Dexamethasone implant in silicone oil: in vitro behavior

Evidence-based guidelines for drug dosing in intravitreal injections in silicone oil-filled eyes: Pharmacokinetics, safety, and optimal dosage

We evaluate the pharmacokinetics, safety, and optimal dosages of intravitreal agents in silicone oil (SO)-filled eyes, addressing challenges in administering such therapies. We assessed the pharmacological properties and safety profiles of intravitreal drugs in SO-filled eyes, deriving conclusions and guidance from available literature and expert consensus. Preclinical data suggest comparable half-lives of anti-vascular endothelial growth factoragents in SO-filled eyes, but clinical evidence is mainly from case reports and small series. Available research prioritizes standard dosages, particularly for bevacizumab (1.25 mg), supported by stronger evidence than aflibercept (2 mg) or ranibizumab (0.5 mg). Intravitreal steroids, especially dexamethasone at 0.7 mg, show efficacy and safety, while evidence for fluocinolone acetonide at 0.19 mg is limited. Intravitreal methotrexate has been reported at the dosage of 250-400 μg, with keratitis as the primary expected side effect. Case reports indicate tolerability of standard dosages of antivirals (foscarnet 1.2-2.4 mg/0.1 mL, ganciclovir 4 mg/0.1 mL) and the antibiotic combination piperacillin/tazobactam (250 μg/0.1 mL). We offer guidance based on current, but limited, literature. Standard dosage of intravitreal agents should be carefully considered, along with close monitoring for potential side effects, which should be discussed with patients.

In Vivo Assessment of an Antioxidant Hydrogel Vitreous Substitute

The vitreous humor undergoes liquefaction with age, resulting in complications that may require a vitrectomy, or surgical removal of the vitreous from the eye. Silicone oil, a common vitreous substitute, lacks properties similar to the natural vitreous. In particular, it lacks antioxidants that may be necessary to reduce oxidative stress in the eye. The purpose of this study was to evaluate antioxidant-loaded hydrogel vitreous substitutes in a pilot in vivo study. Ascorbic acid and glutathione were loaded into synthesized PEGDA hydrogels. Following vitrectomy, experimental antioxidant hydrogels or silicone oil were injected into one eye of rabbits, while the other eye served as untreated or sham control. Ophthalmic assessments, including electroretinography, were performed. Levels of glutathione and ascorbic acid were higher in the eyes treated with the antioxidant-loaded hydrogel vitreous substitute, although this was not found to be significant after 28 days. There were no statistically significant differences between groups with respect to clinical examination, and ocular health scores, electroretinograms, and histology were normal. These results indicate minimal concerns for the hydrogel formulation or high levels of antioxidants. Future research will assess the capability of vitreous substitutes to prolong antioxidant release, with the goal of minimizing cataract after vitrectomy.

INJECTABLE FLUOCINOLONE IMPLANT FOR THE MANAGEMENT OF CHRONIC POSTSURGICAL CYSTOID MACULAR EDEMA IN VITRECTOMIZED EYES

PURPOSE

Long-acting injectable steroids are changing the treatment paradigm for patients with chronic intraocular inflammation and cystoid macular edema (CME). We report the use of the fluocinolone implant 0.18 mg in patients with chronic postsurgical CME after pars plana vitrectomy.

METHODS

This is a retrospective case series of 24 vitrectomized eyes which received fluocinolone implant for the management postsurgical CME. Clinical outcomes and requirement for rescue therapy were studied.

RESULTS

Median length of follow-up was 19.3 months (range 8.3-23.2 months). There was an improvement in median central subfield thickness from 412 µ m (range 167-806 µ m) to 311 µ m (range 157-686 µ m) after fluocinolone implant ( P < 0.001). The injection burden decreased significantly after study treatment ( P < 0.001); however, there was no significant change in visual acuity ( P = 0.334). Eighteen eyes had control of CME that did not require additional intravitreal therapy. Four eyes had initially controlled but recurrent CME requiring intravitreal steroid therapy at median of 7.8 months (range 7.6-15.4 months). One eye never attained sufficient inflammatory control despite rescue therapy.

CONCLUSION

Fluocinolone implant can be an effective treatment in vitrectomized patients with chronic postsurgical CME and can help decrease the overall injection burden.

Single-dose Effect of Intravitreal Dexamethasone Implant for Post-vitrectomy Macular Edema under Silicone Oil

PURPOSE

To investigate the single-dose effect of intravitreal dexamethasone (DEX) implant for patients with post-vitrectomy macular edema (ME) under silicone oil (SO) tamponade.

METHODS

Twelve eyes diagnosed with ME after undergoing pars plana vitrectomy with SO injections were retrospectively reviewed. Each eye received a single intravitreal DEX implant (0.7-mg, Ozurdex; Allergan Inc) injection as treatment for recalcitrant ME. Best-corrected visual acuity (BCVA), central macular thickness (CMT), and intraocular pressure (IOP) were recorded.

RESULTS

Compared with baseline (1.24 ± 0.34), the mean LogMAR BCVA improved at 1 (1.14 ± 0.27), 3 (1.13 ± 0.22), and 6 (1.22 ± 0.30) months without statistical significance. Maximal CMT resolution was observed at 1 month after intravitreal injection. The CMT value improved significantly at 1 (P = .008), 3 (P = .006), and 6 (P = .009) months. IOP did not show significant elevation during follow-up. No serious adverse events were observed.

CONCLUSION

Single-dose treatment of DEX implant may have benefit for recalcitrant post-vitrectomy ME under SO tamponade.

Vitreous Substitutes as Drug Release Systems

Vitreous substitutes are traditionally used to stabilize the retina after vitrectomy. In recent years, various approaches have been developed for using the vitreous substitute not only as a tamponade but also as a drug release system to tackle ocular diseases. This review provides an overview of the requirements for vitreous substitutes and discusses the current clinically applied as well as novel polymer-based vitreous substitutes as drug delivery systems, including their release mechanisms, efficiencies, challenges, and future perspectives.

Difference in the efficacy of intravitreal dexamethasone implant before and after silicone oil removal: A case report

RATIONALE

An intravitreal dexamethasone (IV-DEX) implant is safe and effective for the treatment of macular edemas; however, the efficacy of IV-DEX implants in silicone oil (SO)-filled eyes remains controversial. There is no previous study comparing an IV-DEX implant in the same eye with and without intravitreal SO.

PATIENT CONCERNS

A 72-year-old man with proliferative diabetic retinopathy, macular edema, and rhegmatogenous retinal detachment, treated with pars plana vitrectomy with SO tamponade had refractory macular edema.

DIAGNOSIS

Refractory macular edema.

INTERVENTION

Subtenon triamcinolone injection, intravitreal anti-vascular endothelial growth factor injection, and IV-DEX implantation were performed; this was followed by intravitreal SO removal combined with IV-DEX implantation.

OUTCOMES

The macular edema did not decrease significantly with posterior subtenon triamcinolone injection, intravitreal anti-vascular endothelial growth factor injection, and IV-DEX implantation; however, the edema was relieved after SO removal and a new IV-DEX implantation.

LESSONS

IV-DEX implant may be less efficacious in the treatment of macular edema in an SO-filled eye than that in a normal vitreous cavity.

Non-pharmacological complications associated with Intravitreal dexamethasone implant injection

OBJECTIVE

Intravitreal dexamethasone implant (IID) is an effective and safe treatment for macular oedema as described in the literature. Ocular hypertension and cataracts are the most frequent complications. The indications of IID in the last few years have led to the retrospective reporting of rare complications, with potential visual impact related to the injection procedure.

METHODS

A case series is presented of fifteen patients treated with IID for macular oedema who developed non-pharmacological complications related to the injection procedure or the implant itself, including, among others anterior chamber migration, intracrystalline injection, endophthalmitis, or segmentation. Differentiation was made between true complications and those that did not lead to any ocular damage. Epidemiological and baseline data were collected along with the treatment and outcome in each case. An analysis was made of multimodal imaging available.

RESULTS

The incidence of complications was 0.65% in this series Anterior chamber migration was the most frequent complication (n=4), followed by intracrystalline injection, and endophthalmitis (n=2). The times between the injection and complications were variable. Visual impairment was the most common symptom (n=6). However, despite the complications found, IID was an effective treatment in most of the reported cases.

CONCLUSIONS

Clinicians should be aware of these rare non-pharmacological complications so that they may be prevented and detected early, avoiding irreversible ocular damage.

Preoperative, Intraoperative and Postoperative Corticosteroid Use as an Adjunctive Treatment for Rhegmatogenous Retinal Detachment

The treatment for rhegmatogenous retinal detachment (RRD) is surgery, including pars plana vitrectomy (PPV) and scleral buckling (SB). Despite surgical advances, degeneration of the photoreceptors and post-operative complications, such as proliferative vitreoretinopathy (PVR), often occurs as the result of inflammation, preventing complete visual recovery or causing RRD recurrence. There is increasing evidence that in the presence of RRD, the activation of inflammatory processes occurs and the surgery itself induces an inflammatory response. This comprehensive review focuses on the use of different formulations of corticosteroids (CCS), as an adjunctive treatment to surgery, either PPV or SB, for RRD repair. The purpose was to review the efficacy and safety of CCS in improving functional and anatomical outcomes and in preventing postoperative complications. This review is organized according to the timing of CCS administration: preoperative, intraoperative, and postoperative. The evidence reviewed supported the role of the pre-operative use of CCS in the treatment of combined RRD and choroidal detachment (CD), reducing CD height. No solid consensus exists on intraoperative and postoperative use of CCS to treat and prevent postoperative complications. However, a large randomized clinical trial including more than 200 eyes suggested that oral prednisone after surgery decreases the rate of postoperative grade B PVR.