OUTCOME OF FLUOCINOLONE ACETONIDE IMPLANT (RETISERT™) REIMPLANTATION FOR CHRONIC NONINFECTIOUS POSTERIOR UVEITIS

Pathogenesis and current therapies for non-infectious uveitis

Non-infectious uveitis (NIU) is a disorder with various etiologies and is characterized by eye inflammation, mainly affecting people of working age. An accurate diagnosis of NIU is crucial for appropriate therapy. The aim of therapy is to improve vision, relieve ocular inflammation, prevent relapse, and avoid treatment side effects. At present, corticosteroids are the mainstay of topical or systemic therapy. However, repeated injections are required for the treatment of chronic NIU. Recently, new drug delivery systems that may ensure intraocular delivery of therapeutic drug levels have been highlighted. Furthermore, with the development of immunosuppressants and biologics, specific therapies can be selected based on the needs of each patient. Immunosuppressants used in the treatment of NIU include calcineurin inhibitors and antimetabolites. However, systemic immunosuppressive therapy itself is associated with adverse effects due to the inhibition of immune function. In patients with refractory NIU or those who cannot tolerate corticosteroids and immunosuppressors, biologics have emerged as alternative treatments. Thus, to improve the prognosis of patients with NIU, NIU should be managed with different drugs according to the response to treatment and possible side effects.

Intravitreal injection versus systematic treatment in patients with uveitis undergoing cataract surgery: a systematic review and meta-analysis

PURPOSE

Cataract surgery in patients with uveitis is challenging, and postoperative inflammation control is crucial for successful outcomes. No consensus exists regarding the optimal method of controlling postoperative inflammation. In this systematic review and meta-analysis, we compared the outcome of intravitreal injection (IVI), including steroid (triamcinolone acetonide) or steroid implant (dexamethasone), with systemic anti-inflammatory therapy (ST), such as systemic steroids with or without immunomodulatory therapy, in patients with uveitis undergoing cataract surgery.

METHODS

We searched PubMed, EMBASE, and Cochrane Library databases for randomized controlled trials (RCTs), comparative cohort studies, and case-control studies published through May 2021 that compared intraoperative IVI of triamcinolone acetonide or steroid implant with ST with or without immunomodulatory therapy. The following outcomes were evaluated: preoperative best-corrected visual acuity, intraocular pressure, laser flare photometry, central macular thickness and cystoid macular edema rate.

RESULTS

Five studies were selected. Our analysis indicated that compared with ST, IVI treatment may be associated with less anterior chamber inflammation and a lower cystoid macular edema rate, but the difference in best-corrected visual acuity, intraocular pressure, or central macular thickness was not significant.

CONCLUSIONS

IVI of steroid or steroid implants might be beneficial in controlling postoperative inflammation for uveitis cataract, especially in patients who cannot tolerate ST. To the best of our knowledge, this is the first meta-analysis to compare the efficacy of intraoperative IVI of steroids with standard-of-care treatment as a prophylaxis for uveitis cataract. However, large-scale RCTs are warranted to compare the IVI of steroid implants and steroids.

Ocular Delivery of Therapeutic Proteins: A Review

Therapeutic proteins, including monoclonal antibodies, single chain variable fragment (ScFv), crystallizable fragment (Fc), and fragment antigen binding (Fab), have accounted for one-third of all drugs on the world market. In particular, these medicines have been widely used in ocular therapies in the treatment of various diseases, such as age-related macular degeneration, corneal neovascularization, diabetic retinopathy, and retinal vein occlusion. However, the formulation of these biomacromolecules is challenging due to their high molecular weight, complex structure, instability, short half-life, enzymatic degradation, and immunogenicity, which leads to the failure of therapies. Various efforts have been made to overcome the ocular barriers, providing effective delivery of therapeutic proteins, such as altering the protein structure or including it in new delivery systems. These strategies are not only cost-effective and beneficial to patients but have also been shown to allow for fewer drug side effects. In this review, we discuss several factors that affect the design of formulations and the delivery of therapeutic proteins to ocular tissues, such as the use of injectable micro/nanocarriers, hydrogels, implants, iontophoresis, cell-based therapy, and combination techniques. In addition, other approaches are briefly discussed, related to the structural modification of these proteins, improving their bioavailability in the posterior segments of the eye without affecting their stability. Future research should be conducted toward the development of more effective, stable, noninvasive, and cost-effective formulations for the ocular delivery of therapeutic proteins. In addition, more insights into preclinical to clinical translation are needed.

Standardized care by redesign of an intravitreal injection pathway

PURPOSE:

Intravitreal injection of medication is a rapid rising surgical intervention in modern ophthalmological care. With increasing numbers, the caseload of complications follows and the burden on daily clinical organization increases. This study focuses on developing a standardized treatment protocol to improve care and reduce hazard.

METHODS:

A standardized treatment protocol was designed and educated to the involved medical doctor and registered nurse. An independent observer used this protocol to evaluate the actions performed during the intravitreal injection. Data on the included patients and products injected were collected.

RESULTS:

In total, 180 injections of 134 patients were observed between 1 December 2011 and 18 October 2012, divided over 16 measurements. From the fifth measurement on, a 100% protocol adherence for the time out procedure was achieved and maintained over time, with a transient insignificant decrease. The performance of actions of the medical doctor and assisting registered nurse followed the same trend with a rapid increase and 100% protocol adherence. No microorganism caused development of endophthalmitis was recorded.

CONCLUSION:

The optimization of an intravitreal injection care pathway leads to a more standardized intervention process with no apparent reduction in clinical efficiency and safety.

Ocular delivery of proteins and peptides: Challenges and novel formulation approaches

The impact of proteins and peptides on the treatment of various conditions including ocular diseases over the past few decades has been advanced by substantial breakthroughs in structural biochemistry, genetic engineering, formulation and delivery approaches. Formulation and delivery of proteins and peptides, such as monoclonal antibodies, aptamers, recombinant proteins and peptides to ocular tissues poses significant challenges owing to their large size, poor permeation and susceptibility to degradation. A wide range of advanced drug delivery systems including polymeric controlled release systems, cell-based delivery and nanowafers are being exploited to overcome the challenges of frequent administration to ocular tissues. The next generation systems integrated with new delivery technologies are anticipated to generate improved efficacy and safety through the expansion of the therapeutic target space. This review will highlight recent advances in formulation and delivery strategies of protein and peptide based biopharmaceuticals. We will also describe the current state of proteins and peptides based ocular therapy and future therapeutic opportunities.

DISLODGEMENT OF FLUOCINOLONE ACETONIDE INTRAVITREAL IMPLANT INTO THE INFUSION CANNULA DURING VITRECTOMY FOR RETINAL DETACHMENT

BACKGROUND/PURPOSE

To report a case of dislodgement of an Iluvien (fluocinolone acetonide) intravitreal implant into the infusion cannula during pars plana vitrectomy for retinal detachment.

METHODS

The patient's surgery was video recorded, and the medical notes were reviewed retrospectively.

RESULTS

A patient developed a macula off retinal detachment over 1 year after intravitreal injection of Iluvien for diabetic maculopathy. The patient underwent pars plana vitrectomy, removal of implant, and successful retinal reattachment. Although we planned to remove the implant through a sclerostomy, we were not able to localize it after performing peripheral indented vitrectomy. As the intraocular pressure was fluctuating, we suspected that the implant might have dislodged into the infusion cannula. However, despite increasing the intraocular pressure to 60 mmHg and performing repeated fluid-air exchange, we could not eject the implant back into the vitreous cavity. Therefore, after completing the surgery safely, we flushed the infusion cannula with balanced salt solution and we found the implant.

CONCLUSION

Increasing the intraocular pressure and performing fluid-air exchange were not sufficient to eject the implant probably because of the strong surface adherence between the infusion cannula and the implant's coating material. We, therefore, recommend removing and flushing the infusion cannula if the implant cannot be localized in the eye. In addition, clinicians should be aware that a fluctuating intraocular pressure might be the first sign of a partially blocked infusion cannula by the implant.

New Drugs and New Posterior Delivery Methods in CME

PURPOSE

To discuss the characteristics, indications and adverse events (AEs) of sustained-release corticosteroid devices for the treatment of cystoid macular edema (CME).

RECENT FINDINGS

Ozurdex® is approved for the treatment of diabetic macular edema (DME), retinal vein occlusion related-CME and noninfectious posterior uveitis (NIPU). It releases dexamethasone over a maximum period of 6 months making repeated intravitreal injections necessary for recurrent CME. Iluvien® releases fluocinolone for up to 36 months and is effective for the treatment of chronic DME. Retisert® (Bausch & Lomb, Rochester, NY) also releases fluocinolone, and is approved for chronic NIPU. Both Iluvien® and Retisert® are non-biodegradable devices and are highly associated with cataract and glaucoma.

SUMMARY

Long-acting intraocular corticosteroid formulations offer a more predictable drug-release profile and reduced dosing frequency in comparison to conventional formulations of the same compounds but the risk-benefit ratio must be taken into consideration previous to the implantation of those devices.

Tunable release of ophthalmic therapeutics from injectable, resorbable, thermoresponsive copolymer scaffolds

The sustained release of ophthalmic therapeutics to the posterior segment of the eye is a challenge. Injectable polymer materials have the potential to reduce injection frequency by providing long term therapeutic delivery. Copolymers with varying N-isopropylacrylamide, acrylamide (AAm), acrylic acid N-hydroxysuccinimide, and (r)-α-acryloyloxy-β,β-dimethyl-γ-butyrolactone (DBA) were synthesized by RAFT polymerization to develop injectable, resorbable, and thermoresponsive copolymer scaffolds. Upon injection into physiological conditions, these copolymers undergo a temperature induced gelation to form a drug releasing scaffold. Modification of the copolymer's AAm/DBA ratio and molecular weight afforded significant and precise control over the scaffold's physical properties and subsequent drug release profile. Hydrolytic DBA ring-opening enables redissolution of the copolymers for clearance from the body. Precise control over the drug release profile from these copolymer scaffolds by simple alteration of composition and molecular weight provides an efficient method to customize the minimally invasive delivery of therapeutics to the posterior segment of the eye. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 53-62, 2017.

A sustained intravitreal drug delivery system with remote real time monitoring capability

Many chorioretinal diseases are chronic and need sustained drug delivery systems to keep therapeutic drug level at the disease site. Many intravitreal drug delivery systems under developing do not have mechanism incorporated for a non-invasive monitoring of drug release. The current study prepared rugate porous silicon (pSi) particles by electrochemical etching with the current frequency (K value) of 2.17 and 2.45. Two model drugs (rapamycin and dexamethasone) and two drug-loading strategies were tested for the feasibility to monitor drug release from the pSi particles through a color fundus camera. The pSi particles (k=2.45) with infiltration loading of rapamycin demonstrated progressively more violet color reflection which was negatively associated with the rapamycin released into the vitreous (r=-0.4, p<0.001, pairwise). In contrast, pSi with K value of 2.17 demonstrated progressive color change toward green and a weak association between rapamycin released into vitreous and green color abundance was identified (r=-0.23, p=0.002, pairwise). Dexamethasone was covalently loaded on to the fully oxidized pSi particles that appeared in vitreous as yellow color and fading over time. The yellow color decrease over time was strongly associated with the dexamethasone detected from the vitreous samples (r=0.7, p<0.0001, pairwise). These results suggest that engineered porous silicon particles may be used as a self-reporting drug delivery system for a non-invasive real time remote monitoring.

STATEMENT OF SIGNIFICANCE

The current study, for the first time, demonstrated proof of concept that engineered porous silicon photonic crystal may deliver therapeutics in a controlled fashion while at the same time might offer a noninvasive remote monitoring of its payload release in a living eye. Porous silicon photonic crystal changes color which is in association with its payload release into vitreous. With further optimization, the color change may be harnessed to inform eye care professionals of real time drug concentration in the eye and allow them to make informed decision to re-dose the patients.

Spontaneous dislocation of fluocinolone acetonide implant pellets from their suture struts

PURPOSE

To characterize spontaneous dislocation of the fluocinolone acetonide sustained release implant (Retisert; Bausch & Lomb) drug pellet from its strut.

DESIGN

Retrospective, observational case series.

METHODS

The medical records of 224 patients in whom 407 fluocinolone acetonide implants were placed by either of 2 surgeons between 1998 and 2012 were reviewed for drug pellet-suture strut separation, observed before surgery in clinic or occurring at the time of implant replacement.

RESULTS

Seventeen (4.2%) of 407 drug pellets spontaneously dislocated away from the suture strut at a mean postimplantation time of 77.4 months (range, 33 to 132 months). The rate of spontaneous dislocation increased from 1 dislocation per 262 person years (95% confidence interval, 1 per 1269 to 1 per 89.6 person-years) before 60 months to 1 dislocation per 13.3 person-years (95% confidence interval, 1 per 24.4 to 1 per 7.9 person-years) afterward. Fourteen of 17 dislocated pellets were removed surgically. Of 77 exchanged fluocinolone acetonide implants without dislocated pellets, 11 (14.2%) pellets had separated, but not dislocated away, from the strut; time to exchange of dislocated or dissociated pellets was significantly longer than time to exchange of intact fluocinolone acetonide implants (70.5 vs 44.9 months; P < .001).

CONCLUSIONS

The fluocinolone acetonide drug pellet can dislocate spontaneously from the suture strut as a late event that typically occurs after 3 years. Pellets also may be dissociated from the strut without dislocation, when separation occurs at the time of surgical replacement. Removal of the dislocated pellet can be achieved safely. Time was the major risk factor identified for both events.

Outcome of Multiple Implants and Dissociation of Fluocinolone Acetonide Intravitreal Implant (Retisert) in a Series of 187 Consecutive Implants

PURPOSE

To evaluate outcomes of long-term follow-up of Retisert multiple implantation and dissociation in eyes with chronic noninfectious uveitis.

METHODS

Review of 187 consecutive Retisert implants. Outcomes of multiple implantation and spontaneous medication pellet-strut dissociation were evaluated.

RESULTS

A total of 187 consecutive Retisert implants were reviewed. Eight implants were removed. The prevalence of spontaneous dissociation was 2.6% (5/187). The rate of dissociation increased to 11.11% (2/18) in cases of multiple implants. The mean period between Retisert implantation and spontaneous dissociation was 65.05 months. The mean period between implants in the same eye was 55.25 months. In cases of multiple implantations the old implant was not removed and 17.64% (3/17) of eyes required glaucoma filtering surgery.

CONCLUSION

The rate of spontaneous dissociation of Retisert medication pellet-strut in eyes with single implant for noninfectious uveitis is low, which tends to increase in eyes with multiple implants.

Scleral melt following Retisert intravitreal fluocinolone implant

Intravitreal fluocinolone acetonide implant (Retisert) has a high potency, a low solubility, and a very short duration of action in the systemic circulation, enabling the steroid pellet to be small and reducing the risk of systemic side effects. Scleral melt has not been reported as a possible complication of Retisert implant. The authors describe the occurrence of scleral melt 18 months after the implantation of fluocinolone acetonide implant in a 42-year-old Caucasian woman. To the authors' knowledge, this is the first report of this possible complication.

Ocular delivery of macromolecules

Biopharmaceuticals are making increasing impact on medicine, including treatment of indications in the eye. Macromolecular drugs are typically given by physician-administered invasive delivery methods, because non-invasive ocular delivery methods, such as eye drops, and systemic delivery, have low bioavailability and/or poor ocular targeting. There is a need to improve delivery of biopharmaceuticals to enable less-invasive delivery routes, less-frequent dosing through controlled-release drug delivery and improved drug targeting within the eye to increase efficacy and reduce side effects. This review discusses the barriers to drug delivery via various ophthalmic routes of administration in the context of macromolecule delivery and discusses efforts to develop controlled-release systems for delivery of biopharmaceuticals to the eye. The growing number of macromolecular therapies in the eye needs improved drug delivery methods that increase drug efficacy, safety and patient compliance.

Hydrosilylated porous silicon particles function as an intravitreal drug delivery system for daunorubicin

PURPOSE

To evaluate in vivo ocular safety of an intravitreal hydrosilylated porous silicon (pSi) drug delivery system along with the payload of daunorubicin (DNR).

METHODS

pSi microparticles were prepared from the electrochemical etching of highly doped, p-type Si wafers and an organic linker was attached to the Si-H terminated inner surface of the particles by thermal hydrosilylation of undecylenic acid. DNR was bound to the carboxy terminus of the linker as a drug-loading strategy. DNR release from hydrosilylated pSi particles was confirmed in the excised rabbit vitreous using liquid chromatography-electrospray ionization-multistage mass spectrometry. Both empty and DNR-loaded hydrosilylated pSi particles were injected into the rabbit vitreous and the degradation and safety were studied for 6 months.

RESULTS

The mean pSi particle size was 30×46×15 μm with an average pore size of 15 nm. Drug loading was determined as 22 μg per 1 mg of pSi particles. An ex vivo drug release study showed that intact DNR was detected in the rabbit vitreous. An in vivo ocular toxicity study did not reveal clinical or pathological evidence of any toxicity during a 6-month observation. Hydrosilylated pSi particles, either empty or loaded with DNR, demonstrated a slow elimination kinetics from the rabbit vitreous without ocular toxicity.

CONCLUSIONS

Hydrosilylated pSi particles can host a large quantity of DNR by a covalent loading strategy and DNR can be slowly released into the vitreous without ocular toxicity, which would appear if an equivalent quantity of free drug was injected.

A comparison between the fluocinolone acetonide (Retisert) and dexamethasone (Ozurdex) intravitreal implants in uveitis

PURPOSE

To evaluate the efficacy and safety of the fluocinolone acetonide (Retisert) implant compared with the dexamethasone (Ozurdex) implant in patients with noninfectious uveitis.

DESIGN

Comparative case series.

STUDY PARTICIPANTS

Twenty-seven eyes received either the fluocinolone acetonide (FA) (n=16) or dexamethasone (n=11) implant.

METHODS

Chart review of patients at the Massachusetts Eye Research and Surgery Institution (MERSI) was done and patients were selected and matched according to age, sex, and type of uveitis. Eyes that received either the FA or dexamethasone implant, with follow-up ranging from 6 months to 2 years, were included.

MAIN OUTCOME MEASURE

The recurrence rate of uveitis after implantation.

RESULTS

There were no significant differences in the baseline demographic characteristics. The majority of cases were idiopathic panuveitis, with 36.4% and 31.3% of eyes in the Ozurdex and Retisert groups, respectively. Recurrence rates of uveitis were 1.7 and 0.5 per 100 person-months in the Retisert and Ozurdex groups, respectively, with Retisert-implanted eyes 3.16 times more at risk of recurrence; however, this difference was not statistically significant (P=0.41). No significant differences were seen in terms of improvement in inflammatory score and best-corrected visual acuity (BCVA). The median survival time for a second implant was 13 and 28 months for the Ozurdex and Retisert groups, respectively (P=0.0028). Eyes with the Ozurdex were 5 times more likely to receive a second implant (P=0.02). No eyes in the Ozurdex group needed additional glaucoma medications, surgery, or laser compared to 44% of eyes in the Retisert group. Eyes with the Retisert implant had a statistically higher rate of having more glaucoma medications, surgery, or laser (P=0.02). In the Ozurdex group, 50% of phakic eyes at baseline had cataract progression and subsequent surgery compared with 100% of Retisert phakic eyes. Eyes with the Retisert implant are 4.7 times more at risk of cataract progression (P=0.04).

CONCLUSIONS

The dexamethasone (Ozurdex) implant seems comparable to the fluocinolone acetonide (Retisert) implant in preventing recurrence of noninfectious uveitis and in improving inflammation and BCVA. However, there were higher rates of cataract progression and need for glaucoma medications, laser, and surgery with the Retisert implant.

Evaluation of fluocinolone acetonide sustained release implant (Retisert) dissociation during implant removal and exchange surgery

PURPOSE

To characterize the phenomenon of dissociation of the 2 components of the sustained-release fluocinolone acetonide implant (Retisert; Bausch & Lomb) during removal or exchange procedures, or both, and to evaluate outcomes after these events.

DESIGN

Retrospective, observational case series.

METHODS

Retrospective review of 27 consecutive sustained-release fluocinolone acetonide implant (Retisert) exchanges or removals between 2001 and 2010 at the Cole Eye Institute. All patients had received the implant as treatment for noninfectious uveitis. Preoperative and postoperative characteristics were analyzed, and operative reports were reviewed to characterize the effects of intraoperative implant dissociation.

RESULTS

Twenty-seven sustained-release fluocinolone acetonide implant (Retisert) exchange or removal surgeries were performed by 3 surgeons in 20 eyes of 19 patients. Of these 27 procedures, dissociation of the implant strut from the drug-containing cup occurred in 11 eyes (40.7%). Retrieval of the dislocated cup led to intraoperative complications, including posterior retinal tear (n = 1) and limited suprachoroidal hemorrhage (n = 1). The length of time that the implant resided in the eye correlated significantly with cup dissociation. Dissociated implants resided a mean of 47.4 months, whereas intact implants resided a mean of 32.5 months (P = .0032). There was no long-term or short-term vision loss attributed to intraoperative implant dissociation.

CONCLUSIONS

Sustained-release fluocinolone acetonide implant (Retisert) dissociation is a common occurrence in exchange or removal procedures, or both. The longer an implant resided in the eye, the greater the tendency toward dissociation. Preparation for this complication should be contemplated in any implant removal or exchange procedure.

Intraocular corticosteroids for posterior segment disease: 2012 update

INTRODUCTION

Diabetic macular edema (DME), cystoid macular edema (CME), age-related macular degeneration (AMD), retinal vascular occlusion (RVO) and uveitis are responsible for severe visual impairment worldwide. In some patients with these conditions, treatment with intraocular corticosteroids may be beneficial. Although off-label use of these agents has occurred for many years, novel agents including preservative-free and sustained-release intravitreal implants are currently being studied in clinical trials (CTs).

AREAS COVERED

This paper reviews the use of CTs for vitreoretinal (VR) diseases including choroidal neovascularization, CME, DME, RVO and posterior uveitis. It also discusses the use of corticosteroids for treating VR disease, including dexamethasone, fluocinolone acetonide, intravitreal implants and triamcinolone acetonide.

EXPERT OPINION

Used alone, intravitreal corticosteroids may benefit disorders such as DME, RVO and uveitis compared with standard therapy. Cases of exudative AMD non-responsive to standard treatment may benefit from combination therapy, including usage of intravitreal corticosteroid injections. Intraoperative use of these agents may aid visualization of retinal structures. Sustained-release intraocular implants have been approved for posterior uveitis and RVO associated with macular edema. In spite of this, most intraocular corticosteroids have a limited duration of action along with significant side effects, including cataract and glaucoma. Currently, intravitreal corticosteroid usage for DME is considered off-label.

Long-term follow-up of patients treated with multiple fluocinolone acetonide implants for noninfectious uveitis

Purpose

To evaluate long-term outcomes in eyes undergoing exchange of fluocinolone acetonide intravitreal implants for noninfectious uveitis.

Methods

In this retrospective case series, chart review was conducted of all patients treated for noninfectious uveitis with fluocinolone acetonide implants. All patients were seen at a single center between 2007 and 2010.We studied eight eyes of eight patients who received second implants in exchange for previously placed implants and received follow-up care after the implant was exchanged. Main outcome measures were visual acuity (VA), recurrence of inflammation, need for adjunctive systemic anti-inflammatory treatment and adverse events.

Results

We studied eight eyes of eight patients. Average length of follow-up after the second implant was 32.3 months. Of the eight patients, five experienced improvement or stabilization of VA when acuity prior to the initial implant was compared to acuity on long-term follow-up. After their first implant, five patients experienced disease recurrence. Including all eight patients, the estimated median time to recurrence was 35.7 months after the first implant. The mean time to reimplantation was 42.7 months. After the second implant, three patients experienced recurrence. Including all eight patients, the estimated median time to recurrence was 30.1 months after the second implant. Adverse events included perioperative complications, elevated intraocular pressure (IOP) and cataracts.

Conclusions

Exchanging FA intravitreal implants used to treat noninfectious uveitis may be useful in preventing vision loss and recurrence of inflammation. Development of elevated IOP and cataract is a potentially serious complication. The risks and benefits of implant exchange must be carefully considered with this intervention.

Road to remission: a comprehensive review of therapy in uveitis

INTRODUCTION

Although uveitis remains the third leading cause of preventable blindness in the US, the care and management of patients with uveitis and ocular inflammatory disease sit poised to make evolutionary if not revolutionary changes in the years ahead. This review serves to highlight important advances in the pharmacologic options available for the treatment of uveitis and ocular inflammation.

AREAS COVERED

Advances in steroid therapy (both topical and extended delivery), updates in the clinical safety of systemic immune modulation, and the emerging therapies for uveitis and ocular inflammatory disease are some of the areas covered in this review.

EXPERT OPINION

Corticosteroids have been the mainstay in the care of patients with ocular inflammatory disorders for many years. Indeed, some physicians still use only steroids for treating inflamed eyes. However, the mission is remission of all corticosteroids in order to prevent the complications associated with long-term corticosteroid use. The goal is to achieve quiescence through aggressive use of corticosteroids to extinguish the fire and then move along to achieve steroid-free remission through immunosuppressant agents.

Intraocular pharmacokinetics of a crystalline lipid prodrug, octadecyloxyethyl-cyclic-cidofovir, for cytomegalovirus retinitis

PURPOSE

To evaluate the intraocular pharmacokinetics of octadecyloxyethyl-cyclic-cidofovir (ODE-cCDV) after intravitreal injection into rabbit eyes.

METHODS

Twenty-seven New Zealand red rabbits (27 eyes) received intravitreal injections of (14)C-labeled ODE-cCDV (100 μg drug suspended in 5% dextrose), and ocular tissues were collected from 3 rabbits at each predetermined time point (1 h, 1 day, 3 days, 1 week, 2 weeks, 3 weeks, 5 weeks, and 9 weeks) after the injection. The eye globes were enucleated, and the vitreous, retina, and choroids were separated and harvested into pre-weighed scintillation vials. Levels of ODE-cCDV were measured by counting in a liquid scintillation counter, and pharmacokinetic (PK) parameters were determined. In addition, 3 eyes of 3 animals were used for autoradiography study at day 1, week 3, and week 6.

RESULTS

ODE-cCDV in vitreous as a whole followed a 2-phase first-order elimination, whereas ODE-cCDV in retina and choroid manifested a nearly steady state during the first 3 weeks and then followed a first-order elimination with the apparent elimination half-life of 10.1 and 7.2 days. For vitreous, apparent elimination half-life was 25 days. However, the drug mean residence time was much longer in retina (17.6 days) and choroid (19.6 days) than that in the vitreous (11.6 days). The drug exposure to the retina [area under the curve (AUC) = 1120837.1 ng · day/mL] was greater than the exposure to the vitreous (AUC = 958645.8 ng · day/mL) and the choroid (AUC = 415407.47).

CONCLUSION

A crystalline lipid prodrug, ODE-cCDV, has longer vitreous half-life than that in other ocular tissues due to its solid drug depot formation in vitreous. Over time, dissolved free ODE-cCDV from drug depot feeds and accumulates in the retina.

Scleral thickness following fluocinolone acetonide implant (Retisert)

PURPOSE

To evaluate whether intravitreal fluocinolone acetonide (FA) implantation (Retisert) leads to scleral thinning.

METHODS

Scleral thickness was measured at the pars plana region (4 quadrants) with anterior segment OCT (Visante) in FA implanted eyes (18) with noninfectious posterior uveitis in comparison to eyes with prior vitrectomy (8), and normal eyes without prior surgery (30).

RESULTS

Mean scleral thickness in normal (nonsurgical) eyes was 0.99/0.93/0.88/0.86, and 0.92 mm in the inferonasal/inferotemporal/superotemporal/superonasal quadrants, and overall, respectively. Sclera was thinner in each quadrant of the FA implanted eyes compared to the fellow or nonsurgical eyes, although none reached statistical significance, as the differences were small. However, a few FA implanted eyes demonstrated more dramatic scleral thinning than others.

CONCLUSIONS

FA implant appears to lead to statistically nonsignificant scleral thinning overall with few exceptions. Clinicians should be aware of potential scleral thinning in select cases, important for reimplantation and long-term follow-up.

The use of intraocular corticosteroids

BACKGROUND

Diabetic macular edema (DME), cystoid macular edema (CME), age-related macular degeneration (AMD), retinal vascular occlusion (RVO) and uveitis are responsible for severe visual impairment worldwide. In some patients with these conditions, treatment with intraocular corticosteroids may be beneficial. Although off-label use of these agents has occurred for many years, novel agents including preservative-free and sustained-release intravitreal implants are currently being studied in clinical trials (CTs).

OBJECTIVE

To review the use of intraocular corticosteroids.

METHODS

Literature review.

RESULTS

Used alone, intravitreal corticosteroids may benefit disorders such as DME, RVO and uveitis compared with standard therapy or observation. Patients with AMD may benefit more from combination treatment with photodynamic therapy, intravitreal corticosteroid and intravitreal anti-VEGF injections. Intraoperative use of these agents may assist in visualization and manipulation of fine retinal structures. Sustained-release intraocular implants have been approved for severe posterior uveitis, and have shown benefits in ongoing CTs.

CONCLUSION

Although intraocular corticosteroid injections have a limited duration of action requiring frequent re-treatment, and significant side effects including cataract and glaucoma development, intraocular injections may be of benefit in certain ocular disorders. Corticosteroid implants are emerging as potential treatments for macular edema due to uveitis, DME or RVO.