of Rhizopus sp keratitis in a 15-year-old male patient who had undergone a conventional Epi-off CXL procedure for progressive keratoconus.

METHODS

A 15-year-old male studying at school presented with defective vision in both eyes recently. He was diagnosed with progressive keratoconus in the right eye more than left eye. After the conventional CXL procedure, the patient developed corneal ulcer on third postoperative day.

RESULTS

The microbiological diagnosis of both BCL and ulcer revealed Rhizopus sp. The patient responded to topical antifungals, and the ulcer entirely healed with a large central scar.

CONCLUSION

Rhizopus keratitis is rare in a healthy individual. Ours is the first case report of Rhizopus keratitis in patient undergone CXL.

Current concepts in the management of cataract with keratoconus

This review analyzed all pertinent articles on keratoconus (KCN) and cataract surgery. It covers preoperative planning, intraoperative considerations, and postoperative management, with the aim of providing a simplified overview of treating such patients. Preoperatively, the use of corneal cross-linking, intrastromal corneal ring segments, and topo-guided corneal treatments can help stabilize the cornea and improve the accuracy of biometric measurements. It is important to consider the advantages and disadvantages of traditional techniques such as penetrating keratoplasty and deep anterior lamellar keratoplasty, as well as newer stromal augmentation techniques, to choose the most appropriate surgical approach. Obtaining reliable measurements can be difficult, especially in the advanced stages of the disease. The choice between toric and monofocal intraocular lenses (IOLs) should be carefully evaluated. Monofocal IOLs are a better choice in patients with advanced disease, and toric lenses can be used in mild and stable KCN. Intraoperatively, the use of a rigid gas permeable (RGP) lens can overcome the challenge of image distortion and loss of visual perspective. Postoperatively, patients may need updated RGP or scleral lenses to correct the corneal irregular astigmatism. A thorough preoperative planning is crucial for good surgical outcomes, and patients need to be informed regarding potential postoperative surprises. In conclusion, managing cataracts in KCN patients presents a range of challenges, and a comprehensive approach is essential to achieve favorable surgical outcomes.

Herpes simplex keratitis: A brief clinical overview

The aim of our minireview is to provide a brief overview of the diagnosis, clinical aspects, treatment options, management, and current literature available regarding herpes simplex keratitis (HSK). This type of corneal viral infection is caused by the herpes simplex virus (HSV), which can affect several tissues, including the cornea. One significant aspect of HSK is its potential to cause recurrent episodes of inflammation and damage to the cornea. After the initial infection, the HSV can establish a latent infection in the trigeminal ganglion, a nerve cluster near the eye. The virus may remain dormant for extended periods. Periodic reactivation of the virus can occur, leading to recurrent episodes of HSK. Factors triggering reactivation include stress, illness, immunosuppression, or trauma. Recurrent episodes can manifest in different clinical patterns, ranging from mild epithelial involvement to more severe stromal or endothelial disease. The severity and frequency of recurrences vary among individuals. Severe cases of HSK, especially those involving the stroma and leading to scarring, can result in vision impairment or even blindness in extreme cases. The cornea's clarity is crucial for good vision, and scarring can compromise this, potentially leading to visual impairment. The management of HSK involves not only treating acute episodes but also implementing long-term strategies to prevent recurrences and attempt repairs of corneal nerve endings via neurotization. Antiviral medications, such as oral Acyclovir or topical Ganciclovir, may be prescribed for prophylaxis. The immune response to the virus can contribute to corneal damage. Inflammation, caused by the body's attempt to control the infection, may inadvertently harm the corneal tissues. Clinicians should be informed about triggers and advised on measures to minimize the risk of reactivation. In summary, the recurrent nature of HSK underscores the importance of both acute and long-term management strategies to preserve corneal health and maintain optimal visual function.

A comprehensive review on corneal crosslinking

Corneal crosslinking (CXL) represents a paradigm shift in the management of corneal ectatic disorders. Before CXL was introduced, patients would need specialty contact lenses and possible corneal transplantation. CXL involves a biochemical reaction in which ultraviolet A light is used in conjunction with Riboflavin to form crosslinks in between corneal stromal collagen. This leads to strengthening and stabilizing of the collagen lamellae, resulting in mechanical stiffening of the cornea. Multiple protocols have been proposed including epithelium on versus off and varying light intensity and duration of treatment. All protocols appear to be safe and effective with few reported complications including infection, stromal haze, scarring, and endothelial toxicity. Overall, CXL has demonstrated to halt the progression of the disease clinically and in keratometry readings and improve the quality of life for patients. It is a minimally invasive, cost-effective procedure that can be performed in an outpatient setting with a fast recovery time and long-lasting results.

Investigation of Potential Crucial Genes and Key Pathways in Keratoconus: An Analysis of Gene Expression Omnibus Data

Keratoconus is one of the most common causes leading to visual impairment in young adult population. The pathogenesis of keratoconus remains poorly understood. The aim of this study was to identify the potential key genes and pathways associated with keratoconus and to further analyze its molecular mechanism. Two RNA-sequencing datasets of keratoconus and paired normal corneal tissues from the Gene Expression Omnibus database were obtained. Differentially expressed genes (DEGs) were identified, and the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were conducted. The protein-protein interaction (PPI) network of the DEGs was established, and the hub genes and significant gene modules of PPI were further constructed. Lastly, the GO and KEGG analyses of the hub gene were performed. In total, 548 common DEGs were identified. GO enrichment analysis showed that the DEGs were primarily associated with regulation of cell adhesion, the response to molecule of bacterial origin, lipopolysaccharide and biotic stimulus, collagen-containing extracellular matrix, extracellular matrix, and structure organization. KEGG pathway analysis showed that these DEGs were mainly involved in the TNF signaling pathway, IL-17 signaling pathway, Rheumatoid arthritis, Cytokine-cytokine receptor interaction. The PPI network was constructed with 146 nodes and 276 edges, and 3 significant modules are selected. Finally, top 10 hub genes were identified from the PPI network. The results revealed that extracellular matrix remodeling and immune inflammatory response could be the key links of keratoconus, TNF, IL6, IL1A, IL1B, CCL3, MMP3, MMP9, MMP1, and TGFB1 may be potential crucial genes, and TNF signaling pathway and IL-17 signaling pathway were the potential pathways accounting for pathogenesis and development of keratoconus.

A Case Series of Infectious Keratitis After Corneal Cross-linking

PURPOSE

To present the 7-year experience of a tertiary eye hospital while exploring possible risk factors and incidence of infectious keratitis in patients undergoing standard corneal cross-linking (CXL).

METHODS

This retrospective cohort study included patients with progressive keratoconus undergoing standard CXL in the Farabi Eye Hospital and all other patients who had undergone CXL in other facilities and were diagnosed as having infectious keratitis in the 7-year period of the study.

RESULTS

Among the total of 4,863 eyes that underwent CXL, 6 eyes developed infectious keratitis, yielding an incidence rate of 0.12%. Additionally, 13 eyes from 10 patients with a CXL history in other facilities who developed infectious keratitis were included. The mean age was 23.75 years, and 75% of patients were men and 25% were women. Gram-positive bacteria and Staphylococcus aureus were the most prevalent pathogens. Meibomian gland dysfunction, dry eye disease, or blepharitis were present in 12 patients. Medical treatment did not arrest the disease progress in 5 patients, which eventually required cases to undergo keratoplasty.

CONCLUSIONS

This study supports the need for proper patient selection by using a comprehensive medical history. It also highlights the imperative role of rigorous patient education and follow-up, particularly in the first postoperative week. Finally, the study emphasizes aggressive early therapy for patients with suspicious findings. [J Refract Surg. 2023;39(8):564-572.].

Severe Complications after Corneal Collagen Cross-Linking (CXL)

PURPOSE

To present a case series of rare and severe complications after corneal collagen cross-linking (CXL) of keratoconus patients.

METHODS

Single-center descriptive case series covering the period of 2012 to 2022 at the Department of Ophthalmology at the University Hospital, Zurich, Switzerland.

RESULTS

We present four eyes of four patients that showed severe unusual complications within the first month after CXL. Three patients had been treated with the classical epithelium-off "Dresden" protocol. One patient had been treated with the accelerated epithelium-off protocol. One patient presented with extensive corneal edema due to rubbing the eye after treatment. Two patients showed a bacterial infectious keratitis: one due to Streptococcus pneumoniae and the other due to Staphylococcus hominis, Micrococcus luteus, and Streptococcus epidermidis. The latter of the two patients exhibited extensive infectious crystalline keratopathy. The fourth patient showed a severe ulcerative lesion where no infectious cause could be found. Therefore, an autoimmune keratolytic process had to be suspected. Apart from the corneal edema, which resolved ad integrum, the other complications resulted in permanent corneal scarring and thinning. One patient needed an emergency amniotic transplant.

CONCLUSION

Severe complications after CXL remain rare. Most common causes are complications that are not directly associated with the treatment as such. Those indirect complications occur after the treatment during the healing course of the epithelium. Associations with bandage contact lenses, topical steroids, atopic disease, and inappropriate patient behavior are often suspected. Correctly performed corneal scrapings with repeated microbiological analysis and a detailed patient history are essential for establishing the correct diagnosis, especially in complicated cases that do not respond to a standard therapeutic regimen. This case series supports the efforts that are currently taken to improve the CXL technique in a way that postoperative complications are further reduced. A more efficient epithelium-on technique might be a step in that direction.

Acute Anterior Uveitis with HLA-B27 Positivity after Corneal Cross-Linking with Previous Intrastromal Corneal Ring Segment

Purpose. To describe a case of acute anterior uveitis (AAU) with HLA-B27 positivity following epithelium-off corneal cross-linking (CXL) in a patient with a previous intrastromal corneal ring segment. Observations. A 28-year-old male with keratoconus (KCN) developed ophthalmalgia, perilimbal injection, hypopyon, and decline in corrected distance visual acuity (CDVA) 3 days after CXL. A working diagnosis of inflammatory versus infectious AAU was made, and the patient was treated with topical tobramycin, polymyxin B/trimethoprim, prednisolone, and oral valacyclovir. Clinical appearance and CDVA improved, ultimately returning to baseline by two weeks postoperatively. Diagnostic laboratory workup revealed HLA-B27 positivity. Conclusions and Importance. A comprehensive laboratory workup is helpful to identify potential causative and associated systemic conditions when encountering AAU after CXL. Given the overlap in patient demographics for KCN and HLA-B27 positivity, clinicians should consider this entity in the differential diagnosis and treatment of such cases.

Identification of Key Genes and Molecular Pathways in Keratoconus: Integrating Text Mining and Bioinformatics Analysis

Purpose. To identify the potential key genes and molecular pathways associated with keratoconus and allergic disease. Methods. The pubmed2ensembl database was used to identify the text mining genes (TMGs) collectively involved in keratoconus and allergic disease. The GeneCodis program was used to perform the Gene Ontology (GO) biological process and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of TMGs. The protein-protein interaction (PPI) network of the TMGs was established by STRING; the significant gene modules and hub genes of PPI were further performed using the Cytoscape software. The DAVID database was used to perform the GO and KEGG analyses of the significant module. Results. In total, 98 TMGs collectively involved in keratoconus and allergic disease were identified. 19 enriched biological processes including 71 genes and 25 enriched KEGG pathways including 59 genes were obtained. A TMG PPI network was constructed, and 51 genes/nodes were identified with 110 edges; 3 most significant modules and 12 hub genes were chosen from the PPIs. GO enrichment analysis showed that the TMGs were primarily associated with collagen catabolic process, extracellular matrix organization and disassembly, cell adhesion and migration, collagen-containing extracellular matrix, extracellular matrix, and structure organization. KEGG pathway analysis showed that these DEGs were mainly involved in the IL-17 signaling pathway, inflammatory bowel disease, rheumatoid arthritis, allograft rejection, T cell receptor signaling pathway, cytokine-cytokine receptor interaction, and TNF signaling pathway. Conclusions. The results revealed that IL10, IL6, MMP9, MMP1, HGF, VEGFA, MMP3, MMP2, TGFB1, IL4, IL2, and IFNG were potential key genes involved in keratoconus. IL-17 signaling pathway was the potential pathways accounting for pathogenesis and development of keratoconus.

Polymicrobial keratitis after accelerated corneal collagen cross-linking in keratoconus: Case reports and literature review

PURPOSE

To report two cases of polymicrobial keratitis following corneal collagen cross-linking for keratoconus and to review the literature.

METHODS

Retrospective case note and literature review.

RESULTS

The first case involved a 27-year-old male who presented with amebic corneal ulcers 3 days after the collagen cross-linking procedure. Some gram-negative (gram-ve) cocci were found upon staining, and cysts were observed by confocal microscopy at 7 days after surgery. Acanthamoeba infection mixed with gram-ve organisms was diagnosed. In the second case, a 14-year male developed Staphylococcus aureus corneal infection with anterior chamber empyema 3 days after the collagen cross-linking procedure for keratoconus. Occasional gram-positive (gram + ve) cocci and gram-ve bacilli were observed under a microscope. The mixed keratitis in the two patients resolved after systemic and topical antibiotic therapy, but the infection ultimately resulted in corneal scarring. Follow-up keratoplasty was needed to improve vision acuity in both patients.

CONCLUSION

Although ultraviolet irradiation and the reactive oxygen released by riboflavin during collagen cross-linking have bactericidal effects, a lack of a corneal epithelial barrier, bandage contact lens usage, perioperative hygiene, and an abnormal immune state are risk factors for infectious keratitis after collagen cross-linking. Perioperative management of collagen cross-linking is important to prevent infection.