The therapeutic potential of intraocular depot steroid systems: developments aimed at prolonging duration of efficacy

Corticosteroids play a major role in the treatment of many diseases of the posterior ocular segment. Systemically or topically administered steroids usually do not attain therapeutic concentrations in the retina, as they must first cross the blood-retina barrier. Intravitreal application is a useful alternative means of achieving therapeutic concentrations in the posterior segment but must be repeated every few weeks, because drugs given in this way have a short half-life. Intraocular sustained-release implants have been now developed in order to prolong the effect of intravitreal drugs and to lessen the need for repeated application. Macular edema is a typical indication for intravitreal steroid treatment.

Selective review of the literature.

Various intravitreal corticosteroid implants have been evaluated in prospective, randomized clinical trials in recent years, and some have been approved for clinical use. Implants are either longer-acting and non-resorbable (fluocinolone acetonide implants) or shorter-acting and resorbable (dexamethasone implants). Major adverse effects of intravitreal corticosteroids include the induction or worsening of cataracts and elevated intraocular pressure. The likelihood of a complication varies from implant to implant and depends on the duration of action of the particular one used.

Intravitreal corticosteroid implants are a new option in the treatment of diseases of the posterior ocular segment. Long-term results are not yet available. The optimal treatment for these diseases will need to be the focus of further clinical research.