Efficacy of two chondroitin sulfate ophthalmic solutions in the therapy of spontaneous chronic corneal epithelial defects and ulcerative keratitis associated with bullous keratopathy in dogs

Oxidized chondroitin sulfate eye drops ameliorate the prognosis of fungal keratitis with anti-inflammatory and antifungal effects

Fungal keratitis (FK) is a refractory ophthalmic disease that can result in vision impairment and even blindness due to the severe fungal invasiveness and excessive inflammatory response. Therefore, antifungal treatment combined with local immunosuppressive therapy is regarded as the most effective strategy to improve the clinical outcome of FK. Oxidized polysaccharides with aldehyde groups possess obvious inhibitory activity towards microorganisms. Herein, we use chondroitin sulfate (CS), a recognized anti-inflammatory biopolysaccharide, to prepare oxidized chondroitin sulfate (OCS) via sodium periodate (NaIO₄) oxidation for the treatment of FK. The chemical structure of OCS was characterized by FTIR, ¹H NMR, and XPS, revealing that the O-dihydroxy in the D-glucuronic acid unit of CS was selectively broken by NaIO₄, forming active aldehyde groups. The introduction of aldehydes not only retains the anti-inflammatory activity but also confers OCS with antifungal property. In vitro antifungal experiments showed that OCS inhibits the growth, represses the biofilm formation and alters the membrane integrity of A. fumigatus. The toxicity of OCS was evaluated by cytotoxicity tests (CCK-8) and the Draize eye test in vitro and in vivo. qRT-PCR confirmed that OCS had similar anti-inflammatory activity as CS. In mice with A. fumigatus keratitis, OCS versus CS or PBS showed an excellent therapeutic effect, characterized by a lower corneal inflammation score, less fungal load, reduced neutrophil recruitment, and the downregulated expression of pro-inflammatory factors. Our findings demonstrate that OCS improves the prognosis of A. fumigatus keratitis in mice by inhibiting the growth of fungi, reducing the recruitment of neutrophils and inhibiting the inflammatory response. It provides innovative ideas for the development and application of OCS in medicine and biomaterials fields.

Cotton-tip debridement, scalpel blade debridement, and superficial grid keratotomy for treatment of spontaneous chronic corneal epithelial defects (SCCED): A retrospective evaluation of 308 cases

PURPOSE

To evaluate the clinical course and outcome of canine SCCEDs treated with a combination of cotton-tip debridement (CTD), scalpel blade debridement (SBD), and superficial grid keratotomy (SGK).

METHODS

Medical records of dogs diagnosed with SCCED and treated by the same diplomate (FJO) from 2011 to 2019 were reviewed. Age, breed, sex, affected eye, time of onset before treatment, previous procedures performed, time to healing, need for a second treatment, and complications were reported.

RESULTS

A total of 308 eyes (291 dogs) met the inclusion criteria and were included in the study. All dogs received the same treatment (CTD + SBD + SGK) and the same topical medication (tobramycin 0.3% solution and sodium chloride 5% ointment). All eyes healed. Mean age at presentation was 9 years and 6 months (114.4 ± SD 28.0 months), and Boxer was the most common breed (93/308; 30.2%). Mean corneal healing time was 11.5 days (±SD 6.6). Complications occurred in 15/308 (4.9%) eyes. The three main complications observed were infected epithelial ulcer, infected stromal ulcer, and melting corneal ulcer, and 7/15 (46.7%) of the complications were diagnosed in Boston Terrier. Healing occurred after one treatment in 299/308 (97.1%) eyes, and the remaining cases needed a second treatment.

CONCLUSIONS

CTD + SBD + SGK is an inexpensive and efficient treatment for SCCED in dogs. Boston Terrier may be at higher risk of developing complications following this procedure.

Case Reports for Topical Treatment of Corneal Ulcers with a New Matrix Therapy Agent or RGTA® in Dogs

Superficial corneal ulcers that fail to heal within a normal time period and are refractory to conventional therapy in dogs are common in veterinary practice. Different etiologies can lead to this result, including spontaneous chronic corneal epithelial defects (SCCEDs) and ulcerative keratitis associated with bullous keratopathy. Thus, there is an urgent need to find new therapeutic approaches such as matrix therapy replacement. To determine the efficacy of a new ophthalmic treatment (Clerapliq^®) for SCCEDs and ulcerative keratitis associated with bullous keratopathy, a total of 11 dogs referred to the clinic because of nonhealing erosive ulcers after a classic primary treatment were enrolled to get this new treatment. Dogs underwent ophthalmic exams and 7 dogs (10 eyes) were diagnosed with superficial ulceration and 4 dogs (5 eyes) with bullous keratopathy due to endothelial dystrophy/degeneration. They received eye drops of Clerapliq^® every 3 days until recovery. The results showed that the corneas with recurrences of the ulcers were resolved predominantly by using Clerapliq^® every 3 days in 83.3% of the cases during a period of treatment ranging between 6 to 35 days. Therefore, this new approach using matrix therapy regenerating technology in treating superficial ulcers and bullous keratopathy in dogs can be successfully considered as an adjunctive therapy.

The Effect of Long-Term Use of an Eyewash Solution on the Ocular Surface Mucin Layer

The use of eyewash solutions in Japan, especially in patients with allergic conjunctivitis and contact lens wearers, has been increasing. Our aim was to investigate how the use of preservative-free eyewash solution in healthy eyes for one month affects corneal safety and ocular surface mucin. We analyzed 42 eyes of 21 individuals (17 males, four females; mean age: 36.1 ± 7.4 years) without ocular allergies, dry eyes, or other ocular diseases through a prospective study. Eyes were randomized to a wash group (group one) and a nonwash follow up group (group two). We evaluated the dry eye-related quality-of-life score (DEQS), tear film breakup time (TBUT), fluorescein staining score, mRNA expression of MUC5AC and MUC16, MUC16 immunohistochemistry, and MUC5AC periodic acid Schiff (PAS) staining. There was a significant decrease in DEQS scores after one month of eyewash use (p < 0.05). There were no significant differences in other evaluation items that were analyzed (all p > 0.05). Furthermore, no significant differences were observed between group one and group two in all endpoints (all p > 0.05). The results suggest that one month use of a nonpreserved eyewash solution has no detrimental effects on the tear film and the ocular surface mucins.

Corneal Wound Healing Effects of Mesenchymal Stem Cell Secretome Delivered Within a Viscoelastic Gel Carrier

Severe corneal injuries often result in permanent vision loss and remain a clinical challenge. Human bone marrow-derived mesenchymal stem cells (MSCs) and their secreted factors (secretome) have been studied for their antiscarring, anti-inflammatory, and antiangiogeneic properties. We aimed to deliver lyophilized MSC secretome (MSC-S) within a viscoelastic gel composed of hyaluronic acid (HA) and chondroitin sulfate (CS) as a way to enhance corneal re-epithelialization and reduce complications after mechanical and chemical injuries of the cornea. We hypothesized that delivering MSC-S within HA/CS would have improved wound healing effects compared the with either MSC-S or HA/CS alone. The results showed that a once-daily application of MSC-S in HA/CS enhances epithelial cell proliferation and wound healing after injury to the cornea. It also reduced scar formation, neovascularization, and hemorrhage after alkaline corneal burns. We found that combining MSC-S and HA/CS increased the expression of CD44 receptors colocalized with HA, suggesting that the observed therapeutic effects between the MSC-S and HA/CS are in part mediated by CD44 receptor upregulation and activation by HA. The results from this study demonstrate a reproducible and efficient approach for delivering the MSC-S to the ocular surface for treatment of severe corneal injuries. Stem Cells Translational Medicine 2019;8:478-489.

Clinical trial of adjunctive autologous platelet-rich plasma treatment following diamond-burr debridement for spontaneous chronic corneal epithelial defects in dogs

OBJECTIVE To evaluate the effects of adjunctive treatment with autologous platelet-rich plasma (PRP) on corneal reepithelialization, vascularization, and fibrosis in dogs with spontaneous chronic corneal epithelial defects (SCCEDs). DESIGN Randomized, controlled, double-masked clinical trial. ANIMALS 40 client-owned dogs with uncomplicated SCCEDs. PROCEDURES All dogs were treated with diamond-burr epithelial debridement (DBD) of affected eyes, topical tobramycin solution and atropine sulfate ointment application, and Elizabethan collar placement for 4 weeks. Dogs were randomly assigned to topical ocular administration of autologous PRP (n = 20) or artificial tear solution (control group; 20) 4 times daily for 28 days. Recheck examinations were performed approximately 2 and 4 weeks after treatment began to evaluate SCCEDs for corneal reepithelialization, and semiquantitative corneal vascularization and corneal fibrosis scores were assigned according to affected corneal surface area. Results were compared between groups. RESULTS All dogs completed the study. The SCCEDs had completely reepithelialized in 11 (55%) control dogs and 12 (60%) PRP-treated dogs by the 2-week reevaluation, and in 15 (75%) control dogs and 18 (90%) PRP-treated dogs by the 4-week reevaluation. No significant differences were identified between groups in these proportions nor in mean differences from pretreatment scores for corneal vascularization and fibrosis. CONCLUSIONS AND CLINICAL RELEVANCE In this preliminary study involving dogs with uncomplicated SCCEDs, topical PRP administered as an adjunctive treatment following DBD had no significant effect on healing. A larger study is warranted to support or refute these findings and to determine the effects of adjunctive PRP treatment for dogs with complicated SCCEDs.

Phenotypic Characterization of Corneal Endothelial Dystrophy in German Shorthaired and Wirehaired Pointers Using In Vivo Advanced Corneal Imaging and Histopathology

PURPOSE

To evaluate corneal morphology using ultrasonic pachymetry (USP), Fourier-domain optical coherence tomography (FD-OCT), and in vivo confocal microscopy (IVCM) in 2 related canine breeds-German shorthaired pointers (GSHPs) and German wirehaired pointers (GWHPs)-with and without corneal endothelial dystrophy (CED). This condition is characterized by premature endothelial cell degeneration leading to concomitant corneal edema and is similar to Fuchs endothelial corneal dystrophy.

METHODS

Corneas of 10 CED-affected (4 GSHP and 6 GWHP) and 19 unaffected, age-matched (15 GSHP and 4 GWHP) dogs were examined using USP, FD-OCT, and IVCM. A 2-sample t test or Mann-Whitney rank-sum test was used to statistically compare parameters between both groups. Data are presented as mean ± SD or median (range).

RESULTS

Central corneal thickness determined using USP was significantly greater in CED-affected than in unaffected dogs at 1179 (953-1959) and 646 (497-737) μm, respectively (P < 0.001). Central epithelial thickness was found to be significantly decreased in CED-affected versus unaffected dogs at 47 ± 7.1 and 55 ± 7.1 μm, respectively (P = 0.011), using FD-OCT. With IVCM, corneal endothelial density was significantly less (P < 0.001) in 5 dogs with CED versus 19 unaffected controls at 499 ± 315 versus 1805 ± 298 cells/mm, respectively. CED-affected dogs exhibited endothelial pleomorphism and polymegethism, whereas CED-unaffected dogs had regular hexagonal arrangement of cells.

CONCLUSIONS

GSHPs and GWHPs with CED exhibit marked differences in corneal morphology when compared with age-matched control dogs. These 2 CED-affected breeds represent spontaneous, large animal models for human Fuchs endothelial corneal dystrophy.

Effects of topically applied heterologous serum on reepithelialization rate of superficial chronic corneal epithelial defects in dogs

OBJECTIVE To assess the effects of topical application of undiluted heterologous serum on time to corneal reepithelialization in dogs with superficial chronic corneal epithelial defects (SCCEDs). DESIGN Multicenter, randomized, double-masked, controlled clinical trial. ANIMALS 41 client-owned dogs. PROCEDURES After collection of baseline clinical and historical data, dogs were randomly assigned to receive topically applied undiluted heterologous serum (n = 22) or isotonic saline (0.9% NaCl) solution (19) along with tobramycin and atropine. Epithelial debridement (at all visits) and grid keratotomy (at visits 2, 3, and 4) of SCCEDs were performed. Ophthalmic examination including fluorescein application was performed once weekly for 4 weeks or until corneal reepithelialization. Clinicians and owners were masked to treatment group. RESULTS No differences in baseline data were detected between treatment groups. No difficulties with medication administration, noncompliance, or adverse reactions were noted. All SCCEDs in both groups healed by 4 weeks after treatment began. Median time to reepithelialization (2 weeks) was not significantly different between serum-treated and placebo-treated eyes. Irrespective of treatment group, median time to reepithelialization was not significantly different for Boxers versus non-Boxer breeds. Direct correlations were detected between time to reepithelialization and vascularization score at study entry, vascularization score at time of reepithelialization, and ulcer area at study entry in both groups. Time to reepithelialization was not correlated with age, sex, or duration of signs in either group. CONCLUSIONS AND CLINICAL RELEVANCE Topical application of undiluted heterologous serum was well tolerated by dogs with SCCEDs but, as an adjunct to standard treatment, did not reduce time to corneal reepithelialization.

Effect of bandage contact lens wear and postoperative medical therapies on corneal healing rate after diamond burr debridement in dogs

PURPOSE

To determine the effect of bandage contact lens wear and type of post-operative medical treatment on corneal healing rates in dogs after diamond burr debridement.

ANIMALS STUDIED

237 client-owned dogs.

PROCEDURES

Canine patients having undergone diamond burr debridement (DBD) for treatment of spontaneous chronic corneal epithelial defects (SCCEDs) were included. Patients were put into 1 of 12 different groups based on type of postoperative medical regimen and whether a bandage contact lens (BCL) was utilized. Each dog was examined on a routine basis until the cornea was fluorescein negative. Data points collected included age, sex, breed, diabetic status, eye affected, Schirmer tear test 1, rebound tonometry, type and frequency of topical antibiotic, use of topical sodium chloride, use and retention of BCL, and days until healed.

RESULTS

A total of 237 dogs, each contributing one eye to the study, underwent DBD for SCCEDs. All eyes treated had estimated median ± standard error (SE) days to heal of 9.37 ± 0.42 days. When sodium chloride and BCL were utilized, ofloxacin had a significantly shorter median healing time when compared to oxytetracycline (adjusted P = 0.0158) and tobramycin (adjusted P = 0.0261). BCL use significantly improved healing times (P = 0.0002). Overall BCL retention rate was 62.02% (80 of 129). PureVision lenses were retained more often compared to Acrivet lenses (P < 0.0001). Overall, BCL retention significantly improved healing rates (P = <0.0001).

CONCLUSIONS

Postdebridement antibiotic type or use of sodium chloride ointment had minor effects on healing rates. Bandage contact lens use and retention significantly improves healing times.

Effect of corneal contact lens wear on healing time and comfort post LGK for treatment of SCCEDs in boxers

PURPOSE

To determine whether dogs with spontaneous chronic corneal epithelial defects (SCCEDs) would heal faster and with an improved comfort score following linear grid keratotomy (LGK) combined with corneal contact lens (Acrivet(™) ) wear when compared to dogs having the LGK procedure alone.

STUDY DESIGN

Prospective study.

METHODS

Twenty-seven boxer dogs (27 eyes) diagnosed with a SCCEDs were enrolled in the study. A LGK was performed on all dogs under dexmedetomidine and butorphanol sedation. Fourteen eyes were randomly assigned to receive a corneal contact lens. The dogs were evaluated typically at 7, 10, and 14 days or until the ulceration was healed. Client surveys were completed by the owners to subjectively assess comfort level and contact lens retention. Statistical analyses were performed utilizing generalized linear models and survival analysis with the Wilcoxon-Gehan test to evaluate group differences.

RESULTS

All ulcers healed after the LGK procedure. Dogs with bandage contact lenses had a statistically significant (P = 0.035) decrease in median healing time (7 days (95% CI [7,9]) compared to those without contact lenses (10 days (95% CI [7,12])). There was no difference in subjective comfort score between treatment groups. Early contact loss occurred in 28.6% (95% CI [8.4%, 58.1%]) of dogs. All of the Acrivet(™) ruler corneal measurements agreed to within 1 mm (95% CI [87.2%, 100%]) of the Jameson caliper measurements of horizontal corneal diameter.

CONCLUSIONS

The use of corneal bandage contact lenses significantly decreased median healing time although there was no effect on subjective comfort score. The Acrivet(™) ruler measurements were accurate in determining corneal diameter and therefore contact lens size.

RGTA-based matrix therapy in severe experimental corneal lesions: safety and efficacy studies

Corneal alteration potentially leading to ulceration remains a major health concern in ocular surface diseases. A treatment that would improve both the quality and speed of healing and control the inflammation would be of great interest. Regenerating agents (RGTAs) have been shown to stimulate wound healing and modulate undesired fibrosis in various in vivo systems. We investigated the effects of RGTA-OTR4120(®) in a rabbit corneal model in order to assess its potential use in ocular surface diseases. First, we assessed its safety for 7 and 28 days using the Draize test criteria in healthy rabbit eyes; then, we investigated the effect of a single dose (50μl, 5μg) in an alkali-burned cornea model. Daily follow-up of clinical signs of healing was scored, and histology was performed at D7. RGTA was well tolerated; no signs of ocular irritation were observed. In the corneal alkali-burn model, non-RGTA-treated eyes showed inflammatory clinical signs, and histology confirmed a loss of superficial corneal layers with epithelial disorganization, neovascularization and infiltration of inflammatory cells. When compared to NaCl control, RGTA treatment appeared effective in reducing clinical signs of inflammation, enhancing re-epithelialization, and improving histological patterns: edema, fibrosis, neovascularization and inflammation. Three to four layers of epithelial cells were already organized, stroma was virtually unvascularized and keratocytes well implanted in parallel collagen fibers with an overall reorganization similar to normal cornea. RGTA appears to be a promising agent for controlling ocular surface inflammation and promoting corneal healing and was well tolerated. This study offers preclinical information and supports the findings of other (compassionate or pilot) studies conducted in patients with various ocular surface diseases.

Severe, unilateral, unresponsive keratoconjunctivitis sicca in 16 juvenile Yorkshire Terriers

OBJECTIVE

To present ophthalmic findings, clinical data, and treatment outcomes of 16 juvenile Yorkshire Terriers with severe unilateral keratoconjunctivitis sicca.

RESULTS

Each of the 16 dogs exhibited extreme unilateral dryness associated with blepharospasm, mucoid discharge, and corneal vascularization. Ages of affected dogs at presentation ranged from 5 months to 4 years. Mean Schirmer tear test (STT) result for affected eyes was 1 mm/min. Topical application of 0.2% cyclosporine to the affected eye was not associated with improvement in STT values in any dog. Clinical signs subjectively improved with topical application of 20% chondroitin sulfate ophthalmic solution in some dogs, and transposition of the parotid duct was performed in three dogs. Histopathologic examination in one dog failed to show evidence of orbital lacrimal gland tissue. Clinical signs, age of presentation, disease severity, and lack of response to treatment are consistent with breed-related unilateral aplasia or hypoplasia of the lacrimal gland.

CONCLUSION

Lacrimal gland aplasia or hypoplasia should be considered in young dogs with severe unilateral ocular dryness, especially female Yorkshire Terriers.