Photoactivated Chromophore For Keratitis Research Articles

Evaluation of risk factors for treatment failure in canine patients undergoing photoactivated chromophore for keratitis – corneal cross-linking (PACK-CXL): a retrospective study using additive bayesian network analysis

BackgroundInfectious keratitis is a common ophthalmic condition in canine patients. Sequelae can include keratomalacia and corneal perforation, a vision threatening outcome. Photoactivated chromophore for keratitis – corneal cross-linking (PACK-CXL) is a non-surgical, adjunctive treatment method for infectious keratitis. The goal of this retrospective, multicenter study was to determine risk factors for treatment failure following PACK-CXL in canine patients suffering from suspected infectious keratitis. Medical records from four veterinary ophthalmology services were reviewed, and information related to patient demographics, ophthalmic findings, the PACK-CXL protocol used, and epithelialization time was collected and analyzed. Due to the potential for intervariable relationships, an additive Bayesian network (ABN) analysis was performed to evaluate these complex relationships.ResultsRecords for 671 eyes (668 dogs) were included in the analysis. Based on the ABN, in the population included here, patients who underwent an accelerated PACK-CXL protocol were less likely to experience treatment failure versus patients treated with a slow protocol. Mutual dependencies between exposure variables were identified by ABN, which would have been overlooked using classical regression. Corneal re-epithelialization time was shortened following PACK-CXL combined with topical medical therapy compared to PACK-CXL alone.ConclusionsNo risk factors associated with treatment failure were identified in the population included in the present study. Canine patients may benefit from the use of accelerated PACK-CXL protocols, especially when combined with topical antibiotics and anti-collagenolytic therapy. The reasons for this apparent positive impact on treatment outcome remain unclear.

Применение PACK-кросслинкинга при инфекционных кератитах и неэффективности местной консервативной терапии (клинические случаи)

Purpose. To present the results of PACK (Photo-Activated Chromophore for Keratitis) treatment of infectious keratitis with ineffective drug therapy using the example of clinical cases. Material and method. Under observation were 6 patients aged 28–55 years (5 men and 1 woman) with infectious keratitis (bacterial, viral-bacterial, acanthamoeba-bacterial, fungal). All of them received no effect within 5 weeks – 2.5 months. drug therapy (local and systemic) at the place of residence. All patients underwent PACK crosslinking. Results. Complete relief of the process was observed in all patients within 4–7 weeks (on average, after 39.2 days). As a result of treatment, in half of the patients (3 out of 6) visual acuity increased to 0.4–0.8, in 3 patients it did not change significantly after treatment and corresponded to light perception with the correct projection of light – 0.01–0.02, since the inflammatory process ended with severe corneal clouding. Conclusion. Corneal PACK crosslinking appears to be an effective and promising technique for the treatment of infectious keratitis resistant to ongoing drug therapy. In cases of the outcome of the infectious process with the formation of persistent and pronounced clouding (thorn) in such patients in the «cold» period after the arrest of the infectious process, keratoplasty with an optical purpose can be performed. Key words: infectious keratitis, drug therapy failure, PACK crosslinking, optic keratoplasty

Comparison between three different high fluence UVA levels in corneal collagen cross-linking for treatment of experimentally induced fungal keratitis in rabbits.

The aim of this study was to compare the efficacy of Photo-Activated Chromophore for Keratitis - Corneal Collagen Cross-linking (PACK-CXL) of three different total UVA fluence levels and topical voriconazole in treatment of fungal keratitis experimentally induced in rabbits. This is an interventional experimental study including both eyes of 16 rabbits (32 eyes). Fungal keratitis was induced by intrastromal injection of Fusarium Solani into the cornea. The rabbits were then divided into four groups (8 eyes for each) from which group A received Voriconazole eye drops and considered as control group. Group B, C, D received single PACK-CXL session with total fluence levels of 7.2, 10.0 and 15.0 J/cm2 for each respectively. Daily clinical examination was recorded and all corneas were removed for microbiology and histopathology on day ten. The mean clinical signs score eyes treated with high fluence PACK-CXL showed evident clinical improvement from fourth to tenth day of treatment. This improvement was equivalent to that of Voriconazole treatment. The results showed better improvement with increasing the UVA total fluence levels but this difference was not statistically significant (P < 0.05). Similarly, the median CFU/ml declined on increasing UVA fluence but with no statistically significant values. Histopathological examination revealed better improvement of inflammatory signs on higher fluence levels compared to lower ones. High intensity PACK-CXL (30 mW/cm2) was as effective as Voriconazole in the treatment of fungal keratitis in rabbits. Increasing the fluence of UVA was associated with slightly better clinical outcomes with no added risks. More clinical studies are needed to confirm these results.

Crosslinking and Fulguration in the Treatment of Acanthamoebic Keratitis

Purpose: to study the combined Photo-Activated Chromophore for Keratitis — Corneal Cross-Linking (PACK-CXL) in combination with fulguration of the infiltration zone in the treatment of medically refractive acanthamoebic keratitis.Patients and methods. The study included 9 patients (10 eyes) with medically refractive acanthamoebic keratitis. The diagnosis was confirmed by confocal microscopy data from a microbiological study of scraping of corneal tissue from the lesion site with Romanovsky-Giemsa stain. All patients underwent combined surgical treatment of PACK-CXL with pre-fulguration. Optical coherence tomography (OCT) of the anterior segment of the eye was also performed using an RTVue-100 apparatus (Optovue USA), determination of visual acuity, photographing before and after surgery.Results. In 6 cases (60 %), a positive effect was noted, relief of the symptoms of the disease and the formation of turbidity within a month after the procedure, as well as an increase in the maximum corrected visual acuity. According in vivo confocal microscopy, 6 months after the intervention, no signs of infection were detected. In 4 cases, the therapeutic effect was absent. Subsequently, 3 patients (3 eyes) underwent therapeutic keratoplasty. In one eye, the infectious process was stopped medically for 6 months.Conclusion. The combined PACK-CXL method together with fulguration can be effective and safe in the treatment of medically refractive acanthamoebic keratitis, allowing keratoplasty to be performed with an optical goal if necessary, after stopping the infection process in a distant period.

Effectiveness of adjuvant photoactivated chromophore corneal collagen cross-linking versus standard antimicrobial treatment for infectious keratitis: a systematic review protocol.

The objective of this review is to systematically examine the effectiveness of adjuvant photoactivated chromophore for keratitis - corneal collagen cross-linking (PACK-CXL) versus standard antimicrobial treatment alone for corneal healing in patients with infectious keratitis. Infectious keratitis is a major cause for corneal blindness globally. Broad-spectrum antimicrobial therapy is currently the standard treatment, but there is a growing need for alternative or adjuvant antimicrobial treatment, due to the emerging antimicrobial resistance, long treatment duration and cost of treatment. Photoactivated chromophore for keratitis - corneal collagen cross-linking has been increasingly used as an adjuvant treatment for infectious keratitis but high-quality evidence is limited. This review will consider studies that include patients with infectious keratitis, encompassing bacterial, fungal, acanthamoeba, viral, mixed or culture-negative presumed infectious keratitis cases. Patients who have a previous history of infectious keratitis before the study or those that had less than seven days' follow-up from the start of the treatment will be excluded. The electronic databases to be searched will include MEDLINE, Embase and Cochrane Central Register of Controlled Trials. Only English articles will be included. Titles, abstracts and full text of the relevant studies will be assessed by two independent reviewers. The extracted data will include specific details about the study, including authors and study title, year of publication, sample size, populations, and study methods. A meta-analysis will be performed for the included randomized controlled trials when there are sufficient similarities in the reporting of outcome measures. PROSPERO CRD42019131290.

Effect of Riboflavin/Rose Bengal-Mediated PACK-CXL on Acanthamoeba Trophozoites and Cysts in Vitro

ABSTRACTPurpose: To evaluate the antiamoebic properties of photo-activated chromophore for keratitis (PACK)–corneal cross-linking (CXL) (PACK-CXL), in combination with riboflavin (0.1 and 0.25%) or rose bengal (0.1 and 0.2%), for treatment of Acanthamoeba trophozoites and cysts.Materials and Methods: Cultures of Acanthamoeba castellanii were grown in a fluid medium at a concentration of 2.7 × 105 cell/ml. PACK-CXL was used on A. castellani cells in combination with either riboflavin (0.1 and 0.25%) or rose bengal (0.1 and 0.2%). Riboflavin-containing wells were irradiated with ultraviolet-A (UVA) light (365-nm wavelength). Rose bengal-containing wells were irradiated with green light (523-nm wavelength). A power density of 9 mW/cm2 for 10 min and total irradiation dose of 5.4 J/cm2 was used for both riboflavin and rose bengal. After UVA and green light irradiation, cell viabilities were evaluated, and percentage of dead cells calculated.Results: No significant amoebicidal activity was observed following PACK-CXL/riboflavin at either concentration. PACK-CXL/rose bengal, however, was observed to be highly effective in eradicating Acanthamoeba cells at either concentration, with no significant difference observed between the two concentrations. The percentage of dead cells was 63% following treatment at either rose bengal concentration.Conclusion: PACK-CXL with rose bengal demonstrated pronounced antiamoebic activity against A.castellanii. Further in vitro and in vivo studies are needed to confirm this finding.

Intérêt et applications du Cross-Linking du colagène cornéen en ophtalmologie vétérinaire

Corneal collagen cross-linking : interests and applications in veterinary ophthalmology. Corneal collagen cross-linking (CXL) is a photochemical process based on the production of free radicals by a chromophore (riboflavin) after activation by a UVA beam. Corneal effects are as follows : improvement of the corneal strength and of its resistance to enzymatic digestion, inactivation of in situ microbial germs and modulation of the corneal inflammatory response. Veterinary applications of this process are adapted from human ophthalmology and consist first in the treatment of confirmed or supposed corneal infections. PACK-CXL (Photo-Activated Chromophore for Keratitis – CXL) is a serious option for the treatment of corneal melts in dogs, cats and horses and can replace tectonic surgery. The second application is the treatment of bullous keratopathy in canine patients for which the CXL provides the symptomatic relief of the chronic corneal ulceration although corneal edema remains unchanged.