Infectious interface keratitis (IIK) following lamellar keratoplasty: A literature review

Post-Keratoplasty Microbial Keratitis in the Era of Lamellar Transplants-A Comprehensive Review

Microbial keratitis in a post-transplant cornea should be considered a distinct entity from microbial keratitis in a non-transplant cornea. Firstly, the use of immunosuppressive treatments and sutures in corneal transplants changes the etiology of keratitis. Secondly, corneal transplant has an impact on corneal biomechanics and structure, which facilitates the spread of infection. Finally, the emergence of lamellar transplants has introduced a new form of keratitis known as interface keratitis. Given these factors, there is a clear need to update our understanding of and management strategies for microbial keratitis following corneal transplantation, especially in the era of lamellar transplants. To address this, a comprehensive review is provided, covering the incidence, risk factors, causes, and timing of microbial keratitis, as well as both clinical and surgical management approaches for its treatment in cases of penetrating and lamellar corneal transplants.

A Case of Candida parapsilosis Stromal Keratitis after Descemet's Membrane Endothelial Keratoplasty: A Case Report and Review of the Literature

A 68-year-old diabetic male with Fuchs endothelial corneal dystrophy cataract underwent combined DMEK and cataract surgery of the left eye. Post-operative course was complicated by a partial graft detachment on POD 3, treated with a re-bubbling procedure. The patient subsequently developed a corneal infiltrate, cultured by aqueous sample, that was found to be C. parapsilosis. Oral fluconazole and voriconazole, topical voriconazole 1%, and amphotericin B as well as intracameral and intrastromal voriconazole and amphotericin B were employed. By post-operative day 45, symptoms and signs of DMEK stromal C. parapsilosis keratitis had resolved, and a corneal scar remained. Best corrected visual acuity, at post-operative month 4, was 20/25-2 without correction. Post-DMEK fungal stromal keratitis is a rare post-operative complication. We present a case of C. parapsilosis DMEK stromal keratitis and describe diagnostic and therapeutic modalities that allowed for resolution of the infection, without explantation of the patient's graft, and preservation of visual acuity.

Clinical and in vivo confocal microscopy characteristics of Candida keratitis following keratoplasty

BACKGROUND

We present six patients who developed Candida keratitis postoperatively. The clinical features, diagnostic testing including in vivo confocal microscopy, and outcomes are presented.

METHODS

Six patients who developed Candida keratitis following penetrating and endothelial keratoplasty, were referred to Tianjin Medical University Eye Hospital between 2018 to 2021.The diagnosis was established following cultures of either corneal scraping or biopsy. In vivo confocal microscopy examination was also performed to confirm the diagnosis and characterize the morphology, distribution and the depth of Candida spp. All patients were treated with topical voriconazole (VCZ) 1% and natamycin (NTM) 5%. Patients with mid/deep stromal keratitis or interface infection were treated additionally with intrastromal or interface VCZ irrigation (0.05 mg/0.1mL).

RESULTS

The cultures of corneal scrapings (4 cases) or biopsies (2 cases) were all positive for Candida spp. In vivo confocal microscopy examination was positive for fungal elements in five of the six patients. The infection resolved in five of the six patients. The patients' final uncorrected visual acuity (UCVA) ranged from hand movements (HM) to 20/80.

CONCLUSION

In vivo confocal microscopy is a useful non-invasive clinical technique for confirming the diagnosis of Candida keratitis. Intrastromal and interface irrigated VCZ injections are effective treatment options.

Ocular Bacterial Infections: A Ten-Year Survey and Review of Causative Organisms Based on the Oklahoma Experience

Ocular infections can be medical emergencies that result in permanent visual impairment or blindness and loss of quality of life. Bacteria are a major cause of ocular infections. Effective treatment of ocular infections requires knowledge of which bacteria are the likely cause of the infection. This survey of ocular bacterial isolates and review of ocular pathogens is based on a survey of a collection of isolates banked over a ten-year span at the Dean McGee Eye Institute in Oklahoma. These findings illustrate the diversity of bacteria isolated from the eye, ranging from common species to rare and unique species. At all sampled sites, staphylococci were the predominant bacteria isolated. Pseudomonads were the most common Gram-negative bacterial isolate, except in vitreous, where Serratia was the most common Gram-negative bacterial isolate. Here, we discuss the range of ocular infections that these species have been documented to cause and treatment options for these infections. Although a highly diverse spectrum of species has been isolated from the eye, the majority of infections are caused by Gram-positive species, and in most infections, empiric treatments are effective.

Repeat lamellar keratoplasty treatment for positive rim lamellar keratoplasty

A case describes repeat lamellar keratoplasty (LKP) as a treatment for positive rim of Candida glabrata LKP. As have postulated in the literature, having positive rim is a substantial risk factor for a developing fungal keratitis. Different management approaches of fungal keratitis over a corneal graft have used. Herein, we provide a description of the clinical findings, management approach and used surgical technique with review of the literature.

Long-acting formulation strategies for protein and peptide delivery in the treatment of PSED

The invigoration of protein and peptides in serious eye disease includes age-related macular degeneration, choroidal neovascularization, retinal neovascularization, and diabetic retinopathy. The transportation of macromolecules like aptamers, recombinant proteins, and monoclonal antibodies to the posterior segment of the eye is challenging due to their high molecular weight, rapid degradation, and low solubility. Moreover, it requires frequent administration for prolonged therapy. The long-acting novel formulation strategies are helpful to overcome these issues and provide superior therapy. It avoids frequent administration, improves stability, high retention time, and avoids burst release. This review briefly enlightens posterior segments of eye diseases with their diagnosis techniques and treatments. This article mainly focuses on recent advanced approaches like intravitreal implants and injectables, electrospun injectables, 3D printed drug-loaded implants, nanostructure thin-film polymer devices encapsulated cell technology-based intravitreal implants, injectable and depots, microneedles, PDS with ranibizumab, polymer nanoparticles, inorganic nanoparticles, hydrogels and microparticles for delivering macromolecules in the eye for intended therapy. Furthermore, novel techniques like aptamer, small Interference RNA, and stem cell therapy were also discussed. It is predicted that these systems will make revolutionary changes in treating posterior segment eye diseases in future.

Fungal Infectious Interface Keratitis Presenting 2 Years After Descemet Membrane Endothelial Keratoplasty

PURPOSE

The purpose of this study was to describe infectious interface keratitis after Descemet membrane endothelial keratoplasty (DMEK) more than 2 years after surgery.

METHODS

A case study.

RESULTS

In this study, we report a case of fungal infectious interface keratitis occurring 2 years after uncomplicated Descemet membrane endothelial keratoplasty. The donor corneal rim culture at the time of surgery grew a single colony of Candida albicans/dubliniensis , but the patient was not treated with antifungals at that time. At the onset of clinical infection, more than 2 years postoperatively, the patient was treated with systemic antifungals and adjuvant intrastromal amphotericin-B injection. The patient subsequently required penetrating keratoplasty with ultimately well-preserved visual acuity.

CONCLUSIONS

Fungal infectious interface keratitis (IIK) is a rare complication associated with lamellar keratoplasty. Although most common in the early postoperative period, this complication can occur several years after successful transplantation. Management may require a combination of systemic and stromal antifungal therapy. However, some patients may eventually require penetrating keratoplasty for definitive treatment.

Successful treatment of Candida albicans anterior chamber infection after penetrating keratoplasty

Purpose

To report the successful management of an anterior chamber (AC) infection after penetrating keratoplasty (PK) caused by Candida albicans.

Observation

A 53-year-old female had a PK in her right eye. The donor rim tested positive for Candida albicans one week later. Despite initiation of prophylactic topical 1% voriconazole drops, the patient presented with a white mass in the anterior chamber one month later. Biopsy confirmed Candida. Antifungal therapy was intensified with the addition of intravenous fluconazole, and with repeated irrigations of the AC and intracameral administration of amphotericin B (off-label use). After two weeks of apparent lack of treatment response, the infection suddenly quiesced. The final outcome was visual acuity of 0.2 and a clear graft with an endothelial cell density of 2260 cells/mm. ²

Conclusions and Importance

Fungal intraocular infections after PK are usually devastating. Due to low intraocular penetration of topical antifungals, serial intracameral injections were used to maintain a therapeutic concentration of amphotericin B within the anterior chamber, and intravenous fluconazole was administered to protect against the spread of infection into the vitreous. A clinical response developed after two weeks. The reported case represents a favorable outcome using a multimodal approach.

Keratitis following descemet's stripping endothelial keratoplasty (DSEK): Clinical features and outcome in early vs late presentation

OBJECTIVE

To compare the clinical presentation, risk factors, causative organisms, and final outcome of early- and late- onset microbial keratitis following Descemet's Stripping Endothelial Keratoplasty (DSEK).

MATERIALS AND METHODS

In a retrospective, comparative, case series, twenty-three (10 early-onset keratitis, 13 late-onset keratitis) cases were included for analysis from a single centre tertiary eye care setup. Data about demography, indication, clinical features, and outcome were collected for both the groups. Comparison of clinical presentation, risk factors, microbiology and final outcome were carried out.

RESULTS

The most common indication was failed graft. While all patients with late-onset keratitis presented with ulcerative keratitis, 60% of early-onset keratitis presented with ulcerative keratitis. Four patients in the early-onset group had interface keratitis. Associated endophthalmitis was more in the early-onset compared to the late-onset group. Early-onset interface keratitis cases are mostly associated with donor-related infection. Gram-positive bacteria were the most common organisms isolated from both early- and late- onset infection. Major surgical procedures in both early- and late- onset keratitis included lenticule removal (n = 4) and therapeutic penetrating keratoplasty (n = 5).

CONCLUSIONS

Failed graft is a major risk factor in post-DSEK keratitis. Interface keratitis and endophthalmitis are commonly observed in early-onset keratitis. A majority of the patients need surgical intervention.

Endophthalmitis secondary to donor to host infection in posterior lamellar keratoplasties: A systematic review

Donor to host transmission of infectious agents is a well-recognized entity, more commonly related to Endothelial Keratoplasty (EK) than to Penetrating Keratoplasty (PK), that involves complications ranging from interface keratitis to endophthalmitis. A systematic review of the literature was conducted to identify the published articles until December 2020 reporting cases of endophthalmitis secondary to corneal graft contamination in posterior lamellar keratoplasties (DSAEK and DMEK) along with donor characteristics, microbiological profile, treatment and outcomes. Each identified article was assessed to meet donor to host infection criteria, defined as a post-procedural infection in which the same microbiological agent was identified in both the donor corneoscleral rim or preservation medium and receptor ocular tissue. From 23 research articles, eight reports of endophthalmitis in nine patients following DSAEK or DMEK secondary to donor to host infection fulfilled the inclusion criteria. The majority were male and the median age was 72.0 (45.0-81.0) years old. Indications of surgery were primarily pseudophakic bullous keratopathy and Fuchs dystrophy. A fungal pathogen was identified in eight of nine patients. All the cases underwent surgical management with lenticule removal or endothelial plaque aspiration. The final corrected distance visual acuity (CDVA) in all cases was 20/200 or better. Endophthalmitis after an EK procedure is a rare complication whose outcome depends on the aggressive and precocious treatment. Identification of early signs of interface keratitis and lenticule removal seems mandatory in patients undergoing DSAEK or DMEK to prevent further involvement of the globe.

Suture-Related Fungal Interstitial Interface Keratitis in Deep Anterior Lamellar Keratoplasty: A Case Report

Interstitial interface keratitis (IIK) in lamellar keratoplasty is a term used to describe infectious keratitis that primarily involves the graft-host interface. It poses specific challenges due to impaired access for microbiological testing and poor penetration of antimicrobial drugs, as well as ease of deeper extension of the microorganism. A 33-year-old male with a medical history of left eye deep anterior lamellar keratoplasty (DALK) with keratoconus, subsequently complicated with steroid-induced glaucoma controlled with Xen tube insertion, presented with acute left eye pain and redness for two days due to one broken corneal graft suture at 5 o’clock position with infiltrate at the graft-host junction. He was treated for suture-related bacterial keratitis (culture-negative) with intensive single broad-spectrum topical antibiotic after suture removal. However, the condition worsened, with dense stromal infiltrate extending into the graft-host interface junction which further progressed to an endothelial plaque. Systemic and topical antifungal treatments were started with adjunctive intracameral and subconjunctival voriconazole before improvement was observed. The condition was resolved with localized scarring without the need for repeat keratoplasty. The best-corrected vision was maintained at 6/36 due to residual sutured-related astigmatism with no signs of corneal graft rejection. Lamellar keratoplasty poses an increased risk of fungal IIK even after several years if there is a predisposing factor e.g., steroid usage and broken suture. Timely diagnosis and intervention are the keys to ensure an optimal outcome.

Paradox of complex diversity: Challenges in the diagnosis and management of bacterial keratitis

Bacterial keratitis continues to be one of the leading causes of corneal blindness in the developed as well as the developing world, despite swift progress since the dawn of the "anti-biotic era". Although, we are expeditiously developing our understanding about the different causative organisms and associated pathology leading to keratitis, extensive gaps in knowledge continue to dampen the efforts for early and accurate diagnosis, and management in these patients, resulting in poor clinical outcomes. The ability of the causative bacteria to subdue the therapeutic challenge stems from their large genome encoding complex regulatory networks, variety of unique virulence factors, and rapid secretion of tissue damaging proteases and toxins. In this review article, we have provided an overview of the established classical diagnostic techniques and therapeutics for keratitis caused by various bacteria. We have extensively reported our recent in-roads through novel tools for accurate diagnosis of mono- and poly-bacterial corneal infections. Furthermore, we outlined the recent progress by our group and others in understanding the sub-cellular genomic changes that lead to antibiotic resistance in these organisms. Finally, we discussed in detail, the novel therapies and drug delivery systems in development for the efficacious management of bacterial keratitis.

Propionibacterium acnes endophthalmitis following transplantation of contaminated Descemet's membrane endothelial keratoplasty graft

Purpose

To report the clinical outcomes of a case of Propionibacterium acnes (P. acnes) endophthalmitis following Descemet's membrane endothelial keratoplasty (DMEK) surgery.

Observations

Transplantation of non-sterile DMEK tissue led to development of a retrolenticular white plaque confirmed through PCR testing to be the result of P. acnes endophthalmitis. Intraocular antimicrobial therapy, surgical scraping of the white plaque, and repeat DMEK tissue transplantation resulted in an excellent visual outcome (20/20).

Conclusion

This is the first reported case of P. acnes endophthalmitis following DMEK surgery. Re-transplantation may be a viable option for DMEK patients who experience post-operative endophthalmitis.

Diagnostic armamentarium of infectious keratitis: A comprehensive review

Infectious keratitis (IK) represents the leading cause of corneal blindness worldwide, particularly in developing countries. A good outcome of IK is contingent upon timely and accurate diagnosis followed by appropriate interventions. Currently, IK is primarily diagnosed on clinical grounds supplemented by microbiological investigations such as microscopic examination with stains, and culture and sensitivity testing. Although this is the most widely accepted practice adopted in most regions, such an approach is challenged by several factors, including indistinguishable clinical features shared among different causative organisms, polymicrobial infection, long diagnostic turnaround time, and variably low culture positivity rate. In this review, we aim to provide a comprehensive overview of the current diagnostic armamentarium of IK, encompassing conventional microbiological investigations, molecular diagnostics (including polymerase chain reaction and mass spectrometry), and imaging modalities (including anterior segment optical coherence tomography and in vivo confocal microscopy). We also highlight the potential roles of emerging technologies such as next-generation sequencing, artificial intelligence-assisted platforms. and tele-medicine in shaping the future diagnostic landscape of IK.

Interface Drainage and Antimicrobial Irrigation Avoid Repeat Keratoplasty for Post-DSAEK Cold Interface Abscess

PURPOSE

To describe a surgical technique for the diagnosis and treatment of post-Descemet stripping automated endothelial keratoplasty (DSAEK) infectious interface keratitis presenting as a cold abscess.

METHODS

This study included 2 eyes of 2 patients that developed delayed-onset interface infections after DSAEK. Through an anterior keratotomy, diagnostic samples for microbial culture and histopathology examination were collected, and empiric antibiotic therapy was delivered directly to the site of the infection at the graft-host interface.

RESULTS

In both cases, microbiological examinations confirmed a fungal etiology consistent with Candida. Resolution of infection was achieved, and no signs of posterior segment involvement or recurrence of infection were observed. Both corneas remained clear with final visual acuity of 20/25 and 20/32. No case required additional surgical intervention or repeat keratoplasty after more than 15 months of follow-up.

CONCLUSIONS

Interface drainage with antimicrobial irrigation may be considered for the management of post-DSAEK interface infections presenting as a peripheral cold abscess. By avoiding intraocular seeding of infectious pathogens, the anterior approach can achieve clinical resolution of infection, maintain visual function, and preserve the DSAEK graft, thereby obviating the need for a therapeutic keratoplasty.

Ex vivo photoactivated chromophore for keratitis-corneal crosslinking on inverted graft: new approach to manage interface infectious keratitis after deep anterior lamellar keratoplasty

A 44-year-old man affected by keratoconus underwent deep anterior lamellar keratoplasty (DALK). Two weeks postoperatively, slitlamp examination showed grayish-white lesions in the donor-host interface. Corneal scraping and donor broth culture tested negative for both bacteria and fungi. In vivo confocal microscopy showed elongated particles resembling Candida pseudofilaments. Despite antimicrobial therapy, the clinical picture worsened, and surgical approach was chosen: the graft was peeled off and inverted (epithelium facing down), and ex vivo photoactivated chromophore for infectious keratitis-corneal crosslinking (PACK-CXL) was performed; the recipient bed was washed with antibiotics/antifungals and the graft resutured. Microbiological and histological evaluations of biopsy specimen tested positive for Candida albicans. Postoperative slitlamp examination revealed a progressive recovery of graft transparency with disappearance of the infiltrates. To the authors' knowledge, this is the first report of ex vivo PACK-CXL on inverted DALK graft for the treatment of interface infectious keratitis. This technique allowed the resolution of the infection while sparing the use of new donor tissue.

Post-keratoplasty Infectious Keratitis: Epidemiology, Risk Factors, Management, and Outcomes

Post-keratoplasty infectious keratitis (PKIK) represents a unique clinical entity that often poses significant diagnostic and therapeutic challenges. It carries a high risk of serious complications such as graft rejection and failure, and less commonly endophthalmitis. Topical corticosteroids are often required to reduce the risk of graft rejection but their use in PKIK may act as a double-edged sword, particularly in fungal infection. The increased uptake in lamellar keratoplasty in the recent years has also led to complications such as graft-host interface infectious keratitis (IIK), which is particularly difficult to manage. The reported incidence of PKIK differs considerably across different countries, with a higher incidence observed in developing countries (9.2-11.9%) than developed countries (0.02-7.9%). Common risk factors for PKIK include the use of topical corticosteroids, suture-related problems, ocular surface diseases and previous corneal infection. PKIK after penetrating keratoplasty or (deep) anterior lamellar keratoplasty is most commonly caused by ocular surface commensals, particularly Gramme-positive bacteria, whereas PKIK after endothelial keratoplasty is usually caused by Candida spp. Empirical broad-spectrum antimicrobial treatment is the mainstay of treatment for both PKIK, though surgical interventions are required in medically refractory cases (during the acute phase) and those affected by visually significant scarring (during the late phase). In this paper, we aim to provide a comprehensive overview on PKIK, encompassing the epidemiology, risk factors, causes, management and outcomes, and to propose a treatment algorithm for systematically managing this challenging condition.

Early postoperative infection following lamellar keratoplasty: a review

With the growing popularity of lamellar keratoplasty for selective replacement of diseased corneal tissue, it is important to understand the risk of developing an infection after the procedure. Although lesser than that postpenetrating keratoplasty, the reports on post lamellar keratoplasty infectious keratitis are not negligible. Trends of acute infections arising within 2 months of surgery are a subject of interest. Most of these infections are reported post Descemet's stripping endothelial keratoplasty with a preponderance of Candida species. A donor to host transmission of infection is not uncommon. Among the Candida cases, about 80% seem to occur due to a donor to host transmission. Infections presenting as or progressing to endophthalmitis lead to a poor visual outcome. Strict aseptic measures and protocols during corneal tissue harvesting, tissue processing, tissue storage and surgery are essential to prevent occurrence of these infections. After the infection has occurred, determining the aetiology and drug susceptibility through microbiological testing is vital. This helps to guide treatment protocols and hence determines final outcome of these cases. Most cases require some form of surgical management for resolution of infection, most often a graft removal and therapeutic keratoplasty. Secondary surgical interventions are performed to restore graft clarity and achieve a good final visual outcome.

Usefulness of Prestorage Corneal Swab Culture in the Prevention of Contaminated Corneal Tissue in Corneal Transplantation

PURPOSE

To assess the efficacy of the prestorage corneal swab (PCS) culture to screen for corneal graft contamination after storage in Optisol-GS.

METHODS

A retrospective analysis of all PCS cultures was performed at the Eye Bank of Québec in Hôpital Maisonneuve-Rosemont from September 2013 to June 2016. Whole corneal culture was performed on rejected grafts because of a positive PCS, and a contamination rate was calculated. In addition, contamination rates of corneoscleral rims were compared between corneas tested with PCS and those of imported corneas which did not have PCS.

RESULTS

Among the 1966 PCS cultures performed, 814 (41.4%) were positive for growth. Pathogenic bacteria were present in 144 (7.3%) corneas, including Staphylococcus aureus (n = 96, 11.8% of all positive cultures), Enterobacteriaceae (n = 14, 1.7%), and Pseudomonas aeruginosa (n = 6, 0.7%). After preservation in Optisol-GS, only 7 (6.9%) corneas remained contaminated (95% confidence interval 5.1-9.3). The sensitivity of the PCS culture was 87.5% (95% confidence interval 47.4-99.7). There was no significant difference in corneoscleral rim contamination between corneas tested with PCS (1/388; 0.2%) compared with imported, nonswabbed corneas (3/214; 1.4%) (P = 0.131). Therefore, the cost to recover the loss of tissue rejected because of false-positive PCS by purchasing corneal tissue was calculated to be $142,884 (CAD) per year.

CONCLUSIONS

Despite the high sensitivity of PCS cultures, there was no significant reduction of infection after corneal transplantation using this technique. In consequence, 93% of the corneas possibly suitable for transplantation were rejected. This suggests that the PCS culture alone is a poor test for detecting clinically relevant corneal contamination.

Hybrid natural hydrogels integrated with voriconazole-loaded microspheres for ocular antifungal applications

Fungal keratitis is a major threat to ocular morbidity and blindness. The therapeutic efficacy of eye drops against fungal keratitis is limited by their poor bioavailability, especially in patients with corneal stromal ulcers that lead to tissue defects. Therefore, intervention measures that can control fungal infection while promoting tissue regeneration are desirable. Herein, we designed and fabricated natural antifungal hydrogels that comprise a decellularized porcine cornea (DPC), gelatin and microspheres (MCs) containing voriconazole (Vor) for the management of fungal keratitis with focal corneal stromal defects. The size and structure of the Vor-loaded MCs were characterized by scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The antifungal drug Vor showed that continuous release from the hybrid hydrogel system for up to 7 days and that MCs loading did not affect the mechanical properties, in vitro release profile or cytocompatibility of the hybrid hydrogel. Moreover, the Vor-loaded hydrogels exhibited excellent antifungal properties against F. solani and A. fumigatus. The efficiency of the natural antifungal hydrogel was evaluated by an ex vivo infectious rabbit corneal defect model. After 24 h, the number of fungal colony-forming units (CFU) significantly decreased in antifungal hydrogel-treated corneal tissue compared with that in non-treated corneas and corneas treated with hydrogels without Vor. The above results demonstrated that this natural hydrogel-based drug delivery system holds great promise for preventing fungal keratitis infection while promoting focal corneal stromal regeneration. Additionally, natural hybrid hydrogels might be a candidate material for use with various drugs in the effective treatment of many other ocular diseases.

Incidence of Fungal Infection in Positive Donor Rim Cultures after Corneal Transplantation

PURPOSE

To determine the clinical outcomes of corneal transplant patients that had positive rim cultures for fungi.

METHODS

Retrospective study.

RESULTS

Of 1276 rim cultures obtained between 2009 and 2019, 16 were positive for fungus (incidence of 1.25%). Clinical data were available for 12 patients. Candida and Cladosporium species were the most common organisms. Recipient ages ranged from 51 to 86 (median age 69 years; 9 males, 7 females). The most common surgery was Endothelial Keratoplasty (n = 8). There were no instances of fungal keratitis or endophthalmitis. Three patients were treated with prophylactic antimycotics. One patient developed bacterial keratitis. One patient had a varicella zoster virus reactivation without corneal involvement.

CONCLUSIONS

This study adds to the growing data on the low rate of fungal keratitis and endophthalmitis after a corneal transplant, even in the case of positive rim cultures. This study also suggests that positive rim cultures do not advance the risk of postoperative fungal infection in the recipient.

Delayed postoperative interface keratitis due to Enterococcus faecalis after Descemet membrane endothelial keratoplasty

To report the clinical course and management of interface keratitis due to Enterococcus faecalis after Descemet membrane endothelial keratoplasty (DMEK). A 64-year-old man underwent DMEK, with unevenful immediate postoperative course, with a visual recovery of 20/30 at 2 weeks. At 3 months of clinical visit, interface keratitis was noted. DMEK graft removal with stromal bed scrapings was performed. A diagnosis of E. faecalis interface keratitis was made. The patient responded favourably to antibiotic susceptibility-guided intensive treatment with vancomycin 5% with complete resolution of infection. After 2 months of graft removal, Descemet stripping endothelial keratoplasty (DSEK) was performed. The corneal clarity was restored and the best corrected visual acuity was 20/40 at last follow-up of 1 year. E. faecalis should be kept as a differential in delayed onset interface keratitis after DMEK. After microbiological cure with antibiotic therapy, visual rehabilitation with DSEK restores corneal clarity and results in favourable visual outcome.

Changes of Contamination Rate and Microorganism Evaluation in Organ-Cultured Human Corneas: A 14-Year Review From a French Regional Eye Bank

PURPOSE

This study aimed to assess how the contamination rate of organ-cultured corneas has evolved and to analyze the evolution of microorganisms involved.

METHODS

Data from the Besançon eye bank were reviewed over 14 years (2005-2018). The changes in the contamination rate and the contaminant species found during the organ culture storage were analyzed. Microbiological tests were performed twice on the storage media-at day 5 and before the deswelling phase.

RESULTS

Among the 17,979 donor corneas collected, 1240 corneas were microbiological-test positive. The average annual contamination rate was 6.8% (range: 5.2%-8.9%). Seventy-five percent of contaminations were bacterial. The most frequently found bacterium was Staphylococcus spp. (31.3%), followed by non-Enterobacteriaceae Gram-negative Bacilli (GNB) (27.3%), with most Sphingomonas spp. and Pseudomonas spp. Fungal contamination (21.9%) was dominated by Candida (82.7%). Seventy-seven types of microorganisms were identified. The Staphylococcus rate tended to decrease, whereas non-Enterobacteriaceae GNB rate has increased in the past few years to reach 46% of bacteria. Most of the contaminations were detected in the early phase of organ culture at day 5 (89.2%). The second microbiological test found 44.8% of fungal contaminations (predominantly Candida spp.).

CONCLUSIONS

The annual contamination rate was stable and remains low, but the types of contaminating microorganisms varied from year to year. Staphylococcus spp. and non-Enterobacteriaceae GNB accounted for a significant proportion of the contaminations. We found a significant proportion of contamination, especially fungal, at the late phase of storage. Reassessing the antibiotics and antifungals in the storage medium may be useful to limit corneal disposal.

Excisional penetrating keratoplasty for fungal interface keratitis after endothelial keratoplasty: surgical timing and visual outcome

PURPOSE

In this paper, we describe two cases of fungal interface infectious keratitis (IIK) developed after endothelial keratoplasty (EK) who underwent delayed therapeutic penetrating keratoplasty (TPK) with a poor visual outcome. Furthermore, we conducted a review of the literature and analyzed the visual outcomes of TPK in relation to the time from IIK diagnosis.

METHODS

We searched the literature for fungal IIK cases occurred after EK and treated by TPK. We identified 17 cases of fungal IIK, mostly caused by Candida spp. (88%).

RESULTS

Infection was diagnosed at a median time of 21 (range 1-90 days) days after EK. The median lag time between infection diagnosis and TPK was 30 (range 7-393) days. The median distance corrected visual acuity (DCVA) measured 4-12 months after surgery was 20/40 (range 20/200-20/20). When TPK was performed within one month from diagnosis, the final median DCVA was 20/30 (range 20/100-20/20), with 83% of patients achieving ≥ 20/40 vision. When TPK was carried out later, the final median DCVA was 20/50 (range 20/200-20/22) with 44% of patients achieving ≥ 20/40 vision. One patient in the early surgery and four patients in the late surgery group showed postoperative DCVA ≤ 20/100 despite clear grafts.

CONCLUSION

TPK with removal of the sequestered infection is advocated as a safe and effective measure to treat a post-EK infection. Early surgery allows a reduced exposure time to infection and therefore may result in better visual outcomes and lower risk of complications caused by prolonged inflammation.

Case Report: Suspected Donor Transmission of Acanthamoeba Keratitis After Deep Anterior Lamellar Keratoplasty

PURPOSE

In our report, we present a suspected case of donor-derived Acanthamoeba keratitis after deep anterior lamellar keratoplasty. To the authors' knowledge, there have been no confirmed cases of Acanthamoeba keratitis transmission through corneal transplantation.

METHODS

Deep anterior lamellar keratoplasty was performed on the right eye of a 33-year-old man with severe bilateral keratoconus and an intolerance to all forms of contact lenses. The postoperative visual acuity deteriorated, while inflammation, rising ocular pressure, increasing corneal thickness, and severe eye pain began to present. Confocal imaging revealed hyperreflective cysts and trophozoite figures representative of amoebic keratitis. Despite an additional penetrating keratoplasty, antiamoeba therapy, and corneal crosslinking, the patient's condition worsened, resulting in stromal melt and corneal perforation. Emergent combined surgery of temporary keratoprosthesis, vitrectomy, lensectomy, and iridectomy was performed, along with Ahmed valve shunt placement and another penetrating keratoplasty.

RESULTS

The infection was resistant to aggressive antiamoeba therapy, but after the emergent combined surgery, the graft re-epithelialized quickly and has since remained clear, with no presence of keratitis.

CONCLUSIONS

Several signs led us to believe that this case was donor-derived. There was little opportunity for graft exposure to the amoeba, and deep amoebic cysts and trophozoites were present on postoperative week 1-a highly unusual time course and depth of invasion for primary amoebic infection. In addition, pathological analysis revealed cysts only within the confines of the donor tissue and none in the recipient; Acanthamoeba cysts would have been present in the recipient rim tissue if the infection originated from the patient himself.