RELENTLESS PLACOID CHORIORETINITIS: SUCCESSFUL LONG-TERM TREATMENT WITH INTRAVITREAL TRIAMCINOLONE

PURPOSE

To report a case of relentless placoid chorioretinitis (ampiginous choroiditis) treated with intravitreal triamcinolone acetonide (IVTA).

METHODS

Interventional case report.

RESULTS

A 34-year-old pregnant woman with a history of poor visual acuity in her left eye, secondary to an undetermined cause, developed an acute painless central scotoma and blurred vision in the right eye. The examination revealed decreased visual acuity, active inflammatory placoid choroidal lesions in the posterior pole, and mid-periphery with sharp disk margins and normal-appearing vasculature. A diagnosis of relentless placoid chorioretinitis was made, and the patient was treated biannually with 4 mg IVTA for 3 years with visual improvement to 20/25. Although she experienced a relapse at 12 months, the episode was adequately controlled with repeat IVTA. After the sixth IVTA treatment occurring at 30 months, the decision was made to stop IVTA, ultimately facilitating the preservation of 20/25 in the right eye at 63-month follow-up. The disease course was complicated by cataract progression that was successfully treated with a cataract extraction and episodic increases in intraocular pressure which were successfully treated with timolol ophthalmic solution.

CONCLUSION

Intravitreal triamcinolone acetonide therapy represents an important alternative in the treatment of relentless placoid chorioretinitis. By avoiding the potentially significant side effects of long-term systemic corticosteroid and immunosuppressive therapies, IVTA can be an important alternative in the long-term management of this uncommon and complicated entity.

A preliminary evaluation of dexamethasone palmitate emulsion: a novel intravitreal sustained delivery of corticosteroid for treatment of macular edema

PURPOSE

Dexamethasone palmitate (DXP) is a lipophilic prodrug of dexamethasone (DXM), a potent corticosteroid used to treat a variety of ophthalmic diseases. The aim of the study was to characterize the sustained release capacity (in rabbit), efficacy (in rat and rabbit), and safety (in rabbit, cat, and minipig) of intravitreal (IVT) DXP emulsions in preclinical models.

METHODS

Oil-in-water emulsions of DXP were administered by IVT injections in rats, rabbits, cats, or minipigs. Efficacy was assessed in rabbits by the inhibition of VEGF-induced vascular leakage and in rats by inhibition of laser-induced choroidal neovascularization. Concentrations of DXP and DXM in aqueous humor, vitreous, retina, choroid, and blood were determined to characterize the ocular and systemic pharmacokinetic (PK) profile. Complete ophthalmic examinations (indirect ophthalmoscopy, slit-lamp biomacroscopy, electroretinography, tonometry) were performed to assess the ocular safety of IVT DXP doses up to 2,600 μg in minipig, followed by histopathologic examinations. A validated feline model of DXM-induced elevated intraocular pressure (IOP) was used to assess the ocular hypertensive impact (i.e., the safety) of an IVT injection of DXP emulsion.

RESULTS

Rat and rabbit efficacy data demonstrated that IVT injections of DXP emulsions were effective. Rabbit PK data demonstrated that following a single 1,280 μg IVT injection resulted in sustained DXM levels in the retina and choroid (1,179.6 and 577.7 ng/g with a half-life of 189 and 103 days, respectively) sufficient to inhibit VEGF-induced vascular hyper-permeability for up to 9 months. No adverse ocular findings were observed in the rabbit at the 1,280 μg DXP dose. Plasma levels of DXP and DXM were close to the lower limit of quantification (0.5 ng/mL). In minipigs, no systemic effects were observed at a dose up to 2,600 μg DXP. In steroid responsive cats, IVT DXP emulsions increased IOP to a lesser extent than triamcinolone acetonide with a more rapid return to basal levels and no evidence of cataract formation.

CONCLUSIONS

IVT injections of DXP emulsions were well tolerated and shown to be efficacious for the sustained release of the drug, with the potential to control vascular leakage up to 9 months following a single IVT injection. These data suggest that IVT injections of DXP emulsions could be a safe and effective alternative IVT drug delivery vehicle for corticosteroid to treat back of the eye diseases complicated by macular edema.

[Potential of liposomes for the intravitreal injection of therapeutic molecules]

Intravitreal administration has been widely used since 20 years and has been shown to improve the treatment of diseases of the posterior segment of the eye with infectious origin or in edematous maculopathies. This route of administration allows to achieve high concentration of drug in the vitreous and avoids the problems resulting from systemic administration. However, two basic problems limit the use of intravitreal therapy. Many drugs are rapidly cleared from the vitreous humor; therefore, to reach and to maintain effective therapy repeated injections are necessary. Repeated intravitreal injections increase the risk of endophthalmitis, damage to lens, retinal detachment. Moreover, some drugs provoke a local toxicity at their effective dose inducing side-effects and possible retinal lesions. In this context, the development and the use of new drug delivery systems for intravitreal administration are necessary to treat chronic ocular diseases. Among them, particulate systems such as liposomes have been widely studied. Liposomes are easily injectable and permit to reduce the toxicity and to increase the residence time of several drugs in the eye. They are also able to protect in vivo poorly-stable molecules from degradation such as peptides and nucleic acids. Some promising results have been obtained for the treatment of retinitis induced by cytomegalovirus in human and more recently for the treatment of uveitis in animal. Finally, the fate of liposomes in ocular tissues and fluids after their injection into the vitreous and their elimination routes begin to be more known.

Complications of intravitreal injections

PURPOSE OF REVIEW

Over the past few years, the results of many studies have highlighted the risks and benefits of intravitreal injection of a number of medications, the most common being triamcinolone, antivascular endothelial growth factor (VEGF) agents, antibiotics, antivirals, antifungals, and methotrexate. The purpose of this review is to highlight the complications associated with these injections.

RECENT FINDINGS

Elevated intraocular pressure and glaucoma are the most common complications of intraocular triamcinolone. There is also an increased incidence of cataract formation/progression over time. The immunosuppressive effect of triamcinolone does not appear to increase the risk of endophthalmitis. Recent reports suggest that intravitreal anti-VEGF injections have a low complication rate. Similarly, antimicrobials also have low rates of injection-associated complications.

SUMMARY

Intravitreal injections play a critical role in daily ophthalmic practice. The overall risk of endophthalmitis and retinal detachment appears to be low and most of the commonly used drugs are well tolerated, even with repeat injection. Further long-term studies need to be performed to elucidate ways of increasing the safety of these procedures and medications.