Variations in irradiation energy and rose bengal concentration for photodynamic antimicrobial therapy of fungal keratitis isolates.

The purpose is to assess the efficacy of rose bengal photodynamic antimicrobial therapy (PDAT) using different irradiation energy levels and photosensitizer concentrations for the inhibition of fungal keratitis isolates. Seven different fungi (Aspergillus fumigatus, Candida albicans, Curvularia lunata, Fusarium keratoplasticum, Fusarium solani, Paecilomyces variotii, and Pseudallescheria boydii) were isolated from patients with confirmed infectious keratitis. Experiments were performed in triplicate with suspensions of each fungus exposed to different PDAT parameters including a control, green light exposure of 5.4 J/cm2, 2.7 J/cm2 (continuous and pulsed), and 1.8 J/cm2 and rose bengal concentrations of 0.1%, 0.05%, and 0.01%. Plates were photographed 72 h after experimentation, and analysis was performed to assess fungal growth inhibition. PDAT using 5.4 J/cm2 of irradiation and 0.1% rose bengal completely inhibited growth of five of the seven fungal species. Candida albicans and Fusarium keratoplasticum were the most susceptible organisms, with growth inhibited with the lowest fluence and minimum rose bengal concentration. Fusarium solani, Pseudallescheria boydii, and Paecilomyces variotii were inhibited by lower light exposures and photosensitizer concentrations. Aspergillus fumigatus and Curvularia lunata were not inhibited by any PDAT parameters tested. Continuous and pulsed irradiation using 2.7 J/cm2 produced similar results. Rose bengal PDAT successfully inhibits the in vitro growth of five fungi known to cause infectious keratitis. Differences in growth inhibition of the various fungi to multiple PDAT parameters suggest that susceptibilities to PDAT are unique among fungal species. These findings support modifying PDAT parameters based on the infectious etiology.

Corneal collagen cross-linking for bacterial infectious keratitis.

BACKGROUND: Infectious keratitis is an infection of the cornea that can be caused by bacteria, viruses, fungi, protozoa, or parasites. It may be associated with ocular surgery, trauma, contact lens wear, or conditions that cause deficiency or loss of corneal sensation, or suppression of the immune system, such as diabetes, chronic use of topical steroids, or immunomodulatory therapies. Photoactivated chromophore for collagen cross-linking (PACK-CXL) of the cornea is a therapy that has been successful in treating eye conditions such as keratoconus and corneal ectasia. More recently, PACK-CXL has been explored as a treatment option for infectious keratitis. OBJECTIVES: To determine the comparative effectiveness and safety of PACK-CXL with standard therapy versus standard therapy alone for the treatment of bacterial keratitis. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2019, Issue 7); Ovid MEDLINE; Embase.com; PubMed; Latin American and Caribbean Health Science Information database (LILACS); ClinicalTrials.gov; and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). We did not use any date or language restrictions in the electronic search for trials. We last searched the electronic databases on 8 July 2019. SELECTION CRITERIA: We included randomized controlled trials (RCTs), quasi-RCTs, and controlled clinical trials (CCTs) of PACK-CXL for bacterial keratitis. We included quasi-RCTs and CCTs as we anticipated that there would not be many RCTs eligible for inclusion. DATA COLLECTION AND ANALYSIS: Two review authors working independently selected studies for inclusion in the review, assessed trials for risk of bias, and extracted data. The primary outcome was proportion of participants with complete healing at four to eight weeks. Secondary outcomes included visual acuity, morphology, adverse events, and treatment failure at four to eight weeks. MAIN RESULTS: We included three trials (two RCTs and one quasi-RCT) in this review for a total of 59 participants (59 eyes) with bacterial keratitis. Trials were all single-center and were conducted in Egypt, Iran, and Thailand between 2010 and 2014. It is very uncertain whether PACK-CXL with standard antibiotic therapy is more effective than standard antibiotic therapy alone for re-epithelialization and complete healing (risk ratio (RR) 1.53, 95% confidence interval (CI) 0.88 to 2.66; participants = 15). We judged the certainty of the evidence to be very low due to the small sample size and high risk of selection and performance bias. The high risk of selection bias reflects the overall review. Masking of participants was not possible for the surgical arm. No participant had a best-corrected visual acuity of 20/100 or better at eight weeks (very low certainty evidence). There is also no evidence that use of PACK-CXL with standard therapy results in fewer instances of treatment failure than standard therapy alone (RR 0.50, 95% CI 0.05 to 4.98; participants = 32). We judged the certainty of evidence to be low due to the small sample size and high risk of selection bias. There were no adverse events reported at 14 days (low certainty evidence). Data on other outcomes, such as visual acuity and morphological characteristics, could not be compared because of variable time points and specific metrics. AUTHORS' CONCLUSIONS: The current evidence on the effectiveness of PACK-CXL for bacterial keratitis is of low certainty and clinically heterogenous in regard to outcomes. There are five ongoing RCTs enrolling 1136 participants that may provide better answers in the next update of this review. Any future research should include subgroup analyses based on etiology. A core outcomes set would benefit healthcare decision-makers in comparing and understanding study data.

Chlorin e6 mediated photodynamic inactivation for multidrug resistant Pseudomonas aeruginosa keratitis in mice in vivo.

Following corneal epithelium scratches, mouse corneas were infected with the multidrug resistant (MDR) P. aeruginosa strain PA54. 24 hours later, 0% (for control group), 0.01%, 0.05% or 0.1% Chlorin e6 (Ce6), a second generation photosensitizer derived from chlorophyll, was combined with red light, for photodynamic inactivation (PDI). 1 hour or 2 days later, entire mouse eyes were enucleated and homogenized for counting colony forming units (CFU) of P. aeruginosa. For comparison, 0.1% Ce6 mediated PDI was started at 12 hours post infection, and 0.005% methylene blue mediated PDI 24 hours post infection. Clinical scores of corneal manifestation were recorded daily. Compared to the control, CFU 1 hour after PDI started 24 hours post infection in the 0.01% Ce6 and 0.05% Ce6 groups were significantly lower (more than one log10 reduction), the CFU 2 days post PDI higher in the 0.1% Ce6 group, clinical score lower in the 0.1% Ce6 group at 1 day post PDI. These findings suggest that PDI with Ce6 and red light has a transient efficacy in killing MDR-PA in vivo, and repetitive PDI treatments are required to fully resolve the infection. Before its clinical application, the paradoxical bacterial regrowth post PDI has to be further studied.

Collagen crosslinking in the management of advanced non-resolving microbial keratitis.

AIM: To evaluate the efficacy and safety of corneal collagen crosslinking (CXL) in the management of culture proven microbial keratitis. METHODS: 15 eyes of 15 patients of microbial keratitis were included in the study. Nine patients had bacterial keratitis and six had fungal keratitis. All patients underwent microbiological evaluation to identify the causative organism. The depth of the infiltrate was determined clinically with slit lamp and measured manually using anterior segment optical coherence tomography. Patients were treated with antibiotics/antifungals and those who did not respond to at least 2 weeks of topical medications underwent CXL as per the standard protocol. The same preoperative topical medications were continued post-CXL. All patients were followed up every third day and observed for signs of resolution of microbial keratitis. RESULTS: Six of nine patients with bacterial keratitis and three of six patients with fungal keratitis resolved following CXL treatment. Patients with deep stromal keratitis or endothelial plaque failed to resolve. All patients had resolution of pain on the first postoperative day. There was an appearance of or increase in hypopyon in seven patients. No intraoperative or postoperative complications were noticed. CONCLUSIONS: CXL appears to be an effective procedure in the management of superficial microbial keratitis. It can be used as an adjunctive treatment in the management of non-resolving microbial keratitis.

An overview of corneal collagen cross-linking (CXL).

Corneal collagen cross-linking (CXL) was first described over a decade ago and is now considered to be one of the most important surgical innovations of modern ophthalmology. Prior to its introduction, no interventions were available to arrest, or slow down ectatic disease progression, with corneal transplantation required in the majority of cases. Unlike earlier treatments of corneal ectasias that attempted to only improve the consequences of the disease, CXL aims to address the corneal biomechanical weakening itself. The long-term safety and efficacy of CXL have been established in several studies that have documented significant improvements in all outcome measures (visual acuity, spherical equivalent, astigmatism, and keratometric findings). The emerging combination of CXL with other interventions (termed 'CXL plus') optimizes the visual and topographic outcomes. This, along with the expansion of the techniques' indications for other clinical conditions, such as microbial keratitis, highlights the continuous improvement of the initial technique and confirms its wide acceptance. Overall, CXL has already demonstrated much promise and has several clinical indications, representing a clear example of recent advances in ocular therapy.

Treatment of fungal keratitis from Fusarium infection by corneal cross-linking.

PURPOSE: To evaluate the efficacy of corneal cross-linking (CXL) (riboflavin-UV-A) as a simple therapy in Fusarium keratitis. METHODS: Twenty-four rabbits were systemically anesthetized, and the stromata of their right corneas were inoculated with Fusarium solani [10(5) colony-forming units (CFU) per milliliter]. Rabbits were divided into 2 groups: one was treated with CXL 72 hours after infection and the other did not receive any treatment (control). All eyes in both the groups were examined before (days 0 and 3) and after (day 7) CXL treatment. The eyes were enucleated, and corneal buttons were sent for microbiological and histological examinations. RESULTS: All animals developed Fusarium keratitis; there was no statistically significant difference between groups before treatment (day 0, P = 0.397 and day 3, P = 0.702). After CXL treatment, the difference in clinical scores on day 7 between groups was statistically significant (P = 0.00); the CXL group showed significant lower clinical score. The CXL group had 22.45 ± 5.09 CFU/g compared with 42.5 ± 3.12 CFU/g in the control group; this difference was statistically significant (P = 0.01). In the 3 buttons of the control group, similar amounts of Fusarium hyphae and inflammatory cells were observed. In 2 of the 3 buttons analyzed from the CXL group, fewer Fusarium hyphae, inflammatory cells, and nonspecific stromal changes were observed compared with the control group. CONCLUSIONS: Treatment of fungal keratitis with CXL seems to be effective in decreasing the intensity and severity of infectious keratitis by F. solani. This therapy may be useful as a coadjuvant in the medical treatment of resistant infections.

Radiotherapy for canine chronic superficial keratitis using soft X-rays (15 kV).

OBJECTIVE: To evaluate the effect of soft X-ray therapy in the treatment of refractory chronic superficial keratitis (CSK). ANIMALS STUDIED: Thirteen dogs with severe CSK, that had been refractory to prior medical and/or surgical therapy were treated with soft X-ray therapy. PROCEDURES: Both corneas of each dog were irradiated with soft X-rays (15 kV), to a total dose of 30 Gy, administered as two fractions over 48-96 h. Treatment was carried out under deep sedation in all dogs. Three dogs were treated by superficial lamellar keratectomy 48 h prior to radiotherapy. Changes in the extent of corneal pigmentation, pigment density and corneal vascularization were documented using a semi-quantitative grading scheme, schematic drawings and clinical photographs. RESULTS: Only minor, transient adverse effects of treatment, such as photophobia, epiphora and blepharitis were noted. Overall the effect of soft X-rays on the course of the keratitis was superior when compared to the effect of Sr-90 irradiation that had been determined in a previous study. CONCLUSION: Soft X-ray irradiation combined with keratectomy is a safe and effective new treatment option for severe and advanced CSK with significant visual impairment due to corneal pathology.

Modulation of matrix metalloproteinases by ultraviolet radiation in the canine cornea.

PURPOSE: To determine whether ultraviolet (UV) radiation can modulate expression and regulation of matrix metalloproteinases (MMP) in the canine cornea and to examine the expression of MMPs in canine chronic superficial keratitis (CSK). METHODS: Immunohistochemistry for MMP-2 and MMP-9 was performed on samples of CSK. In vitro, canine corneal epithelial cell (CEC) and stromal cell cultures were exposed to UV-irradiation. Following 2, 8 or 24 h, cells were harvested. MMP expression was examined by zymography, and RT-PCR was used to examine expression of Slug and Snail. CEC cultures treated with an EGFR inhibitor or a p38 inhibitor were UV-exposed and harvested 24 h later to examine expression of MMPs, Slug and Snail. RESULTS: Canine CSK had increased immunopositivity for both MMP-2 and MMP-9 compared to normal canine corneas. In vitro, CEC and stromal cell cultures exposed to UV showed generally increased expression of MMP-2, -9, Slug, and Snail; this response was dose and time dependent. Inhibition of the EGFR pathway did not prevent increased expression of MMP-2, -9, Slug or Snail in UV-exposed CEC; however, p38 inhibition did attenuate UV induction. CONCLUSIONS: We have found increased expression of MMPs in clinical samples of CSK compared to normal corneas. In addition, we have shown that there is a temporal association and dose dependency between UV exposure and production of MMPs, Slug, and Snail. These findings suggest that overexpression of MMPs due to UV-exposure may be linked to changes in the cornea that allow an influx of inflammatory cells and vascularization.

[Treatment of keratitis superficialis chronica of the dog with strontium 90]. / Die Behandlung der Keratitis superficialis chronica des Hundes mit Strontium-90.

BACKGROUND: Corneal pannus is a disease which, if untreated, nearly always is progressive and may lead to blindness of the affected dog. A therapeutic standard is yet to be defined. Beta-ray irradiation with Sr-90 is often recommended on a casuistic basis, but systematic studies are sparse. The aim of the present study was to evaluate efficacy and to document side effects of radiotherapy with Sr-90. MATERIAL AND METHODS: 17 animals were treated. 13 of them received treatment of 15 Gy surface dose twice within 2 days with additional medical therapy with ciclosporin and prednisolon. Only the more affected eye was treated with radiation which was applied with an eye-applicator, the other eye served as control. Four animals with already advanced impairment of vision received keratectomy, afterwards radiation was applied on both sides. RESULTS: Medical treatment alone led to deterioration in vascularization and spread of pigmentation in eleven of 13 (85%) of the control-eyes, density of pigmentation increased in eight of 13 (62%). After radiation therapy, almost all animals showed a marked initial improvement. Even if progressive disease occurred later on, further worsening as it happened in the control-eyes could be stopped in nine resp. ten of 13 eyes (69% and 77%). All animals with keratectomy and radiotherapy regained and preserved adequate vision. Besides short-term blepharospasm, no side effects were recorded. CONCLUSION: Corneal pannus is responsive to radiation therapy with Sr-90 and long-term benefit can be achieved. Side effects are minimal. Optimal sequencing of therapy and dosage still have to be examined.

[Intravasal laser irradiation of autologous blood in the treatment of eye diseases]. / Intravazal'noe lazernoe obluchenie autokrovi v lechenii nekotorykh glaznykh zabolevanii.

Treatment of central nonexudative chorioretinal dystrophies, vascular opticopathies, keratitis and uveitis associated with disorders of immunity status is a pressing problem of ophthalmology. Intravascular laser exposure of the blood was used for the treatment of these conditions. ALOK-1 device for low-energy He-Ne intravenous irradiation of the blood was used. The authors analyze the results attained in 15 patients (24 eyes) with central nonexudative chorioretinal dystrophies and vascular opticopathies (group 1) and in 16 ones (20 eyes) with chronic relapsing keratitis and uveitis (group 2). A positive effect was attained in all the cases, manifesting in group 1 in improvement of vision acuity, widening of visual field, normalization of electrophysiological parameters and in group 2 in improvement of vision acuity, rapid resorption of corneal precipitate, reduced injection of the eyeball and opacities in the vitreous body, a more rapid corneal epithelialization, and normalization of blood and lacrimal immunograms. The attained effect may be explained by a complex neurotrophic and immunomodulating effect of laser. The method is sufficiently effective and simple, this permitting its use on an outpatient basis.