Lamellar keratoplasty for the treatment of fungal keratitis

Overview of Mycotic Keratitis

ABSTRACT

Keratomycosis is a serious corneal infection associated with high ocular morbidity that can lead to severe vision loss. It is estimated to affect more than 1 million patients annually, most commonly occurring in tropical climates, and represents a growing threat to patients worldwide. Despite aggressive medical management, fungal infections have a higher rate of perforation requiring surgical intervention compared with other infectious etiologies. Early diagnosis and appropriate treatment are keys to preserving vision and saving patients' eyes.Timely diagnosis of fungal keratitis helps minimize corneal damage and scarring and increases the likelihood of a favorable outcome. Studies have shown that correct identification of fungal infections is often delayed up to 2 to 3 weeks after initial presentation. This leads to incorrect or ineffective treatment for many patients. Diagnostic techniques explored in this study include corneal scrapings with staining and culture, visualization with in vivo confocal microscopy, molecular diagnostic techniques including polymerase chain reaction, and recently developed omics-based technologies.Treatment of fungal keratitis begins with topical antifungals. Medical management has been proven to be effective, but with limitations including poor drug penetration and low bioavailability. Cases that do not respond to topical therapy require more invasive and novel treatments to control the infection. We review the clinical trials that have shaped current practice patterns, with focus on the efficacy of topical natamycin as the primary therapy for filamentous fungal keratitis. We explore additional management strategies such as localized intrastromal and intracameral injections of antifungal medications, photodynamic therapy, and surgical intervention.

Different Thicknesses of Acellular Porcine Corneal Stroma on Prognosis of Fungal Corneal Ulcers Treated by Lamellar Keratoplasty: A Five-Year Retrospective Study

PURPOSE

To compare the prognosis and efficacy of acellular porcine corneal stroma (APCS) with different thicknesses for the treatment of fungal corneal ulcers by lamellar keratoplasty (LKP).

METHODS

A total of 52 patients who underwent LKP with APCS for the treatment of fungal corneal ulcers were included in this retrospective study. Patients were divided into 2 groups according to the different thicknesses of APCS (0.30 ± 0.05 mm, L2 group, n = 20; 0.40 ± 0.05 mm, L3 group, n = 32). Observation indicators included best corrected visual acuity, graft transparency, corneal neovascularization, ocular irritation symptoms, corneal epithelial healing time, graft survival, central corneal thickness at 1 year after surgery, and postoperative complications.

RESULTS

Compared with the L3 group, the L2 group had better postoperative best corrected visual acuity and graft transparency (P < 0.001), less corneal neovascularization (P < 0.001), and lower incidence of complications (P < 0.05). There were significant differences in ocular irritation symptoms between the 2 groups (P < 0.05) at 3 and 6 months postoperatively, which might be related to the higher recurrence rate and graft rejection rate in the L3 group. The comparison of postoperative epithelial healing time also showed significant differences in 2 groups (P < 0.01). The 1-year survival rate was up to 63.5% in both groups, with no significant difference (P < 0.05). However, the risk of transplantation was less in the L2 group. Both APCS thicknesses could provide adequate central corneal thickness at 1 year after surgery (P > 0.05).

CONCLUSIONS

APCS was safe and effective in the treatment of fungal corneal ulcers by LKP. Thinner grafts should be preferred for LKP for fungal corneal ulcers to reduce the risk of grafting.

Amniotic membrane transplantation combined with conjunctival flap covering surgery for the treatment of corneal perforations in fungal keratitis

Purpose

To investigate the efficiency of amniotic membrane transplantation (AMT) combined with conjunctival flap covering surgery (CFCS) for patients with corneal perforations in fungal keratitis (FK).

Methods

In this non-comparative, retrospective case series, 16 participants of corneal perforation in FK were successfully treated by a combination of multilayer AMT and bipedicle conjunctival flap with partial tenon's capsule. Corneal healing, recurrence of FK, visual acuity, and relevant complications were reported as outcome measures.

Results

Sixteen patients (13 male, 3 female) had a mean age of 58.8 ± 10.3 (range 29-72) years. The mean diameter of corneal perforation was 1.9 ± 0.7 (range 0.5-2.8) mm. Corneal perforations healed and all the patients preserved their eyeballs. During the 11.0 ± 4.4 (range 6-18) months of follow-up, there was no recurrence of FK in any of these cases. Visual acuity improved in 15 eyes (93.8 %) and remained unchanged in 1 patient (6.3 %) who had no light perception when first admitted. All 6 patients who accepted secondary keratoplasty showed improved best corrected visual acuity of more than 4 lines. The most frequently found fungi were Aspergillus species (6 of 16, 37.5 %) and Fusarium species (4 of 16, 25.0 %), followed by 1 Scedosporium apiospermum (1 of 16, 6.3 %).

Conclusions

Combination AMT with CFCS is a safe and effective surgery for patients with corneal perforations in FK, particularly where eye banks and fresh corneas are not available. This surgery could preserve the integrity of the eyeball and avoid the recurrence of FK. Besides, it provides a greater opportunity for further optical keratoplasty.

Characteristics of In Vitro Culture and In Vivo Confocal Microscopy in Patients with Fungal Keratitis in a Tertiary Referral Hospital in Central China

PURPOSE

To investigate the characteristics of in vitro culture and in vivo confocal microscopy (IVCM) in patients with fungal keratitis (FK) presented in a tertiary referral hospital in central China.

METHODS

In this noncomparative retrospective study, patients with the diagnosis of FK between October 2021 and November 2022 were reviewed. An IVCM and fungal culture (corneal scraping specimens) were performed, and the characteristics were analyzed.

RESULTS

During October 2021 and November 2022, 85 patients were diagnosed with FK. From 63 culture-positive cases, 8 species of fungus were identified. The proportions of isolated fungal species were Fusarium and Aspergillus equally accounting for 33.3% (21 of 63), Alternaria 9.5% (6 of 63), Curvularia 6.3% (4 of 63), Scedosporium apiospermum 6.3% (4 of 63), Paecilomyces lilacinus 3.2% (2 of 63), Exserohilum 3.2% (2 of 63), and Candida 4.8% (3 of 63), respectively. In positive culture cases, IVCM was found to be positive for hyphae or spores in 61 of 63 patients (96.8%). Different fungal species had a variety of cultural characteristics and IVCM manifestations.

CONCLUSIONS

In a tertiary referral hospital in central China, Fusarium species, Aspergillus species, and Alternaria species were the 3 most common isolated fungal pathogens, and the proportion of Aspergillus species was significantly higher than that in other regions of China. Careful lesion depth examination by IVCM and OCT should be taken before lamellar keratoplasty to avoid postoperative recurrence. Identifying the IVCM image and culture characteristics will facilitate rapid diagnosis and proper treatment, but IVCM cannot yet replace fungal cultures to distinguish between different fungal species.

Management of Filamentous Fungal Keratitis: A Pragmatic Approach

Filamentous fungal infections of the cornea known as filamentous fungal keratitis (FK) are challenging to treat. Topical natamycin 5% is usually first-line treatment following the results of several landmark clinical trials. However, even when treated intensively, infections may progress to corneal perforation. Current topical antifungals are not always effective and are often unavailable. Alternatives topical therapies to natamycin include voriconazole, chlorhexidine, amphotericin B and econazole. Surgical therapy, typically in the form of therapeutic penetrating keratoplasty, may be required for severe cases or following corneal perforation. Alternative treatment strategies such as intrastromal or intracameral injections of antifungals may be used. However, there is often no clear treatment strategy and the evidence to guide therapy is often lacking. This review describes the different treatment options and their evidence and provides a pragmatic approach to the management of fungal keratitis, particularly for clinicians working in tropical, low-resource settings where fungal keratitis is most prevalent.

Microbial Profile and Clinical Outcomes of Fungal Keratitis at a Single-Center Tertiary Care Hospital

PURPOSE

To evaluate baseline characteristics, microbiological spectrum, management, and outcomes of patients with culture-proven fungal keratitis.

METHODS

Retrospective review of all patients with culture-proven fungal keratitis seen over 6 years at a tertiary referral center.

RESULTS

The present study included 62 eyes from 62 patients. Infection with filamentous organisms was more common than with yeast (66.1% vs 27.4%). The most common filamentous organisms were Fusarium (17.7%) and Aspergillus (16.1%), while the most common yeast was Candida (24.2%). The main predisposing factor for filamentous keratitis was contact lens use. Yeast keratitis is most associated with an immunocompromised host and ocular surface disease. Corneal perforation (20.0%) and surgical interventions (46.8%) were common, with 27.4% of eyes requiring at least one penetrating keratoplasty. Filamentous keratitis is more likely than yeast keratitis to require urgent penetrating keratoplasty or enucleation and to receive more than one topical and systemic antifungal agent. Visual outcomes were poor with nearly half of the eyes remaining at 20/200 or worse upon resolution of infection. Worse visual outcomes were associated with poor vision at presentation and a history of ocular surface disease. Antifungal susceptibility testing was not routinely performed, but it demonstrated a relatively high minimum inhibitory concentration for at least one antifungal drug in 90% of cases when performed (16.1%) and guided the direction of treatment for 80% of the cases.

CONCLUSION

Fungal keratitis is visually devastating. Infections with filamentous fungi predominated over yeast and were generally treated more aggressively both medically and surgically. Filamentous and yeast keratitis had similar durations of infections and visual outcomes. Antifungal susceptibility testing influenced treatment in 80% of cases in which it was performed.

Recent Perspectives in the Management of Fungal Keratitis

Mycotic keratitis is common in warm, humid regions with a varying profile of pathogenic fungi according to geographical origin, socioeconomic status, and climatic condition. Clinical diagnosis can be challenging in difficult cases and those refractory to treatment. Fungal hyphae on microscopic examination and culture isolation have been the gold standard in the laboratory diagnosis of fungal keratitis. A culture isolate of the aetiological fungus is essential to perform antifungal susceptibility testing. As the culture isolation of fungi is time-consuming, causing delays in the initiation of treatment, newer investigative modalities such as in vivo confocal microscopy and molecular diagnostic methods have recently gained popularity. Molecular diagnostic techniques now help to obtain a rapid diagnosis of fungal keratitis. Genomic approaches are based on detecting amplicons of ribosomal RNA genes, with internal transcribed spacers being increasingly adopted. Metagenomic deep sequencing allows for rapid and accurate diagnosis without the need to wait for the fungus to grow. This is also helpful in identifying new emerging strains of fungi causing mycotic keratitis. A custom-tear proteomic approach will probably play an important diagnostic role in future in the management of mycotic keratitis. Positive repeat cultures are being suggested as an important gauge indicative of a poor prognosis. Positive repeat fungal cultures help to modify a treatment regimen by increasing its frequency, providing the addition of another topical and oral antifungal agent along with close follow-up for perforation and identifying need for early therapeutic keratoplasty. The role of collagen crosslinking in the treatment of fungal keratitis is not convincingly established. Rapid detection by multiplex PCR and antifungal susceptibility testing of the pathogenic fungi, adopted into a routine management protocol of fungal keratitis, will help to improve treatment outcome. Early therapy is essential in minimizing damage to the corneal tissue, thereby providing a better outcome. The role of conventional therapy with polyenes, systemic and targeted therapy of antifungal agents, newer azoles and echinocandins in fungal keratitis has been widely studied in recent times. Combination therapy can be more efficacious in comparison to monotherapy. Given the diversity of fungal aetiology, the emergence of new corneal pathogenic fungi with varying drug susceptibilities, increasing the drug resistance to antifungal agents in some genera and species, it is perhaps time to adopt recent molecular methods for precise identification and incorporate antifungal susceptibility testing as a routine.

Indications and Surgical Techniques for Repeat Corneal Transplantation in Eastern China: A Twelve-Year Study

Purpose

To analyze the indications and surgical procedures for repeat keratoplasty in eastern China from 2008 to 2019.

Methods

This retrospective descriptive study included 418 eyes of 411 patients who underwent no less than 2 keratoplasties at the Eye, Ear, Nose and Throat Hospital of Fudan University from 2008 to 2019. Medical charts were reviewed. The primary indications for repeat keratoplasty, the reasons for regrafting, and the surgical techniques used in the treatment were collected and analyzed.

Results

Among 418 eyes, 337 eyes (80.6%) had one repeat keratoplasty, and 81 eyes (19.4%) had multiple repeat keratoplasties (≥2 repeat keratoplasties). The median interval between the initial keratoplasty and the first repeat keratoplasty was 25 months, and that between two keratoplasties after the first repeat keratoplasty was 27.5 months. Infectious keratitis was the leading primary indication for single repeat keratoplasty (80 cases, 23.7%) and multiple repeat keratoplasties (19 cases, 23.5%). The second most common primary indication was bullous keratopathy for single repeat keratoplasty (49 eyes, 14.5%) and chemical injury for multiple repeat keratoplasties (14 eyes, 17.3%). The main reason for regrafting was allograft rejection (262 cases, 49.3%), followed by endothelial dysfunction (92 cases, 17.3%), and for vision improvement after tectonic keratoplasty (60 cases, 11.3%). Penetrating keratoplasty (PKP) was the major technique used in repeat keratoplasty (447 cases, 84.2%). However, Descemet stripping endothelial keratoplasty was more frequently used than PKP (72.4% vs. 27.6%, P < 0.001) in the treatment of failed endothelial keratoplasty.

Conclusion

Infectious keratitis was still the leading cause of repeat keratoplasty in eastern China. Although PKP remains the major technique of repeat keratoplasty, the application of customized lamellar keratoplasty has greatly expanded in the last decade. Cautious selection of indications, surgical techniques, and timing for surgery is crucial for a good prognosis after repeat keratoplasty.

A case of fungal conjunctivitis with giant papillae treated surgically

Fungal conjunctivitis is a rare disorder, with low incidence and difficulty in diagnosis due to a lack of specific clinical findings. We report a case of fungal conjunctivitis which exhibited a specific clinical feature of giant papilla formation, and its diagnosis was a complex process. A 19-year-old woman with a history of atopic dermatitis and hard contact lens use was referred to us with a 3-month history of giant papillary conjunctivitis of the right eye in spite of treatment with antiallergic and corticosteroid eye drops, complicated by intraocular pressure elevation. The left eye showed no symptom of ocular surface disorder throughout the clinical course. The right eye did not respond to oral corticosteroid. Polymerase chain reaction of conjunctival scrapings against Chlamydia trachomatis was negative, and she was treated surgically by total papilla resection. Conjunctival giant papilla recurrence was not observed after surgery. Although the primary histopathological diagnosis was chronic inflammation due to atopic keratoconjunctivitis, repeated histopathological survey of excised conjunctival tissue including immunohistochemical staining revealed histiocytes, yeast type spores and hyphae, and phagocytosed spores and hyphae in macrophages. The causative organism was identified morphologically as a Candida species. Later, histopathological examination of a cervical swab revealed the presence of Candida sp. This rare case indicates that a fungal organism may underlie refractory conjunctivitis with specific giant papillary hypertrophy mimicking vernal keratoconjunctivitis.

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.

Large-Diameter Penetrating Keratoplasties are Mostly Due to Very Severe Infectious Keratitis and Cannot Always Prevent Secondary Enucleation

PURPOSE

To report the indications and outcomes of penetrating keratoplasties with a graft diameter > 8.5 mm in severe corneal diseases at the Department of Ophthalmology at Saarland University Medical Centre.

STUDY DESIGN

Retrospective (6 years), descriptive, and observational.

METHODS

Thirty-five large-diameter penetrating keratoplasties (LDPKPs) in 27 patients (mean age, 62 ± 22 years) were performed from March 2010 to December 2016. The indication for surgery, number of previous corneal transplantations, best-corrected visual acuity (BCVA) before surgery, intraocular pressure, graft status, and BCVA at last follow-up were recorded.

RESULTS

Infectious keratitis represented 83% of the indications (of those, 45% fungal). The mean corneal graft diameter was 10.8 ± 1.7 (min 8.75, max 15.0) mm. Twenty-three eyes (65% absolute) had at least one previous penetrating keratoplasty (mean graft size, 9.2 ± 1.6 mm). The mean pre-surgery BCVA was 1.96 ± 0.23 logMAR. With a mean follow-up period of 20.2 ± 13.4 months, the mean BCVA was 1.57 ± 0.57 logMAR at last follow-up. Overall, 12 grafts (35%) remained clear until the last follow-up, and in 23 grafts (65%), the primary disease recurred, or corneal decompensation developed. Up to the last follow-up, 6 eyes (17%) had to be enucleated.

CONCLUSIONS

In complex cases of infectious keratitis requiring a LDPKP to remove the complete pathology and preserve eye integrity, the visual outcomes are generally expected to be poor, not only because of the well-known risks of LDPKP but also because of the consequences of the infectious disease itself. This knowledge is important for adequate counselling of the patient preoperatively.

Topical Corticosteroids and Fungal Keratitis: A Review of the Literature and Case Series

The management of fungal keratitis is complex since signs and symptoms are subtle and ocular inflammation is minimal in the preliminary stages of infection. Initial misdiagnosis of the condition and consequent management of inflammation with corticosteroids is a frequent occurrence. Topical steroid use is considered to be a principal factor for development of fungal keratitis. In this review, we assess the studies that have reported outcomes of fungal keratitis in patients receiving steroids prior to diagnosis. We also assess the possible rebound effect present when steroids are abruptly discontinued and the clinical characteristics of three patients in this particular clinical scenario. Previous reports and the three clinical descriptions presented suggest that in fungal keratitis, discontinuing topical steroids can induce worsening of clinical signs. In these cases, we recommend to slowly taper steroids and continue or commence appropriate antifungal therapy.

Deep anterior lamellar keratoplasty with cross-linked acellular porcine corneal stroma to manage fungal keratitis

PURPOSE

To evaluate the effects of deep anterior lamellar keratoplasty (DALK) with cross-linked acellular porcine corneal stroma (APCS) and post-operative topical tacrolimus treatment in patients with fungal keratitis.

METHODS

This multicenter prospective study involved 25 cases of fungal keratitis that were treated by DALK with cross-linked APCSs and post-operative topical tacrolimus from December 2013 to November 2014 at the Wenzhou Eye Hospital and the Henan provincial Eye Hospital. Signs of post-operative inflammation, corneal reepithelialization, corneal neovascularization, and graft rejection were assessed, and best corrected visual acuity (BCVA), intraocular pressure (IOP), and APCS graft transparency were monitored for the 12-month follow-up period.

RESULTS

All 25 patients underwent DALK without Descemet's membrane perforation. Corneal epithelium recovered completely in 17 patients in the first week, and APCS grafts maintained transparency in 18 patients at 1-year follow-up. The mean BCVA significantly improved from 2.16 ± 0.32 (LogMAR) at baseline to 1.56 ± 0.70 at 1-week (P < .001), 0.95 ± 0.57 at 1-month (P < .001), and 0.70 ± 0.51 at 3-month follow-ups (P < .001). The BCVA kept stable at 6-month and 12-month follow-ups. Post-operative topical tacrolimus alleviated the ciliary injection, except in one case which acute stromal rejection occurred. One patient developed fungal reinfection and underwent penetrating keratoplasty. Graft rejection occurred in three patients. No case was noted with graft splitting, elevated IOP or tacrolimus intolerance.

CONCLUSIONS

DALK using cross-linked APCS combining topical tacrolimus treatment is safe and effective in managing fungal keratitis. It may ameliorate the shortage of corneal donation globally.

Endothelial Plaques as Sign of Hyphae Infiltration of Descemet's Membrane in Fungal Keratitis

Background

To evaluate the relationship between corneal endothelial plaques and fungal hyphae infiltration in fungal keratitis.

Methods

Retrospective cross-sectional study of 60 fungal keratitis patients who underwent keratoplasty between January 2013 and March 2017. The endothelial plaques were graded as follows: grade 1, 1–3 endothelial plaques; grade 2, 4–8 endothelial plaques; and grade 3, more than 8 endothelial plaques or dense, merging endothelial plaques. The fungal pathogen culture and histopathology of diseased Descemet's membrane were evaluated.

Results

According to endothelial plaque grading, 3 patients were grade 1, 29 patients were grade 2, and 28 patients were grade 3. The PK surgery was performed in 57 patients with endothelial plaques of grade 2 and grade 3 and DALK surgery in 3 patients of grade 1. The predominating fungal pathogens were Aspergillus species (63.2%). All 57 patients with grade 2 and grade 3 had fungal hyphae in Descemet's membrane based on calcofluor white staining or PAS staining. In patients with grade 3, more hyphae and inflammatory cells were found in Descemet's membrane. The immunohistochemical staining of endothelial plaques revealed that CD15 and CD68 were positive in most cells. During the follow-up, 2 out of 3 patients who underwent DALK had recurrent fungal keratitis.

Conclusions

Endothelial plaques are considered as a sign of hyphae infiltrating Descemet's membrane. PK should be performed once plaques are detected in endothelium during the surgery.

Clinical outcome after air-assisted manual deep anterior lamellar keratoplasty for fungal keratitis poorly responsive to medical treatment

Purpose

Fungal keratitis remains an important disorder because of difficulty in its diagnosis, and some patients do not respond to medical treatment using antifungal local and systemic agents. This study was carried out to determine the therapeutic value of air-assisted manual therapeutic deep anterior lamellar keratoplasty (TDALK) in the treatment of fungal keratitis not curable by antifungal chemotherapy.

Methods

Seventeen patients (18 eyes) who were referred to Fukuoka University Hospital and treated surgically from January 2006 to April 2018, in whom a diagnosis of fungal keratitis was confirmed by typical clinical findings and microbiological or histological analysis of corneal specimens, and who were poorly responsive to topical and systemic antifungal medication, whereas the lesion had not resulted in corneal perforation, were enrolled in this study and were treated by air-assisted manual TDALK. Clinical outcomes including treatment course, therapeutic success rate, visual acuity outcomes and graft clarity rate were analyzed.

Results

The most common pathogen was Fusarium, followed by Candida and Aspergillus. Beneficial therapeutic results (a clear or translucent graft) were achieved in 15 of 18 eyes (83%). There was no recurrence of infection and resulting visual acuity ≤0.15 logarithm of minimal angle of resolution unit was achieved in 15 eyes (83%). Intraoperative microperforation of Descemet’s membrane (DM) was not observed in any patients.

Conclusion

Air-assisted manual TDALK can be effective for treating severe fungal keratitis. In addition, air-assisted manual TDALK might be an alternative procedure to big-bubble DALK, because it can provide ambulatory vision and can preserve potentiality of vision with less risk of intraoperative perforation of DM.

Incidence and Outcomes of Positive Donor Rim Cultures and Infections in the Cornea Preservation Time Study

PURPOSE

To assess donor rim culture results and outcomes of ocular infections in the Cornea Preservation Time Study (CPTS).

METHODS

Donor corneal rim cultures were optional. Donor characteristics were assessed for association with positive cultures using the Fisher exact test and Poisson regression analyses. Incidence rates of ocular infections were estimated, and 95% confidence intervals were calculated.

RESULTS

Cultures were performed in 784 (58.9%) of the 1330 cases. For the 0 to 7-day versus 8 to 14-day preservation time groups, respectively, positive fungal growth occurred in 10 of 397 (2.5%) versus 5 of 387 (1.3%) corneas (P = 0.30), whereas positive bacterial cultures occurred in 6 of 397 (1.5%) versus 4 of 387 (1.0%) corneas (P = 0.75). Surgeon-prepared tissue remained a significant risk for positive fungal cultures [relative risk (RR) of surgeon- versus eye-bank-prepared, 2.85; 95% CI (1.02-7.98)], whereas younger donors [RR per year of age, 0.96; 95% CI (0.93-1.00)] and accidental death donors [RR of accident versus disease, 3.71; 95% CI (1.36-10.13)] were at a greater risk for positive bacterial cultures. Fungal infection (Candida glabrata) developed in 1 (6.7%) of 15 recipients with a positive fungal culture, and no recipient infections occurred with positive bacterial culture. With one additional fungal keratitis (Candida albicans) and one bacterial endophthalmitis (E. coli) with no rim culture performed, a total of 2 of 1330 eyes (0.15%) developed fungal and 1/1330 eyes (0.08%) developed bacterial postkeratoplasty infections.

CONCLUSIONS

A longer preservation time was not associated with a higher rate of positive donor rim cultures. The overall rate of infection across the entire cohort was low.

Etiology and failure analysis of anterior lamellar keratoplasty

AIM

To analyze indications and reasons for failure of anterior lamellar keratoplasty (ALK).

METHODS

The clinical records were retrospectively reviewed. Main outcome measures included indications for ALK and reasons for failure of ALK.

RESULTS

A total of 434 patients (462 eyes) were treated with ALK at Qingdao Eye Hospital, Shandong Eye Institute from June 1, 2009 to May 31, 2016. The main indications were infectious keratitis (33.3%), keratoconus (23.6%), corneal dystrophy and degeneration (9.8%), Mooren's ulcer (8.4%), corneal neoplasm (7.8%), viral keratitis (6.5%) and regrafting (3.7%). Fungal keratitis accounted for 73.4% in the infectious keratitis cases. ALKs were failed in 36 patients, with the major causes being recurrence of primary diseases (63.9%). The leading causes of graft failure was Mooren's ulcer (36.1%), followed by infectious keratitis (30.6%). Recurrence of fungal keratitis accounted for 81.8% in the failed cases after ALK for infectious keratitis cases.

CONCLUSION

Infectious keratitis and keratoconus are the main indications for ALK, of which fungal keratitis was the major cause of corneal infections. Recurrence of primary disease is the main reason of graft failure after ALK, in which the main primary diseases associated with graft failure are Mooren's ulcer and fungal keratitis.

Early deep anterior lamellar keratoplasty for fungal keratitis poorly responsive to medical treatment

PurposeTo investigate the efficacy of early therapeutic deep anterior lamellar keratoplasty (DALK) in eradicating fungal keratitis that is poorly responsive to medical treatment.Patients and methodsTwenty-three eyes (23 patients) underwent early therapeutic DALK within 15 to 50 days from the onset of symptoms. The adopted eligibility criteria for early DALK included the following: active fungal keratitis affecting the optical zone with ulcer confined in the 6.00 mm central cornea; deeper than 150 μm but not exceeding 300 μm; and poorly responsive to medical treatment.ResultsThe big bubble technique was accomplished in 74% (17) of eyes, whereas manual dissection was performed in the remaining 26% (6) of eyes. Histopathological examination did not show any sign of fungal colonization in the peripheral and deep stromal lamellae in any case. All grafts were transparent postoperatively, and no recurrence of infection occurred. Median best spectacle corrected visual acuity significantly improved from 2.0 (1.0 interquartile range) logMAR to 0.1 (0.1 interquartile range) logMAR (P<0.01). The mean follow-up was 32±10 months. Neither episode of rejection nor graft failure was noted during the follow-up period.ConclusionEarly DALK could represent a safe therapeutic approach to eradicate fungal keratitis that affects the optical zone and is poorly responsive to medical treatment.

Altered Patterns of Fungal Keratitis at a London Ophthalmic Referral Hospital: An Eight-Year Retrospective Observational Study

PURPOSE

In previous studies of fungal keratitis (FK) from temperate countries, yeasts were the predominant isolates, with ocular surface disease (OSD) being the leading risk factor. Since the 2005-2006 outbreak of contact lens (CL)-associated Fusarium keratitis, there may have been a rise in CL-associated filamentary FK in the United Kingdom. This retrospective case series investigated the patterns of FK from 2007 to 2014. We compared these to 1994-2006 data from the same hospital.

DESIGN

Retrospective observational study.

METHODS

All cases of FK presenting to Moorfields Eye Hospital between 2007 and 2014 were identified. The definition of FK was either a fungal organism isolated by culture or fungal structures identified by light microscopy (LM) of scrape material, histopathology, or in vivo corneal confocal microscopy (IVCM). Main outcome measure was cases of FK per year.

RESULTS

A total of 112 patients had confirmed FK. Median age was 47.2 years. Between 2007 and 2014, there was an increase in annual numbers of FK (Poisson regression, P = .0001). FK was confirmed using various modalities: 79 (70.5%) by positive culture, 16 (14.3%) by LM, and 61 (54.5%) by IVCM. Seventy-eight patients (69.6%) were diagnosed with filamentary fungus alone, 28 (25%) with yeast alone, and 6 (5.4%) with mixed filamentary and yeast infections. This represents an increase in the proportion of filamentary fungal infections from the pre-2007 data. Filamentary fungal and yeast infections were associated with CL use and OSD, respectively.

CONCLUSIONS

The number of FK cases has increased. This increase is due to CL-associated filamentary FK. Clinicians should be aware of these changes, which warrant epidemiologic investigations to identify modifiable risk factors.

Therapeutic dilemma in fungal keratitis: administration of steroids for immune rejection early after keratoplasty

PURPOSE

To investigate the timing and dosage of topical corticosteroid use after keratoplasty for fungal keratitis, and to evaluate the results with regard to anterior segment inflammation, immune rejection, and fungal recurrence.

METHODS

This prospective observational study included a total of 244 patients (244 eyes) who underwent penetrating keratoplasty (PK, 118 patients) or lamellar keratoplasty (LK, 126 patients) for fungal keratitis at the Shandong Eye Hospital between January 2009 and April 2014. Topical administration of steroid eye drops was initiated at 1 week after surgery. Changes in ocular inflammation before and after steroid use, percentages of eyes with fungal recurrence and immune rejection, and the relationship between the timing of local administration of steroids and therapeutic anti-inflammatory effects after keratoplasty were evaluated. The follow-up period was 6 months.

RESULTS

Anterior segment inflammation was aggravated within 1 week after surgery, with ocular pain, photophobia, redness, and tearing, but was controlled at 7.51 ± 1.76 days after steroid use. Fungal keratitis recurred in three eyes (1.23 %) at 3 to 5 days after administration of corticosteroids, including two eyes receiving PK and one eye receiving LK. Recurrence was controlled with antifungal medications. Allograft rejection occurred in eight (6.78 %) of 118 patients treated by PK, but did not occur in patients treated by LK.

CONCLUSIONS

Initiating the use of topical corticosteroids in patients with fungal keratitis 1 week after keratoplasty can aid in rapid control of anterior segment inflammation and reduction of immune rejection, with no increase in the rate of fungal recurrence.

Effects of Lamellar Keratectomy and Intrastromal Injection of 0.2% Fluconazole on Fungal Keratitis

Purpose. To evaluate effects of lamellar keratectomy and intrastromal injection of 0.2% fluconazole (LKIIF) on fungal keratitis. Methods. Data for 54 eyes of consecutive patients with fungal keratitis treated with LKIIF were retrospectively analyzed. The lesions in these eyes did not heal or were aggravated after antifungal chemotherapy for 7 days. The maximum lesion diameters were ≤5 mm and maximum depth was not more than half of full corneal thickness. Cases were followed up for at least 90 days. Results. Forty-six eyes were cured (85.2%). The wound healing times were 3–16 days and were less than 7 days in 28 cases (51.9%). In cured eyes, uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) were both 20/250–20/20. The UCVA improved in 38 eyes and was unchanged in seven eyes. BCVA improved in 44 eyes and was unchanged in two eyes. When followed up for more than 90 days, 89% (41 of 46 eyes) showed improvement in UCVA and 11% were unchanged. Regarding BCVA, 98% improved and one eye was unchanged. No other complications were observed except neovascularization in one eye and thinner corneas. Conclusions. LKIIF was quick and effective for small fungal keratitis confined to half of the corneal thickness.

Lamellar keratoplasty treatment of fungal corneal ulcers with acellular porcine corneal stroma

The fundamental problem of corneal transplantation is a severe shortage of donor tissues worldwide, resulting in approximately 1.5 million new cases of blindness annually. To explore an alternative to donor corneas, we conducted a clinical study in which implanted acellular porcine corneal stromas (APCSs) replaced the pathologic anterior corneas in 47 patients who had experienced fungal corneal infections. Subsequently, we demonstrated the safety and efficacy of APCSs in human keratoplasty for a minimum follow-up period of 6 months, during which time no recurrence of infection was observed. All corneal ulcers healed with the return of neovascularization. In addition, our results indicated that epithelialization occurred in all APCS grafts except four grafts; for these four, the grafts dissolved to varying degrees. Furthermore, most porcine grafts (n = 41) gradually became transparent without rejection, and an improvement of more than two lines in best corrected visual acuity (BCVA) was achieved in 34 eyes (∼72%). Finally, no patients showed any severe adverse reaction or any significant change in postoperative systemic safety indicators. Thus, we concluded that APCS grafts are safe and efficacious during lamellar keratoplasty in treating corneal fungal ulcers and potentially for other clinical diseases.

Experimental study on cryotherapy for fungal corneal ulcer

Background

Fungal corneal ulcer is one of the major causes of visual impairment worldwide. Treatment of fungal corneal ulcer mainly depends on anti-fungal agents. In the current study, we developed an integrated combination therapy of cryotherapy and anti-fungal agents to facilitate effective treatment of fungal corneal ulcer.

Methods

Rabbit models of cornea infection were established using a combined method of intrastromal injection and keratoplasty. After treatment with cryotherapy and anti-fungal agents, scanning electron microscopy, transmission electron microscopy, and confocal microscopy were conducted to observe changes in microstructure in the rabbits. Periodic acid Schiff A and hematoxylin and eosin staining were used for detection of histological changes.

Results

Continuous scanning electron microscopy and transmission electron microscopy observations showed that cryothermal treatment inhibited growth of fungal mycelium by destroying fungal cellular structures. Typical cryotherapy was effective in curing fungal corneal ulcer. Different fungi showed different susceptibilities to treatment. The curative effect of Candida albicans was the best, while that of Aspergillus fumigates was the worst.

Conclusions

Our study provides a novel method of a combination of cryotherapy and anti-fungal agents for treatment of fungal corneal ulcer. This treatment could help facilitate the practice of fungal keratitis treatment in the future.

Electronic supplementary material

The online version of this article (doi:10.1186/s12886-015-0011-5) contains supplementary material, which is available to authorized users.

Deep anterior lamellar keratoplasty using irradiated acellular cornea with amniotic membrane transplantation for intractable ocular surface diseases

Purpose

To report the clinical outcomes of deep anterior lamellar keratoplasty (DALK) when sterile gamma-irradiated acellular corneal tissues (VisionGraft) are used in combination with amniotic membrane transplantation (AMT) for intractable ocular surface diseases.

Methods

The medical records of fifteen patients who had DALK with AMT were retrospectively reviewed. Indications for surgery included ocular burn, bacterial keratitis, herpes simplex virus keratitis, corneal opacity with Stevens-Johnson syndrome, Mooren's ulcer, idiopathic myxoid degeneration of corneal stroma, and recurrent band keratopathy. DALK was performed using partial-thickness acellular corneal tissue and a temporary amniotic membrane patch was added at the end of the operation.

Results

All cases that underwent DALK with AMT became epithelialized within 2 postoperative weeks. Twelve patients showed favorable outcomes without graft rejection, corneal opacification, or neovascularization. The other three grafts developed corneal opacification and neovascularization, and required additional penetrating keratoplasty (PK). Unlike the results of previous PKs, there were no graft rejections and the graft clarity was well-maintained in these three cases for at least 8 months after PK.

Conclusions

DALK using sterile acellular corneal tissues in combination with AMT may be a good therapeutic strategy for treating intractable ocular surface diseases because of lowered immune rejection, fibroblast activation, and facilitation of epithelialization. Furthermore, DALK can help stabilize the ocular surface, prolong graft survival, and may allow better outcomes when combined with subsequent PK.

Big bubble deep anterior lamellar keratoplasty for management of deep fungal keratitis

Objective. To evaluate the therapeutic effect of big bubble deep anterior lamellar keratoplasty (DALK) in patients with deep fungal keratitis. Methods.Consecutive patients who had DALK for deep fungal keratitis at Shandong Eye Hospital between July 2011 and December 2012 were included. In all patients, the infiltration depth was more than 4/5ths of the corneal thickness. DALK surgery was performed with bare Descemet membrane (DM) using the big bubble technique. Corrected distance visual acuity (CDVA), graft status, and intraoperative and postoperative complications were monitored. Results. Big bubble DALK was performed in 23 patients (23 eyes). Intraoperative perforation of the DM occurred in two eyes (8.7%) during stromal dissection. The patients received lamellar keratoplasty with an air bubble injected into the anterior chamber. Double anterior chamber formed in 3 eyes (13.0%). Mean CDVA of the patients without cataract, amblyopia, and fungal recurrence was improved from preoperative HM/20 cm−1.0 (LogMAR) to 0.23 ± 0.13 (LogMAR) at the last followup (P < 0.01). Fungal recurrence was found in two patients (8.7%). Corneal stromal graft rejection was noted in one patient (4.3%). Conclusions. DALK using the big bubble technique seems to be effective and safe in the treatment of deep fungal keratitis unresponsive to medication.

Corneal blindness and xenotransplantation

Approximately 39 million people are blind worldwide, with an estimated 285 million visually impaired. The developing world shoulders 90% of the world's blindness, with 80% of causative diseases being preventable or treatable. Blindness has a major detrimental impact on the patient, community, and healthcare spending. Corneal diseases are significant causes of blindness, affecting at least 4 million people worldwide. The prevalence of corneal disease varies between parts of the world. Trachoma, for instance, is the second leading cause of blindness in Africa, after cataracts, but is rarely found today in developed nations. When preventive strategies have failed, corneal transplantation is the most effective treatment for advanced corneal disease. The major surgical techniques for corneal transplantation include penetrating keratoplasty (PK), anterior lamellar keratoplasty, and endothelial keratoplasty (EK). Indications for corneal transplantation vary between countries, with Fuchs' dystrophy being the leading indication in the USA and keratoconus in Australia. With the exception of the USA, where EK will soon overtake PK as the most common surgical procedure, PK is the overwhelming procedure of choice. Success using corneal grafts in developing nations, such as Nepal, demonstrates the feasibility of corneal transplantation on a global scale. The number of suitable corneas from deceased human donors that becomes available will never be sufficient, and so research into various alternatives, for example stem cells, amniotic membrane transplantation, synthetic and biosynthetic corneas, and xenotransplantation, is progressing. While each of these has potential, we suggest that xenotransplantation holds the greatest potential for a corneal replacement. With the increasing availability of genetically engineered pigs, pig corneas may alleviate the global shortage of corneas in the near future.

Lamellar corneal transplantation

Penetrating keratoplasty (PK) has been the gold standard for the surgical treatment of most corneal pathologies; lamellar keratoplasty that only replaces the diseased corneal layers has recently evolved as an alternative, however. Innovations in surgical technique and instrumentation provide visual outcomes comparable to PK. We review the indications and outcomes of various techniques of anterior lamellar surgery developed to treat stromal disorders. Similarly, we discuss posterior lamellar keratoplasty techniques such as Descemet stripping automated endothelial keratoplasty and Descemet membrane endothelial keratoplasty. Posterior lamellar keratoplasty provides faster visual rehabilitation than PK in cases of Fuchs endothelial dystrophy and pseudophakic bullous keratopathy. In addition, for medically unresponsive infectious keratitis, therapeutic anterior lamellar keratoplasty yields similar graft survival to PK without an increased risk of disease recurrence.

Amniotic membrane transplantation: An option for ocular surface disorders

BACKGROUND

Ocular surface disorders (OSD) are challenging to treat. They can introduce serious morbidity and might even lead to visual loss. In such situations, keratoplasty remains the last option. Amniotic membrane transplantation (AMT) has been shown to be effective in the management of ocular surface pathologies. The aim of the study was to assess the efficacy of AMT for various indications of OSD.

MATERIALS AND METHODS

Experience of AMT in 65 patients with different OSD was evaluated. The aim of AMT was to achieve symptomatic relief, reduced inflammation, recurrence, and corneal haze; improve epithelization, stromal healing and visual acuity; and delay keratoplasty. Fresh amniotic membrane was used in all cases by a single surgeon. Follow-up and observations were done to evaluate success of achieving the goal.

RESULTS

Indications for AMT included primary and recurrent pterygium, various types of corneal ulcers (non-healing ulcer, descemetocele, corneal thinning and perforation), spheroidal degenerations, chemical burn and bullous keratopathy. The aim of AMT was different in different etiological indications. Postoperative follow-up was between 6 and 18 months. Success and complication rate were observed. Symptomatic relief (reduced pain and redness) was seen in patients with various corneal ulcers, chemical burn and bullous keratopathy. Improved epithelialization and stromal healing was noted in corneal ulcer cases. In spheroidal degenerations, keratectomy with AMT improved vision. Recurrence of pterygium was low (4.61%); graft failure in the form of graft rejection was seen in only 3.07% cases of acute keratitis. Corneal vascularization (4.61%) was present but not severe enough to hamper vision. Success in gaining intended effect was the most significant result with AMT.

CONCLUSION

AMT in various ocular surface pathologies shows success in achieving the goal of symptomatic relief, improved epithelialization, stromal healing and vision. Reduction in inflammation, corneal haze and recurrence of original disease is achieved with minimum complications.

Deep anterior lamellar keratoplasty using acellular corneal tissue for prevention of allograft rejection in high-risk corneas

PURPOSE

To determine whether deep anterior lamellar keratoplasty (DALK) using acellular glycerol-cryopreserved corneal tissue (GCCT) could prevent allograft rejection in high-risk corneas.

DESIGN

Prospective, randomized, comparative study.

METHODS

SETTINGS

The Eye Hospital, Wenzhou Medical College, Zhejiang, China.

STUDY POPULATION

All patients with herpes simplex virus keratitis, bacterial keratitis, fungal keratitis, or ocular burn, who were eligible as per study design, were invited to participate.

OBSERVATION PROCEDURES

According to randomized block design, all patients received either GCCT or fresh corneal tissue (FCT) during DALK. Best-corrected visual acuity (BCVA), slit-lamp microscopy, and in vivo confocal microscopy examinations at 1 week and 1, 3, 6, 12, and 24 months after surgery were analyzed. Kaplan-Meier survival analysis was used to evaluate graft survival rate.

MAIN OUTCOME MEASURES

Therapeutic success, 2-year rejection-free graft survival rate and 2-year graft survival rate, in vivo confocal microscopy results, BCVA, and endothelial cell density.

RESULTS

Postoperative BCVA of 20/40 or better at the last follow-up visit was achieved in 57.6% (19/33) of eyes in the GCCT group and in 54.8% (17/31) of the FCT group. No graft rejection occurred in the GCCT group, while in the FCT group 10 episodes of stromal rejection developed in 7 eyes. Overall, the rejection-free graft survival rate at 2 years was significantly higher in the GCCT group as compared with the FCT group (100.0%, 78.8% respectively, P = .006).

CONCLUSIONS

Deep anterior lamellar keratoplasty using acellular glycerol-preserved cornea could prevent allograft rejection and promote graft survival rate in high-risk corneas.

Association of HSV-1 antigen distribution in the cornea with clinical characteristics of herpetic stromal keratitis

PURPOSE

To investigate whether the clinical characteristics of stromal herpetic simplex keratitis (HSK) are associated with herpes simplex virus type 1 (HSV-1) antigens distribution in the pathologic cornea.

MATERIALS AND METHODS

Pathologic corneal buttons from 8 eyes were obtained during keratoplasty at the Shandong Eye Institute from 2006 to 2009. Immunohistochemical examination was performed to detect the distribution of HSV-1 antigens, including position, depth, and load in the cornea.

RESULTS

Each of the 8 pathologic corneal buttons was positive for HSV-1 antigen by immunohistochemical staining, and HSV-1 antigen was detected in the corneal stroma but not in the corneal epithelium or endothelium. Combined with the clinical characteristics, it was found that the distribution depth of HSV-1 antigen in the cornea was partly related to the disease course, and the load was related to the delay time for treatment. Furthermore, HSK could be effectively cured by deep anterior lamellar keratoplasty (DALK).

CONCLUSIONS

The distribution characteristics of HSV-1 in HSK corneal stroma supports the theory of HSV-1 latency in the cornea and guides the selection of DALK, rather than penetrating keratoplasty (PKP), for clinical stromal HSK treatment.

Use of Potassium Hydroxide, Giemsa and Calcofluor White Staining Techniques in the Microscopic Evaluation of Corneal Scrapings for Diagnosis of Fungal Keratitis

The aim of this study was to develop a quick and economical method for the diagnosis of fungal keratitis. Corneal scrapings were obtained from consecutive patients (n = 165) with clinically suspected fungal keratitis and were used for culture and to prepare two smears. Potassium hydroxide stain followed by calcofluor white stain was added to one smear and Giemsa stain followed by calcofluor white stain was added to the second. In comparison with the fungal culture results, the sensitivity of potassium hydroxide wet mounts was 81.0% and following the addition of calcofluor white was 96.6% in diagnosing fungal keratitis, whereas sensitivity using Giemsa stain was 39.7% and following the addition of calcofluor white was 98.3%. The Giemsa stain detected 23 cases of bacterial infection, of which six cases were mixed fungal and bacterial infections. Giemsa stain followed by calcofluor white was considered to be the better method for diagnosing fungal keratitis due to its high sensitivity combined with its ability to identify bacterial or mixed infections.

[Mycotic keratitis in an eye care hospital in Mexico City]

BACKGROUND

Some of the most common precipitating events for keratomycoses (fungal keratitis), include surgical trauma (after cornea transplantation), the use of contaminated contact lenses or alterations in lacrimal secretions. Diagnosis and treatment (to avoid loss of vision) for these type of infections are challenging.

OBJECTIVE

Retrospective review of the diagnosis, epidemiology, etiology and response to treatment in 219 patients with fungal keratitis in Mexico.

METHODS

We have studied the diagnosis, epidemiology, etiology and response to treatment in 219 patients from different states in the Mexican Republic in the Cornea Department at an Ophthalmology Hospital in Mexico D.F.

RESULTS

Trauma was the precipitating event in 77 patients (36%), of which 12 (5.4%) were due to surgical trauma; 152 patients (64.8%) did not report any prior trauma. There were 165 male (75.3%) and 54 female (24.6%) patients, with an average age of 46 years old. For clinical and visual treatment patients were treated with topical and oral antifungals and surgery. One or more surgeries were performed on a total of 81 patients (36.9%). A total of 62 patients (28.3%) received a corneal transplant, and 19 patients (8.7%) were subjected to conjunctival flap or scleral-conjunctival surgery.

CONCLUSIONS

In Mexico, keratomycoses affect mostly male patients in a 4:1 ratio over females. Fusarium solani was the most frequent agent of fungal keratitis in our study (37.2%), and the highest number of corneal ulcers and eviscerations (26%) was present in patients infected by Aspergillus. The best therapeutic responses were with combination of topical antifungals against dematiaceous fungi.

Anterior lamellar keratoplasty: 'Back to the Future'- a review

Newer forms of lamellar keratoplasty techniques have emerged in the last decade or so revolving around the concept of targeted replacement of diseased corneal layers. These include anterior lamellar keratoplasty (ALK) techniques that aim to selectively replace diseased corneal stroma and, endothelial keratoplasty techniques aiming to replaced damaged endothelium in endothelial disorders. ALK surgery has a distinct advantage over penetrating keratoplasty (PK) in that it minimizes unnecessary replacement of the unaffected healthy endothelial layer thereby almost eliminating the risk of endothelial rejection, a major cause of graft failure in PK. Overall it provides increased life expectancy to the graft and with advancements in the surgical technique and instrumentation for ALK, the visual outcomes are now comparable if not better to standard PK. There are several forms of ALK procedures that have evolved to cater to a wide range of stromal disorders. This article reviews the various emerging techniques of anterior lamellar surgery, its indications and visual outcomes, to emphasize the shift from PK to ALK for stromal disorders with a healthy endothelium.

Retracted: Roles of Adherence and Matrix Metalloproteinases in Growth Patterns of Fungal Pathogens in Cornea

PURPOSE

To investigate the roles of adherence and matrix metalloproteinases (MMPs) in growth patterns of major fungal pathogens in cornea.

METHODS

Ninety-six eyes in 96 rabbits were equally divided into four groups receiving inoculation of fungal conidia of Aspergillus fumigatus, Candida albicans, Fusarium solani, and Penicillium citreo-viride, respectively, to induce fungal keratitis. Corneas in each group were obtained at 2, 8, 16 hr, and 1, 2, 3, 5, and 8 days after inoculation and were subjected to scanning electron microscopy, histopathological examination, and gelatin zymography. Eight saline-inoculated eyes in another eight rabbits served as controls.

RESULTS

All eyes in the fungus-inoculated groups developed fungal keratitis. The binding of conidia to corneal epithelial basement membrane was initiated earlier in the A. fumigatus and C. albicans groups than in the F. solani and P. citreo-viride groups. Destruction of basement membrane began at 1 to 3 days. Histopathologically, infiltration of inflammatory cells was more evident in the A. fumigatus and C. albicans groups than the F. solani and P. citreo-viride groups at 3 days. The hyphae of A. fumigatus and C. albicans traversed the cornea in a plane perpendicular to the stromal lamellae, whereas the hyphae of F. solani and P. citreo-viride lay parallel to the corneal lamellae. MMP-9 and MMP-2 were found in all infected corneas. At 3 days, proteolysis was most active; the level of MMP-9 was higher in the A. fumigatus and C. albicans groups than in the F. solani and P. citreo-viride groups. There were positive correlations among the number of binding conidia, degree of inflammation, and level of MMP-9 (p < 0.05).

CONCLUSIONS

The adherence ability, chemotaxis to neutrophils, and MMP-9 expression level differ in eyes with different fungal pathogens, which may contribute to the different growth patterns of fungi in cornea.

Antifungal susceptibility for common pathogens of fungal keratitis in Shandong Province, China

PURPOSE

To analyze common pathogens of fungal keratitis and results of antifungal drug sensitivity test in Shandong Province, China and provide guidance for appropriate choice of antifungal drugs in clinic.

DESIGN

Retrospective, noncomparative study.

METHODS

The pathogens isolated from 674 fungal keratitis patients between January 1, 2001 and December 31, 2006 were cultured and identified in Shandong Eye Institute, of which some common strains were tested for sensitivity to antifungal drugs.

RESULTS

Fungi were positively cultured in 549 (81.5%) patients, in which the dominating pathogen was genus Fusarium (77.6%), with F. solani (37.3%), F. moniliforme (30.0%), and F. oxysporum (27.9%) being common species; Fusarium was mostly sensitive to natamycin, next to amphotericin B, and then to terbinafin. The second common pathogen was genus Aspergillus (10.8%), in which the main species were A. flavus (49.2%) and A. fumigatus (35.6%); Aspergillus was mostly sensitive to natamycin, next to terbinafin, and then to amphotericin B. Relatively, both Fusarium and Aspergillus were insensitive to ketoconazole, miconazole, itraconazole, fluconazole, and fluorocytosine.

CONCLUSIONS

Fusarium is the most common pathogen of fungal keratitis, followed by Aspergillus, in Shandong Province, China. Natamycin is still the first choice in the treatment of hyphomycetic keratitis. Fusarium and Aspergillus are also sensitive to amphotericin B and terbinafin. Early diagnosis and treatments are vital to good prognosis in the treatment of fungal keratitis.