Intracameral Injection in Rats with Low Risk of Adverse Effects.

Intracameral injection is a standard administration routine in ophthalmology. The application of intracameral injection in rodents for research is challenging due to the limiting dimensions and anatomy of the eye, including the small aqueous humor volume, the lens curvature, and lens thickness. Potential damage during intracameral injections introduces adverse effects and experimental variability. This protocol describes a procedure for intracameral injection in rats, allowing precision and reproducibility. Sprague-Dawley rats were used as experimental models. Since the lens position in rats protrudes into the anterior chamber, injecting from the periphery, as done in humans, is unfavorable. Therefore, an incision is created in the central corneal region using a 31 gauge 0.8 mm stiletto blade to form a self-sealing tunnel into the anterior chamber. An incision at an angle close to the flat allows to create a long tunnel, which minimizes the loss of aqueous humor and shallowing of the anterior chamber. A 34 gauge nanoneedle is inserted into the tunnel for injection. This enables penetration with minimal friction resistance and avoids touching the lens. Injection of trypan-blue allows visualization by slit microscopy the presence of the dye in the anterior chamber and exclude leakage. Bioavailability to the corneal endothelial layer is demonstrated by injection of Hoechst dye, which stained the nuclei of corneal endothelial cells after injection. In conclusion, this protocol implements a procedure for accurate intracameral injection in rats. This procedure may be used for intracameral delivery of various drugs and compounds in experimental rat models, increasing the efficiency and reproducibility of ophthalmic research.

Sharper vision, steady hands: can robots improve subretinal drug delivery? Systematic review.

Subretinal injection (SI) is a novel drug delivery method, directly to retina for treatment of various eye disease. However, manual injection requires surgical experience and precision due to physiological factors. Robots offer solution to this issue, by reducing hand tremor and increased accuracy. This systematic review analyzes current status on robot-assisted SI compared to conventional techniques. Systematic search across 5 databases was conducted to identify studies comparing manual and robot-assisted SI procedures. Extracted data included robotic systems, complications, and success rates. Four studies, including one human trial, two ex vivo porcine eye studies, and one artificial eye model study were included in the synthesis. The findings show early advantages of robot-assisted SI. Compared to traditional interventions, robot procedures result in reduced tremor, what potentially lowers the risk of complications, including retinal tears and reflux. The first in-human randomized trial showed encouraging results, with no significant differences in surgical times or complications between robot-assisted and manual SI. However, major limitation of robot-assisted procedures is longer procedure time. Robot-assisted SI holds promise by offering increased precision and stability, reducing human error and potentially improving clinical outcomes. Challenges include cost, availability, and learning curve. Overall, early stage of robot-assisted SI suggests advantages in precision, complication reduction, and potentially improved drug delivery. Further research in human randomized trials is needed to fully assess its full-scale clinical application.

Gene Editing for CEP290-Associated Retinal Degeneration.

BACKGROUND: CEP290-associated inherited retinal degeneration causes severe early-onset vision loss due to pathogenic variants in CEP290. EDIT-101 is a clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) gene-editing complex designed to treat inherited retinal degeneration caused by a specific damaging variant in intron 26 of CEP290 (IVS26 variant). METHODS: We performed a phase 1-2, open-label, single-ascending-dose study in which persons 3 years of age or older with CEP290-associated inherited retinal degeneration caused by a homozygous or compound heterozygous IVS26 variant received a subretinal injection of EDIT-101 in the worse (study) eye. The primary outcome was safety, which included adverse events and dose-limiting toxic effects. Key secondary efficacy outcomes were the change from baseline in the best corrected visual acuity, the retinal sensitivity detected with the use of full-field stimulus testing (FST), the score on the Ora-Visual Navigation Challenge mobility test, and the vision-related quality-of-life score on the National Eye Institute Visual Function Questionnaire-25 (in adults) or the Children's Visual Function Questionnaire (in children). RESULTS: EDIT-101 was injected in 12 adults 17 to 63 years of age (median, 37 years) at a low dose (in 2 participants), an intermediate dose (in 5), or a high dose (in 5) and in 2 children 9 and 14 years of age at the intermediate dose. At baseline, the median best corrected visual acuity in the study eye was 2.4 log10 of the minimum angle of resolution (range, 3.9 to 0.6). No serious adverse events related to the treatment or procedure and no dose-limiting toxic effects were recorded. Six participants had a meaningful improvement from baseline in cone-mediated vision as assessed with the use of FST, of whom 5 had improvement in at least one other key secondary outcome. Nine participants (64%) had a meaningful improvement from baseline in the best corrected visual acuity, the sensitivity to red light as measured with FST, or the score on the mobility test. Six participants had a meaningful improvement from baseline in the vision-related quality-of-life score. CONCLUSIONS: The safety profile and improvements in photoreceptor function after EDIT-101 treatment in this small phase 1-2 study support further research of in vivo CRISPR-Cas9 gene editing to treat inherited retinal degenerations due to the IVS26 variant of CEP290 and other genetic causes. (Funded by Editas Medicine and others; BRILLIANCE ClinicalTrials.gov number, NCT03872479.).

Subconjunctival injection of rapamycin-loaded polymeric microparticles for effective suppression of noninfectious uveitis in rats.

Noninfective uveitis is a major cause of vision impairment, and corticosteroid medication is a mainstay clinical strategy that causes severe side effects. Rapamycin (RAPA), a potent immunomodulator, is a promising treatment for noninfective uveitis. However, because high and frequent dosages are required, it is a great challenge to implement its clinical translation for noninfective uveitis therapy owing to its serious toxicity. In the present study, we engineered an injectable microparticulate drug delivery system based on biodegradable block polymers (i.e., polycaprolactone-poly (ethylene glycol)-polycaprolactone, PCEC) for efficient ocular delivery of RAPA via a subconjunctival injection route and investigated its therapeutic efficacy in an experimental autoimmune uveitis (EAU) rat model. RAPA-PCEC microparticles were fabricated using the emulsion-evaporation method and thoroughly characterized using scanning electron microscopy, fourier transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry. The formed microparticles exhibited slow in vitro degradation over 28 days, and provided both in vitro and in vivo sustained release of RAPA over 4 weeks. Additionally, a single subconjunctival injection of PCEC microparticles resulted in high ocular tolerance. More importantly, subconjunctival injection of RAPA-PCEC microparticles significantly attenuated the clinical signs of EAU in a dose-dependent manner by reducing inflammatory cell infiltration (i.e., CD45+ cells and Th17 cells) and inhibiting microglial activation. Overall, this injectable microparticulate system may be promising vehicle for intraocular delivery of RAPA for the treatment of noninfective uveitis.

Posterior eye delivery of angiogenesis-inhibiting RNA nanoparticles via subconjunctival injection.

Neovascularization contributes to various posterior eye segment diseases such as age-related macular degeneration and diabetic retinopathy. RNA nanoparticles were demonstrated previously to enter the corneal and retinal cells after subconjunctival injection for ocular delivery. In the present study, antiangiogenic aptamers (anti-vascular endothelial growth factor (VEGF) and anti-angiopoietin-2 (Ang2) aptamers) were conjugated to RNA nanoparticles. The objectives were to investigate the clearance and distribution of these angiogenesis-inhibiting RNA nanoparticles after subconjunctival injection in vivo and their antiangiogenic effects for inhibiting ocular neovascularization in vitro. The results in the whole-body fluorescence imaging study showed that the clearance of RNA nanoparticles was size-dependent with no significant differences between RNA nanoparticles with and without the aptamers except for pRNA-3WJ. The distribution study of RNA nanoparticles by confocal microscopy of the dissected eye tissues in vivo indicated cell internalization of the larger RNA nanoparticles in the retina and retinal pigment epithelium after subconjunctival injection, and the larger nanoparticles with aptamers showed higher levels of cell internalization than those without. In the cell proliferation assay in vitro, RNA nanoparticles with multiple aptamers had higher antiangiogenic effects. With both longer retention time and high antiangiogenic effect, SQR-VEGF-Ang2 could be a promising RNA nanoparticle for posterior eye delivery.

Comparison of photodynamic therapy with two different parameters combined with subconjunctival injection of bevacizumab for corneal neovascularization.

BACKGROUND: To the best of our knowledge, no studies have been performed to determine the optimal parameters of photodynamic therapy (PDT) combined with subconjunctival injection of bevacizumab for corneal neovascularization. This study aimed to compare the effect of photodynamic therapy with two different sets of parameters combined with subconjunctival injection of bevacizumab for corneal neovascularization. METHODS: Patients with stable corneal neovascularization (CNV) unresponsive to conventional treatment (topical steroid) were included in this study. Patients were divided into two groups, receiving PDT with two different sets of parameters (group 1 receiving fluence of 50 J/cm2 at 15 min after intravenous injection of verteporfin with, group 2 receiving fluence of 150 J/cm2 at 60 min after intravenous injection of verteporfin with). Subconjunctival injection of bevacizumab was performed immediately after PDT. All patients were followed for 6 months. Best-corrected visual acuity and intraocular pressure were evaluated, and slit-lamp biomicroscopy as well as digital photography were performed. Average diameter and cumulative length of corneal neovascular were measured to evaluate the corneal neovascularization. RESULTS: Seventeen patients (20 eyes) were included in this study. At the last visit, the vision was improved in 12 eyes (60 %), steady in 4 eyes (20 %) and worsen in 4 eyes (20 %). The intraocular pressure (IOP) of all patients remained in normal range. A significant decrease in corneal neovascularization was showed in all the eyes after treatment. At 6 months after the combined treatment, the average diameter and cumulative length of vessels significantly decreased to 0.041 ± 0.023 mm (P < 0.05) and 18.78 ± 17.73 mm (P < 0.05), respectively, compared with the pretreatment data (0.062 ± 0.015 mm, 31.48 ± 18.21 mm). The reduction was more remarkable in group 2 compared to group 1.In group 1, the average diameter was 0.062 ± 0.013mm before and 0.056 ± 0.017mm after, the cumulative length of vessels was 38.66 ± 22.55mm before and 31.21 ± 17.30 after. In group 2, the date were 0.061 ± 0.016mm before and 0.029 ± 0.020mm after, 25.60 ± 8.95 mm before and 8.61 ± 8.26 mm. The reported complications included epithelial defect in four eyes, small white filaments in two eyes and corneal epithelial erosion in two eyes. CONCLUSION: The PDT combined with subconjunctival injection of bevacizumab was effective for the chronic corneal neovascularization. A more promising treatment outcome was observed when PDT was performed at 60 min after intravenous injection of verteporfin with fluence of 150 J/cm2. No serious complications or systemic events were observed throughout the follow-up period.

SUPRACHOROIDAL SPACE INJECTION TECHNIQUE: Expert Panel Guidance.

PURPOSE: To develop professional guidelines for best practices for suprachoroidal space (SCS) injection, an innovative technique for retinal therapeutic delivery, based on current published evidence and clinical experience. METHODS: A panel of expert ophthalmologists reviewed current published evidence and clinical experience during a live working group meeting to define points of consensus and key clinical considerations to inform the development of guidelines for in-office SCS injection. RESULTS: Core consensus guidelines for in-office SCS injection were reached and reported by the expert panel. Current clinical evidence and physician experience supported SCS injection as a safe and effective method for delivering retinal and choroidal therapeutics. The panel established consensus on the rationale for SCS injection, including potential benefits relative to other intraocular delivery methods and current best practices in patient preparation, pre- and peri-injection management, SCS-specific injection techniques, and postinjection management and follow-up. CONCLUSION: These expert panel guidelines may support and promote standardization of SCS injection technique, with the goal of optimizing patient safety and outcomes. Some aspects of the procedure may reasonably be modified based on the clinical setting and physician judgment, as well as additional study.

VITRECTOMY WITH SUBRETINAL INJECTION OF RECOMBINANT TISSUE PLASMINOGEN ACTIVATOR FOR SUBMACULAR HEMORRHAGE WITH OR WITHOUT VITREOUS HEMORRHAGE.

PURPOSE: To evaluate the outcomes and prognostic factors of pars plana vitrectomy combined with subretinal injection of recombinant tissue plasminogen activator for submacular hemorrhage (SMH) patients with or without vitreous hemorrhage (VH). METHODS: Sixty-four eyes of 64 patients with SMH underwent pars plana vitrectomy with subretinal injection of recombinant tissue plasminogen activator. Best-corrected visual acuity, SMH displacement, and postoperative complications were analyzed. Predictive factors of the final best-corrected visual acuity were determined using multivariant linear regression. RESULTS: There were 26 eyes with VH and 38 eyes without VH best-corrected visual acuity significantly improved in both VH group (from 2.27 ± 0.40 to 1.25 ± 0.70 logarithm of the minimum angle of resolution) and non-VH group (from 1.76 ± 0.55 to 0.85 ± 0.65 logarithm of the minimum angle of resolution). Complete displacement of SMHs was observed in 47 (73.43%) eyes. Postoperative complications included recurrent SMH (4.69%), recurrent VH (10.94%), rhegmatogenous retinal detachment (3.13%), and epiretinal membrane (4.68%). Treatment-naive condition, early surgery, and younger age were significantly associated with better final best-corrected visual acuity ( B = 0.502, 0.303, and 0.021, respectively, with all P < 0.05). CONCLUSION: Pars plana vitrectomy combined with subretinal recombinant tissue plasminogen activator injection is an effective treatment for SMH patients with and without VH.

Iris atrophy following intracameral dexamethasone injection: a report of two pediatric cases.

We report 2 pediatric cases of iris atrophy that developed roughly 1 month after intracameral injection of dexamethasone suspension 9% following unilateral goniotomy and cataract extraction.

Intraocular cetuximab: Safety and effect on axial elongation in young Guinea pigs with lens-induced myopization.

This study aimed to examine the intraocular tolerability of the epidermal growth factor receptor antibody cetuximab, when applied intravitreally, and its effect on axial elongation. Guinea pigs aged 2-3 weeks were subjected to bilateral plano glasses and bilateral lens-induced myopization (LIM) as a single procedure for group I (n = 8) and group II (n = 8), respectively. In the animals of group III (n = 8), group IV (n = 8), and group V (n = 8), the right eyes of the animals, in addition to LIM, received four weekly intravitreal injections of cetuximab (Erbitux®) in doses of 6.25 µg, 12.5 µg, and 25 µg, respectively. As controls, the left eyes, in addition to LIM, received corresponding intraocular injections of phosphate-buffered saline. The animals underwent regular ophthalmoscopic examinations and biometry for axial length measurements. With increasing doses of cetuximab, the inter-eye difference in axial elongation (at study end, left eyes minus right eyes) were significantly the smallest in group I (0.00 ± 0.02 mm) and group II (-0.01 ± 0.02 mm), they were larger in group III (0.04 ± 0.04 mm) and group IV (0.10 ± 0.03 mm), and they were the largest in group V (0.11 ± 0.01 mm). The inter-eye difference in axial elongation enlarged (P < 0.001) with the number of injections applied. Retinal thickness at the posterior pole (right eyes) was significantly thicker in group V than in group II (P < 0.01). The density of apoptotic cells (visualized by TUNEL-staining) did not vary significantly between any of the groups (all P > 0.05). The results suggest that intravitreal injections of cetuximab in young guinea pigs with LIM resulted in a reduction in axial elongation in a dose-dependent and number of treatment-dependent manner. Intraocular toxic effects, such as intraocular inflammation, retinal thinning, or an increased density of apoptotic cells in the retina, were not observed in association with the intravitreally applied cetuximab.

The impact of SARS-Cov-2 infection on the periocular injection pain and hypersensitive reaction to botulinum toxin type A: results from clinical questionnaires.

Background: The COVID-19 pandemic has brought about significant changes in the medical field, yet the use of botulinum toxin type A has remained uninterrupted. Plastic surgeons must carefully consider the timing of administering botulinum toxin type A to patients who have recovered from COVID-19. Methods: A questionnaire survey was conducted among patients who had contracted and recovered from SARS-CoV-2 within a month. The survey aimed to investigate various indicators in patients who had received botulinum toxin A injections at the same site before and after their infection, including pain scores and allergic reactions and the occurrence of complications. Results: The pain scores of patients who contracted SARS-CoV-2 infection between 14-21 days post-infection exhibited significant variation from previous injections. However, patients who contracted the infection between 22-28 days post-infection did not exhibit significant variation from previous injections. Furthermore, the incidence of allergic reactions and complications following botulinum toxin injection within one month after contracting the infection did not significantly differ from that observed prior to infection. Conclusion: Administering botulinum toxin type A three weeks after COVID-19 recovery is a justifiable and comparatively secure approach.

Periocular methotrexate versus periocular triamcinolone injections for active thyroid-associated orbitopathy: a randomized clinical trial.

PURPOSE: To assess the efficacy and safety of periocular injections of methotrexate versus triamcinolone in the management of active thyroid-associated orbitopathy. STUDY DESIGN: Prospective, double-masked, randomized clinical trial. METHODS: Participants with bilateral active, moderate-to-severe thyroid-associated orbitopathy were randomly assigned to receive three periocular injections of 7.5 mg methotrexate in one orbit and three periocular injections of 20 mg triamcinolone in the contralateral orbit. RESULTS: Among the enrolled 25 patients, 18 patients completed the study. A statistically significant reduction of the mean clinical activity score was detected in both arms (from 5.2 ± 0.89 at baseline to 0.9 ± 1.7 at study endpoint, p-value < 0.001 in the methotrexate arm, and from 5.1 ± 0.9 at baseline to 1 ± 1.7 at study endpoint, p-value < 0.001 in the triamcinolone arm), mean proptosis also decreased in both arms (from 25.2 ± 3.4 mm at baseline to 23.8 ± 3.7 mm at study endpoint, p-value = 0.01 in the methotrexate arm, and from 24.2 ± 3.06 mm at baseline to 23.2 ± 3.3 mm at study endpoint, p-value = 0.049 in the triamcinolone arm). Lid aperture and soft tissue signs improved significantly in both arms in comparison to baseline. A statistically significant reduction in the intraocular pressure was observed in the methotrexate arm but not in the triamcinolone arm. 88.9% of patients in both arms were overall responders at 6 months. There was no significant difference in mean CAS, proptosis, lid aperture or rate of responders between the two arms at any visit. Both drugs were found to be safe with minimal local and systemic complications. CONCLUSION: Periocular injections of methotrexate represent an effective and safe alternative option for the management of active, moderate-to-severe thyroid-associated orbitopathy. Although no serious complications occurred during the 6-month follow-up, the possibility of late complications such as orbital fat atrophy cannot be ruled out.

Displacement of Submacular Hemorrhage With Vitrectomy Combined With Subretinal Balanced Salt Solution and Air.

PURPOSE: To describe a technique of displacement of submacular hemorrhage (SMH) using subretinal injection of balanced salt solution and filtered air. METHODS: Patients presenting within 2 weeks of massive SMH (>4 disk diameter) were prospectively included. All patients underwent 25-gauge pars plana vitrectomy, posterior vitreous detachment, injection of subretinal balanced salt solution and filtered air followed by partial fluid air exchange, 20% sulfur hexafluoride tamponade, and heads-up positioning postoperatively. Degree of displacement of SMH was assessed at 1 month and change in best-corrected visual acuity was assessed at 3 months. RESULTS: Ten patients with massive SMH who underwent the aforementioned procedure were included. Complete displacement of bleed from the macula was achieved in nine (90%) of 10 eyes at 1 month. There was significant improvement in best-corrected visual acuity from baseline at 1 month ( P = 0.015) and 3 months ( P = 0.043). CONCLUSION: Pars plana vitrectomy with injection of subretinal balanced salt solution and filtered air was well-tolerated and efficacious in displacing large and thick SMH in patients operated within 2 weeks of onset of symptoms.

Recent advances and future prospects: Current status and challenges of the intraocular injection of drugs for vitreoretinal diseases.

Effective drug therapy for vitreoretinal disease is a major challenge in the field of ophthalmology; various protective systems, including anatomical and physiological barriers, complicate drug delivery to precise targets. However, as the eye is a closed cavity, it is an ideal target for local administration. Various types of drug delivery systems have been investigated that take advantage of this aspect of the eye, enhancing ocular permeability and optimizing local drug concentrations. Many drugs, mainly anti-VEGF drugs, have been evaluated in clinical trials and have provided clinical benefit to many patients. In the near future, innovative drug delivery systems will be developed to avoid frequent intravitreal administration of drugs and maintain effective drug concentrations for a long period of time. Here, we review the published literature on various drugs and administration routes and current clinical applications. Recent advances in drug delivery systems are discussed along with future prospects.

Modified-dropless protocol (nil intraocular) for micro-incision vitrectomy surgery (MIVS): a retrospective pilot study.

BACKGROUND: Perioperative infection and inflammation prophylaxis after ocular surgery has evolved over the years along with improvements in surgical equipment and a growing interest in alternatives to the standard topical eye drops. The purpose of this study is to evaluate the outcomes of a novel, modified-dropless protocol for 23-gauge (23-G), 25-gauge (25-G) and 27-gauge (27-G) micro-incision vitrectomy surgery (MIVS) that omits any intraocular injections of antibiotics or steroids. METHODS: This Institutional Review Board-approved, single-surgeon retrospective study reviewed MIVS post-surgical outcomes in patients who received a modified-dropless protocol from February 2020 to March 2021. A total of 158 charts were reviewed, of which 150 eyes met the eligibility criteria. After each case, patients were administered a 0.5 cc subconjunctival injection of a 1:1 Cefazolin (50 mg/cc):Dexamethasone (10 mg/cc) in the inferior fornix and 0.5 cc of posterior Sub-Tenon's Kenalog (STK). No intravitreal injections were administered, and no pre- or postoperative antibiotic or steroid eye drops were prescribed. For patients allergic to penicillin, separate subconjunctival injections of 0.25 cc each of Vancomycin (10 mg/cc) and Dexamethasone (10 mg/cc) were administered. The primary safety parameter was postoperative cases of endophthalmitis. Secondary endpoints consisted of Best-Corrected Distance Visual Acuity (BCVA), intraocular pressure (IOP), and postoperative complications (retinal detachments, inflammation, need for additional surgery) within three months of surgery. Statistical analysis was performed using chi-square (χ²) tests for categorical values, and a Student's t-test to compare continuous outcomes. RESULTS: The majority of surgeries (96%) were performed with the 27G MIVS platform. There were no cases of postoperative endophthalmitis. Mean logMAR BCVA improved from 0.71 (± 0.67) to 0.61 (± 0.60) post-operatively (p = 0.02). Excluding patients who had silicone oil tamponade, postoperative BCVA improved from 0.67 (± 0.66) to 0.54 (± 0.55) (p = 0.003). Mean IOP increased from 14.6 (± 3.8) to 15.3 (± 4.1) (p = 0.05). Ten patients required further medication therapy for an increase in IOP, one had inflammatory signs, and 14 required a second surgical intervention mostly due to recurrences of initial surgical indication. CONCLUSION: A modified-dropless postoperative protocol involving subconjunctival and posterior sub-Tenon's injections only may be a safe and convenient alternative to topical eye drops for patients undergoing MIVS, but additional and larger studies are needed.

Effects of the periocular botulinum toxin on the ocular surface and anterior chamber: a prospective study in patients with hemifacial spasm and blepharospasm.

PURPOSE: To analyze using Pentacam®, the corneal and anterior chamber changes following periocular botulinum toxin injection in patients with facial dystonia. METHODS: Prospective study that included patients with facial dystonia that were going to receive a periocular botulinum toxin injection for the first time or six months or more after the previous injection. A Pentacam® examination was carried out in all patients before and 4 weeks after the injection. RESULTS: Thirty-one eyes were included. Twenty-two had a diagnosis of blepharospasm and nine of hemifacial spasm. Analysis of corneal and anterior chamber parameters revealed a significant decrease in iridocorneal angle after botulinum toxin injection (from 35 ± 10º to 33.8 ± 9.7º, p = 0.022). No other corneal or anterior chamber parameters changed significantly after the injection. CONCLUSIONS: Periocular botulinum toxin injection causes narrowing of the iridocorneal angle.

A novel recombinant human microplasminogen induced complete posterior vitreous detachment without morphological change of retina in juvenile rabbits.

Vitreomacular traction syndrome results from persistent vitreoretinal adhesions in the setting of partial posterior vitreous detachment (PVD). Vitrectomy and reattachment of retina is an effective therapeutic approach. The adhesion between vitreous cortex and internal limiting membrane (ILM) of the retina is stronger in youth, which brings difficulties to induce PVD in vitrectomy. Several clinical investigations demonstrated that intravitreous injection of plasmin before vitrectomy could reduce the risk of detachment. In our study, a novel recombinant human microplasminogen (rhµPlg) was expressed by Pichia pastoris. Molecular docking showed that the binding of rhµPlg with tissue plasminogen activator (t-PA) was similar to plasminogen, suggesting rh µPlg could be activated by t-PA to generate microplasmin (µPlm). Moreover, rhµPlg had higher catalytic activity than plasminogen in amidolytic assays. Complete PVD was found at vitreous posterior pole of 125 µg rhµPlg-treated eyes without morphological change of retina in juvenile rabbits via intraocular injection. Our results demonstrate that rhµPlg has a potential value in the treatment of vitreoretinopathy.

Generating Widespread and Scalable Retinal Lesions in Adult Zebrafish by Intraocular Injection of Ouabain.

Zebrafish regenerate functional retinal neurons after injury. Regeneration takes place following photic, chemical, mechanical, surgical, or cryogenic lesions, as well as after lesions that selectively target specific neuronal cell populations. An advantage of chemical retinal lesion for studying the process of regeneration is that the lesion is topographically widespread. This results in the loss of visual function as well as a regenerative response that engages nearly all stem cells (Müller glia). Such lesions can therefore be used to further our understanding of the process and mechanisms underlying re-establishment of neuronal wiring patterns, retinal function, and visually mediated behaviors. Widespread chemical lesions also permit the quantitative analysis of gene expression throughout the retina during the period of initial damage and over the duration of regeneration, as well as the study of growth and targeting of axons of regenerated retinal ganglion cells. The neurotoxic Na+/K+ ATPase inhibitor ouabain specifically offers a further advantage over other types of chemical lesions in that it is scalable; the extent of damage can be targeted to include only inner retinal neurons, or all retinal neurons, simply by adjusting the intraocular concentration of ouabain that is used. Here we describe the procedure through which these "selective" vs. "extensive" retinal lesions can be generated.

In Situ Formation of Injectable Gelatin Methacryloyl (GelMA) Hydrogels for Effective Intraocular Delivery of Triamcinolone Acetonide.

A novel drug delivery system designed for intraocular injection, gelatin methacryloyl (GelMA), has attracted much attention due to its sustained-release character and low cytotoxicity. We aimed to explore the sustained drug effect of GelMA hydrogels coupled with triamcinolone acetonide (TA) after injection into the vitreous cavity. The GelMA hydrogel formulations were characterized using scanning electron microscopy, swelling measurements, biodegradation, and release studies. The biological safety effect of GelMA on human retinal pigment epithelial cells and retinal conditions was verified by in vitro and in vivo experiments. The hydrogel exhibited a low swelling ratio, resistance to enzymatic degradation, and excellent biocompatibility. The swelling properties and in vitro biodegradation characteristics were related to the gel concentration. Rapid gel formation was observed after injection, and the in vitro release study confirmed that TA-hydrogels have slower and more prolonged release kinetics than TA suspensions. In vivo fundus imaging, optical coherence tomography measurements of retinal and choroid thickness, and immunohistochemistry did not reveal any apparent abnormalities of retinal or anterior chamber angle, and ERG indicated that the hydrogel had no impact on retinal function. The GelMA hydrogel implantable intraocular device exhibited an extended duration, in situ polymerization, and support cell viability, making it an attractive, safe, and well-controlled platform for treating the posterior segment diseases of the eye.

RETINAL TOXICITY FOLLOWING PRESUMED INADVERTENT INTRAOCULAR INJECTION OF MITOMYCIN C DURING TRABECULECTOMY.

PURPOSE: To describe a case of postoperative retinal toxicity following the use of mitomycin C during a routine trabeculectomy. METHODS: Case report of a single patient who underwent complete ophthalmic examination and multimodal imaging, including color fundus photos, optical coherence tomography, fundus autofluorescence, and fluorescein angiography. The study was declared exempt by the Institutional Review Board of Northwestern University. This research followed the tenets of the Declaration of Helsinki. RESULTS: The patient developed profound vision loss and retinal damage during the postoperative course. Posterior segment findings include loss of vascular perfusion, diffuse loss of the outer, then inner, retinal layers, and subsequent total retinal detachment. CONCLUSION: Although mitomycin C is commonly used in glaucoma filtering surgeries, reports of postoperative posterior segment toxicity are rare. The etiology of postoperative toxicity in this case is probable inadvertent intraocular injection of mitomycin C.