Randomized clinical trial of a new dexamethasone delivery system (Surodex) for treatment of post-cataract surgery inflammation

Factors influencing aqueous flare after cataract surgery and its evaluation with laser flare photometry

Despite the refinement of modern cataract surgery, postoperative inflammation still constitutes a substantial amount of visual morbidity worldwide. A surrogate for intraocular inflammation and blood-aqueous barrier breakdown can be objectively quantified by Laser flare photometry (LFP). This review outlines the utility of LFP in assessing the assessment of post-cataract surgery inflammation. It highlights the impact of preoperative pathological states such as uveitis and diabetes, intraoperative techniques, including efficient phacoemulsification and direct comparisons between postoperative anti-inflammatory regimes. There is a large interobserver variation in the subjective flare measurement after cataract surgery and the continued use of LFP amongst other objective, noninvasive measurements of intraocular inflammation, particularly in the further development of cataract surgery, is recommended.

Synthetic biodegradable polyesters for implantable controlled-release devices

INTRODUCTION

: Implantable devices can be designed to release drugs to localized regions of tissue at sustained and reliable rates. Advances in polymer engineering have led to the design and development of drug-loaded implants with predictable, desirable release profiles. Biodegradable polyesters exhibit chemical, physical, and biological properties suitable for developing implants for pain management, cancer therapy, contraception, antiviral therapy, and other applications.

AREAS COVERED

: This article reviews the use of biodegradable polyesters for drug-loaded implants by discussing the properties of commonly used polymers, techniques for implant formulation and manufacturing, mechanisms of drug release, and clinical applications of implants as drug delivery devices.

EXPERT OPINION

: Drug delivery implants are unique systems for safe and sustained drug release, providing high bioavailability and low toxicity. Depending on the implant design and tissue site of deployment, implants can offer either localized or systemic drug release. Due to the long history of use of degradable polyesters in medical devices, polyester-based implants represent an important class of controlled release technologies. Further, polyester-based implants are the largest category of drug delivery implants to reach the point of testing in humans or approval for human use.

Advances in ophthalmic drug delivery technology for postoperative management after cataract surgery

INTRODUCTION

Cataract surgery is becoming more common due to an aging world population. Intraocular lenses and surgical technique have developed remarkably recently, but the development of postoperative medication to prevent postsurgery complications has been relatively delayed. We still largely depend on eye drops for the management of post-cataract-surgery patients. Mental and physical problems that often occur in elderly cataract patients make it difficult for patients to apply eye drops by themselves. It is necessary to develop new effective drug delivery methods.

AREAS COVERED

This updated review article provides a brief review of why drug management is needed following cataract surgery and an overview of current developments in new drug delivery methods for ophthalmic treatment. In particular, various novel drug delivery methods that can be used for post-cataract-surgery management and their current development stages are extensively reviewed.

EXPERT OPINION

Rapidly developing technologies, such as intraocular and external ophthalmic implants, polymers, and nanotechnology, are being actively applied to develop novel drug delivery systems for safe and effective management after cataract surgery. Their goal is to achieve sufficient drug release for the desired duration with a single application. These will largely replace the inconvenience of eye drops for elderly patients in the future.

Liposomal drug delivery system for anti-inflammatory treatment after cataract surgery: a phase I/II clinical trial

Liposomes as a drug delivery system may overcome the problems associated with non-compliance to eyedrops and inadequate control of inflammation after cataract surgery. We evaluated the safety and efficacy of a single subconjunctival injection of liposomal prednisolone phosphate (LPP) for the treatment of post-cataract surgery inflammation. This is a phase I/II, open-label non-comparative interventional trial of patients undergoing cataract surgery. All patients received a single injection of subconjunctival LPP intraoperatively. The primary outcome measure was the proportion of eyes with an anterior chamber cell count of 0 at postoperative month 1. Ocular and non-ocular adverse events, including elevated intraocular pressure, rebound iritis and pseudophakic macular edema were monitored. Five patients were enrolled in this study. The mean age was 66.6 ± 6.2 and 4 (80%) were male. The proportion of patients with AC cell grading of 0 was 0%, 80%, 80%, and 100% at day 1, week 1, month 1, and month 2 after cataract surgery, respectively. Mean laser flare photometry readings were significantly elevated at week 1 after cataract surgery (48.8 ± 18.9, p = 0.03) compared with baseline, decreasing to 25.8 ± 9.2 (p = 0.04) at month 1 and returned to baseline by month 2 (10.9 ± 5.1, p = 1.0). No ocular or non-ocular adverse events were observed. Liposomal prednisolone phosphate, administered as a single subconjunctival injection intraoperatively, can be a safe and effective treatment for post-cataract surgery inflammation. The delivery of steroids with a liposomal drug delivery system could potentially replace eyedrops as anti-inflammatory therapy following cataract surgery.

Morphological Characteristics of Drug-Eluting Biodegradable Polymeric Thin Films Developed on the Surface of Intraocular Lenses by Three Techniques: A Comparative Study

Background

Cataract surgery is a very popular operation that requires a postoperative period of frequent instillation of antibiotic and anti-inflammatory eye drops. Modified drug-eluting intraocular lenses (IOLs) may eliminate the need for eye drops after surgery.

Aim

The purpose of this study is to compare the morphological characteristics of dexamethasone eluting biodegradable polymeric thin films developed on the surface of commercially available IOLs by three different methods.

Method

This experimental study was conducted between May and August of 2021 in the Lab for Thin Films - Nanobiomaterials - Nanosystems & Nanometrology (LTFN) of the Aristotle University of Thessaloniki. A mixture of two organic polymers [Poly (D, L-lactide-co-glycolide)(PLGA), lactide: glycolide (75:25) and Polycaprolactone (PCL)] and dexamethasone was prepared and then deposited on the surface of three-piece IOLs by spin coating, by spray coating, and by gravure printing. The modified IOLs were sterilized with the use of ultraviolet (UV) radiation and plasma treatment. Their structural properties were studied with the use of atomic force microscopy (AFM).

Results

Spin coating and gravure printing produced uniform thin films on the surface of the IOLs which were not damaged during the sterilization process. Spray coating led to the partial coating of the surface of the IOLs; the thin films underwent alterations following plasma treatment.

Conclusions

Thin films developed by spin coating and gravure printing on IOLs demonstrate the desired morphological characteristics that make them suitable candidates for further research.

Polymeric Implants for the Treatment of Intraocular Eye Diseases: Trends in Biodegradable and Non-Biodegradable Materials

Intraocular/Intravitreal implants constitute a relatively new method to treat eye diseases successfully due to the possibility of releasing drugs in a controlled and prolonged way. This particularity has made this kind of method preferred over other methods such as intravitreal injections or eye drops. However, there are some risks and complications associated with the use of eye implants, the body response being the most important. Therefore, material selection is a crucial factor to be considered for patient care since implant acceptance is closely related to the physical and chemical properties of the material from which the device is made. In this regard, there are two major categories of materials used in the development of eye implants: non-biodegradables and biodegradables. Although non-biodegradable implants are able to work as drug reservoirs, their surgical requirements make them uncomfortable and invasive for the patient and may put the eyeball at risk. Therefore, it would be expected that the human body responds better when treated with biodegradable implants due to their inherent nature and fewer surgical concerns. Thus, this review provides a summary and discussion of the most common non-biodegradable and biodegradable materials employed for the development of experimental and commercially available ocular delivery implants.

Intraocular lenses as drug delivery devices

Cataract surgery is one of the most common and safe surgical procedures nowadays. However, it is not free of risks as endophthalmitis, ocular inflammation and posterior capsule opacification (PCO) can appear as post-surgery complications. The usual eye drop therapy used as prophylaxis for the former two complications has limited bioavailability. In turn, the prevention of PCO involves an adequate surgical technique and a careful choice of intraocular lens (IOL) design and material. Also, different drugs have been tested to reduce incidence of PCO, but no prophylaxis demonstrated to be completely effective. In the past few years, IOLs have been proposed as drug delivery devices to replace or/assist the usual eye drop therapy in the post-operatory period. The great advantage of drug loaded IOLs would be to ensure a continuous drug delivery, independent of patient's compliance without requiring any further action besides IOL implantation. The biggest challenge of drug loaded IOLs production is to achieve a controlled and extended release that meet therapeutic needs without inducing toxicity to the surrounding ocular tissues or affecting the physical properties of the lens. This review starts by addressing the possible complications after cataract surgery, as well as the most commonly adopted prophylaxis for each of them. The various types of IOLs are described and their main advantages/disadvantages are discussed. The different strategies pursued to incorporate drugs into the IOLs and control their release, which include soaking the IOL in the drugs solution, supercritical impregnation, surface modifications, and attachment of drug reservoirs to the IOL, among others, are reported. For each strategy, a summary of the publications is presented, which includes the target complication, the types and amounts of released drugs and the IOL materials. A brief description of each individual study is given afterwards. Optimization of drug loaded IOLs through mathematical modelling and possible issues raised by their sterilization are also tackled. At the end, the future commercialization of drug loaded IOLs is commented.

Local drug delivery systems for inflammatory diseases: Status quo, challenges, and opportunities

Inflammation that is not resolved in due course becomes a chronic disease. The treatment of chronic inflammatory diseases involves a long-term use of anti-inflammatory drugs such as corticosteroids and nonsteroidal anti-inflammatory drugs, often accompanied by dose-dependent side effects. Local drug delivery systems have been widely explored to reduce their off-target side effects and the medication frequency, with several products making to the market or in development over the years. However, numerous challenges remain, and drug delivery technology is underutilized in some applications. This review showcases local drug delivery systems in different inflammatory diseases, including the targets well-known to drug delivery scientists (e.g., joints, eyes, and teeth) and other applications with untapped opportunities (e.g., sinus, bladder, and colon). In each section, we start with a brief description of the disease and commonly used therapy, introduce local drug delivery systems currently on the market or in the development stage, focusing on polymeric systems, and discuss the remaining challenges and opportunities in future product development.

Thermoresponsive GenisteinNLC-dexamethasone-moxifloxacin multi drug delivery system in lens capsule bag to prevent complications after cataract surgery

Cataract surgery is the most common intraocular procedure. To decrease postsurgical inflammation, prevent infection and reduce the incidence of secondary cataract, we built a temperature-sensitive drug delivery system carrying dexamethasone, moxifloxacin and genistein nanostructured lipid carrier (GenNLC) modified by mPEG-PLA based on F127/F68 as hydrogel. Characterizations and release profiles of the drug delivery system were studied. In vitro functions were detected by CCK-8 test, immunofluorescence, wound-healing assay, real time-PCR and western blotting. The size of GenNLCs was 39.47 ± 0.69 nm in average with surface charges of - 4.32 ± 0.84 mV. The hydrogel gelation temperature and time were 32 °C, 20 s with a viscosity, hardness, adhesiveness and stringiness of 6.135 Pa.s, 54.0 g, 22.0 g, and 3.24 mm, respectively. Transmittance of the gel-release medium was above 90% (93.44 ± 0.33% to 100%) at range of 430 nm to 800 nm. Moxifloxacin released completely within 10 days. Fifty percent of dexamethasone released at a constant rate in the first week, and then released sustainably with a tapering down rate until day 30. Genistein released slowly but persistently with a cumulative release of 63% at day 40. The thermoresponsive hydrogel inhibited the proliferation, migration and epithelial-mesenchymal transition of SRA 01/04 cells, which were confirmed by testing CCK-8, wound-healing assay, western blot, real time-PCR (RT-PCR) and immunofluorescence. These results support this intracameral thermoresponsive in situ multi-drug delivery system with programmed release amounts and release profiles to cut down the need of eye drops for preventing inflammation or infection and to reduce posterior capsular opacification following cataract surgery.

A review of the clinical applications of drug delivery systems for the treatment of ocular anterior segment inflammation

Ocular anterior segment inflammation is a medical problem that is seen in cases of cataract surgery and non-infectious anterior uveitis. Inadequately treated anterior segment inflammation can lead to sight-threatening conditions such as corneal oedema, glaucoma and cystoid macular oedema. The mainstay of treatment for anterior segment inflammation is topical steroid eye-drops. However, several drawbacks limit the critical value of this treatment, including low bioavailability, poor patient compliance, relatively difficult administration manner and risk of blurring of vision and ocular irritation. A drug delivery system (DDS) that can provide increased bioavailability and sustained delivery while being specifically targeted towards inflamed ocular tissue can potentially replace daily eye-drops as the gold standard for management of anterior segment inflammation. The various DDS for anti-inflammatory drugs for the treatment of anterior segment inflammation are listed and summarised in this review, with a focus on commercially available products and those in clinical trials. Dextenza, INVELTYS, Dexycu and Bromsite are examples of DDS that have enjoyed success in clinical trials leading to FDA approval. Nanoparticles and ocular iontophoresis form the next wave of DDS that have the potential to replace topical steroids eye-drops as the treatment of choice for anterior segment inflammation. With the current relentless pace of ophthalmic drug delivery research, the pursuit of a new standard of treatment that eliminates the problems of low bioavailability and patient compliance may soon be realised.

Corticosteroids in ophthalmology: drug delivery innovations, pharmacology, clinical applications, and future perspectives

Corticosteroids remain the mainstay of the treatment for various ocular conditions affecting the ocular surface, anterior and posterior segments of the eye due to their anti-inflammatory, anti-oedematous, and anti-neovascularization properties. Prednisolone, prednisolone acetate, dexamethasone, triamcinolone acetonide, fluocinolone acetonide, and loteprednol etabonate are amongst the most widely used ophthalmic corticosteroids. Corticosteroids differ in their activity and potency in the eye due to their inherent pharmacological and pharmaceutical differences. Different routes and regimens are available for ocular administration of corticosteroids. Conventional topical application to the eye is the route of choice when targeting diseases affecting the ocular surface and anterior segment, while periocular, intravitreal, and suprachoroidal injections can be potentially effective for posterior segment diseases. Corticosteroid-induced intraocular pressure elevation and cataract formation remain the most significant local risks following topical as well as systemic corticosteroid administration. Invasive drug administration via intracameral, subconjunctival, and intravitreal injection can enhance ocular bioavailability and minimize dose and dosing frequency of administration, yet may exacerbate ocular side effects of corticosteroids. This review provides a critical appraisal of the ophthalmic uses of corticosteroid, routes of administration, drug delivery fundamentals and novel ocular implantable steroid delivery systems, factors influencing side effects, and future perspectives for ocular corticosteroid therapy.

Dry Tablet Formulation of PLGA Nanoparticles with a Preocular Applicator for Topical Drug Delivery to the Eye

To enhance ocular drug bioavailability, a rapidly dissolving dry tablet containing alginate and drug-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles was proposed. For hygienic and easy administration of an accurate drug-dose with this tablet, the use of a preocular applicator was suggested. Herein, a dry tablet was prepared by embedding dexamethasone-loaded PLGA nanoparticles in alginate, which was deposited on the tip of the applicator. The nanoparticles were loaded with 85.45 μg/mg drug and exhibited sustained drug release for 10 h. To evaluate in vivo efficacy, dexamethasone concentration in the aqueous humor was measured after topical administration of the dry tablet, with the applicator, to rabbit eyes and was compared to that achieved with Maxidex^®, a commercially-available dexamethasone eye drops. When applied with the preocular applicator, the dry tablet containing alginate could be fully detached and delivered to the eye surface. In fact, it showed up to 2 h of nanoparticle retention on the preocular surface due to tear viscosity enhancement, causing an estimated 2.6-fold increase in ocular drug bioavailability compared to Maxidex^®. Therefore, the preocular applicator combined with a dry alginate tablet containing PLGA nanoparticles can be a promising system for aseptically delivering an accurate dose of ophthalmic drug with enhanced bioavailability.

Safety & efficacy of single subconjunctival triamcinolone 5 mg depot vs topical loteprednol post cataract surgery: less drop cataract surgery

AIM

To do a randomized prospective interventional study for comparing the effects of a single subconjunctival triamcinolone acetonide (SCTA) injection to tapering topical loteprednol in patients undergoing phacoemulsification surgery under topical anesthesia.

METHODS

A total of 400 patients were randomized into 2 groups; Group A (200 patients) received 5 mg SCTA at the end of surgery and topical ketorolac tromethamine (0.5%) with ofloxacin (0.3%) combination for 3wk. Group B (200 patients) received tapering topical loteprednol etabonate (0.5%) along with ofloxacin (0.3%) and ketorolac tromethamine (0.5%) for 3wk. Outcomes evaluated were intraocular pressure (IOP), anterior chamber cells/flare and macular oedema postoperatively at 1, 6 and 12wk.

RESULTS

Baseline parameters were almost similar in both the groups. No statistical difference was seen between the preoperative and postoperative IOP values for Group A (P=0.82) and Group B (P=0.61) and postoperative IOP values in between both groups (P=0.14) at 1wk. Incidence of cells/flare postoperative was statistically not significant (P=0.82) in both groups at all follow up visits. Postoperative macular oedema was not observed at any follow up visit.

CONCLUSION

SCTA appears to be an effective alternative to prolong postoperative topical steroid use.

Anterior chamber migration of a sustained-release dexamethasone intravitreal implant: A case report and review of literature

The purpose of the study was to report a case of migration of a dexamethasone intravitreal implant (Ozurdex^®) into anterior chamber and review the literature pertaining to the anterior chamber migration of implant. Clinical data were collected from a patient, in whom a dexamethasone intravitreal implant migrated to anterior chamber. A review of literature was conducted to analyze additional reports. A 59-year-old aphakic patient with recalcitrant cystoid macular edema due to chronic idiopathic uveitis was treated with intravitreal injection of dexamethasone implant. Migration of the implant into anterior chamber was noted after a month of injection. Since his cornea was clear and intraocular pressure was normal, he was managed conservatively. Sixteen such reports of migration of implant into anterior chamber was analyzed to look into the possible etiologies and outcome. Disruption of lens capsule, large basal iridectomy, and prior vitrectomy are the primary risk factors for migration of dexamethasone implant into the anterior chamber.

Intracameral dexamethasone injection in the treatment of cataract surgery induced inflammation: design, development, and place in therapy

Cataract surgery is one of the most commonly performed surgeries worldwide, with nearly 20 million cases annually. Appropriate prophylaxis after cataract surgery can contribute to a safe and quick visual recovery with high patient satisfaction. Despite being the current standard of care, the use of multiple postoperative eye drops can create a significant burden on these patients, contributing to documented and significant non-adherence to the postoperative regimen. Over the past 25 years, there have been a few studies analyzing the use of intracameral dexamethasone (DXM) in controlling inflammation following cataract surgery. This review explores various drug delivery approaches for managing intraocular inflammation after cataract surgery, documenting the strengths and weaknesses of these options and examining the role of intracameral DXM (among these other strategies) in controlling postoperative intraocular inflammation. Intracameral DXM has a particular advantage over topical steroids in possibly decreasing postoperative inflammatory symptoms and objective anterior cell and flare scores. Compared to topical steroids, there may be a slightly less theoretical risk of significant intraocular pressure spikes and systemic absorption. In addition, surveys indicate patients prefer an intraoperative intracameral injection over a self-administered postoperative eye drop regimen. However, there are several adverse effects associated with intracameral DXM delivery that are not seen with the noninvasive topical approach. Although it is unlikely that intracameral DXM will replace topical medications as the standard management for postoperative inflammation, it is seemingly another safe and effective strategy for controlling postoperative inflammation after routine cataract surgery.

Management of postoperative inflammation after cataract and complex ocular surgeries: a systematic review and Delphi survey

Prevention and management of postoperative ocular inflammation with corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs) have been evaluated in several randomised controlled trials (RCTs). However, neither consensus regarding the efficacies of different regimens nor established guidelines are currently available. This has resulted in different practice patterns throughout the world. A systematic literature review found that for the management of postcataract inflammation nepafenac produced a positive outcome in three of three RCTs (3/3), as did ketorolac (1/1), bromfenac (7/7), loteprednol (3/3) and difluprednate (6/6), but not flurbiprofen (0/1). A single study found that betamethasone produced inconclusive results after retinal detachment (RD) surgery; ketorolac was effective (1/1) after vitrectomy, but triamcinolone was ineffective (0/1) after trabeculectomy. A two-round Delphi survey asked 28 international experts to rate both the inflammatory potential of different eye surgeries and their agreement with different treatment protocols. They rated trabeculectomy, RD surgery and combined phacovitrectomy as more inflammatory than cataract surgery. Vitrectomies for macular hole or epiretinal membrane were not deemed more inflammatory than cataract surgery. For trabeculectomy, they preferred to treat longer than for cataract surgery (NSAID + corticosteroid three times a day for 2 months vs 1 month). For vitrectomy alone, RD surgery and combined phacovitrectomy, the panel preferred the same treatment as for cataract surgery (NSAID + corticosteroid three times a day for 1 month). The discrepancy between preferred treatment and perception of the eye's inflammatory status by the experts for RD and combined vitreoretinal surgeries highlights the need for RCTs to establish treatment guidelines.

Anterior segment migration of dexamethasone implant: risk factors, complications, and management

PURPOSE OF REVIEW

To describe the risk factors, clinical course, and complications related to anterior segment migration of a dexamethasone (DEX) intravitreal implant, and review over potential management strategies.

RECENT FINDINGS

Recent reports have demonstrated that migration of a DEX implant into the anterior chamber may occur in patients with higher risk ocular characteristics. Although a relatively rare occurrence, DEX implant migration carries the possibility of inducing potentially vision-threatening corneal endothelial decompensation and edema.

SUMMARY

Any combination of previous pars plana vitrectomy, an open/defective lens capsule, and/or iris defects may increase the risk of DEX implant migration into the anterior chamber. In the setting of a DEX implant that has moved into the anterior segment with corneal edema already present, urgent removal of the implant is warranted to reduce the risk of permanent visual compromise.

Evaluation of the Safety and Tolerability of Conjunctival Ring for Posterior Segment of the Eye

PURPOSE

To evaluate the safety and tolerability of conjunctival rings (CRs), a novel device for drug delivery to the posterior segment of the eye.

METHODS

In animal studies, CRs containing 5% dexamethasone sodium phosphate (DSP) or vehicle solution were placed on the right and left eyes of C57BL/6J mice, respectively. Contact lenses (CLs) containing vehicle solution were used as a control. Twenty-four hours after placement of the CRs, corneal fluorescein staining was graded based on the McDonald-Shadduck scoring system, ranging from 0 to 4. In humans, CRs containing vehicle solution were placed on the right eye of healthy volunteers for 9 hours. The corneal curvature, corneal thickness, intraocular pressure, visual acuity, tear production (Schirmer I test), tear film break-up time and fluorescein staining scores of the cornea (scores ranging from 0 to 3) and conjunctiva (scores ranging from 0 to 6) were assessed before and after wearing the CRs. The release characteristics of DSP from CRs were also evaluated.

RESULTS

In animal experiments, corneal fluorescein staining scores were 1 or less in all the groups, and there was no significant difference between the CR group and the CL group. In the preclinical safety evaluation of CR for humans, ophthalmic examination revealed that CR caused no significant changes in all the parameters investigated including corneal curvature (p = 0.77), corneal thickness (p = 0.96), intraocular pressure (p = 0.59), visual acuity (p = 0.14), Schirmer I test results (p = 0.76), tear film break-up time (p = 0.68), corneal fluorescein staining scores (p = 0.64), and conjunctival fluorescein staining scores (p = 0.52). The DSP release from CRs occurs within a few hours, which is similar to the drug-release property of medicated CL, as reported previously.

CONCLUSIONS

The current data showed the safety and tolerability of CR as a drug delivery device for the treatment of posterior segment diseases.

Sustained-release dexamethasone for the treatment of ocular inflammation and pain after cataract surgery

PURPOSE

To evaluate the safety and efficacy of dexamethasone as a sustained-release drug depot when placed in the canaliculus for the treatment of ocular inflammation and pain in cataract surgery patients.

SETTING

Four private practice sites in the United States.

DESIGN

Multicenter randomized double-masked clinical trial.

METHODS

Patients were randomized (1:1) to receive either the sustained-release dexamethasone or a placebo vehicle punctum plug inserted into the inferior distal canaliculus of the operated eye intraoperatively during cataract surgery. The primary endpoints were the proportions of patients with absence of cells or pain in the anterior chamber at 8 days. Secondary endpoints included cells, flare, pain, and the presence of the device at various timepoints through 30 days.

RESULTS

Approximately one fifth (20.7%) of patients in the sustained-release dexamethasone group had an absence of anterior chamber cells at 8 days compared with 10.0% in the placebo group (P = .1495). A higher proportion of patients in the sustained-release dexamethasone group (79.3%) than in the placebo group (30.0%) had an absence of ocular pain at 8 days (P < .0001) and at all other timepoints (P < .0002). There were significantly higher proportions of patients in the sustained-release dexamethasone group than in the placebo group with an absence of anterior chamber cells, anterior chamber flare, and pain at several timepoints through 30 days (P ≤ .0251).

CONCLUSION

Sustained-release dexamethasone provided elution of drug for up to 1 month after cataract surgery, providing clinically significant reductions in inflammation and pain.

FINANCIAL DISCLOSURE

Dr. Masket is a consultant to and shareholder in Ocular Therapeutix, Inc. No other author has a financial or proprietary interest in any material or method mentioned.

Carriers for the tunable release of therapeutics: etymological classification and examples

Introduction Physiological processes at the molecular level take place at precise spatiotemporal scales, which vary from tissue to tissue and from one patient to another, implying the need for carriers that enable tunable release of therapeutics. Areas covered Classification of all drug release to intrinsic and extrinsic is proposed, followed by the etymological clarification of the term 'tunable' and its distinction from the term 'tailorable'. Tunability is defined as analogous to tuning a guitar string or a radio receiver to the right frequency using a single knob. It implies changing a structural parameter along a continuous quantitative scale and correlating it numerically with the release kinetics. Examples of tunable, tailorable and environmentally responsive carriers are given, along with the parameters used to achieve these levels of control. Expert opinion Interdependence of multiple variables defining the carrier microstructure obstructs the attempts to elucidate parameters that allow for the independent tuning of release kinetics. Learning from the tunability of nanostructured materials and superstructured metamaterials can be a fruitful source of inspiration in the quest for the new generation of tunable release carriers. The greater intersection of traditional materials sciences and pharmacokinetic perspectives could foster the development of more sophisticated mechanisms for tunable release.

Intraocular Implants for the Treatment of Autoimmune Uveitis

Uveitis is the third leading cause of blindness in developed countries. Currently, the most widely used treatment of non-infectious uveitis is corticosteroids. Posterior uveitis and macular edema can be treated with intraocular injection of corticosteroids, however, this is problematic in chronic cases because of the need for repeat injections. Another option is systemic immunosuppressive therapies that have their own undesirable side effects. These systemic therapies result in a widespread suppression of the entire immune system, leaving the patient susceptible to infection. Therefore, an effective localized treatment option is preferred. With the recent advances in bioengineering, biodegradable polymers that allow for a slow sustained-release of a medication. These advances have culminated in drug delivery implants that are food and drug administration (FDA) approved for the treatment of non-infectious uveitis. In this review, we discuss the types of ocular implants available and some of the polymers used, implants used for the treatment of non-infectious uveitis, and bioengineered alternatives that are on the horizon.

Advances in ophthalmic drug delivery

Various strategies for ocular drug delivery are considered; from basic formulation techniques for improving availability of drugs; viscosity enhancers and mucoadhesives aid drug retention and penetration enhancers promote drug transport into the eye. The use of drug-loaded contact lenses and ocular inserts allows drugs to be better placed where they are needed for more direct delivery. Developments in ocular implants gives a means to overcome the physical barriers that traditionally prevented effective treatment. Implant technologies are under development allowing long-term drug delivery from a single procedure, these devices allow posterior chamber diseases to be effectively treated. Future developments could bring artificial corneas to eliminate the need for donor tissue and one-off implantable drug depots lasting the patient's lifetime.

Comparison of peroperative subconjunctival injection of methylprednisolone and standard postoperative steroid drops after uneventful cataract surgery

PURPOSE

To compare the safety and efficacy of a single subconjunctival injection of methylprednisolone and a standard postoperative steroid regimen in terms of intraocular inflammation and intraocular pressure (IOP) after uncomplicated phacoemulsification surgery.

METHODS

Two groups of 25 patients each were included in this prospective randomized controlled trial. Patients in the injection group were given a subconjunctival injection of 20 mg methylprednisolone and the topical group received the conventional postoperative care with steroid eye drops (dexamethasone 1 mg/ml). The patients were examined 1 week and 1 month after surgery. Slit-lamp evaluation of anterior chamber inflammation and IOP were performed. Changes in IOP of ≥2.4 mmHg were considered clinically relevant.

RESULTS

In the injection group, mean IOP decreased from 15.4 ± 2.2 mmHg (baseline) to 14.1 ± 3.2 mmHg at 1 week (p = 0.03). The topical group had a stable IOP at 1 week (16.3 ± 2.6 mmHg) compared to baseline (16.1 ± 2.7 mmHg; p = 0.74). At 1 month, mean IOP was 14.3 ± 2.6 mmHg (p = 0.03) in the injection group and 15.6 ± 2.3 mmHg (p = 0.2) in the topical group. The intragroup changes were neither statistically significant nor clinically relevant at any postoperative visit. Both groups had the highest values of intraocular inflammation at the 1-week postoperative visit, followed by a decline to barely traceable levels at 1 month. The difference was not clinically relevant at any postoperative visit.

CONCLUSIONS

The subconjunctival injection of methylprednisolone appears to be as safe and effective as the conventional treatment, and it might therefore be considered for treatment of individuals with compliance issues.

Anterior eye segment drug delivery systems: current treatments and future challenges

New technologies for delivery of drugs, such as small molecules and biologics, are of growing interest among clinical and pharmaceutical researchers for use in treating anterior segment eye disease. The challenge is to deliver effective drugs at therapeutic concentrations to the targeted ocular tissue with minimal side effects. To achieve this, a better understanding of the unmet needs, what is required of the various methods of delivery to achieve successful delivery, and the potential challenges of anterior segment drug delivery is necessary and the primarily aim of this review. This review covers the various physiological and anatomical barriers that exist for effective delivery to the targeted tissue of the eye, the pathological conditions of the anterior segment, and the unmet needs for treatment of these ocular diseases. Second, it reviews the novel delivery technologies that have the potential to maintain and/or improve the drug's therapeutic index and improving both patient adherence for chronic therapy and potential patient outcomes. This review bridges the pharmaceutical and clinical research/challenges and provides a detailed overview of anterior segment drug delivery accomplishments thus far, for researchers and clinicians.

Drug delivery implants in the treatment of vitreous inflammation

The eye is a model organ for the local delivery of therapeutics. This proves beneficial when treating vitreous inflammation and other ophthalmic pathologies. The chronicity of certain diseases, however, limits the effectiveness of locally administered drugs. To maintain such treatments often requires frequent office visits and can result in increased risk of infection and toxicity to the patient. This paper focuses on the implantable devices and particulate drug delivery systems that are currently being implemented and investigated to overcome these challenges. Implants currently on the market or undergoing clinical trials include those made of nonbiodegradable polymers, containing ganciclovir, fluocinolone acetonide, triamcinolone acetonide, and ranibizumab, and biodegradable polymers, containing dexamethasone, triamcinolone acetonide, and ranibizumab. Investigational intravitreal implants and particulate drug delivery systems, such as nanoparticles, microparticles, and liposomes, are also explored in this review article.

Local therapies for inflammatory eye disease in translation: past, present and future

Despite their side-effects and the advent of systemic immunosuppressives and biologics, the use of corticosteroids remains in the management of patients with uveitis, particularly when inflammation is associated with systemic disease or when bilateral ocular disease is present. The use of topical corticosteroids as local therapy for anterior uveitis is well-established, but periocular injections of corticosteroid can also be used to control mild or moderate intraocular inflammation. More recently, intraocular corticosteroids such as triamcinolone and steroid-loaded vitreal inserts and implants have been found to be effective, including in refractory cases. Additional benefits are noted when ocular inflammation is unilateral or asymmetric, when local therapy may preclude the need to increase the systemic medication.

Implants in particular have gained prominence with evidence of efficacy including both dexamethasone and fluocinolone loaded devices. However, an appealing avenue of research lies in the development of non-corticosteroid drugs in order to avoid the side-effects that limit the appeal of injected corticosteroids. Several existing drugs are being assessed, including anti-VEGF compounds such as ranibizumab and bevacizumab, anti-tumour necrosis factor alpha antibodies such as infliximab, as well as older cytotoxic medications such as methotrexate and cyclosporine, with varying degrees of success. Intravitreal sirolimus is currently undergoing phase 3 trials in uveitis and other inflammatory pathways have also been proposed as suitable therapeutic targets. Furthermore, the advent of biotechnology is seeing advances in generation of new therapeutic molecules such as high affinity binding peptides or modified high affinity or bivalent single chain Fab fragments, offering higher specificity and possibility of topical delivery.

Dexamethasone implant anterior chamber migration: risk factors, complications, and management strategies

OBJECTIVE

To describe the risk factors, clinical course, and complications of migration of a dexamethasone (DEX) intravitreal implant (OZURDEX; Allergan, Inc., Irvine, CA) into the anterior chamber and subsequent management strategies.

DESIGN

Retrospective, observational case series.

PARTICIPANTS

Fifteen patients had 18 episodes of migration of the DEX implant into the anterior chamber.

METHODS

The medical records of 15 patients with spontaneous migration of a DEX implant were retrospectively reviewed.

MAIN OUTCOME MEASURES

Migration of the DEX implant into the anterior chamber.

RESULTS

Migration of a DEX intravitreal implant into the anterior chamber occurred in 6 patients who were aphakic, 4 patients with an anterior chamber intraocular lens, 2 patients with a scleral-fixated posterior chamber intraocular lens (PCIOL), 2 patients with a PCIOL, and 1 patient with an iris-fixated PCIOL. All 15 patients had prior pars plana vitrectomy, and 14 patients (93%) had no lens capsule. The average interval from DEX implant injection to detection of the implant migration into the anterior chamber was 13 days (range, 5-44 days). In 14 patients, corneal edema developed. Among those eyes undergoing surgical removal of the implant, earlier intervention reduced the likelihood of permanent corneal edema (0.5 days [from diagnosis of migration to surgical removal of the implant] vs. 5.5 days; P = 0.04). Aspiration was necessary to remove the implant in 6 patients. Among the 14 patients with corneal edema, the corneal edema did not resolve in 10 patients (71%), 6 (43%) of whom required corneal transplantation.

CONCLUSIONS

Absence of lens capsule and prior vitrectomy are risk factors for migration of the DEX implant into the anterior chamber. Early removal of the implant may be necessary to minimize the risk of chronic corneal edema.

Intravitreal devices for the treatment of vitreous inflammation

The eye is a well-suited organ for local delivery of therapeutics to treat vitreous inflammation as well as other pathologic conditions that induce visual loss. Several conditions are particularly challenging to treat and often require chronic courses of therapy. The use of implantable intravitreal devices for drug delivery is an emerging field in the treatment of vitreous inflammation as well as other ophthalmologic diseases. There are unique challenges in the design of these devices which include implants, polymers, and micro- and nanoparticles. This paper reviews current and investigational drug delivery systems for treating vitreous inflammation as well as other pathologic conditions that induce visual loss. The use of nonbiodegradable devices such as polyvinyl alcohol-ethylene vinyl acetate polymers and polysulfone capillary fibers, and biodegradable devices such as polylactic acid, polyglycolic acid, and polylactic-co-glycolic acid, polycaprolactones, and polyanhydrides are reviewed. Clinically used implantable devices for therapeutic agents including ganciclovir, fluocinolone acetonide, triamcinolone acetonide, and dexamethasone are described. Finally, recently developed investigational particulate drug delivery systems in the form of liposomes, microspheres, and nanoparticles are examined.

Single perioperative subconjunctival steroid depot versus postoperative steroid eyedrops to prevent intraocular inflammation and macular edema after cataract surgery

PURPOSE

To compare the efficacy of dexamethasone 0.1% eyedrops after phacoemulsification versus a single perioperative subconjunctival injection of betamethasone acetate 5.7 mg/mL to prevent anterior segment inflammation and macular edema.

SETTING

Rotterdam Eye Hospital, Rotterdam, The Netherlands.

DESIGN

Randomized clinical trial.

METHODS

Patients scheduled for cataract surgery were randomly assigned to receive a perioperative subconjunctival injection of betamethasone acetate 5.7 mg/mL (Group 1) or postoperative administration of dexamethasone 0.1% eyedrops (Group 2). Primary outcomes were foveal thickness and macular edema on optical coherence tomography (OCT) and anterior chamber flare by a laser flare meter preoperatively and 4 weeks postoperatively. Secondary outcomes were intraocular pressure, need for additional outpatient clinic visits, phacoemulsification energy, verbal-rating pain scale, and corrected distance visual acuity.

RESULTS

The study enrolled 400 patients (400 eyes). Four weeks postoperatively, the mean flare values were significantly higher in Group 1 than in Group 2 (P=.003). The incidence of macular edema on OCT and clinically significant macular edema were not significantly different between groups (P=.685 and P=.386, respectively). No significant difference was observed in any other outcome measure.

CONCLUSION

A single subconjunctival betamethasone acetate injection appears to be a useful alternative to prolonged postoperative administration of dexamethasone eyedrops in controlling intraocular inflammation and development of macular edema after phacoemulsification.

Migration of ozurdex implant into the anterior chamber

PURPOSE

The purpose of this study was to report a novel complication of Ozurdex implantation in which the implant migrates into the anterior chamber and to describe the subsequent clinical course.

METHODS

After identification of the implant in the inferior anterior chamber, clinical photographs were obtained. Baseline measurements of vision, corneal thickness, and corneal cell counts were likewise collected. The patent was followed for clinical sequelae.

RESULTS

After 4 months, the implant was clearly observed to be degrading. Repeat corneal pachymetry, slit-lamp examination, and visual acuity were stable.

DISCUSSION

Patients with a patent peripheral iridotomy who received Ozurdex intravitreal implants are at risk for migration of the implant into the anterior chamber. However, the implant itself appears to be benign, causing no detrimental effects to the corneal endothelium.

Controlled transscleral drug delivery formulations to the eye: establishing new concepts and paradigms in ocular anti-inflammatory therapeutics and antibacterial prophylaxis

IMPORTANCE OF THE FIELD

The use of topical agents poses unique and challenging hurdles for drug delivery. Topical steroids effectively control ocular inflammation, but are associated with the well-recognized dilemma of patient compliance. Although administration of topical antimicrobials as prophylaxis is acceptable among ophthalmologists, this common practice has no sound evidence base. Developing a new antimicrobial agent or delivery strategy with enhanced penetration by considering the anatomical and physiological constraints exerted by the barriers of the eye is not a commonly perceived strategy. Exploiting the permeability of the sclera, subconjunctival routes may offer a promising alternative for enhanced drug delivery and tissue targeting.

AREA COVERED IN THIS REVIEW

Ocular drug delivery strategies were reviewed for ocular inflammation and infections clinically adopted for newer class of antimicrobials, which use a multipronged approach to limit risks of endophthalmitis.

WHAT THE READER WILL GAIN

The analysis substantiates a new transscleral drug delivery therapeutic approach for cataract surgery.

TAKE HOME MESSAGE

A new anti-inflammatory and anti-infective paradigm that frees the patient from the nuisance of topical therapeutics is introduced, opening a large investigative avenue for future improved therapies.

Implants as drug delivery devices for the treatment of eye diseases

The treatment of diseases affecting the posterior segment of the eye is limited by the difficulty in transporting effective doses of drugs to the vitreous, retina, and choroid. Topically applied drugs are poorly absorbed due to the low permeability of the external ocular tissues and tearing. The blood-retina barrier limits drug diffusion from the systemic blood to the posterior segment, thus high doses of drug are needed to maintain therapeutic levels. In addition, systemic side effects are common. Intraocular injections could be an alternative, but the fast flowing blood supply in this region, associated with rapid clearance rates, causes drug concentration to quickly fall below therapeutic levels. To obtain therapeutic levels over longer time periods, polymeric sustained-drug release systems implanted within the vitreous are being studied for the treatment of vitreoretinal disorders. These systems are prepared using different kinds of biodegradable or non-biodegradable polymers. This review aims to demonstrate the main characteristics of these drug delivery implants and their potential for clinical application.

Biodegradable implants for sustained drug release in the eye

The safety and effectiveness of systemic and topical medical therapies for ocular disorders are limited due to poor ocular drug uptake, nonspecificity to target tissues, systemic side effects, and poor adherence to therapy. Intravitreal injections can enhance ocular drug delivery, but the need for frequent retreatment and potential injection-related side effects limit the utility of this technique. Sustained-release drug delivery systems have been developed to overcome these limitations; such systems can achieve prolonged therapeutic drug concentrations in ocular target tissues while limiting systemic exposure and side effects and improving patient adherence to therapy. A critical factor in the development of safe and effective drug delivery systems has been the development of biocompatible polymers, which offer the versatility to tailor drug release kinetics for specific drugs and ocular diseases. Ocular implants include nonbiodegradable and biodegradable designs, with the latter offering several advantages. The polymers most commonly used in biodegradable delivery systems are synthetic aliphatic polyesters of the poly-α-hydroxy acid family including polylactic acid, polyglycolic acid, and polylactic-co-glycolic acid. The characteristics of these polymers for medical applications as well as the pharmacological properties, safety, and clinical effectiveness of biodegradable drug implants for the treatment of ocular diseases are reviewed herein.

Nonsteroidal anti-inflammatory drugs in ophthalmology

Nonsteroidal anti-inflammatory drugs (NSAIDs) are increasingly employed in ophthalmology to reduce miosis and inflammation, manage scleritis, and prevent and treat cystoid macular edema associated with cataract surgery. In addition, they may decrease postoperative pain and photophobia associated with refractive surgery and may reduce the itching associated with allergic conjunctivitis. In recent years, the U.S. Food and Drug Administration has approved new topical NSAIDs, and previously approved NSAIDs have been reformulated. These additions and changes result in different pharmacokinetics and dosing intervals, which may offer therapeutic advantages. For example, therapeutic effects on diabetic retinopathy and age-related macular degeneration may now be achievable. We provide an updated review on NSAIDs and a summary of their current uses in ophthalmology with attention to potential future applications.

Intraocular lens as a drug delivery system for dexamethasone

PURPOSE

To evaluate the effect of an intraocular lens (IOL) coated with dexamethasone on postoperative inflammation after cataract surgery.

METHODS

Clear lens extraction was performed bilaterally in eight 8-week-old rabbits. An uncoated silicone IOL (CeeOn; AMO, Santa Ana, CA, USA) was implanted in one randomly selected eye. In the other eye, the same silicone IOL model was implanted but was coated with dexamethasone. Aqueous humour was obtained preoperatively and on days 1, 3, 7, 14 and 28 postoperatively. Three inflammatory parameters were measured and compared between the eyes: prostaglandin E2 (PGE2), white blood cell (WBC) count and protein content. The animals were killed on day 28 postoperatively.

RESULTS

PGE2 levels measured on days 1, 3 and 7 were significantly lower in eyes with a coated IOL compared to eyes with an uncoated IOL (p < 0.01). The WBC count was significantly lower in eyes with a coated IOL on days 1 (p < 0.01) and 3 (p < 0.05). There was significantly less protein in eyes with a coated IOL on days 1 and 3 (p < 0.01).

CONCLUSION

Coating a silicone IOL with dexamethasone significantly reduced postoperative inflammation after clear lens extraction in rabbits.