Complications of intravitreal steroid injections

Anterior uveitis for the comprehensive ophthalmologist

Anterior uveitis presents a diagnostic challenge due to its wide array of etiologies and clinical manifestations. This narrative review aims to equip general ophthalmologists with a comprehensive understanding of anterior uveitis epidemiology, diagnosis, and treatment. Particular emphasis is placed on developing a tailored and stepwise strategy, rather than a one-size-fits-all approach, for the workup and treatment of anterior uveitis. Chest radiography and serologic testing for syphilis, human leukocyte antigen B27, and angiotensin-converting enzyme are appropriate routine investigations in cases of severe, bilateral, recurrent, or chronic anterior uveitis. Additional testing should be guided by clinical findings and regional epidemiology, especially when considering expensive and invasive modalities. Investigations that are obtained in the absence of clinical and epidemiologic orientation are of limited utility and incur significant costs to patients and health care systems. Most cases of anatomically isolated anterior uveitis resolve with topical corticosteroids, but some patients require escalation to systemic immunomodulatory therapy (IMT). IMT should be considered in patients who respond poorly to corticosteroids, develop side effects related to corticosteroids that limit their use, require high doses to maintain disease remission, or have concomitant systemic inflammatory disease. Comprehensive ophthalmologists should feel comfortable comanaging patients that require conventional disease-modifying antirheumatic drugs/antimetabolite therapy (i.e., methotrexate, azathioprine, and mycophenolate mofetil) with rheumatologists and providing guidance on ocular dosing. When uveitis quiescence cannot be achieved despite maximally tolerated antimetabolite therapy, patients should be referred to a uveitis specialist for consultation and consideration of IMT escalation. The timing of uveitis referral may depend on local factors specific to health care jurisdictions.

Management of Uveitis Patients on Anti-TNF Agents Who Develop Demyelinating Disease - A Case Series

BACKGROUND/AIMS

Anti-tumor necrosis factor (Anti-TNF) agents have proven beneficial for the treatment of chronic non-infectious uveitis, yet rare neurological complications and demyelinating disease can occur with their use. Management of uveitis and neurological disease after developing these rare complications is not well understood. We sought to identify these specific cases and their outcomes through a retrospective observational case series.

METHODS

Electronic Medical Record (EMR) chart review of 394 non-infectious uveitis patients on anti-TNF therapy focused on identifying patients seen by uveitis specialists at a single institution who were on anti-TNF therapy and had developed neurological symptoms. Cases were reviewed for subsequent management and outcomes of both their neurologic and ocular inflammatory disease.

RESULTS

Five (5) patients were included following complaints of neurological symptoms while on anti-TNF therapy. Subsequent demyelinating diagnosis, acute treatment, and long-term course were described. All five patients continue to be inactive at around three years of anti-TNF discontinuation.

CONCLUSION

Unidentified rare neurological symptoms and demyelinating disease associated with the use of anti-TNF agents can be detrimental to patient treatment outcomes. Emphasis is given on possible avoidance and early identification of exacerbating underlying disease through a detailed neurologic history and use of imaging when suspicion is high. Patients may have no evidence of higher neurological risk prior to starting an anti-TNF treatment. Discontinuation of an anti-TNF agent and subsequent control of disease is possible with alternative immunosuppressive treatments.

Effects of intrapolyp steroid injection on intraocular pressure and recurrent polyp treatment

Purpose

To examine the effects of intrapolyp triamcinolone acetonide (TA) injections on intraocular pressure (IOP) and recurrence of nasal polyps after endoscopic sinus surgery.

Patients and methods

This was a prospective, randomized, double-blind, placebo-controlled study. Patients were randomized into either the TA injection group (Group I, 20 mg/ml, 2 mL) or the placebo normal saline injection group (group II, 2 mL). There were a total of five study visits: one baseline visit and one at 2, 4, 8, and 12 w after the injection. The primary safe outcome was the change in IOP between two groups at 4 w. The secondary safe outcome was the IOP at each visit and proportion of patients having IOP above 21 mmHg at 4 and 8 w. Changes in the nasal polyp size were measured between two groups at each visit.

Results

A total of 43 consenting participants completed this study (22 in group I and 21 in group II). The mean IOP elevation in both eyes was not significantly different between the groups (p > 0.05) and was not over 2 mmHg at the 4-w mark. There was also no significant difference in the proportion of patients having IOP above 21 mmHg at 4 and 8 w between the groups (p > 0.05). However, there was a significant difference in the change in polyp size until 8 w between both groups (p < 0.01).

Conclusions

Intrapolyp TA injection is a safe and effective method for the management of recurrent polyps after endoscopic sinus surgery.

Intravitreal injection associated rhegmatogenous retinal detachment: outcomes of a European analysis

Purpose

As the number of intravitreal injections (IVI) increases annually, this study aimed to assess the anatomical and functional outcomes following rhegmatogenous retinal detachment (RRD) surgery for IVI-associated RRD (IVARD).

Methods

All non-vitrectomized eyes developing IVARD since 2007 in two European vitreoretinal centers (Department of Ophthalmology, LMU Munich, Germany, and Eye Clinic Luigi Sacco, University of Milan, Milan, Italy) were included. Main outcomes were primary and secondary retinal attachment rate after surgery, rate of proliferative vitreoretinopathy (PVR), and final functional result. Ten years of incidence rates per injection were calculated for one center.

Results

Fifty-two eyes of 52 patients comprised the study. Primary anatomic success rate was 83% (n = 43) and secondary 96% (n = 50). PVR was observed in all uveitic eyes (n = 3), in eyes with postoperative cystoid macular edema (n = 2), and in 8 of 9 eyes that received the dexamethasone implant (DEX). Age, number of prior injections, duration of symptoms, or time between last IVI and RRD did not show any statistically significant differences with regard to presence of PVR or not. Mean BCVA improved in 28 cases, remained stable in 16 cases, and worsened in 8 cases. The RRD incidence rate was statistically significant higher for DEX and ocriplasmin compared with that for anti-VEGF agents.

Conclusion

The anatomical result after one surgical intervention seems acceptable, but the final visual outcome remains rather poor, because of the underlying macular disease. In our population, injection with DEX is associated with higher IVARD rate, presence and development of PVR, and recurrent RRD in comparison with anti-VEGF agents.

Ophthalmic Drops with Nanoparticles Derived from a Natural Product for Treating Age-Related Macular Degeneration

There is a continuing, urgent need for an ophthalmic (eye) drop for the clinical therapy of age-related macular degeneration (AMD), a leading cause of blindness. Here, we report the first formulation of an eye drop that is effective via autophagy for AMD treatment. This eye drop is based on a single natural product derivative (ACD), which is an amphiphilic molecule containing a 6-aminohexanoate group (H₂N(CH₂)₅COO-). We demonstrate that this eye drop reverses the abnormal angiogenesis induced in a primate model of AMD that has the pathological characteristics close to that of human AMD. The ACD molecule was self-assembled in an aqueous environment leading to nanoparticles (NPs) about 9.0 nm in diameter. These NPs were encapsulated in calcium alginate hydrogel. The resulting eye drop effectively slowed the release of ACD and displayed extended release periods in both simulated blood (pH 7.4) and inflammatory (pH 5.2) environments. We show that the eye drop penetrated both the corneal and blood-eye barriers and reached the fundus. With low cellular toxicity, the drop targeted S1,25D₃-membrane-associated rapid response steroid-binding protein (1,25D₃-MARRS) promoting autophagy in a dose-dependent manner. In addition, the drop inhibited cell migration and tubular formation. On the other hand, when protein 1,25D₃-MARRS was knocked down, the eye drop did not exhibit such inhibition functionalities. Our study indicates that the 6-aminohexanoate group on self-assembled NPs encapsulated in hydrogel leads to the positive in vivo outcomes. The present formulation offers a promising approach for clinical treatment of human AMD.

Implantable anti-angiogenic scaffolds for treatment of neovascular ocular pathologies

The retinal physiology can accrue oxidative damage and inflammatory insults due to age and metabolic irregularities. Two notable diseases that involve retinal and choroidal neovascularization are proliferative diabetic retinopathy and wet age-related macular degeneration. Currently, these diseases are mainly treated with anti-VEGF drugs (VEGF = vascular endothelial growth factor), generally on a monthly dosage scheme. We discuss recent developments for the treatment of these diseases, including bioactive tissue-engineered materials, which may reduce frequency of dosage and propose a path forward for improving patient outcomes. Graphical abstract Development of materials for long-term intravitreal delivery for management of posterior segment diseases.

[Modern approaches to treatment of postsurgical macular edema]

Postsurgical macular edema, known as Irvine-Gass syndrome, is one of the possible causes of reduced visual acuity in ophthalmic surgery. The article reviews and summarizes data on the main approaches to the treatment of this pathology, discusses the main groups of drugs used to manage postoperative macular edema.

[Medicamental correction of pathomorphological changes of the ocular surface in patients with steroid therapy intolerance after photorefractive keratectomy]

INTRODUCTION

The problems of controlling inflammatory and proliferative response of the retina and correcting tear production in the post-operative period after photorefractive keratectomy (PRK) have not been fully solved yet. Patients intolerable to local steroids require an alternative. One drug that covers those needs is Cyclosporine 0.05%.

PURPOSE

To analyze clinical effectiveness of Restasis eye drops in solving inflammatory-degenerative response and tear production insufficiency (dry eye syndrome) for post-PRK patients with steroid eye drops intolerance accompanied with increasing intraocular pressure (IOP).

PATIENTS AND METHODS

Retrospective analysis of 14 myopic patients (28 eyes) was conducted; mean patient age was 25.9±6 years; myopia was (-)5.65±1.5 Diopters of spherical equivalent (SE); corneal-compensated IOP was 16.98±3.68 mm Hg before the surgery. All patients underwent excimer laser correction (PRK or Trans-PRK) with Schwind Amaris (SCHWIND eye-tech-solutions). After epithelization, all patients were prescribed 0.1% Dexamethasone solution 4 times a day (with decreasing dosing frequency) for 2 months, as well as local lubricants. The article also describes a separate clinical case of subepithelial fibroplasia that occurred post-PRK and was successfully stopped.

RESULTS

All patients had transitory IOP increase caused by local steroid therapy. Mean IOP at 1-month post-op was 20.5±7 mm Hg. At that point local steroids were replaced with 'Restasis' 0.05% (Cyclosporine) eye drops prescribed 2 times per day for 2 months. As the result, IOP values decreased to 16.2±3.21 mm Hg (without any additional therapy); at 6 months mean uncorrected visual acuity reached 0.98±0.05, best corrected visual acuity achieved 1.03±0.06 and SE was 0.04±0.12 Diopters.

CONCLUSION

Local Cyclosporine ('Restasis') is the method of choice for regulation of inflammatory and degenerative response and tear production insufficiency (dry eye syndrome) for post-PRK patients with intolerance to steroid eye drops.

Enhancing the efficacy of fluocinolone acetonide by encapsulating with PLGA nanoparticles and conjugating with linear PEG polymer

Fluocinolone acetonide (FA), a glucocorticoid is used to treat inflammation in the posterior segment of the eye. Due to short half-life and body clearance, it will not be able to give therapeutic effect for long time with a single injection. Formulating FA nanoparticles (NPs) or PEG conjugates can be an effective way to overcome these disadvantages. We prepared two formulations, FA loaded in PLGA nanoparticles (NPs-FA) and FA conjugated to linear PEG (PEG-FA). The NPs-FA were characterised for size and zeta potential using particle size analyser and shape and morphology by using scanning electron microscope (SEM). The amount of drug loaded per mg of NPs and in-vitro release of FA from NPs were calculated using reverse phase high pressure liquid chromatography (RP-HPLC). NPs synthesis was optimized with factorial and Response Surface Methodology (RSM). Chemically synthesized PEG-FA conjugates were characterized using H-NMR and purity of the conjugate was analysed using RP-HPLC. Visualization of cellular uptake of NPs was done by coumarin-6 loaded NPs under fluorescent microscope. RAW 264.7 macrophages were treated with NPs-FA and PEG-FA conjugates to study their effectiveness in inhibiting TNF-α levels compared to free FA treatment. Stability test confirmed that FA is more stable within NPs than in free form. Particle size and zeta potential were found to be 183.6 ± 12.47nm and -25.6 ± 4.4mV, respectively. 149.58 ± 11.3µg of FA was encapsulated per mg of NPs and 61 µg of FA was present per mg of PEG-FA conjugate. In vitro drug release study showed a sustained release of FA from the NPs for a period of 30 days. Fluorescent microscope images showed uptake of NPs by RAW 264.7 cells. TNF-α assay confirmed that substantial inhibition of TNF-α levels from both formulations compared to free FA. From the results, we conclude that new formulations will greatly reduce drug dosage and frequency of administration for long term treatment of inflammation in posterior part of the eye.

Humanin Nanoparticles for Reducing Pathological Factors Characteristic of Age-Related Macular Degeneration

BACKGROUND

Humanin is a novel neuronal peptide that has displayed potential in the treatment of Alzheimer's Disease through the suppression of inflammatory IL-6 cytokine receptors. Such receptors are found throughout the body, including the eye, suggesting its other potential applications. Age-related Macular Degeneration (AMD) is the leading cause of blindness in the developing world. There is no cure for this disease, and current treatments have several negative side effects associated with them, making finding other treatment options desirable.

OBJECTIVE

In this study, the potential applications in treating AMD for a more potent humanin derivative, AGA-HNG, were studied.

METHODS

AGA-HNG was synthesized and encapsulated in chitosan Nanoparticles (NPs), which were then characterized for their size, Encapsulation Efficiency (EE), and drug release. Their ability to suppress VEGF secretion and protect against oxidative apoptosis was studied in vitro using ARPE-19 cells. The chitosan NPs exhibited similar anti-VEGF properties and oxidative protection as the free protein while exhibiting superior pharmaceutical characteristics including biocompatibility and drug release.

RESULTS

Drug-loaded NPs exhibited a radius of 346nm with desirable pharmacokinetic properties including a stable surface charge (19.5 ± 3.7 mV) and steady drug release capacity. AGA-HNG showed great promise in mediating apoptosis in hypoxic cells. They were also able to significantly reduce VEGF expression in vitro with reduced cellular toxicity compared to the free drug.

CONCLUSION

The ability of this drug delivery system to reduce retinal apoptosis with desirable pharmacokinetic and biocompatible properties makes this a promising therapeutic option for AMD.

Nanodelivery of doxorubicin for age-related macular degeneration

OBJECTIVE

Polymeric nanoparticles (NPs) containing doxorubicin (DOX) were prepared for the inhibition of hypoxia-induced factor 1α (HIF-1α).

SIGNIFICANCE

HIF-1α is responsible for the upregulation of several angiogenic factors, including vascular endothelial growth factor (VEGF). DOX inhibits HIF-1α but is highly toxic. By encapsulating DOX in NPs, drug delivery will be sustained and toxicity will be reduced without limiting efficacy.

METHODS

DOX NPs were prepared using both polylactic coglycolic acid (PLGA) and chitosan. PLGA NPs were prepared via nanoprecipitation (NPC) and single and double emulsion diffusion (SE; DE). Chitosan NPs were formulated using ionic gelation (IG), and complex coacervation (CC). Size, polydispersity index (PDI), and zeta potential (ZP) were determined via dynamic light scattering (DLS) (n = 3). The encapsulation efficiency (EE), drug loading capacity (DLC) (n = 3) and in vitro drug release profiles (IVR) at 37 °C (n = 4) were analyzed via spectroscopy at 480 nm (λ_max). The cytotoxicity of each formulation as well as free DOX solution in ARPE-19 cells was determined via MTT assay after 24 h (n = 3). HIF-1α and VEGF inhibition in ARPE-19 cells were measured via ELISA (n = 3).

RESULTS

The results were consistent with the hypothesis; the NP formulations decreased HIF-1α and VEGF-A expression in ARPE-19 cells with reduced cytotoxicity. SE, DE, and CC demonstrated low ZP as well as the most rapid drug release of the tested formulations. FTIR confirmed the presence of DOX on the SE NP surface, indicating instability.

CONCLUSIONS

SE, DE, and CC destabilized. NPC was the most efficient formulation for the nanodelivery of DOX for AMD.

The USER Study: A Chart Review of Patients Receiving a 0.2 µg/day Fluocinolone Acetonide Implant for Diabetic Macular Edema

Introduction

To determine anatomical, functional, and intraocular pressure (IOP) responses to diabetic macular edema (DME) treatments pre- and post-0.2 µg/day fluocinolone acetonide (FAc) implant administration compared with baseline and the preceding 3 years.

Methods

This was a retrospective, chart review, cohort study in four U.S. centers. Patients received the 0.2 µg/day FAc implant for the treatment of DME in at least one eye before January 1, 2016. DME treatments administered up to 36 months pre-FAc implant and up to 24 months post-FAc implant were recorded, and treatment frequency was calculated. Visual acuity (VA) was assessed using a Snellen eye chart and converted to early treatment diabetic retinopathy study (ETDRS) letters, and central subfield thickness (CST) was measured using optical coherence tomography (OCT). Treatment frequency, mean VA, mean CST, percentage of patients with CST of ≤ 300 µm, mean IOP, IOP events, and IOP treatments pre- and post-FAc implant administration were measured. Positive and negative predictive values for the IOP response to prior steroid therapy were also determined.

Results

In total, 160 eyes of 130 patients were studied. VA was maintained at pre-FAc levels from baseline to month 24, despite a significant reduction in treatment frequency from one treatment every 2.9 months pre-FAc implant to one treatment every 14.3 months post-FAc implant. Patients with better baseline VA required fewer DME treatments post-FAc than did patients with worse baseline VA. The majority of patients did not require additional DME treatment during the post-FAc follow-up period. A significant reduction in CST and an increase in the percentage of patients with CST of ≤ 300 µm were seen up to month 21 post-FAc implant. Pre-FAc implant IOP was maintained during the post-FAc implant period; increased IOP with prior steroid therapy was found to be highly predictive of increased IOP post-FAc implant.

Conclusion

The results of this study confirm the positive safety and efficacy profile of the FAc implant and demonstrate for the first time the effectiveness of the U.S. label indication of FAc in reducing the incidence of post-treatment pressure elevation. The FAc implant significantly reduced treatment burden in the overall population without significantly increasing the risk of steroid-induced pressure elevation.

Funding

Alimera Sciences.

Aflibercept Nanoformulation Inhibits VEGF Expression in Ocular In Vitro Model: A Preliminary Report

Age-related macular degeneration (AMD) is one of the leading causes of blindness in the United States, affecting approximately 11 million patients. AMD is caused primarily by an upregulation of vascular endothelial growth factor (VEGF). In recent years, aflibercept injections have been used to combat VEGF. However, this treatment requires frequent intravitreal injections, leading to low patient compliance and several adverse side effects including scarring, increased intraocular pressure, and retinal detachment. Polymeric nanoparticles have demonstrated the ability to deliver a sustained release of drug, thereby reducing the necessary injection frequency. Aflibercept (AFL) was encapsulated in poly lactic-co-glycolic acid (PLGA) nanoparticles (NPs) via double emulsion diffusion. Scanning electron microscopy showed the NPs were spherical and dynamic light scattering demonstrated that they were uniformly distributed (PDI < 1). The encapsulation efficiency and drug loading were 75.76% and 7.76% respectively. In vitro release studies showed a sustained release of drug; 75% of drug was released by the NPs in seven days compared to the full payload released in 24 h by the AFL solution. Future ocular in vivo studies are needed to confirm the biological effects of the NPs. Preliminary studies of the proposed aflibercept NPs demonstrated high encapsulation efficiency, a sustained drug release profile, and ideal physical characteristics for AMD treatment. This drug delivery system is an excellent candidate for further characterization using an ocular neovascularization in vivo model.

Distribution of fluorescein sodium and triamcinolone acetonide in the simulated liquefied and vitrectomized Vitreous Model with simulated eye movements

Intravitreal administration is the method of choice for drug delivery to the posterior segment of the eye with special emphasis on the vitreous body and its surrounding retinal vasculature. In order to gain a better understanding of the underlying distribution processes, an in vitro model simulating the vitreous body (Vitreous Model, VM) and a system simulating the impact of movement on the VM (Eye Movement System, EyeMoS) was previously developed. In the study reported here, these systems were modified in regard to a standardized injection procedure, the diversity of simulated eye movements, extended periods of investigation, the opportunity to simulate the state after vitrectomy and in considering the physiological temperature. Fluorescein sodium (FS) and triamcinolone acetonide (TA) were used as (model) drugs to examine the drug distribution within the VM. Vitrectomy was simulated by replacing half the volume of the polyacrylamide gel that was used as vitreous substitute with the clinically used Siluron® 5000 whereas for a simulated liquefaction half the volume of the gel was replaced by buffer. A simulated liquefaction caused a 12-fold faster distribution of FS compared to the simulated juvenile VM, which was most likely caused by convective forces and mass transfer. Also, the injection technique (injection into the gel or into the buffer compartment) influenced the resulting distribution pattern. Without any liquefaction, the previously described initial injection channel occurred with both (model) drugs and, in the case of TA, remained almost unchanged during the investigation period of 72h. Simulating vitrectomized eyes, TA did not spread uniformly, but either remained in the depot or strongly sedimented within the VM suggesting that a homogenous distribution of a TA suspension is highly unlikely in vitrectomized eyes. High variabilities were observed with ex vivo animal eyes, demonstrating the limited benefit of explanted tissues for such distribution studies. The combination of the modified VM and EyeMoS seems a valuable tool for characterizing intravitreal dosage forms in a reproducible simulation of diversified eye movements and a partially liquefied or vitrectomized vitreous body.

Antiangiogenic activity of PLGA-Lupeol implants for potential intravitreal applications

Uncontrolled angiogenesis is directly associated with ocular diseases such as macular degeneration and diabetic retinopathy. Implantable polymeric drug delivery systems have been proposed for intravitreal applications and in the present work, we evaluated the antiangiogenic potential of PLGA ocular implants loaded with the triterpene lupeol using in vitro and in vivo models. The drug/polymer physiochemical properties of the lupeol-loaded PLGA were validated as functionally similar using differential scanning calorimetry, Fourier transform infrared spectroscopy, and scanning electron microscopy. Interestingly, in an in vitro culture system, lupeol (100μg/mL and 250μg/mL) was capable to inhibited the proliferation as well as the migration of Human Umbilical Vein Endothelial Cells (HUVEC), without interfering in cell viability, promoting a significant reduction in the percentage of vessels (39.41% and 44.12%, respectively), compared with the control group. In vivo test, by using the chorioallantoic membrane (CAM) model, lupeol-loaded PLGA ocular implants showed antiangiogenic activity comparable to the FDA-approved anti-VEGF antibody Bevacizumab. Overall, our results suggest lupeol-loaded PLGA ocular implants were able to inhibit the angiogenic process by impairing both proliferation and migration of endothelial cells.

Management of pseudophakic cystoid macular edema

Pseudophakic cystoid macular edema (PCME) is a common complication following cataract surgery. Acute PCME may resolve spontaneously, but some patients will develop chronic macular edema that affects vision and is difficult to treat. This disease was described more than 50 years ago, and there are multiple options for clinical management. We discuss mechanisms, clinical efficacy, and adverse effects of these treatment modalities. Topical non-steroidal anti-inflammatory agents and corticosteroids are widely used and, when combined, may have a synergistic effect. Intravitreal corticosteroids and anti-vascular endothelial growth factor (anti-VEGF) agents have shown promise when topical medications either fail or have had limited effects. Randomized clinical studies evaluating anti-VEGF agents are needed to fully evaluate benefits and risks. When PCME is either refractory to medical therapy or is associated with significant vitreous involvement, pars plana vitrectomy has been shown to improve outcomes, though it is associated with additional risks.

Protective effects of N-acetylcysteine on triamcinolone acetonide-induced lens damage in rats

OBJECTIVE

To examine the relationship of cataract forming effect of intravitreal triamcinolone acetonide (IVTA) injection with oxidative status and the effect of N-acetylcysteine (NAC) on these alterations.

MATERIALS AND METHODS

Twenty-six Wistar-Albino rats were included in the study. Rats were assigned into four groups as follows: intravitreal saline injection group (controls); IVTA injection group; IVTA + intraperitoneal NAC injection group (IVTA + NAC); and intraperitoneal NAC injection group (NAC). Triamcinolone acetonide was intravitreally injected at a dose of 1 mg. NAC was intraperitoneally injected at a dose of 150 µg/g body weight. Animals were sacrificed and lens specimens were analyzed for levels of malondialdehyde (MDA) and protein carbonyl (PC) and activities of glutathione (GSH) and glutathione peroxidase (GSH-Px).

RESULTS

We found that the MDA and PC levels of lenses were increased in the IVTA group (p < 0.01). It was seen that GSH and GSH-Px in lenses were decreased in the IVTA group (p < 0.01). NAC administration significantly ameliorated these changes in the IVTA + NAC group (p < 0.05).

CONCLUSION

These results indicate that the NAC produces a protective mechanism against IVTA-induced cataract and suggest a role of oxidative stress in pathogenesis.

Steroid-induced iatrogenic glaucoma

Steroids in susceptible individuals can cause a clinical condition similar to primary open-angle glaucoma. Five percent of the population are high steroid responders and develop an intraocular pressure (IOP) elevation of more than 15 mm Hg above baseline. IOP elevation may occur as early as 1 day to as late as 12 weeks after intravitreal triamcinolone in 20-65% of patients. On average, 75% of eyes with steroid implants require IOP-lowering therapy at some point within 3 years of follow-up. The exact mechanism of steroid-induced glaucoma is not totally understood, but decreased trabecular meshwork outflow is regarded as the main cause of IOP elevation. High-risk patients who receive steroids should be monitored closely and if they develop elevated IOP, steroids with lower potency or steroid-sparing agents should be used. The IOP usually returns to normal within 2-4 weeks after stopping the steroid. About 1-5% of patients do not respond to medical therapy and need surgery. Trabeculectomy, trabeculotomy, shunt surgery, and cyclodestructive procedures are among the methods employed. Removal of residual sub-Tenon or intravitreal steroids may help hasten the resolution of the steroid response. Early results with anecortave acetate, an analog of cortisol acetate with antiangiogenic activity, in controlling IOP have been promising.

Trans-scleral iontophoretic delivery of low molecular weight therapeutics

The fundamental understanding of ocular drug delivery using iontophoresis is not at the same level as that for transdermal electrotransport. Research has therefore been undertaken to characterise the electrical properties of the sclera (charge, permselectivity, and isoelectric point (pI)) and to determine the basics of iontophoretic transport of model neutral, cationic, and anionic species (respectively, mannitol, timolol, and dexamethasone phosphate). Like the skin, the sclera supports a net negative charge under physiological pH conditions and has a pI between 3.5 and 4. Equally, the principles of trans-scleral iontophoretic transport of low molecular weight compounds are consistent with those observed for skin. Iontophoretic delivery of timolol and dexamethasone phosphate was proportional to applied current and drug concentration, and trans-scleral iontophoresis in rabbits led to enhanced intraocular levels of these compounds compared to passive delivery. The behaviour of higher molecular weight species such as peptide drugs and other biopharmaceuticals (e.g., proteins and oligonucleotides) has not been fully characterised. Further work has been undertaken, therefore, to examine the trans-scleral iontophoresis of vancomycin, a glycopeptide antibiotic with a relatively high molecular weight of 1448 Da. It was indeed possible to deliver vancomycin by iontophoresis but trans-scleral transport did not increase linearly with either increasing current density or peptide concentration.

Inhibition of Endotoxin-Induced Uveitis by Methylprednisolone Acetate Nanosuspension in Rabbits

PURPOSE

In this study, nanoformulations of methylprednisolone acetate (MPA) were formulated by using a copolymer of poly(ethylacrylate, methyl-methacrylate and chlorotrimethyl-ammonioethyl methacrylate) to study their impacts on the inhibition of inflammatory symptoms in rabbits with endotoxin-induced uveitis (EIU).

METHODS

A modified quasiemulsion solvent diffusion technique was used for the preparation of the nanoparticles. The drug-release profiles and physicochemical characteristics of the nanoformulations were studied by means of X-ray crystallography, differential scanning calorimetry, and Fourier transform infrared spectroscopy. Particle-size analysis yielded mean diameters of approximately 380, 460, and 580 (nm) for copolymer nanoparticles at the ratios of 1:2.5, 1:5, and 1:10, respectively. Major clinical symptoms of EIU (e.g., morphologic changes, leukocytes numbers, and protein levels within the aqueous humor) were examined.

RESULTS

Upon the physicochemical characterizations, no crystal changes or chemical interactions were observed for the copolymer nanoparticles. The 1:2.5 ratio of drug polymer resulted in the most controlled release of MPA. The in vivo examinations revealed that the endotoxin-induced inflammation can be inhibited by the copolymer nanosuspension more significantly than by the microsuspension of MPA itself in the rabbits with EIU.

CONCLUSIONS

Based on our findings, we suggest that the copolymer nanosuspension may favor the localized, controlled ocular delivery of MPA for the prevention of inflammatory symptoms in ocular diseases.

Intravitreal triamcinolone acetonide in the management of cystoid macular edema in Behçet's disease

PURPOSE

To determine the efficacy of intravitreal triamcinolone acetonide (ivTA) injection in the management of cystoid macular edema (CME) due to uveitis in patients with Behçet's disease.

METHODS

Ten eyes of seven patients with CME associated with Behçet's disease were included in the study. A quantity of 4 mg of triamcinolone acetonide was injected intravitreally in all of the eyes. The maculas of the patients were evaluated with optical coherence tomography (OCT) and fluorescein angiography (FA). The change in visual acuity, fluorescein leakage, macular thickness, and potential complications were assessed.

RESULTS

The mean follow-up was 15.6 months (range 7-19 months). There was an increase of more than two Snellen lines in the visual acuity in seven of the ten eyes (70%) at the last examination. Macular edema regressed completely in eight of the ten eyes (80%) at the last visit on OCT and FA. The mean central macular thickness assessed by OCT was 406 mum before treatment and 186.9 mum at the last visit. The intraocular pressure (IOP) exceeded 21 mmHg in six eyes of five patients (60%) during the follow-up. At the last visit, the IOP was less than 21 mmHg in five eyes with medication. One eye underwent glaucoma filtration surgery. Four eyes of three patients had cataract progression. In four eyes of four patients (40%), a second ivTA injection was given due to relapsing CME.

CONCLUSION

Intravitreal triamcinolone acetonide (ivTA) may be beneficial in the management of CME in patients with Behçet's disease. Repeated ivTA injections might be required if CME reoccurs.