Epithelial infectious crystalline keratopathy

Paraproteinaemic keratopathy simulating a crystalline keratopathy

BACKGROUND

Paraproteinemic keratopathy is a rare disorder characterized by the bilateral accumulation of polychromatic deposits diffusely in all corneal layers together or not with diffuse or patchy pseudo lipid deposits. We present an atypical case of paraproteinemic keratopathy which lead to an initial misdiagnosis of infectious crystalline keratopathy.

CASE PRESENTATION

a 69-year-old woman with an asymptomatic keratopathy detected during a cataract intervention. Slit-lamp examination revealed several hyper refringent subepithelial foci with fern-shaped branches, resembling crystalline keratopathy, in her left eye. Anterior segment optical coherence tomography revealed exclusively subepithelial hyperreflective lesions limited to the anterior stroma. The progressive bilateralization and progression of the condition prompted us to include other entities with crystalline corneal deposits in our differential diagnosis. Hematological analysis showed a high number of free Kappa light chains. Despite the typical clinical appearance of crystalline keratopathy, the atypical evolution and test results led us to consider that monoclonal gammopathy could be the cause of this entity.

CONCLUSIONS

Paraproteinemic keratopathy may present in its early stages as a unilateral subepithelial crystalline keratopathy. Thus, it must always be taken into account in the differential diagnosis of any crystalline keratopathy, particularly when there are no predisposing factors for an infectious crystalline keratopathy. Early recognition of this rare entity is important to address the associated potentially serious systemic disease.

Atypical microbial keratitis

Atypical microbial keratitis refers to corneal infections caused by micro-organisms not commonly encountered in clinical practice. Unlike infections caused by common bacteria, cases of atypical microbial keratitis are often associated with worse clinical outcomes and visual prognosis. This is due to the challenges in the identification of causative organisms with standard diagnostic techniques, resulting in delays in the initiation of appropriate therapies. Furthermore, due to the comparatively lower incidence of atypical microbial keratitis, there is limited literature on effective management strategies for some of these difficult to manage corneal infections. This review highlights the current management and available evidence of atypical microbial keratitis, focusing on atypical mycobacteria keratitis, nocardia keratitis, achromobacter keratitis, and pythium keratitis. It will also describe the management of two uncommonly encountered conditions, infectious crystalline keratopathy and post-refractive infectious keratitis. This review can be used as a guide for clinicians managing patients with such challenging corneal infections.

Intrastromal Injections in the Management of Infectious Keratitis

Infectious keratitis is a major global cause of vision loss and blindness. Prompt diagnosis and targeted antibiotic treatment are crucial for managing the condition. Topical antimicrobials are the most effective therapy for bacterial keratitis, but they can lead to unsatisfactory results due to ocular perforation, scarring, and melting. Intrastromal injection is a newer technique for delivering antimicrobials directly to the site of infection and has been successful in treating severe, treatment-resistant infectious keratitis, especially when surgery is not recommended. In cases where deep stromal disease is resistant to topical treatment, intrastromal antimicrobial injections may be necessary to achieve higher drug concentration at the infection site. However, the use of intrastromal antibiotics is limited, as topical antibacterial agents have better penetration than antifungal agents. Bacterial and fungal keratitis have been extensively researched for intrastromal medication injections, while there is limited evidence for viral keratitis. This review emphasizes the potential of intrastromal antimicrobial injections as an alternative for managing severe refractory infectious keratitis. The technique offers direct targeting of the infection site and faster resolution in some cases compared to topical therapy. However, further research is needed to determine the safest antimicrobials options, minimal effective doses, and concentrations for various pathogens. Intrastromal injections may serve as a non-surgical treatment option in high-risk cases, with benefits including direct drug delivery and reduced epithelial toxicity. Despite promising findings, more studies are required to confirm the safety and efficacy of this approach.

Infectious Crystalline Keratopathy after Penetrating Keratoplasty with Light and Electron Microscopic Examination

PURPOSE

To highlight the typical histological and ultrastructural features of severe infectious crystalline keratopathy (ICK) in a corneal graft, which required excimer laser-assisted repeat penetrating keratoplasty (PKP) and to present the challenging treatment conditions associated with ICK.

METHODS

An 85-year-old female patient underwent PKP for secondary graft failure after Descemet membrane endothelial keratoplasty (DMEK) for Fuchs' endothelial corneal dystrophy in the left eye. One year later, white branched opacities were observed in the superficial corneal stroma of the graft without surrounding inflammation in the left eye. The patient underwent excimer laser-assisted repeat PKP (8.0/8.1 mm) in the left eye after prolonged refractory topical anti-infectious treatment for 1 month. The corneal explant was further examined by light and transmission electron microscopy (TEM).

RESULTS

The light microscopic examination of the corneal explant demonstrated aggregates of coccoid bacteria in the superficial and mid-stromal region that were positive for periodic acid-Schiff (PAS) and Gram stain. The bacterial aggregates extended into the interlamellar spaces, showed a spindle-shaped appearance, and were not surrounded by an inflammatory cellular reaction. TEM demonstrated lamellae separation within the anterior corneal stroma with spindle-shaped aggregates of bacteria, which were embedded in an extracellular amorphous matrix with incipient calcification, being consistent with a biofilm. No inflammatory cellular reaction was evident by TEM. At discharge from hospital, the corrected visual acuity was 20/80 in the left eye.

CONCLUSION

ICK is often challenging due to the difficult diagnosis and treatment conditions. The refractory courses are mainly attributed to a biofilm formation, which inhibits effective topical anti-infectious treatment. In such cases, (repeat) PKP may be necessary to completely remove the pathology, prevent recurrences, and improve vision.

Successful Management of Infectious Crystalline Keratopathy with Intrastromal Antibiotic Injections

Purpose. To report the successful treatment of a case of presumed infectious crystalline keratopathy with repeated intrastromal antibiotic injections in a cornea graft in the setting of severe ocular graft-vs.-host-disease (GVHD). Observations. A 62-year-old man with a history of ocular GVHD and tectonic penetrating keratoplasty (PK) for corneal melt from herpes zoster keratopathy developed presumed infectious crystalline keratopathy (ICK) in the corneal graft. Given the patient's complicated ocular history, chronic immunosuppression and new cardiac comorbidities, a therapeutic PK would most likely fail. Efforts were then directed to rescue the graft with minimally invasive approaches. Two separate intrastromal injections of cefuroxime and moxifloxacin successfully treated his ICK. Conclusions and Importance. This case supports a role for repeated intrastromal antibiotic injections in patients with ICK refractory to topical antibiotic therapy, which might eliminate the need for therapeutic PK and preserve vision.

Diagnostic Utility of CDC DPDx for an Atypical Presentation of Infectious Crystalline Keratopathy-Like Infiltrate Secondary to Microsporidia

PURPOSE

To report a case of atypical infectious crystalline keratopathy-like stromal infection secondary to microsporidia wherein diagnosis of the causative organism was aided by use of the Center for Disease Control (CDC) DPDx program.

METHODS

We report the case of a 73-year-old woman who presented with atypical infectious crystalline keratopathy-like corneal infection without previous surgical history.

RESULTS

The patient had previously been treated for recalcitrant corneal infection with topical antibiotics and steroids at an outside provider before referral. Further treatment with topical fortified antibiotics failed to improve the infection. Corneal biopsy was performed and sent to the CDC DPDx for diagnostic confirmation for presumptive microsporidia. The patient underwent therapeutic penetrating keratoplasty without recurrence of ocular infection.

CONCLUSIONS

Utilization of the DPDx resource may help guide appropriate and timely diagnosis and management strategies in atypical presentations of infectious keratitis.

Management of Candida glabrata infectious crystalline keratopathy with endophthalmitis following penetrating keratoplasty

A 33-year-old male underwent an optical keratoplasty elsewhere in the right eye following which he developed endophthalmitis and subsequently underwent a pars plana vitrectomy and lensectomy. At presentation, he had a deep stromal crystalline infiltration along the graft–host junction. A large therapeutic keratoplasty was performed, and the excised corneal button was evaluated. Histopathology revealed gram-positive round-to-oval budding structures and microbiology identified the organism as Candida glabrata. He was treated with antifungals in the postoperative period. At 4 months after therapeutic keratoplasty, the patient developed recurrent endophthalmitis, following stoppage of antifungals. The treatment was reinstituted for another year, and the patient did well with a clear graft at 18-month-follow-up period after the recurrence episode. Management of infectious crystalline keratopathy with endophthalmitis is a challenging situation and requires long-term treatment.

Infectious crystalline keratopathy

Infectious crystalline keratopathy was first reported by Gorovoy and colleagues in 1983 when they identified bacteria colonizing a cornea after a penetrating keratoplasty. Subsequent cases have elaborated on the organisms responsible and the management outcomes. Patients present with a white or gray branching opacity originating from an epithelial defect, commonly after a penetrating keratoplasty. Local immunosuppression contributes to the quiescent nature and the limited inflammatory response associated with infectious crystalline keratopathy. Diagnosis of the infective pathogens may be difficult, with a corneal scraping often being too superficial to obtain an adequate specimen. A biofilm is present that advantages microorganism survival, reduces antibiotic bioavailability, and inhibits diagnostic microbial detection. Treatment begins with topical antimicrobials, initially broad spectrum and then targeted to microorganism sensitivity. Adjunctive therapies to enhance the efficacy of treatment include disruption of the microorganism biofilm by laser, intrastromal antibiotics, and keratectomy. In recalcitrant cases, or where corneal scarring ensues, corneal transplantation is required.