Subconjunctival Administration Research Articles

Robo 4 Counteracts Angiogenesis in Herpetic Stromal Keratitis.

The cornea is a complex tissue that must preserve its transparency to maintain optimal vision. However, in some circumstances, damage to the eye can result in neovascularization that impairs vision. This outcome can occur when herpes simplex virus type 1 (HSV-1) causes the immunoinflammatory lesion stromal keratitis (SK). Potentially useful measures to control the severity of SK are to target angiogenesis which with herpetic SK invariably involves VEGF. One such way to control angiogenesis involves the endothelial receptor Robo4 (R4), which upon interaction with another protein activates an antiangiogenic pathway that counteracts VEGF downstream signaling. In this study we show that mice unable to produce R4 because of gene knockout developed significantly higher angiogenesis after HSV-1 ocular infection than did infected wild type (WT) controls. Moreover, providing additional soluble R4 (sR4) protein by subconjunctival administration to R4 KO HSV-1 infected mice substantially rescued the WT phenotype. Finally, administration of sR4 to WT HSV-1 infected mice diminished the extent of corneal angiogenesis compared to WT control animals. Our results indicate that sR4 could represent a useful therapeutic tool to counteract corneal angiogenesis and help control the severity of SK.

Corticosteroid-loaded biodegradable nanoparticles for prevention of corneal allograft rejection in rats

Immunologic graft rejection is one of the main causes of short and long-term graft failure in corneal transplantation. Steroids are the most commonly used immunosuppressive agents for postoperative management and prevention of corneal graft rejection. However, steroids delivered in eye drops are rapidly cleared from the surface of the eye, so the required frequency of dosing for corneal graft rejection management can be as high as once every 2h. Additionally, these eye drops are often prescribed for daily use for 1year or longer, which can result in poor patient compliance and steroid-related side effects. Here, we report a biodegradable nanoparticle system composed of Generally Regarded as Safe (GRAS) materials that can provide sustained release of corticosteroids to prevent corneal graft rejection following subconjunctival injection provided initially during transplant surgery. Poly(lactic-co-glycolic acid) (PLGA) nanoparticles containing dexamethasone sodium phosphate (DSP) exhibited a size of 200nm, 8wt.% drug loading, and sustained drug release over 15days in vitro under sink conditions. DSP-loaded nanoparticles provided sustained ocular drug levels for at least 7days after subconjunctival administration in rats, and prevented corneal allograft rejection over the entire 9-week study when administered weekly. In contrast, control treatment groups that received weekly injections of either placebo nanoparticles, saline, or DSP in solution demonstrated corneal graft rejection accompanied by severe corneal edema, neovascularization and opacity that occurred in ≤4weeks. Local controlled release of corticosteroids may reduce the rate of corneal graft rejection, perhaps especially in the days immediately following surgery when risk of rejection is highest and when typical steroid eye drop administration requirements are particularly onerous.

Effect of Allogeneic Limbal Mesenchymal Stem Cell Therapy in Corneal Healing: Role of Administration Route

Aims: To investigate whether allogeneic limbal mesenchymal stem cell (LMSC) therapy affects corneal healing after a severe chemical burn and whether the route of administration of LMSCs differs in its therapeutic effect in this respect. Methods: A total of 60 Sprague-Dawley rats with clinically proven alkali injury were divided into four equal groups (n = 15) as follows: group 1: 2 × 10⁵ cells/drop LMSCs, topically applied 6 times a day for 2 days; group 2: 2.4 × 10⁶ cells in 0.5 ml LMSCs, subconjunctivally applied; group 3: 2.4 × 10⁶ cells in 1 ml LMSCs, intraperitoneally applied, and group 4: no LMSC treatment. The groups were compared according to grades of corneal opacity (CO), corneal neovascularization (CNV) and corneal fluorescein staining (CFS). The migration of LMSCs into the cornea and the inflammatory characteristics of the groups were evaluated with BrdU (5-bromo-2′-deoxyuridine bromodeoxyuridine) immunostaining and histopathologically in a 4-week follow-up. Results: There were statistically significant differences between the LMSC-treated and control groups in each week regarding mean CO scores and in the 3rd week regarding the mean CNV and CFS scores (p < 0.05). The statistical significance was due to the differences between the topical and the control group and between the subconjunctival and the control group. BrdU+ LMSCs were seen in the corneal epithelium of the all LMSC-administered rats, and fewer inflammatory changes were observed in these rats. Conclusion: Allogeneic LMSC treatment, especially topical and subconjunctival administration, seems to be helpful in affecting corneal healing after a severe corneal burn.

Subconjunctival and topical application of recombinant tissue plasminogen activator in rabbits.

To quantify fibrin degradation products after topical and subconjunctival administration of recombinant tissue plasminogen activator in rabbits. Fibrin formation was induced in the anterior chamber in 25 rabbits. Subsequently, five rabbits received an injection of r-TPA (positive control) in the anterior chamber, another 10 received a subconjunctival injection of r-TPA, and the remaining 10 received instillations of topical r-TPA. Afterwards, samples of aqueous humor were collected and semi-quantitative analysis of fibrin degradation products (FDP) was performed. No statistical differences were noted between the treatment and control groups at any time point. Fibrin degradation products semi-quantification showed statistical improvement in the control group and the subconjunctival group. Fibrin degradation products were observed in the anterior chamber after subconjunctival administration of r-TPA. However, it was probably not sufficient to cause fibrin degradation. Topical r-TPA did not effectively absorb anterior chamber fibrin.

Using intracameral cefuroxime reduces postoperative endophthalmitis rate: 5 years experience at the University Eye Hospital Tübingen

Cataract surgery is the most commonly performed surgical procedure in developed countries. The annual number of cataract surgeries in Germany is about 600,000. Acute postoperative endophthalmitis is a very severe and the most dreaded complication of cataract surgery. Various operative and non-operative measures have been suggested to prevent this serious complication. The European Society of Cataract & Refractive Surgeons (ESCRS) study of intracameral cefuroxime was the first prospective, randomised and partially placebo-controlled clinical trial showing the efficacy of antibiotic prophylaxis to prevent endophthalmitis in 2007. The aim of this retrospective study is to investigate a possible reduction of intracameral cefuroxime to prevent postoperative endophthalmitis at the University Eye Hospital Tübingen. During the period from January 2002 to August 2013, 2 time periods were determined based on the adoption of intracameral cefuroxime injections after cataract surgery. From January 2002 to May 2009 patients received at the end of cataract surgery a subconjunctival administration of 50 mg of mezlocillin and postoperative antibiotic eye drops (gentamicin) without intracameral injection. From June 2009 to August 2013, patients received an intracameral injection of cefuroxime while antibiotic drops (moxifloxacin) were used too. The rates of postoperative infectious endophthalmitis during these 2 periods were calculated. 31 cases of endophthalmitis occurred in 31,386 cataract surgeries. The overall cumulative incidence was 0.99 per 1000 patients. The incidence in the first period without intracameral cefuroxime injection was 1.38 (95 % confidence interval [CI]: 1.03-1.72) per 1000 patients and in the second period 0.44 (95 % CI: 0.34-0.54) per 1000 patients (p < 0.001). Intracameral injection of cefuroxime reduces the rate of postoperative infectious endophthalmitis in cataract surgery significantly.

Tumor necrosis factor alpha and interleukin-6 facilitate corneal lymphangiogenesis in response to herpes simplex virus 1 infection.

Herpes simplex virus 1 (HSV-1) is a common human pathogen of clinical significance due to its association with vision impairment and encephalitis. In a mouse model of ocular neovascularization, we have previously shown that HSV-1 elicits the genesis of lymphatic vessels into the cornea proper through epithelial cell expression of vascular endothelial growth factor A (VEGFA) dependent upon expression of VEGFR2 during acute infection. We hypothesized that other factors may be involved in lymphangiogenesis, with proinflammatory cytokines as the leading candidates. In the absence of infection or inflammation, intrastromal administration of tumor necrosis factor alpha (TNF-α) coupled with VEGFA elicited lymphatic vessel genesis significantly above either factor alone as well as a vehicle control. Consistent with this observation, anti-TNF-α antibody (Ab) blocked HSV-1-mediated corneal lymphangiogenesis within the first 5 days postinfection. However, TNF-α-deficient (TNF-α(-/-)) mice displayed a level of corneal vessel growth similar to that shown by wild-type (WT) controls. To investigate the likely redundant nature of cytokines, PCR array analysis of HSV-1-infected TNF-α(-/-) mice was conducted, and it revealed several factors elevated above those found in HSV-1-infected WT mice, including interleukin-1β (IL-1β), platelet-derived growth factor, angiopoietin 2, insulin-like growth factor 2, and IL-6. Subconjunctival administration of neutralizing Ab to IL-6 blocked lymphangiogenesis in TNF-α(-/-) mice. Whereas the cornea levels of IL-6 were significantly reduced, there was no appreciable change in the level of IL-1β or other proangiogenic factors analyzed. Collectively, the results suggest in addition to VEGFA, TNF-α and IL-6 promote and likely synergize with VEGFA in corneal lymphangiogenesis during acute HSV-1 infection. We have identified at least two proinflammatory cytokines expressed locally that are involved in the genesis of lymphatic vessels in the normally avascular cornea in response to HSV-1 infection. This finding provides the basis to target IL-6 and TNF-α as additional proangiogenic factors in the cornea during the development of herpetic stromal keratitis as a means to alleviate further neovascularization and tissue pathology associated with the host immune response to the pathogen.

Targeting Robo4 pathway reduces corneal angiogenesis induced by herpes simplex virus. (VIR1P.967)

Abstract The cornea is a complex tissue that must preserve its transparency to maintain optimal vision. Eye infections such as with herpes simplex virus (HSV) can result in a chronic immuno-inflammatory syndrome and pathological neovascularization that impairs vision. Recent reports demonstrate that angiogenic sprouting shows morphological similarities to axon growth. Moreover there are several key molecules that upon binding to receptors regulate the direction of both capillary and axon guidance. In this study we show that Roundabout 4 (ROBO4) receptor plays a significant role reducing angiogenesis. Using ROBO4 -/- mice we demonstrate that these mice are hyper-susceptible to HSV induced corneal angiogenesis compared to wild type mice. Moreover, providing additional soluble ROBO4 protein by subconjunctival administration significantly diminished the extent of corneal angiogenesis in wild type animals. Finally, by administration of soluble ROBO4 protein to ROBO-/- HSV infected mice it was possible to rescue the wild type phenotype. In conclusion, the administration of soluble ROBO4 protein promotes the activation of the ROBO4 pathway. This could represent a valuable therapeutic tool to control corneal angiogenesis related to HSV induced stromal keratitis.

Pharmacological characteristics and efficacy of a novel anti-angiogenic antibody FD006 in corneal neovascularization

BackgroundVascular endothelial growth factor (VEGF) is a key angiogenic factors. It plays an important role in both physiologic and pathologic angiogenesis and increases permeability across the vessels. Using antibody phage display technology, we obtained a novel anti-VEGFA IgG, named as FD006. In this study, the pharmacological characteristics and efficacy of FD006 in corneal neovascularization (CoNV) were evaluated.ResultsFD006 was predicted to have similar binding mode to bevacizumab. Experimental analysis showed that the binding ability of FD006 seemed a little stronger than bevacizumab, for the EC50 of FD006 to bind VEGF analyzed by ELISA was about 0.037 μg/mL while that of bevacizumab was 0.18 μg/mL. Binding kinetics assays showed similar results that FD006 possessed 2-fold higher affinity to bind VEGF than bevacizumab due to slower dissociation rate of FD006; meanwhile, FD006 inhibited the VEGF-induced proliferation of HUVEC with an IC50 value of 0.031 ± 0.0064 μg/ml, which seemed similar or a litter better than bevacizumab (0.047 ± 0.0081 μg/ml). The subconjunctival administration of FD006, bevacizumab or dexamethasone could significantly inhibit the growth of CoNV contrasting to N.S (p < 0.01). At the early stage, FD006 showed better inhibitory effect on the growth of CoNV compared with bevacizumab (p < 0.05). Western blot analysis showed that FD006 could inhibit the expression of VEGF, VEGFR-1, VEGFR-2, MMP-9 and ICAM-1, which could explain its favorable anti-angiogenic activity.ConclusionsThe pharmacological characteristics of FD006 were similar or even a little better than bevacizumab in inhibiting corneal neovascularization.

Poly(HEMA)/cyclodextrin‐based hydrogels for subconjunctival delivery of cyclosporin A

ABSTRACTTo enhance the solubility and ocular permeability of immunosuppressive agent, cyclosporine A (CsA), three types of delivery systems were prepared using (2‐hydroxypropyl)‐β‐cyclodextrin (HPβCD), and 2‐hydroxyethyl methacrylate (HEMA). Those systems are (i) hydrogels of HPβCD with crosslinking agent ethylene glycol diglycidylether, (ii) poly(HEMA) hydrogels, and (iii) different amounts of HPβCD‐containing poly(HEMA) hydrogels indicated as poly(HEMA‐co‐HPβCD). In the presence of HEMA, hydrogels have desired mechanical integrity with lower equilibrium content than that of hydrogels without HEMA. CsA was loaded into the HPβCD‐based hydrogels by embedding from its aqueous suspensions in higher amounts than that of the poly(HEMA) hydrogels that were loaded by CsA–HPβCD complex solution. Although the poly(HEMA) hydrogels are releasing total CsA in 3 days, long‐term release was realized from HPβCD‐based hydrogels. For subconjunctival administration, regarding to the amounts of loaded CsA, release profiles, and mechanical integrity, the most suitable system is poly(HEMA‐co‐HPβCD) hydrogels in high HPβCD content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40397.

Antiangiogenic Effect of Itraconazole on Corneal Neovascularization: A Pilot Experimental Investigation

Purpose: To investigate the antiangiogenic effect of itraconazole for the prevention of experimentally induced corneal neovascularization and whether the efficacy depends on the route of administration. Materials and Methods: Thirty-six rats were randomly divided into 6 groups with 6 rats in each group. Chemical cauterization of the cornea was performed using silver nitrate/potassium nitrate sticks, and the rats were subsequently treated daily with topical (10 mg/ml), subconjunctival (10 mg/ml) or intraperitoneal (19 mg/kg) itraconazole for 7 days. Control rats received topical, subconjunctival or intraperitoneal 0.9% saline. On the 8th day of the experiment, the rat corneas were photographed to determine the percentage area of the cornea covered by neovascularization. The maximum density of corneal neovascularization was determined by microscopy. Results: The median percentage of corneal neovascularization for group 1 was 31.5% (95% confidence interval, 27.5-35.5%); in group 3, it was 32% (23.5-39.8%); in group 5, it was 47% (36.3-60.0%). The percentages of corneal neovascularization in groups 2, 4 and 6 (the control groups) were 70% (95% confidence interval, 60.7-77.3%), 69% (63.0-77.7%) and 68% (56.5-78.5%), respectively. The area of neovascularization was smaller after itraconazole treatment as compared to saline treatment. Further, the area of neovascularization was smaller after topical and subconjunctival administration than after intraperitoneal administration. Histological evaluation of the corneas showed the most extensive corneal neovascularization in the control group. No local or systemic adverse effects were seen from either treatment group. Conclusion: Itraconazole reduces corneal neovascularization shortly after chemical burn. However, a larger experimental study is necessary to confirm the data of this investigation.

Inhibition of corneal neovascularization by topical and subconjunctival tigecycline.

Objective. To investigate the effects of topical and subconjunctival tigecycline on the prevention of corneal neovascularization. Materials and Methods. Following chemical burn, thirty-two rats were treated daily with topical instillation of 1 mg/mL tigecycline (group 1) or subconjunctival instillation of 1 mg/mL tigecycline (group 3) for 7 days. Control rats received topical (group 2) or subconjunctival (group 4) 0.9% saline. Digital photographs of the cornea were taken on the eighth day after treatment and analyzed to determine the percentage area of the cornea covered by neovascularization. Corneal sections were analyzed histopathologically. Results. The median percentages of corneal neovascularization in groups 1 and 3 were 48% (95% confidence interval (CI), 44.2–55.8%) and 33.5% (95% CI, 26.6–39.2%), respectively. The median percentages of corneal neovascularization of groups 1 and 3 were significantly lower than that of the control group (P = 0.03 and P < 0.001, resp.). Histologic examination of samples from groups 1 and 3 showed lower vascularity than that of control groups. Conclusion. Topical and subconjunctival administration of tigecycline seems to be showing promising therapeutic effects on the prevention of corneal neovascularization. Furthermore, subconjunctival administration of tigecycline is more potent than topical administration in the inhibition of corneal neovascularization.

The Effect of Subconjunctival Ranibizumab on Corneal and Anterior Segment Neovascularization: Study on an Animal Model

To evaluate the effect of subconjunctival anti-vascular endothelial growth factor (VEGF) ranibizumab on corneal and anterior segment neovascularization. In this experimental study and laboratory investigation, chemical cauterization was utilized to induce corneal neovascularization in 16 rabbits randomly divided in 2 equal groups. Cauterized eyes were either treated with 0.1 mL (1 mg) of subconjunctival ranibizumab or administered a sham injection. A third group of 4 rabbits served as control for side effects after ranibizumab administration. All animals were monitored daily for 14 days and the extent of corneal scarring and neovascularization was measured on days 1, 7, and 14. After enucleation, ocular tissues were separated under a surgical microscope and VEGF levels were measured with ELISA. Statistical analysis was performed to compare the extent of corneal neovascularization and VEGF levels between treated and untreated eyes. Subconjunctival ranibizumab inhibited corneal neovascularization significantly both in the first and the second week compared to untreated controls (p = 0.006 and p = 0.001, respectively). The VEGF levels were significantly lower in all anterior segment tissues like the cornea, iris, aqueous humor, and conjunctiva of the treated eyes (p<0.01). The reduction of VEGF levels ranged from 19% to 73% in different ocular tissues. Corneal scarring was not significantly affected by anti-VEGF treatment (p = 0.7). No side effects were noticed. Early subconjunctival administration of ranibizumab may successfully inhibit alkali-induced corneal neovascularization in an animal model. Subconjunctival ranibizumab reduces VEGF levels significantly not only in the cornea and the bulbar conjunctiva but also in the aqueous humor and the iris.

The Inhibitory Effect of Thalidomide Analogue on Corneal Neovascularization in Rabbits

To evaluate the effect of thalidomide analogue CC-3052 on corneal neovascularization in the rabbit model. Corneal neovascularization was induced in 15 rabbits by a silk suture in the corneal stroma. At 1 week after suturing, 30 eyes were divided into 5 groups of 6 eyes each. Three groups were treated with topical CC-3052 at 3 different concentrations: 0.25% (group 1), 0.5% (group 2), and 1.0% (group 3). All treatments were performed twice a day for a week. A 0.5% concentration of CC-3052 was injected subconjunctivally once in group 4. In group 5, a topical balanced salt solution was added twice a day for a week as the experimental control group. Rabbit corneas were photographed by a digital camera and examined by the operating microscope. Half of the corneal specimens were analyzed histopathologically, and the other half were used to measure the concentration of tumor necrosis factor α and vascular endothelial growth factor (VEGF) messenger RNA by reverse transcriptase-polymerase chain reaction. The neovascularized area was decreased in all treatment groups compared with the control group. There was a significant difference in the percentage and score of corneal neovascularization between the control and all treatment groups. Inflammation, fibroblast, neovascularization, and anti-VEGF antibody intensities were significantly lower in the control group. The concentration of VEGF and tumor necrosis factor α was significantly lower in the control group. There was no difference between the treatment groups. Topical and subconjunctival administration of thalidomide analogue CC-3052 was found to be effective for the inhibition of corneal neovascularization.

Topical and subconjunctival ranibizumab (lucentis) for corneal neovascularization in experimental rat model

Purpose: To compare the effectiveness of the topical and subconjunctival (SC) ranibizumab treatment in experimental corneal neovascularization (NV) model in rats.Methods: A model of NV was generated by cauterizing right corneas of 30 Sprague-Dawley rats with silver nitrate. The animals were separated into five groups randomly. first group (control group) received topical artificial tear drops two times daily while second and third groups received topical ranibizumab four times daily at concentrations of 5 mg/mL and 10 mg/mL, respectively. Forth and fifth groups were given 0.5 mg/0.05 mL and 1 mg/0.1 mL of SC ranibizumab in the 1st, 3rd and 7th days. The measurements (percentage of NV area and number of vessels) from digital photographs of the corneas were determined and analyzed using analysis software (ImageJ, v1.38). The animals were sacrificed on the 10th day and their corneas were subjected to hemotoxylin-eosin histopathological staining and antisera against CD34 and von-Willebrand factor to evaluate microvascular structures immunohistochemically.Results: The percentage of the corneal NV area and number of vessels in all treatment groups was found to be significantly lower than the control group. There was no significant difference in relation to the percentage of NV area and number of vessels in the treatment groups. Score of the corneal edema was determined to be significantly less in the groups that undertook treatment. Number of vessels and inflammatory cells were significantly lower in the histological and immunohistochemical sections in the treated groups than in the control group. In all treatment groups, fibroblast intensity was significantly lower than the control group (p = 0.005).Conclusion: Topical or SC administration of ranibizumab seems to be a promising and effective medication in the treatment of corneal NV. Further research is recommended to assess the potential side effects and effective dose.

Klinik und Therapie des Steroidglaukoms

In steroid responders, topical or systemic application of steroids leads to extracellular deposits in the trabecular meshwork which increase trabecular meshwork outflow resistance. 30-40 % of the normal population are steroid responders. About 5 % develop an intraocular pressure (IOP) rise of > 15 mmHg. These patients are termed "high responders". In patients with primary open angle glaucoma (POAG), the proportion of steroid responders sums up to 90 %. The extent of steroid response depends on the kind of steroid used and on the duration of its administration. Dexamethasone has the highest IOP increasing potency. Differential diagnoses are POAG, ocular hypertension, normal tension glaucoma, pseudoexfoliation glaucoma and secondary glaucoma due to different reasons. To make the diagnosis, a detailed anamnesis is crucial. A recompensated IOP after the end of steroid use proves the diagnosis. The treatment of steroid glaucoma includes topical antiglaucoma medications, glaucoma filtration surgery, trabeculotomy, and laser surgery. So far, only few comparative studies on different treatment options have been published on steroid glaucoma. In some cases of therapy-resistant IOP increases following intravitreal or subconjunctival steroid administration, operative removal of the steroids can be considered. A gene therapy treatment of steroid glaucoma is still a topic of research.

Alternative route for erythropoietin ocular administration

This study aimed to find an alternative route for erythropoietin (EPO) ocular administration because of its neuroprotective and neuroregenerative known properties. Ocular penetration of EPO after subconjunctival injection was assessed, and potential side-effects on the haematocrit for a 28-day period were also evaluated. Wistar Hannover female albino rats (n = 42) divided into seven groups of six were used. One group (n = 6) served as control. Six groups (n = 36) received 1,000 UI of EPO through the subconjunctival route in one of the eyes. According to the group, animals were humanely killed at 12 h (n = 6), 24 h (n = 6), 36 h (n = 6), 48 h (n = 6), and 60 h (n = 6), after EPO administration, in a total of 30 animals. Enucleation of both eyes was performed, and EPO protein distribution in the rat's retina was analyzed by immunohistochemistry. Another group of animals (n = 6) was used to collect blood samples and perform haematocrit analysis at 0, 7, 14, 21, and 28 days after unilateral EPO subconjunctival administration. The evaluation of EPO expression in the animals' retinas after subconjunctival administration yielded a strong immunostaining signal. Among the retina's layers, EPO expression was more evident in the RGC layer 24 h after the administration, and was still present on that layer till the end of the study (60 h). When administered subconjunctivally EPO reached several neuronal cells, in all retinal layers. The subconjunctival EPO administration did not cause significant changes in the haematocrit values over a 28-day period. In this study, it was demonstrated that EPO reached the retinal ganglion cell layers when administered subconjunctivally. EPO reached the retina 24 h after the subconjunctival administration, and was still present 60 h after the administration. Furthermore, it was also proved that EPO subconjunctival administration did not cause any haematopoietic significant side-effects. The subconjunctival route was shown to be a promising alternative for EPO ocular delivery.

Biodegradable nanoparticles for controlled subconjunctival delivery of latanoprost acid: In vitro and in vivo evaluation. Preliminary results

Purpose of the study was to develop and assess a novel controlled drug delivery system of latanoprost acid (LA). Poly(lactide)/Monomethoxy-poly(ethyleneglycol) (PLA-PEG) nanoparticles (NPs) were prepared using an emulsification-solvent evaporation technique. NPs were characterized in vitro according to their size, ζ-potential, drug entrapment efficiency and LA release. LA-loaded NPs (equivalent to 8.5 μg LA) were administered into the subconjunctival space of normotensive rabbits (group A). A free LA solution of the same drug content was subconjunctivally injected in a second rabbit group (group B), while blank NPs were administered in a third group (group C). A group of untreated animals (group D) served as the control. Intraocular pressure (IOP) was monitored for 8 consecutive days, using the Tono-pen XL. Aqueous humor (AH) levels of LA were evaluated for 6 days post-administration, by means of HPLC. Mean nanoparticle size was 80 nm. The drug entrapment efficiency was 18.3%. NPs sustained the release of LA over several days in vitro. Non-significant differences in baseline IOP were found between groups (p = 0.22). LA-loaded NPs exerted a significant hypotensive effect on group A, while IOP values remained significantly lower compared to the rest groups, throughout the study (p = 0.04). LA AH concentrations in group B continuously decreased with time, while LA levels in group A steadily increased. On day 6, LA levels were higher in group A compared to group B (344 ± 73.5 ng/ml and 228 ± 41.01 ng/ml, respectively). No adverse effects were observed. In conclusion, after subconjunctival administration, the LA-loaded NPs provided sustained LA delivery in vivo. They appear to be a promising system for the controlled subconjunctival delivery of LA.

Inhibition of Corneal Neovascularization with the Combination of Bevacizumab and Plasmid Pigment Epithelium-Derived Factor-Synthetic Amphiphile INTeraction-18 (p-PEDF-SAINT-18) Vector in a Rat Corneal Experimental Angiogenesis Model

Bevacizumab, a 149-kDa protein, is a recombinant humanized monoclonal antibody to VEGF. PEDF, a 50-kDa glycoprotein, has demonstrated anti-vasopermeability properties. In this study, we demonstrated that the combination of bevacizumab and plasmid pigment epithelium-derived factor-synthetic amphiphile INTeraction-18 (p-PEDF-SAINT-18) has a favorable antiangiogenic effect on corneal NV. Four groups (Group A: 0 μg + 0 μg, B: 0.1 μg + 0.1 μg, C: 1 μg + 1 μg, and D: 10 μg + 10 μg) of bevacizumab + p-PEDF-SAINT-18 were prepared and implanted into the rat subconjunctival substantia propria 1.5 mm from the limbus on the temporal side. Then, 1 μg of p-bFGF-SAINT-18 was prepared and implanted into the rat corneal stroma 1.5 mm from the limbus on the same side. The inhibition of NV was observed and quantified from days 1 to 60. Biomicroscopic examination, western blot analysis and immunohistochemistry were used to analyze the 18-kDa bFGF, 50-kDa PEDF and VEGF protein expression. No inhibition activity for normal limbal vessels was noted. Subconjunctival injection with the combination of bevacizumab and p-PEDF-SAINT-18 successfully inhibited corneal NV. The bFGF and PEDF genes were successfully expressed as shown by western blot analysis, and a mild immune response to HLA-DR was shown by immunohistochemistry. We concluded that the combination of bevacizumab and p-PEDF-SAINT-18 may have more potent and prolonged antiangiogenic effects, making it possible to reduce the frequency of subconjunctival bevacizumab administration combined with a relatively safe profile and low toxicity.

Corneal stromal abscessation in two horses treated with intracorneal and subconjunctival injection of 1% voriconazole solution

To describe and evaluate intrastromal and subconjunctival injection of voriconazole for the therapy of deep corneal stromal abscess (DSA) in horses. A retrospective clinical study describing the indications for intrastromal and subconjunctival voriconazole injection and the outcomes of this procedure in two eyes of two horses. The two horses in this study failed to respond to medical therapy. Treatment with intracorneal and subconjunctival administration of 1% voriconazole was performed in this study. Treatment with intracorneal and subconjunctival administration of 1% voriconazole was successful in resolving the corneal stromal abscess and the secondary uveitis. Immediate complications from the intracorneal injection occurred, which included corneal stromal lamellar fracture (2/2) and conjunctival hyperemia/chemosis (2/2). Also subconjunctival hemorrhage (1/2) due to the subconjuctival voriconazole injection occurred (2/2). Chronic complications of the intracorneal injection included mild-moderate corneal stromal fibrosis (2/2). This procedure may be an effective technique to treat refractory or relapsing DSA in horses. Intracorneal and subconjunctival voriconazole administration results in a visual and cosmetically acceptable globe. In equine DSA cases, the advantages of this technique compared with other medical and surgical approaches to this disease include shortened anesthesia times, minimal resultant scarring and shorter healing times, and lower cost of therapy.

Evaluation of the effects of resveratrol and bevacizumab on experimental corneal alkali burn

PurposeTo evaluate the effects of resveratrol and bevacizumab on experimental corneal neovascularization. MethodA corneal alkali burn was performed in 62 eyes of 31 male white Vienna rabbits. Resveratrol (group 1), dimethyl sulfoxide (group 2), bevacizumab (group 3) and 0.9% NaCl (group 4) were administered to both eyes of the rabbits by subconjunctival injection for 7 days. Corneal photos were taken at 15 days after alkali injury. Inflammatory index scores and neovascularization areas were calculated. ResultsIn bevacizumab group both inflammatory index scores and the calculation of the corneal neovascularization area was significantly less than the groups. ConclusionThe subconjunctival administration of bevacizumab inhibits corneal neovascularization effectively in the rabbit corneal alkali burn model. No effect of resveratrol to the corneal neovascularization on experimental model of the corneal alkali burn was seen at the doses of usage.