Mesenchymal stem cell-based adjunctive therapy for Pseudomonas aeruginosa-induced keratitis: A proof-of-concept in-vitro study

PURPOSE

Pseudomonas aeruginosa-induced keratitis is one of the most severe and challenging forms of corneal infection, owing to its associated intense inflammatory reactions leading to corneal necrosis and dense corneal scar with loss of vision. Since mesenchymal stem cells (MSCs) are reported to possess antimicrobial and immunomodulatory properties, they can be tested as an adjuvant treatment along with the antibiotics which are the current standard of care. This study aims to investigate the anti-bacterial and immunomodulatory roles of human bone marrow MSC-derived conditioned medium (MSC-CM) in P. aeruginosa-infected human corneal epithelial cells (HCECs) in vitro.

METHODS

The effect of MSC-CM on the growth of clinical isolates of P. aeruginosa was evaluated by colony-forming unit assay. The expression of inflammatory cytokines (IL-6 and TNF-α) and an antimicrobial peptide (Lipocalin 2) in lipopolysaccharide-treated MSCs and HCECs was analyzed through ELISA. Corneal epithelial repair following infection with P. aeruginosa was studied through scratch assay.

RESULTS

Compared to control (P. aeruginosa (5*105) incubated in DMEM (1 ml) at 37 °C for 16 h), MSC-CM significantly: i) inhibits the growth of P. aeruginosa (159*109 vs. 104*109 CFU/ml), ii) accelerates corneal epithelial repair following infection with P. aeruginosa (9% vs. 24% closure of the wounded area after 12 h of infection), and iii) downregulates the lipopolysaccharide-induced expression of IL-6, TNF-α and Lipocalin 2 in HCECs. A combination of MSC-CM with an antibiotic, Ciprofloxacin moderately regulated the expression of IL-6, TNF-α, and Lipocalin 2.

CONCLUSION

MSC-CM holds promise as an adjunctive therapeutic approach for P. aeruginosa-induced corneal epithelial damage.

Preliminary observations on tear film interferometry performed in horses

This retrospective study evaluated tear film (TF) interferometry on horses examined in Northern Italy in 2019-2021. The objectives were to evaluate horses affected by keratitis, and to describe TF values in horses with no evidence of ocular disease. All horses received a complete ophthalmic examination and were examined with the Ocular Surface Analyser, Veterinary-setting, prior to eye manipulation, staining and sample collection. Eighteen horses with no evidence of ocular disease were included in the comparison group. Additionally, 46 horses displaying signs of keratitis (neovascularization, corneal opacities, ulceration, epithelial and subepithelial infiltrates) were evaluated. These horses were divided into presumed non-infectious and infectious or presumed infectious keratitis groups (one with proven bacterial origin, and the others with diagnosed or presumptive keratomycosis) with the former including immune-mediated keratitis. From the observations of TF interferometry in the comparison population the authors concluded that for non-invasive break-up time (NIBUT), the estimated preliminary reference interval was 10.4-31.2s, and for tear meniscus height (TMH), it was 0.215-0.457mm. Moreover, within the keratitis population, from an interferometric point of view punctate lesions of the ocular surface were present in all cases of active diagnosed or presumptive subepithelial keratomycosis but not in any of the non-infectious cases, either non-ulcerative or ulcerative. Limitations of the study include a relatively low number of horses examined and the fact that the diagnosis of infectious keratitis was presumptive and based on clinical improvement after treatment in some cases. To the authors' knowledge, this is the first report of TF interferometry performed in horses.

Insights into mustard gas keratopathy- characterizing corneal layer-specific changes in mice exposed to nitrogen mustard

Exposure to mustard agents, such as sulfur mustard (SM) and nitrogen mustard (NM), often results in ocular surface damage. This can lead to the emergence of various corneal disorders that are collectively referred to as mustard gas keratopathy (MGK). In this study, we aimed to develop a mouse model of MGK by using ocular NM exposure, and describe the subsequent structural changes analyzed across the different layers of the cornea. A 3 μL solution of 0.25 mg/mL or 5 mg/mL NM was applied to the center of the cornea via a 2-mm filter paper for 5 min. Mice were evaluated prior to and after exposure on days 1, 3, 7, 14, and 28 for 4 weeks using slit lamp examination with fluorescein staining. Anterior segment optical coherence tomography (AS-OCT) and in vivo confocal microscopy (IVCM) tracked changes in the epithelium, stroma, and endothelium of the cornea. Histologic evaluation was used to examine corneal cross-sections collected at the completion of follow-up. Following exposure, mice experienced central corneal epithelial erosion and thinning, accompanied by a decreased number of nerve branches in the subbasal plexus and increased activated keratocytes in the stroma in both dosages. The epithelium was recovered by day 3 in the low dose group, followed by exacerbated punctuate erosions alongside persistent corneal edema that arose and continued onward to four weeks post-exposure. The high dose group showed persistent epitheliopathy throughout the study. The endothelial cell density was reduced, more prominent in the high dose group, early after NM exposure, which persisted until the end of follow-up, along with increased polymegethism and pleomorphism. Microstructural changes in the central cornea at 4 weeks post-exposure included dysmorphic basal epithelial cells and reduced epithelial thickness, and in the limbal cornea included decreased cellular layers. We present a mouse model of MGK using NM that successfully replicates ocular injury caused by SM in humans who have been exposed to mustard gas.

Implementation of the Corneal Sweep Test in the Diagnosis of Recurrent Corneal Erosion: A 2-Year Retrospective Study

PURPOSE

The purpose of this study was to evaluate the incidence and epidemiology of recurrent corneal erosion within a clinical population using standard diagnostic techniques and a new technique called the corneal sweep test (CST).

METHODS

A retrospective chart review was conducted on 58 eyes of 51 patients with the diagnosis of recurrent corneal erosion from July 2018 to June 2020. All underwent a thorough history and physical examination. The CST was performed as a confirmatory test and on any patient who lacked visible corneal pathology.

RESULTS

The CST was necessary on 49 of the 58 eyes to help confirm the diagnosis of a corneal erosion. Among them, 34 had an occult corneal erosion, which is defined as having a normal-appearing cornea on slitlamp examination but found to have loose corneal epithelium with the CST. Clear corneal cataract surgery (28 eyes, 48.2%) was the most common presumed mechanism of injury, with 20 (71.4%) developing symptoms only after cataract surgery. All 20 eyes had an erosion located directly over a clear corneal cataract incision.

CONCLUSIONS

The CST is a new and effective technique to help diagnose corneal erosions in the absence of visible corneal findings. Clear corneal cataract surgery is an under-recognized but important risk factor to consider because the incision can be the source for an erosion. Using the CST could lead to a paradigm shift in the way clinicians approach RCEs and patients with a persistent ocular pain syndrome.

A deep learning approach in diagnosing fungal keratitis based on corneal photographs

Fungal keratitis (FK) is the most devastating and vision-threatening microbial keratitis, but clinical diagnosis a great challenge. This study aimed to develop and verify a deep learning (DL)-based corneal photograph model for diagnosing FK. Corneal photos of laboratory-confirmed microbial keratitis were consecutively collected from a single referral center. A DL framework with DenseNet architecture was used to automatically recognize FK from the photo. The diagnoses of FK via corneal photograph for comparing DL-based models were made in the Expert and NCS-Oph group through a majority decision of three non-corneal specialty ophthalmologist and three corneal specialists, respectively. The average percentage of sensitivity, specificity, positive predictive value, and negative predictive value was approximately 71, 68, 60, and 78. The sensitivity was higher than that of the NCS-Oph (52%, P < .01), whereas the specificity was lower than that of the NCS-Oph (83%, P < .01). The average accuracy of around 70% was comparable with that of the NCS-Oph. Therefore, the sensitive DL-based diagnostic model is a promising tool for improving first-line medical care at rural area in early identification of FK.

Comparison of two methods for obtaining and transporting corneal samples in suspected infectious keratitis

BACKGROUND AND PURPOSE

The purpose of this study is to compare two alternative methods of collecting and transporting media for the diagnosis of corneal ulcers, as not all clinical settings have conventional culture materials and transport media available.

METHODS

In this open-label, prospective, comparative, and randomized study, patients with clinical suspicion of infectious keratitis with high risk of loss of vision had corneal specimens collected using two methods and transport media: Eswab scraping with Amies transport medium and 23-gauge needle scraping in BACTEC Peds broth. The order of each collection method was randomized. The samples were processed by standard methods, comparing the positivity frequencies for both by parametric and nonparametric tests, according to normality criteria.

RESULTS

Corneal infiltrates from 40 eyes of 40 patients were analyzed. Culture positivity rate was 50% for Eswab and 35% for 23-gauge needle (P=0.258). The overall growth rate of the two methods combined was not higher than with the swab alone. The results obtained with a swab were not influenced by the collection sequence (P=0.112); however, the positivity rate was significantly higher when the sample taken with the needle was performed first (P=0.046).

CONCLUSIONS

The single sample Eswab method of collection and transportation for the diagnosis of high risk corneal ulcers is a valid alternative and can be used in cases in which, for various reasons, there is no access to the full set of traditional culture materials.

Corneal melt secondary to eosinophilic granulomatosis with polyangiitis

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare antineutrophil cytoplasmic antibody-associated vasculitis that can affect any organ system. It is most often characterised by chronic airway inflammation along with prominent peripheral blood eosinophilia, although the disease can affect the cardiovascular, gastrointestinal, renal or central nervous systems. Ocular manifestations are uncommon and when they do occur, are varied in their clinical presentations. To the best of our knowledge, this is the first case of corneal melt secondary to EGPA to have been reported.

Clinical course and risk factors of recurrent corneal erosion: Observational study

Recurrent corneal erosion (RCE) is a common disorder causing ocular pain, tearing, photophobia, and visual impairments. Various factors such as ocular trauma, ocular surgery, corneal dystrophy, contact lens wear, and diabetes mellitus (DM) can cause RCE. The purpose of this study was to determine the causative factors and clinical course of RCE.We retrospectively examined 21 eyes of 21 patients with RCE and investigated the patients' background, type of treatments, and clinical course after the treatments. All patients were treated with eye drops, ocular lubrication, or contact lens bandage for the RCE.Among the 21 patients with RCE, 9 were caused by trauma (Trauma group), 8 by DM (DM group), 1 by bacterial corneal ulcer, 1 by lagophthalmus and bacterial corneal ulcer, 1 by bandkeratopathy, and 1 by eyelid tumor (one eye). The mean age of the patients was 57.8 years with a range 34-91 years. The mean duration from the trauma to the onset of RCE was 5.2 ± 5.0 months (mean ± SD). The time required for a complete recovery of RCE was longer in the DM group (10.3 ± 3.1 weeks) than in the Trauma group (2.7 ± 1.1 weeks, P < .01). The presence of DM was significantly associated with the recovery duration of RCE (r = 0.72; P < .01). Multivariate analyses showed that the recovery duration of RCE was associated with the presence of DM (odds ratio = 139.8, P = .04). On the other hand, the type of treatments had no effect on the recovery duration of RCE.These findings suggest that trauma and DM are important causes of RCE. Wound recovery after RCE may be delayed in patients with DM.

Repeated Melting of Corneal Grafts in a Patient with Rheumatoid Arthritis and Sjögren's Syndrome

We present a case of corneal melting in a patient with severe rheumatoid arthritis and Sjögren's syndrome. The melting appeared in the area of a bacterial corneal ulcer that healed after treatment with antibiotics. No signs of scleritis were present. Repeated melting of two corneal grafts was seen after surgery.

Plasma rich in growth factors for the treatment of rapidly progressing refractory corneal melting due to erlotinib in nonsmall cell lung cancer

RATIONALE

Erlotinib, an antineoplastic agent, is indicated for the treatment of patients with advanced nonsmall cell lung cancer. Most common adverse events are manageable, although more severe ones require dose reduction or discontinuation of erlotinib treatment.

PATIENT CONCERNS

We present a case of severe corneal ulcer treated with autologous plasma rich in growth factors.

DIAGNOSES

A 76-year-old woman with stage IVB (cT2a N0 M1c) lung cancer under erlotinib treatment presented with rapidly progressing corneal ulcer. Evolution was torpid and refractory to conventional treatment.

INTERVENTIONS

Surgical options were dismissed because of the poor performance status of the patient. Despite temporary discontinuation of erlotinib treatment, the corneal ulcer continued to worsen with peripheral corneal neovascularization, stromal thinning, corneal edema, and profuse inflammation of the ocular surface.

OUTCOMES

Treatment with autologous plasma rich in growth factors prevented an imminent corneal perforation and improved the corneal ulcer for over a year of follow-up.

LESSONS

Considering the poor results of conventional treatment, both medical and surgical, management of the inflammation of the ocular surface together with the stimulation of the healing processes through regenerative therapy such as PRGF, can be an option worth considering in these cases.

Degeneration and Regeneration of Subbasal Corneal Nerves after Infectious Keratitis: A Longitudinal In Vivo Confocal Microscopy Study

PURPOSE

To investigate the longitudinal alterations of subbasal corneal nerves in patients with infectious keratitis (IK) during the acute phase, cessation of treatment, and the recovery phase by in vivo confocal microscopy (IVCM).

DESIGN

Prospective, longitudinal, case-control, single-center study.

PARTICIPANTS

Fifty-six eyes of 56 patients with the diagnosis of bacterial (n=28), fungal (n=15), or Acanthamoeba (n=13) keratitis were included in the study. Thirty eyes of 30 normal volunteers constituted the control group.

METHODS

Corneal sensation and serial IVCM of the central cornea were performed prospectively using the Heidelberg Retina Tomograph 3/Rostock Cornea Module (Heidelberg Engineering, Heidelberg, Germany). The IVCM images were assessed at 3 time points: at the acute phase (first visit to the cornea service), at cessation of antimicrobial treatment, and up to 6 months after the resolution of infection.

MAIN OUTCOME MEASURES

Total nerve number and length, main nerve trunks, branching, and corneal sensation were assessed during the follow-up period.

RESULTS

Corneal nerves were reduced significantly during the acute phase in eyes with IK compared with controls across all subgroups, with total nerve length of 5.47±0.69 mm/mm2 versus 20.59±1.06 mm/mm2 (P<0.0001). At the cessation of treatment, corneal nerves in patients with IK had regenerated, including total nerve length (8.49±0.94 mm/mm2; P=0.02) and nerve branch length (4.80±0.37 mm/mm2; P=0.005). During the recovery phase, after resolution of infection, corneal nerves regenerated further, including total nerve length (12.13±1.97 mm/mm2; P=0.005), main nerve trunk length (5.80±1.00 mm/mm2; P=0.01), and nerve branch length (6.33±0.76 mm/mm2; P=0.003) as compared with the acute phase, but were still significantly lower when compared with controls (P<0.05 for all parameters). Corneal degeneration and regeneration correlated with corneal sensation (r=0.47; P=0.0009).

CONCLUSIONS

Patients with IK who sustain profound loss of corneal nerves during the acute phase of infection demonstrate increased corneal nerve density during the first 6 months after the resolution of infection. However, despite significant nerve regeneration, corneal nerve density does not recover fully and remains low compared to controls. By providing an objective methodology to monitor corneal re-innervation, IVCM adds potentially important findings that may have implications for clinical management and surgical planning.

Perforating corneal injury in rat and pentadecapeptide BPC 157

Based on its healing effects in various tissues, we hypothesized that the stable gastric pentadecapeptide BPC 157 heals corneal ulcerations in rats and effects corneal transparency. We made a penetrant linear 2-mm incision in the paralimbal region of the left cornea at the 5 o'clock position with a 20-gauge MVR incision knife at 45° under an operating microscope. Medication was BPC 157 (2 pg/mL, 2 ng/mL, and 2 μg/mL distilled water, two eye drops/left rat eye) immediately after injury induction and then every 8 h up to 120 h; controls received an equal volume of distilled water. In contrast to the poor healing response in controls, BPC 157 significantly accelerated the healing process in 2 μg and 2 ng BPC 157-treated eyes, starting 24 h after the injury, and the fluorescein and Seidel tests became negative. The epithelial defects were completely healed at 72 h (2 μg BPC 157-treated group) and at 96 h (2 ng BPC 157-treated group) after injury. Aqueous cells were absent at 96 h and 120 h after injury in the 2 μg and 2 ng BPC 157-treated groups, respectively. In conclusion, BPC 157 effects the rapid regaining of corneal transparency. Whereas controls developed new vessels that grew from the limbus to the penetrated area, BPC 157-treated rats generally had no new vessels, and those that did form in the limbus did not make contact with the penetrated area. Thus, BPC 157 eye drops successfully close perforating corneal incisions in rats.

Keratitis due to Fusarium langsethiae: clinical profile, molecular identification, and susceptibility to antifungals

We report a case of keratitis due to Fusarium langsethiae in a 56-year-old man. The patient presented with pain and tearing of 10 days duration in the right eye, which had sustained a paddy stalk injury. On examination, a hypopyon corneal ulcer was noted in the right eye. Multiple scrapings were obtained from the affected part of the cornea. A lactophenol cotton blue wet mount and a Gram-stained smear of scrapings were made. Scrapings were also inoculated on various culture media, including Sabouraud dextrose agar (SDA). A fungal etiology was sought by conventional microbiological techniques and polymerase chain reaction. In vitro susceptibility testing was performed by an agar dilution method. Direct microscopy of corneal scrapings revealed septate hyphae, leading to initiation of intensive topical therapy with natamycin (5 %). However, the keratitis progressed, necessitating therapeutic penetrating keratoplasty. White, powdery-like colonies, with abundant aerial mycelium, were recovered on SDA from corneal scrape material. Based on macroscopic and microscopic morphological features, the isolated fungus was initially identified as a Fusarium species. Sequence analysis of the 28S rRNA region of the fungal genome led to a specific identification of F. langsethiae. Antifungal susceptibility testing results suggested that the strain isolated was susceptible to voriconazole, ketoconazole, and itraconazole. To our knowledge, this is the first reported case of keratitis due to F. langsethiae; attention is drawn to the unique characteristics of the fungal isolate, difficulties in identification and non-responsiveness to medical therapy.

Infliximab for peripheral ulcerative keratitis treatment

Biologic agents such as anti-TNFα have been employed in treatment paradigms for ocular inflammation. Peripheral corneal ulceration (PUK) is a devastating disorder consisting of a crescent-shaped area of destructive inflammation at the margin of the corneal stroma. It is associated with an epithelial defect, the presence of stromal inflammatory cells, and progressive stromal degradation and thinning, leading to ocular perforation and devastating visual loss. Macroulcerative PUK is usually a local manifestation of a systemic vasculitis. In many cases, the disease may be resistant to high doses of systemic corticosteroids and immunosuppressants. Chimeric anti-TNFα has been employed when all other treatments have failed. Isolated cases and short series of cases have been reported. This paper summarizes the available reports on the use, efficacy, and safety of infliximab in the treatment of PUK.

A rat model of autologous oral mucosal epithelial transplantation for corneal limbal stem cell failure

PURPOSE

To establish an animal model of autologous oral mucosa grafting for limbal stem cell deficiency.

METHODS

The study was carried from August to October 2012. Fourteen SD rats were randomly and evenly allocated to study group A and control group B. Limbal stem cell deficiency was established by alkali burn in the right eye of each rat in both groups. Rats in group A received autologous oral mucosa strip transplantation following the chemical burn. Rats in group B did not receive surgery after the chemical burn. Topical antibiotics and dexamethasone were used in all rats. Corneal clarity, corneal fluorescein staining, oral mucosal graft survival, and complications at postoperative days 1, 3, 7, 14 were observed.

RESULTS

The oral mucosa strip graft was detached in one rat in group A. Reepithelialization was observed starting from the graft position and was completed within 14 days in the remaining 6 eyes in group A. However, persistent corneal epithelium defect was observed in all eyes in group B, among which corneal melting and perforation was observed in 2 eyes and corneal opacification with neovascularization was observed in the remaining 5 eyes.

CONCLUSION

Autologous oral mucosa strip grafting for limbal stem cell deficiency can be achieved by a rat model following chemical burn. The fate of the transplanted oral mucosal epithelial cells warrants further study.

Experimental differentiation of intraocular masses using ultrahigh-field magnetic resonance imaging--a case series

PURPOSE

The case reports presented here were compiled to demonstrate the potential for improved diagnosis and monitoring of disease progress of intraocular lesions using ultrahigh-field magnetic resonance microscopy (MRM) at 7.1 Tesla.

METHODS

High-resolution ex vivo ocular magnetic resonance (MR) images were acquired on an ultrahigh-field MR system (7.1 Tesla, ClinScan, Bruker BioScan, Germany) using a 2-channel coil with 4 coil elements and T2-weighted turbo spin echo (TSE) sequences of human eyes enucleated because of different intraocular lesions. Imaging parameters were: 40×40 mm field of view, 512×512 matrix, and 700 µm slice thickness. The results were correlated with in vivo ultrasound and histology of the enucleated eyes.

RESULTS

Imaging was performed in enucleated eyes with choroidal melanoma, malignant melanoma of iris and ciliary body with scleral perforation, ciliary body melanoma, intraocular metastasis of esophageal cancer, subretinal bleeding in the presence of perforated corneal ulcer, hemorrhagic choroidal detachment, and premature retinopathy with phthisis and ossification of bulbar structures. MR imaging allowed differentiation between solid and cystic tumor components. In case of hemorrhage, fluid-fluid levels were identified. Melanin and calcifications caused significant hypointensity. Microstructural features of eye lesions identified by MRM were confirmed by histology.

CONCLUSION

This study demonstrates the potential of MRM for the visualization and differential diagnosis of intraocular lesions. At present, the narrow bore of the magnet still limits the use of this technology in humans in vivo. Further advances in ultrahigh-field MR imaging will permit visualization of tumor extent and evaluation of nonclassified intraocular structures in the near future.

Corneal cross-linking in 9 horses with ulcerative keratitis

BACKGROUND

Corneal ulcers are one of the most common eye problems in the horse and can cause varying degrees of visual impairment. Secondary infection and protease activity causing melting of the corneal stroma are always concerns in patients with corneal ulcers. Corneal collagen cross-linking (CXL), induced by illumination of the corneal stroma with ultraviolet light (UVA) after instillation of riboflavin (vitamin B2) eye drops, introduces crosslinks which stabilize melting corneas, and has been used to successfully treat infectious ulcerative keratitis in human patients. Therefore we decided to study if CXL can be performed in sedated, standing horses with ulcerative keratitis with or without stromal melting.

RESULTS

Nine horses, aged 1 month to 16 years (median 5 years) were treated with a combination of CXL and medical therapy. Two horses were diagnosed with mycotic, 5 with bacterial and 2 with aseptic ulcerative keratitis. A modified Dresden-protocol for CXL could readily be performed in all 9 horses after sedation. Stromal melting, diagnosed in 4 horses, stopped within 24 h. Eight of nine eyes became fluorescein negative in 13.5 days (median time; range 4-26 days) days after CXL. One horse developed a bacterial conjunctivitis the day after CXL, which was successfully treated with topical antibiotics. One horse with fungal ulcerative keratitis and severe uveitis was enucleated 4 days after treatment due to panophthalmitis.

CONCLUSIONS

CXL can be performed in standing, sedated horses. We did not observe any deleterious effects attributed to riboflavin or UVA irradiation per se during the follow-up, neither in horses with infectious nor aseptic ulcerative keratitis. These data support that CXL can be performed in the standing horse, but further studies are required to compare CXL to conventional medical treatment in equine keratitis and to optimize the CXL protocol in this species.

The wound healing effects of vitamin A eye drops after a corneal alkali burn in rats

PURPOSE

We investigated the wound healing effect of retinyl palmitate eyedrops following a corneal alkali burn in rats.

METHODS

A total of 160 Sprague-Dawley male rats were divided into two groups and central corneas were injured by contacting eyes with filter paper saturated with 0.01 m NaOH for 45 seconds. Vitamin A group was treated with retinyl palmitate and antibiotic (Cravit(®) : 0.5% levofloxacin) eye drops four times daily for 3 days and the control group with vehicle and antibiotic eye drops. Corneal wound healing by fluorescein staining and impression cytologic analysis were conducted at 0, 24, 48 and 72 hr after injury. Vascular endothelial growth factor A (VEGF-A), thrombospondin 2, matrix metalloproteinase 9 (MMP 9) and transforming growth factor-β (TGF-β) were measured in corneas by ELISA, immunofluorescent staining and real-time PCR.

RESULTS

Corneal wound healing was better in the vitamin A group than in the control group. Early sprouting of new vessel was observed in the control group at 72 hr, but not in the vitamin A group. Corneal thrombospondin 2 proteins in ELISA were higher in the vitamin A group, but VEGF-A, MMP 9 and TGF-β proteins were higher in the control group (p < 0.05). Similarly, thrombospondin 2 immunofluorescent staining was stronger, whereas VEGF-A, MMP 9 and TGF-β staining were weaker in the vitamin A group (p < 0.05). In addition, thrombospondin 2 mRNA levels were higher, whereas VEGF-A, MMP 9 and TGF-β mRNA levels were lower in the vitamin A group (p < 0.05).

CONCLUSIONS

Retinyl palmitate eye drops can inhibit VEGF-A and activate thrombospondin 2 and improve conjunctival impression cytologic findings. Furthermore, retinyl palmitate eye drops were found to promote corneal healing after an alkali burn in rats.

Bone marrow cells and CD117-positive haematopoietic stem cells promote corneal wound healing

PURPOSE

The present study was conducted to evaluate the therapeutic effects of topically applied bone marrow (BM) cells and CD117-positive haematopoietic stem (CD117(+)) cells on alkali-induced corneal ulcers.

METHODS

Bone marrow cells and CD117(+) cells were isolated from syngenic mice and labelled with an intracellular cell tracer. Defined corneal wounds were produced in 89 eyes of syngenic mice and allowed to partially heal in vivo for 6 hr. The alkali-burned eyes were enucleated 6 hr postinjury and randomly divided into three groups. Control group (33 eyes) was incubated with medium only. The treatment groups received either BM cells (30 eyes) or CD117(+) cells (26 eyes) suspended in medium. Re-epithelialization process of corneal defects was qualitatively and quantitatively assessed and statistically analysed. The corneas were examined by histological and immunohistochemical methods.

RESULTS

We found that the re-epithelialization of corneal wounds in both treatment groups was significantly accelerated as compared to the control group. During the follow-up period (85 hr), the corneal transparency was comparable in all groups. Morphological investigations of corneas from control and treatment group showed no evident differences in the phenotype of the regenerated epithelium. Additionally, corneas in the treatment groups were devoid of donor-derived BM cells and CD117(+) cells, respectively.

CONCLUSIONS

This study provides evidence that topical application of BM cells or CD117(+) cells can be used to reconstruct corneal surfaces. Because neither BM cells nor CD117(+) cells were integrated into the corneal epithelium, we suggest that soluble factors could be responsible for the positive effect of BM cells and CD117(+) cells on corneal wound healing.

[Leukoplakia of the lower tarsal conjunctiva]

The case of a 73-year-old woman with a perforated corneal ulcer in the remaining eye with migrating endophthalmitis is presented. In addition, the affected eye had non-abradable whitish coating (leukoplakia) on the tarsal conjunctiva. The cause of leukoplakia was initially histologically diagnosed after an incisional biopsy as focal invasive sebaceous carcinoma with pagetoid growth. After exenteration of the orbit it was confirmed to be an early invasive, non-keratinizing squamous cell carcinoma (G2) of the conjunctiva, which had emerged from a spinocellular carcinoma in situ. The early histological differentiation of malignant lesions in the conjunctiva can be extremely difficult because the pathological changes in the tissue are very similar due to the cell metaplasia.

In vivo confocal microscopy of equine fungal keratitis

OBJECTIVE

To describe in vivo corneal confocal microscopy of horses with fungal keratitis and correlate findings with clinical, histopathological, and microbiological evaluations of clinical cases and an ex vivo experimental equine fungal keratitis model.

ANIMALS STUDIED

A total of 12 horses with naturally-acquired fungal keratitis and ex vivo equine corneas experimentally infected with clinical fungal isolates.

PROCEDURES

Horses with naturally-acquired fungal keratitis were examined with a modified Heidelberg Retina Tomograph II and Rostock Cornea Module. Confocal microscopy images of clinical isolates of Aspergillus fumigatus, Fusarium solani, and Candida albicans were obtained by examination of in vitro cultures and experimentally infected ex vivo equine corneas.

RESULTS

Non-specific in vivo corneal confocal microscopic findings in horses with fungal keratitis included leukocyte infiltrates, activated keratocytes, anterior stromal dendritic cell infiltrates, and vascularization. Linear, branching, hyper-reflective structures that were 2-6 μm in width and 200 to >400 μm in length were detected in all horses with filamentous fungal keratitis. Round to oval hyper-reflective structures that were 2-8 μm in diameter were detected in a horse with yeast fungal keratitis. The in vivo confocal microscopic appearance of the organisms was consistent with fungal morphologies observed during examination of in vitro cultures and infected ex vivo equine corneas.

CONCLUSIONS

In vivo corneal confocal microscopy is a rapid and non-invasive method of diagnosing fungal keratitis in the horse. This imaging technique is useful for both ulcerative and non-ulcerative fungal keratitis, and is particularly advantageous for confirming the presence of fungi in deep corneal stromal lesions.

[Cornea in diabetus mellitus]

Diabetus mellitus is associated with numerous ocular complications. Diabetic keratopathy occurs in response to a neuropathy of the ophthalmic division of the trigeminal nerve, but also as a result of epithelial subclinical abnormalities, limbal vasculopathy and decrease in tear production. It comprises several symptomatic corneal conditions inducing superficial punctate keratopathy and persistent corneal epithelial erosions; the latter can progress to corneal ulceration and is often resistant to routine clinical management.

Effects of α-Toxin-DeficientStaphylococcus aureuson the Production of Peripheral Corneal Ulceration in an Animal Model

PURPOSE

To examine the role of Staphylococcus aureus alpha-toxin in contact lens-induced peripheral ulceration (CLPU).

MATERIALS AND METHODS

Proteolytic enzyme, hyaluronidase, alpha-toxin, and beta-toxin production by S. aureus 8325-4 and its alpha-toxin-deficient mutant (S. aureus DU1090) were examined. Using a rabbit model of CLPU, animals were fitted with hydrogel contact lenses colonized by either S. aureus 8325-4 or the mutant strain. The clinical presentation, bacterial cultures, and histology of the ulceration were examined.

RESULTS

Both strains of S. aureus produced similar levels of caseinase, gelatinase, elastase, hyaluronidase, and beta-toxin. S. aureus DU1090 induced weaker haemolysis of rabbit blood cells than S. aureus 8325-4. Ulceration in the S. aureus DU1090 eye was less frequent and less severe than that caused by S. aureus 8325-4.

CONCLUSIONS

The enzyme production profile of S. aureus DU1090 was similar to the parent strain. S. aureus strains may produce CLPU-like lesions irrespective of alpha-toxin production, but severe infectious lesions are produced only in the presence of alpha-toxin.

Healing of alkali burned rabbit corneas with persistent superficial ulceration after excimer laser phototherapeutic keratectomy. Clinical and electron microscopic findings

PURPOSE

To evaluate epithelial and stromal healing of kakali-bumed rabbit corneas with persistent superficial ulceration after phototherapeutic keratectomy (PTK).

MATERIAL AND METHODS

36 rabbits (36 eyes), with superficial corneal ulcers, which were formed after 10% NaOH corneal burn, were used. PTK was performed on the 18th day after the burn in 18 rabbits. The base and edges of corneal ulcers in 18 other rabbits were scraped with scalpel on the 18th day after the burn (control group). Clinical course and electron microscopic changes of post-burn corneal ulcers were investigated after PTK and in the control group.

RESULTS

Clinical course of corneal ulcers has shown that PTK promoted corneal epithelialization and led to formation of less dense corneal opacities compared to control group. Electron microscopy investigations have shown that PTK (1) activated basal layer epithelial cells at the corneal ulcer edge; (2) accelerated epithelial basal complex renewal; (3) increased amount of macrophages with cytoplasmic inclusions of necrotic tissues in corneal stroma; (4) increased amount of fibroblasts with activated intracellular organellae in corneal stroma. It led to acceleration of corneal epithelization, cleaning of corneal stroma from necrotic tissues in the area of corneal ulcer and to more physiologic stromal architecture renewal.

CONCLUSIONS

PTK promotes healing of post-burn persistent corneal ulcers in rabbits.

Chlorhexidine gluconate 0.02% as adjunct to primary treatment for corneal bacterial ulcers

BACKGROUND

It is common practice to use topical antiseptic formulations prior to specific therapy in superficial infections and injuries, but not in corneal bacterial ulcers. There is accumulating evidence proving chlorhexidine gluconate 0.02%, an antiseptic agent, as an effective treatment for infectious keratitis.

OBJECTIVES

To investigate the safety and efficacy of chlorhexidine gluconate 0.02% as an adjunct therapy for corneal bacterial ulcers.

METHODS

Twenty-six patients with corneal bacterial ulcers were treated with standard empirical antibiotic treatment. The study group was treated with chlorhexidine gluconate 0.02% while controls received placebo for one week. The patients were followed for at least 1 month.

RESULTS

No allergic or toxic reactions were noted. Although a higher baseline severity of ulcers existed in the study group, no differences were found in final vision, scarring extent, or recovery duration.

CONCLUSIONS

Chlorhexidine gluconate 0.02% may improve the clinical course of corneal ulcers.

Susceptibility of aged mice toStaphylococcus aureuskeratitis

PURPOSE

To determine the effect of age on the extent of pathogenesis of Staphylococcus keratitis in the mouse.

METHODS

Corneas of young and aged mice (BALB/c, A/J, and C57BL/6) were scarified and topically inoculated with S. aureus. Slit lamp examination (SLE) and histopathology were performed, and bacterial colony forming units and myeloperoxidase activity were determined.

RESULTS

SLE scores of infected eyes of aged mice were significantly higher at days 1 and 3 postinfection (PI) as compared to infected young mice. Histopathological changes observed in all aged mice were more severe than those in young mice. Young BALB/c and A/J mice demonstrated minimal signs of keratitis by day 3 PI, whereas aged mice of both strains demonstrated severe keratitis by day 3. Young C57BL/6 mice showed no clinical signs of keratitis, whereas aged C57BL/6 mice demonstrated moderate keratitis.

CONCLUSIONS

Aged mice with S. aureus keratitis demonstrated increased pathology as compared to young mice.

Distribution of collagenase and cell types in sterile ulceration of human corneal grafts

Extensive clinical and experimental evidence has suggested a role for corneal epithelium, keratocytes, and acute inflammatory cells in sterile corneal ulceration, although the precise role of these cell types in stromal matrix degradation has not been elucidated. We studied two corneal buttons and two whole corneas from 4 patients with corneal grafts and sterile stromal ulceration. Each cornea was divided into several sections and examined morphologically, while adjacent sections were placed in tissue culture and assayed for collagenase activity against type I collagen. In each case, collagenase activity was present in tissue from ulcerating and nonulcerating areas and, in most regions assayed, exceeded collagenase activity in normal control peripheral donor corneas. Collagenase levels were not always greatest in areas of most advanced ulceration. Although polymorphonuclear leukocytes were extensively present histologically in two cases, one case had a mixed inflammatory cell population at the site of ulceration, and another had only keratocytes (fibroblasts) present in the entire cornea. We conclude that regional differences in collagen degradation are due not only to the presence of collagenase, but also to cellular and humoral activators and inhibitors that determine collagenolytic activity.

[Bacterial corneal ulcer treated with intrastromal antibiotic. Experimental model in vivo]

OBJECTIVE

To compare the therapeutic effectiveness of a single intrastromal dose of gentamycin, tobramycin, ciprofloxacin and ofloxacin for the treatment of corneal ulcers due to Pseudomonas aeruginosa.

METHODS

Twelve white female New Zealand rabbits underwent mechanical removal of corneal epithelium; then one drop of salt suspension containing Pseudomonas aeruginosa (75,000,000 colony forming units) was instilled over the Bowman's layer. Rabbits were distributed in five groups according to the type of antibiotic used: group A: gentamycin, group B: tobramycin, group C: ciprofloxacin, group D: ofloxacin and control groups. A single intrastromal dose of antibiotic (0.3 mg/ml) was injected 48 to 72 hours post-inoculation. A clinical digital picture was taken daily for a week. Then rabbits were sacrificed, all the corneas were collected and a histopathologic study was performed.

RESULTS

We observed a significant reduction of the size of the corneal ulcer in all groups (F = 8.861; p = 0.000). Rabbits treated with ciprofloxacin, had a significant reduction in the size of the ulcer (21.1 SD 5.7 mm(2)). The epithelial growth was slow and incomplete in all groups. The histopathologic study showed Bowman's layer absence. The antibiotic used was not effective in groups A, B and D for the control of the corneal ulcer showing tissular necrosis.

CONCLUSION

Group C showed greater degree of epithelization, with increased number of keratocites as well as inflammatory infiltrate as a result of greater therapeutic effectiveness (CIM < 1 mcg).

Systemic Wegener's granulomatosis with severe orbito-ocular involvement

Orbito-ocular involvement in Wegener's granulomatosis is the result of both focal ischaemic vasculitis and granulomatous soft tissue inflammation. Necrotising keratoscleritis and orbital inflammation are two most characteristic ophthalmic presentations. We describe a 56-year-old man with systemic limited Wegener's granulomatosis, presenting with pulmonary fibrosis, pansinusitis and left mastoiditis. This was complicated by the development of a left severe necrotising anterior scleritis, peripheral ulcerative keratitis and orbital apex syndrome. Both c-ANCA and anti-PR3 were positive. Despite mainstay systemic immunosuppressive therapy with cyclophosphamide and prednisolone, the visual prognosis remained very poor. This was largely due to the presence of an irreversible ischaemic optic neuropathy, extensive corneoscleral melt and corneal neovascularisation. This case highlights the possible extent of orbital and ocular surface involvement in Wegener's granulomatosis, and hence the importance of vigilance by the physician.

The effect of tricaine on use of the fluorescein test for detecting skin and corneal ulcers in fish

Fluorescein has been used for rapid and sensitive detection of fish skin and corneal ulceration. Effective use of the fluorescein test requires knowledge of conditions that might cause misleading interpretations or otherwise interfere with test reliability. Examination of fish health and the clinical workup often require tricaine as one of the most commonly used anesthetics. However, tricaine may interfere with correct interpretation of the fluorescein test and might also cause significant fish injury. The effects of tricaine exposure sequence on the fidelity of the fluorescein test was studied in Pacific halibut Hippoglossus stenolepis, walleye pollock Theragra chalcogramma, and northern rock soles Lepidopsetta polyxystra by examining the fluorescence of experimentally induced epidermal wounding. Tricaine can quench fluorescence that is emitted by fluorescein retained in skin ulcers, causing a false-negative reaction. Thus, for the fluorescein test to work properly, it is important to avoid the exposure of fluorescein-treated and rinsed ulcers to tricaine. The effects of exposure to buffered versus unbuffered tricaine on epidermal and corneal integrity were studied in Nile tilapia Oreochromis niloticus and channel catfish Ictalurus punctatus subjected to the fluorescein test and histological examination. Fluorescein could detect not only ulcers but also areas with only a partial loss of epithelium (i.e., erosion). The use of unbuffered tricaine to anesthetize these fish caused serious epidermal and corneal damage. If fish are euthanized with unbuffered tricaine for clinical workup, this severe epidermal or corneal damage could be misinterpreted as an antemortem lesion, leading to misdiagnosis. Even in water with alkalinity exceeding 50 mg/L as CaCO3, it would seem prudent to always buffer tricaine with sodium bicarbonate to prevent a pH change that might lead to iatrogenic effects from unbuffered tricaine. Thus, current general recommendations suggesting that tricaine does not need to be buffered in waters with alkalinity greater than 50 mg/L might need to be modified.

Deviated mechanism of wound healing in diabetic corneas

We examined phenotypic changes during the wound healing process in the corneal epithelium of Goto-Kakizaki (GK) rats, a spontaneous model of type 2 diabetes mellitus. In this article, we provide an overview of our and other groups' research and describe the clinical features of diabetic keratopathy. We observed that the rate of corneal epithelial wound closure was decreased in GK rats compared with Wistar rats. Immunoreactivity for Cx43, K14, and Ki-67 was detected in the 2 layers of cells adjacent to the basement membrane in the corneal epithelium of GK rats, whereas only the single basal layer of cells was positive for these proteins in the corneal epithelium of Wistar rats. The frequency of Ki-67-positive cells was greater in GK rats than in Wistar rats in the intact corneal epithelium and during wound healing. The GK rat represents delayed corneal epithelial wound closure as well as that which is observed in human diabetic keratopathy. Furthermore, these results indicate a possibility of functional deviation in corneal epithelial cells with diabetes mellitus.

Anterior segment complications secondary to continuous positive airway pressure machine treatment in patients with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is a disorder that, when left untreated, can have serious complications, mainly cardiovascular. OSA is commonly treated with a continuous positive airflow pressure (CPAP) machine. Patients using CPAPs routinely complain of dryness of the nose and eyes.

CASES

Case 1: A keratoconic woman, wearing gas-permeable lenses began therapy with a CPAP, and vascularized limbal keratitis (VLK) developed. She now wears soft lenses, compromising visual acuity, but preventing the VLK. Case 2: A man with 20/20 visual acuity in the right eye (O.D.) and hand motion in the left eye (O.S.), presented with recurring corneal ulcers O.D. after starting treatment with a CPAP. Case 3: A man with pellucid degeneration started using a CPAP, which increased his complaint of dryness with his lenses. He subsequently had 2 occurrences of bacterial conjunctivitis.

CONCLUSION

It is unclear if the complications seen in these cases come from leakage of air into the eyes causing drying, from bacteria trapped under the mask being forced up into the eyes, or from air passing from the nose into the eye via the nasolacrimal duct. In the care of these patients, being aware of complications, suggesting nighttime lubricants, and knowing the alternatives to CPAP could help maintain ocular health and successful lens wear.

Peripheral ulcerative keratitis due to a 'long lost' hard contact lens

Peripheral ulcerative keratitis (PUK) is a disorder consisting of a crescent-shaped destructive inflammation of the perilimbal corneal stroma. PUK can occur in a variety of ocular and systemic conditions including infections, lid abnormalities, dermatological disorders and connective tissue disorders. We present a case of PUK associated with a hard contact lens (CL) retained in the superior fornix for over 16 years. After removal of the embedded CL, a superior forniceal conjunctival pedicle graft was performed to prevent corneal perforation. The patient was managed postoperatively with a combination of topical steroids and antibiotics. The use of systemic immunosuppressive therapy was not necessary. Micro-trauma and micro-keratitis may have occurred as a result of the mechanical effect of the CL but if this was the sole mechanism, one would expect presentation at a much earlier date. We discuss the pathogenetic mechanisms which may have contributed to the development of this ulceration. This report highlights the importance of lid eversion when examining patients with anterior segment pathology.

Keratitis Caused by a Rare Fungus, Malassezia restricta

BACKGROUND

Malassezia species rarely cause keratitis, and, thus, the clinical manifestations of Malassezia keratitis are not well known.

CASE

We report the clinical findings in a 70-year-old woman who complained of pain in her left eye. Slit-lamp biomicroscopy showed a corneal ulcer with irregular infiltration, which resembled keratitis caused by filamentous fungi. KOH Parker ink stain of a corneal scraping showed mold hyphae and yeast, but cultures on Sabouraud's glucose agar plates and blood agar plates were negative. Treatment with antibacterial agents failed.

OBSERVATIONS

Polymerase chain reaction (PCR) and DNA typing of the fungal gene between the internal transcribed spacer 2 (ITS2) and the 5.8S ribosomal DNA of the scraping were performed. PCR amplified a band with a sequence that was 99% homologous with Malassezia restricta. Antifungal agents, topical 5% pimaricin ointment and 0.2% miconazole, and oral itraconazole 150 mg/day, were applied, and the corneal ulcer disappeared within 5 weeks.

CONCLUSION

Malassezia restricta can cause keratitis, and the clinical findings resemble keratitis caused by filamentous fungi. PCR and DNA typing of ITS2 and 5.8S ribosomal DNA are valuable techniques for detecting and identifying Malassezia species. Proper identification of Malassezia keratitis permits a prompt and successful treatment by antifungal agents.

Corneal virulence of Candida albicans strains deficient in Tup1-regulated genes

PURPOSE

To evaluate the role of rbt genes downstream of Tup1p, a transcription factor regulating fungal filamentation, in experimental Candida albicans keratitis.

METHODS

Corneas of BALB/c mice were scarified and topically inoculated with 10(5) or 10(6) colony-forming units (CFU) of a wild-type human isolate of C. albicans (SC5314), a mutant strain with a transposon-induced homozygous disruption of the rbt1 gene (Tn7-rbt1), its control (DAY286), homozygous rbt knockout mutants deficient in rbt1 (BCa7-4) or rbt4 (BCa11-3), or their parental control (CAF2-1). Eyes were scored daily for clinical severity of fungal keratitis and were examined histopathologically.

RESULTS

With a 10(5) CFU inoculum, the CAF2-1 control and its mutant derivatives (BCa7-4 and BCa11-3) produced significantly lower keratitis scores than did the moderately severe keratitis induced by control strains SC5314 and DAY286 and the Tn7-rbt1 mutant (P < 0.05). At a 10(6) CFU inoculum, all strains induced severe disease except for the rbt4-deficient mutant. Fungal keratitis caused by Tn7-rbt1 was as severe as that of control strains (P > 0.2), and the BCa7-4 mutant initially caused severe disease that gradually waned (P < 0.02). However, the BCa11-3 mutant produced moderate disease that was significantly less severe than that induced by control strains (P < 0.04) and resolved within 1 week.

CONCLUSIONS

The rbt4 gene of C. albicans is a potential virulence factor in posttraumatic corneal infection. Genetically regulated hyphal morphogenesis appears to be involved in the initial pathogenesis of experimental keratomycosis.

Proteinases of the cornea and preocular tear film

Maintenance and repair of corneal stromal extracellular matrix (ECM) requires a tightly coordinated balance of ECM synthesis, degradation and remodeling in which proteolytic enzymes (proteinases) perform important functions. There are natural proteinase inhibitors present in preocular tear film (PTF) and cornea simultaneously with proteinases that prevent excessive degradation of normal healthy tissue. Disorders occur when there is an imbalance between proteinases and proteinase inhibitors in favor of the proteinases, causing pathologic degradation of stromal collagen and proteoglycans in the cornea. Two matrix metalloproteinases (MMPs), MMP-2 and MMP-9, are of major importance in terms of remodeling and degradation of the corneal stromal collagen. Immunohistochemical studies have shown different origins of MMP-2 and -9. MMP-2 is synthesized by corneal keratocytes and performs a surveillance function in the normal cornea, becoming locally activated to degrade collagen molecules that occasionally become damaged. Alternatively, MMP-9 may be produced by epithelial cells and polymorphonuclear neutrophils following corneal wounding. Because the cornea is in close contact with the preocular tear film (PTF), proteinases have been evaluated in the PTF. In damaged corneas, total proteolytic activity in the tear fluid was found to be significantly increased compared to normal eyes and contralateral eyes. Studies analyzing the proteolytic activity in serial PTF samples during corneal healing led to the following conclusions: ulcerative keratitis in animals is associated with initially high levels of tear film proteolytic activity, which decrease as ulcers heal; proteinase levels in melting ulcers remain elevated leading to rapid progression of the ulcers. The success of medical and surgical treatment of the corneal ulcers is reflected by the proteolytic activity in tears. In animals, successful treatment leads to a rapid reduction in tear film proteolytic activity that corresponds with the improvement in the clinical signs of corneal ulceration. The in vitro effects of various compounds on proteolytic activity in the tear fluid of animals with ulcerative keratitis have been evaluated and their important inhibitory effects have been confirmed. Because these various compounds utilize different mechanisms to inhibit various families of proteinases, a combination of these proteinase inhibitors may be beneficial.