Deep Anterior Lamellar Keratoplasty to Treat Microsporidial Stromal Keratitis

Microsporidial Stromal Keratitis in Post-Keratoplasty Eyes

PURPOSE

The purpose of this paper is to report the clinical manifestations, diagnostic evaluation, management and outcomes of microsporidial keratitis in post-keratoplasty eyes.

METHODS

This is a retrospective review of three patients diagnosed with microsporidial stromal keratitis in post-keratoplasty eyes between January 2012 and December 2021 at a tertiary referral center (Ospedali Privati Forlì "Villa Igea", Forlì, Italy).

RESULTS

All patients presented with fine multifocal granular infiltrates following keratoplasty for a presumed herpetic keratitis. No microorganisms were isolated from the corneal scrapings and no clinical response was observed with broad-spectrum antimicrobial therapy. In all cases, confocal microscopy demonstrated spore-like structures. The histopathologic examination of the excised corneal buttons confirmed the diagnosis of microsporidial stromal keratitis. Following therapeutic keratoplasty and treatment with an initial high dose and extended taper of topical fumagillin, clinical resolution was achieved in all eyes. The Snellen visual acuities at the final follow-up were 20/50, 20/63 and 20/32.

CONCLUSIONS

Prior to definitive surgery, confocal microscopy can be employed for the in vivo detection of pathogenic microorganisms such as Microsporidium. In post-keratoplasty eyes, therapeutic keratoplasty and an initial high dose of topical fumagillin with extended taper can allow the resolution of microsporidial stromal keratitis with a satisfactory visual prognosis.

Microsporidial Endotheliitis Mimicking Graft Rejection After Deep Anterior Lamellar Keratoplasty

PURPOSE

The purpose of this study was to report a case of microsporidial endotheliitis masquerading as graft rejection after deep anterior lamellar keratoplasty (DALK).

METHODS

A 36-year-old man visited the clinic with complaints of blurred vision, redness, pain, watering, and whitish appearance of the black portion of his left eye. On evaluation, there was diffuse stromal edema with epithelial defect and hypopyon. Microbial keratitis resolved with macular grade scar. He underwent DALK. After 3 years, he presented with complaints of sudden diminution of vision in the same eye for 10 days. His unaided visual acuity was counting finger 1 meter. The clinical findings were circumcorneal congestion, diffuse graft edema, Descemet membrane folds, and diffuse keratic precipitates. A presumptive diagnosis of left eye graft rejection was made. Topical steroids were administered. There was significant improvement within a week. However, at 1 month, there was an increase in graft edema after the steroids were tapered. At this point, a diagnosis of endotheliitis of viral origin was made. He was then administered oral antivirals and steroids. There were 2 such waxing and waning episodes of graft edema before the graft failed. Patient underwent penetrating keratoplasty with cataract extraction with intraocular lens implantation.

RESULTS

The previous donor and host Descemet endothelium complex was sent for histopathology and polymerase chain reaction. Both histology and polymerase chain reaction were positive for microsporidia.

CONCLUSIONS

Microsporidial endotheliitis may present as graft rejection. There should be a suspicion of microsporidial infection in cases of features mimicking as endothelial rejection after DALK.

Microsporidial Stromal Keratitis: Epidemiological Features, Slit-Lamp Biomicroscopic Characteristics, and Therapy

PURPOSE

Microsporidial stromal keratitis is a rare form of infectious keratitis, with only 7 cases reported in the United States to date. This study was performed to evaluate risk factors, clinical features, and response to therapy.

METHODS

A retrospective review of the medical records of all patients diagnosed with microsporidial stromal keratitis seen in the practices of the authors between 1999 and 2020 was performed. Diagnosis was determined by cytology or histopathology in corneal specimens. Risk factors, presence or absence of distinctive clinical features, and response to medical and surgical therapies were recorded.

RESULTS

Nine patients-7M:2F, aged 7 to 99 years-with microsporidial stromal keratitis were identified. Exposures to recreational water and hymenopteran insect bites, both epidemiologically linked risk factors for systemic microsporidial infection, were identified in our patients. Presence of stromal edema with features of disciform keratitis and a distinctive granular keratitis were observed in 6 of 9 and 5 of 9 patients, respectively. Poor response to medical therapy was noted. Penetrating keratoplasty was effective in curing the infection. Final visual acuity was 20/40 or better in 6 of 9 patients.

CONCLUSIONS

In patients with slowly progressive keratitis, history of exposure to recreational water or hymenopteran insects should be sought. In patients with corneal edema consistent with disciform keratitis, with evolution to a granular keratitis, microsporidia should be considered in the differential diagnosis. In cases of established microsporidial stromal keratitis, penetrating keratoplasty should be considered if prompt response to medical therapy is not noted.

Tectonic Deep Anterior Lamellar Keratoplasty to Treat Corneal Perforation and Descemetocele from Microbial Keratitis

Purpose

To evaluate the result of tectonic deep anterior lamellar keratoplasty (DALK) for keratitis with perforation and descemetocele.

Patients and Methods

A prospective clinical study of 36 patients (36 eyes) treated with tectonic DALK for corneal perforation or descemetocele from microbial keratitis managed at the Vietnam National Eye Hospital over a two-year period. The surgical technique was manual lamellar dissection. The grafts were harvested from the anterior corneal cap of pre-cut donor tissues used for DSAEK or donor corneas with a low endothelial cell count.

Results

A mean age was 55.36 ± 13.98 years (ranged from 25 to 75 years). Female gender represented 52%. causative agents were herpes simplex virus (58.3%), bacteria (22.2%), fungi (13.9%) and microsporidia (5.6%). There were 24 eyes with descemetocele (66.7%) and 12 with perforation (33.3%). There were 33 successful cases (91.7%) and 3 failed cases (8.3%). Best corrected visual acuity (BCVA) improved in 28 eyes (84.8%). The range of post-operative BCVA was from hand motions to 20/70. Eleven eyes (33.3%) attained vision 20/200 and higher. Clear graft was obtained in 15 eyes (45.5%), while mild or severe graft opacity was observed in 14 eyes (42.4%), and 4 eyes (12.1%), respectively. Surgical complications included descemet rupture (20.8%), pseudo anterior chamber (41.6%), persistent corneal epithelial defects (8.3%), reinfection (11.1%), glaucoma or ocular hypertension (5.6%) and cataract (8.3%).

Conclusion

The study demonstrates that DALK is an effective procedure to treat corneal descemetocele, especially when an urgent penetrating keratoplasty (PKP) cannot be performed.

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.

A Narrative Review of Microsporidial Infections of the Cornea

Microsporidia are a rare and commonly misdiagnosed cause of corneal infection, accounting for approximately 0.4% of cases of microbial keratitis in some populations. Ocular microsporidiosis most often presents as either microsporidial keratoconjunctivitis (MKC) or microsporidial stromal keratitis (MSK). Though these two clinical entities exhibit similar symptomology, they are distinguished from one another by the time course for disease progression, findings on slit-lamp examination, and response to medical therapy. This review summarizes the current literature on the etiology and clinical presentation of microsporidial infections of the cornea and highlights ongoing developments in available diagnostic modalities and treatment regimens.

Microsporidial keratopathy in two dogs

A microsporidial keratopathy is described in two dogs. Both dogs presented with a unilateral stromal keratopathy characterized by multifocal coalescing opacities, and the diagnosis was made on histopathologic examination of keratectomy specimens. Transmission electron microscopy (TEM) on formalin-fixed, paraffin-embedded corneal tissue was performed in one dog, and the morphologic features were consistent with Nosema species infection. Both dogs were initially diagnosed and treated by superficial keratectomy. One dog received additional antifungal medication and underwent a penetrating keratoplasty following local recurrence two years later. No other systemic lesions attributable to the microsporidial infection were identified clinically. The clinical and diagnostic pathology findings, treatment, and follow-up are discussed.

Case of isolated Rhizobium radiobacter contact lens-related infectious keratitis: A plant microbe now emerging as a human pathogen

Purpose

To report a case of contact lens-related infectious keratitis caused by the Gram-negative plant pathogen Rhizobium radiobacter.

Observations

A 26-year old lady with history of contact lens use presented with three weeks history of right eye redness and pain, with the left eye also being involved in the past week. Slit lamp examination of the right eye demonstrated multiple faint subepithelial and stromal infiltrates with no overlying epithelial defect, and no anterior chamber activity. Anterior segment optical coherence tomography demonstrated multiple hyper-reflective foci scattered at various depths of the corneal stroma. Corneal scrapings grew Rhizobium radiobacter, and culture-directed antibiotic therapy with topical gentamicin and levofloxacin resulted in slow clinical improvement of the R. radiobacter keratitis without visual sequelae.

Conclusions and importance

We have described the clinical features, microbial susceptibilities, and response to treatment in a case of R. radiobacter infectious keratitis.

R. radiobacter has recently emerged as a source for several ocular and systemic infections and was identified in a series of polymicrobial keratitis cases. Our case report of monomicrobial R. radiobacter keratitis adds to the sparse literature on this uncommon but potentially sight-threatening infection.

Novel application of In Vivo Micro-Optical Coherence Tomography to assess Cornea scarring in an Animal Model

This pilot study uses a micro-optical coherence tomography (micro-OCT) system with ~1 μm axial resolution specifically to image the cornea and corneal scars in vivo. We used an established murine corneal scar model by irregular phototherapeutic keratectomy in ten C57BL/6 mice, with serial imaging using the micro-OCT and compared to anterior segment (AS-OCT) (RTvue, Optovue, Fremont, CA) before and after scar induction. Main outcome was agreement between the AS-OCT and micro-OCT using Bland-Altman plots (95% limits of agreement, LoA).We analysed 10 control eyes and 10 eyes with corneal scars and found that there was good agreement between AS-OCT and micro-OCT (P > 0.05) LOA: lower limit -14 µm (95% CI: -19 to -8.8 µm) upper limit 23 µm (95% CI: 18 to 28.5 µm) in terms of central corneal thickness. There was also good agreement between AS-OCT and micro-OCT in terms of corneal scar measurements (P > 0.5; correlation coefficient >0.99) LOA lower limit -2.1 µm (95% CI: -2.8 to -1.5 µm); upper limit 1.8 µm (95% CI: 1.1 to 2.4 µm). Our pilot study suggests that this novel in vivo micro-OCT imaging technique was able to measure central corneal thickness and scar thickness in agreement with current AS-OCT techniques.

Microsporidial Stromal Keratitis: Clinical Features, Unique Diagnostic Criteria, and Treatment Outcomes in a Large Case Series

PURPOSE

To describe the history, clinical features, and outcomes of a large case series of microsporidial stromal keratitis with emphasis on probable predictors of the etiology in this rare and unspecified form of keratitis.

METHODS

Retrospective analysis of cases seen between January, 2002, and December, 2013, diagnosed at LV Prasad Eye Institute as having microsporidial stromal keratitis based on clinical, microbiology, and histopathology examination. Outcomes of medical and surgical management with visual recovery were documented.

RESULTS

There were 34 cases of microsporidial stromal keratitis with a mean age of 43.3 years (range 2-77 years) and male preponderance. The duration of symptoms was chronic in most cases (mean duration of 288 days). Nearly half of the cases had a history of trauma, in the age group of 20 to 50 years. The most common clinical misdiagnosis was herpes simplex virus keratitis (26.5%) followed by fungal keratitis (17.6%). This could be attributed to the nonspecific clinical picture of diffuse multifocal stromal lesions in 82.4% of cases. The organisms were detected in microbiological evaluation of corneal scrapings in 47% cases, and histopathological detection of the organisms showed a positivity rate of 92.3%. Surgical management was necessary in the majority of the cases (73.5% of patients).

CONCLUSIONS

The typical history of trauma with a smoldering, diffuse form of keratitis refractory to conventional medical therapy, responding to surgical removal for recovery is clearly demonstrated as a recurring feature in the majority of the cases. Patients presenting with this characteristic clinical picture should be suspected to harbor this rare pathogen, and early surgical interventions should be considered.

Coexistence of herpes simplex virus infection in microsporidial stromal keratitis associated with granulomatous inflammation

Background:

Microsporidial stromal keratitis poses several diagnostic challenges. Patients may present with corneal ulceration, marked stromal thinning, or even as a quite corneal scar. The presentation of microsporidial stromal keratitis commonly mimics viral keratitis. Microbiology scrapings are usually helpful; however, scraping and culture-negative cases pose a significant diagnostic dilemma. Histopathological examination is diagnostic but shows varying degree of inflammation, predominantly composed of polymorphonuclear leukocytes. Granulomatous inflammation, in microsporidial stromal keratitis, is never well described, and the authors in this article aim to describe the presence of granulomatous inflammation in microsporidial stromal keratitis, in patients with associated herpes simplex virus (HSV) keratitis.

Methods:

This was a retrospective and observational study conducted at a tertiary eye care center.

Results:

Of 263 patients who underwent therapeutic penetrating keratoplasty for infectious keratitis, during 2011–2013, seven patients were diagnosed as microsporidial stromal keratitis. Microsporidial spores could be demonstrated on microbiological scrapings in 5/7 (71%) of cases, but identified on histopathological examination and also confirmed on polymerase chain reaction (PCR) for microsporidium in 100% of cases. There was evidence of diffuse stromal necrosis with markedly severe degree of polymorphonuclear leukocytic infiltrates, with granulomatous inflammation in 42% of cases. Interestingly, these were positive for HSV-1 DNA on PCR. Review of medical records revealed much severe clinical presentations in patients with granulomatous inflammation, in comparison to cases without granulomatous inflammation.

Conclusions:

The authors hereby recommend that severe clinical presentation in patients with microsporidial stromal keratitis, markedly dense polymorphonuclear leukocytic infiltrates or the presence of granulomatous inflammation on the histopathological examination, should be investigated further for the presence of HSV-1 DNA for better patient management and good visual outcome.

Outcomes of deep anterior lamellar keratoplasty using the big-bubble technique in various corneal diseases

PURPOSE

To report clinical outcomes of deep anterior lamellar keratoplasty (DALK) using the big-bubble technique in various original diagnoses.

DESIGN

Prospective interventional study.

METHODS

Single hospital study of 115 unselected consecutive patients (131 eyes) with various diagnoses undergoing DALK using the big-bubble technique. The main outcome measures were intraoperative and postoperative complications, postoperative best spectacle-corrected visual acuity (BSCVA), and endothelial cell density (ECD).

RESULTS

Descemet membrane was exposed successfully in 25 eyes (80.6%) with advanced keratoconus, 11 (73.3%) with chemical or thermal burns, 20 (71.4%) with corneal dystrophy, 21 (70%) with a herpes simplex (HSK) keratitis scar, 4 (36.4%) with moderate keratoconus, and 5 (31.3%) with a bacterial keratitis scar (P < .05). Loosening of the sutures occurred in 24 eyes (23.8%) between postoperative4 and 7 months. Epithelial rejection was observed in 2 eyes and stromal rejection occurred in 5 eyes. BSCVA was improved in HSK scarring and corneal dystrophy vs keratoconus and corneal burns at 1 year (P < .05), but not after a mean follow-up of 21.4 months (P < .05). Patients who experienced stromal rejection had lower ECD than patients with no rejection at 18 and 24 months (P < .05). At all follow-up times after 6 months, patients with multiple air injection attempts had lower ECD than patients with 1 injection attempt (P < .05).

CONCLUSIONS

Different Descemet membrane exposure rates were observed in different diagnoses using the big-bubble technique. Both severe stromal rejection and additional manipulation may have a deleterious effect on the corneal endothelium.

Microsporidial keratitis: Literature review and report of 2 cases in a tertiary eye care center

Microsporidia are getting more recognized as causative organism of ocular, gastrointestinal, renal, pulmonary, and sinus diseases, in both immunocompetent and immunosuppressed patients. Ocular microsporidiosis can be isolated or may present as part of systemic infection. Recent reports showed increasing number of cases of ocular microsporidiosis in immunocompetent individuals. The ocular type occurs mainly in two forms: keratoconjunctivitis form which is mostly seen in immunocompromised individuals and stromal keratitis form seen in immunocompetent individuals. The ocular cases which present with superficial keratitis in acquired immune deficiency syndrome (AIDS) patients differ from the cases seen in immunocompetent individuals which present mainly as deep stromal keratitis. We are presenting the only two documented cases of microsporidial keratitis diagnosed over 25 years of practice in our institution. The cases are diagnosed by identification of the Acid-fast organisms. Ultrastructure and additional information on species identification in one of the cases. Both cases are eventually managed by therapeutic PKP. Diagnosis and treatment modalities are discussed based on a comprehensive literature review.

Clinical spectrum of microsporidial keratoconjunctivitis

The purpose of this paper was to analyse the causes, pathogenesis, diagnostic modalities and treatment outcomes of microsporidial keratoconjunctivitis (MKC). Microsporidia are increasingly recognized as opportunistic infectious pathogens in immunocompromized patients causing keratoconjunctivitis. In the recent years, there has been a surge in reports of MKC in immunocompetent individuals presenting with stromal keratitis. A detailed literature search was done using Medline, OVID, Cochrane Library, UptoDate and Google Scholar databases with the terms microsporidia, keratitis, conjunctivitis, immunocompromized and immunocompetent. The articles were reviewed to determine the spectrum of clinical presentation, disease course, investigations, treatment modalities and outcome. Thirty-six publications were reviewed, and 151 cases of MKC were included for this review. The main presenting features included pain, redness, photophobia, epiphora and blurring of vision. Duration of the symptoms lasted between 4 days and 18 months. Light microscopy with modified trichrome stain was most commonly used to diagnose MKC. Resolution of symptoms was most commonly achieved with oral albendazole and/or topical fumidil B. Topical fluoroquinolones are also effective as a monotherapy as suggested by recent studies. Clinical outcome was good (visual acuity ≤ 6/12) for the patients who presented earlier (≤1 month) (75% of cases with documented final best-corrected visual acuity). MKC occurs more commonly in immunocompetent individuals than expected and can be diagnosed in earlier stages. From our review, we conclude that the patients, who were diagnosed early and treated, had complete resolution of symptoms with a better clinical outcome.

Deep anterior lamellar keratoplasty: indications, surgical techniques and complications

The concept of lamellar keratoplasty (LK) is not new. However, it had been abandoned and largely replaced by the time-honored technique of penetrating keratoplasty (PK) because LK is technically demanding, time consuming and gives suboptimal visual outcomes due to interface irregularity arising from manual lamellar dissection. Recent improvements in surgical instruments and introduction of new techniques of maximum depth of corneal dissection as well as inherent advantages such as preservation of globe integrity and elimination of endothelial graft rejection have resulted in a re-introduction of LK as an acceptable alternative to conventional PK. This review article describes the indications, different techniques, clinical outcomes and complications of deep anterior LK.