By Ramana S. Moorthy, MD
This study reports the much-anticipated results of a phase 3 clinical study investigating different doses of the biodegradable dexamethasone intravitreal (DEX) implant in patients with noninfectious uveitis. The 26-week, multi-center trial shows that it improves intraocular inflammation and visual acuity in eyes with intermediate and posterior non-infectious uveitis. A total of 229 eyes were randomized to a single treatment with a 0.7 mg DEX implant (77 patients), 0.35 mg DEX implant (76 patients), or a control sham procedure (76 patients).
Of the patients given the 0.7 mg DEX implant, 47 percent of eyes had a vitreous haze score of zero at week eight, compared with 36 percent in those treated with the 0.35 mg DEX implant and 12 percent of control eyes. This benefit lasted through the 26-week trial. Improved visual acuity, a gain of 15 or more letters from baseline, was seen in significantly more DEX eyes, regardless of dose, compared with controls.
More importantly, increased IOP occurred less frequently than has been reported with the fluocinolone implant. The current study shows that less than 10 percent of patients in each DEX implant group had an IOP of > 25 mm Hg, compared to nearly 50 percent of patients in the fluocinolone study who developed IOP elevation.
Similarly, the cataract risk appears lower with the DEX implant compared to the fluocinolone implant. The cataract incidence in phakic eyes was greater in the 0.7mg DEX implant (15 percent) the smaller-dose implant (12 percent). Again, these rates are substantially less than that reported in the fluocinolone study in which all phakic patients developed cataract often requiring cataract extraction. However, the authors do note that this study's six-month time period limits its ability to assess cataract risk.
It's also important to note that the DEX implant lasts only about six months, compared to more than 34 months for the fluocinolone implant, and therefore needs to be re-injected every six months requiring up to six injectable implants over three years. As a result, it would be valuable to determine rates of glaucoma, cataract, and other complications after three years of treatment with the DEX implant rather than six months.
Nevertheless, the DEX implant has been shown to be safe and effective for intermediate and posterior uveitis. This device may also be a good way to pulse corticosteroid therapy locally while long term immunomodulation is instituted, thereby bypassing the need for oral corticosteroid therapy and its systemic complications and risks.