Implant

The Ozurdex implant consists of dexamethasone integrated within a polymer matrix of lactic and glycolic acid. Following implantation in the vitreous cavity, the polymer gradually breaks down into water and carbon dioxide. The implant's pharmacokinetics are such that by 90 days the concentration of dexamethasone will have fallen to just below the clinical level. The current practice with the implant is to re-inject it every six months. The FDA and the European Medicines Agency (EMA) have approved Ozurdex as a treatment for macular oedema resulting from either non-infectious uveitis or retinal vein occlusion.

Dr Callanan noted that the results of the PLACID study indicate that the use of the implant in combination with conventional laser treatment in patients with macular oedema can provide significantly better improvements in visual acuity and greater reductions in macular thickness and leakage area than laser alone.

In the prospective randomised double-masked trial, which involved patients with diffuse macular oedema, 126 patients initially received the implant, while 127 patients received a sham injection. Patients in both groups underwent laser photocoagulation one month later, and received repeat dexamethasone or sham injections at six or nine months as required, and repeat laser treatments, as required at three-month intervals.

The inclusion criteria for the study were: age of over 18 years, a diagnosis of Type 1 or 2 diabetes, a best corrected visual acuity from 20/40 to 20/200 and retinal thickening due to diffuse macular oedema with a central retinal thickness at baseline 275 microns or more as determined by OCT.

Among patients with reader-verified diffuse macular oedema, those receiving the combination treatment had significantly higher mean increases in letters of best-corrected visual acuity compared to patients treated with laser alone at months one, four, six, seven and nine.

The overall rate of ocular adverse events was significantly higher in patients receiving the implant (73.6 per cent), compared to those receiving laser alone (58.3 per cent). However, the only specific adverse event to occur significantly more often in the implant group was increased IOP.

In addition, cataracts, which have been a near universal complication of fluocinolone acetate implants, occurred in only 13 (14.3 per cent) of phakic patients in the implant group, of whom four only required cataract surgery. That compared to six (6.3 per cent) of phakic patients in the laser alone group, five of whom required cataract surgery.

Results from another trial, the CHAMPLAIN study, indicated that previous vitrectomy does not reduce the longevity of its effect in eyes with diabetic macular oedema that have previously undergone vitrectomy, said Anat Loewenstein MD, Tel-Aviv, University, Tel Aviv, Israel.

In the six-month, prospective, multicentre, open-label study, 56 patients with treatment-resistant DME and a history of pars plana vitrectomy received a single injection of Ozurdex 0.7mg. At eight weeks' follow-up, there was a mean central retinal thickness decrease of 156 μm from a baseline value of 403 μm, by (P < 0.001). By 26 weeks' follow-up there was still a mean decrease of 39 μm (P = 0.004), Dr Loewenstein said.

Conjunctival haemorrhage, conjunctival hyperaemia, eye pain and increased intraocular pressure were the most common adverse events. Eight patients initiated IOP medication during the study.

'Ozurdex has shown promising results in Phase II trials, with no significant side effects and with better final visual acuity results in laser-treated eyes and a good response to treatment in vitrectomised eyes,' Dr Loewenstein concluded.

contacts
David Callanan – dcallanan@texasretina.com
Anat Loewenstein – anatlow@tasmc.health.gov.il