Clinical & Experimental Ophthalmology | 2019
The efficacy of intravitreal dexamethasone implants for non‐infectious posterior segment uveitis: Increasing the uveitis armamentarium
Abstract
Uveitic macular oedema (UME) is a common complication affecting many types of uveitis. It is the most common cause of moderate visual loss (with visual acuities ranging from 6/12-6/60) in patients with uveitis. It is often recurrent and does not self-resolve. Chronic CME leads to retinal structure damage and irreversible vision loss. In this editorial, we will discuss a practical treatment algorithm for UME. Prior to treatment, infectious and masquerade causes of a patient s uveitis must be excluded with a thorough history, dilated fundus examination and targeted serological and imaging investigations. Strong caution is warranted with the used of injectable steroids when there is any possibility of an infection. There are case reports of uncontrollable spread of retinitis in the setting of inadvertent use of depot corticosteroid injections in unrecognized toxoplasmosis or viral retinitis, with disastrous visual outcomes. With the current rise in syphilis which has now reached epidemic proportions in key population, syphilis serology should be included as a screening test for all cases of uveitis. With the exception of UME secondary to acute anterior uveitis, topical steroid drops are not adequate as monotherapy. High doses of oral corticosteroids (average dose between 40 and 60 mg) with rapid taper is the usual treatment of choice when UME is bilateral, due to its rapid onset of action. However, the systemic side effects of oral corticosteroids limit their long term use, with the acceptable “safe” dose currently being set at <=7.5 mg/day. Injectable depot corticosteroids are the treatment of choice when UME is unilateral. The caveat is that there are limitations to their repeated use as mono therapy for persistent intermediate, posterior and panuveitis, as demonstrated by the MUST 7-year study results. This randomized prospective clinical trial showed that the group treated with regional corticosteroid alone (Retisert, Bausch + Lomb, Rochester, New York) had worse visual outcomes in the long term than systemic immunosuppression. This was postulated to be due to permanent structural sequelae from severe relapses in uveitis activity that occurs when the steroid implants are suddenly depleted, in comparison to the more gradual and controlled step wise reduction in treatment that is possible with reducing systemic treatment. Thus, in persistent non-infectious intermediate, posterior or panuveitis, injectable depot steroid corticosteroids are best used as rescue therapy or adjunctive treatment with systemic immunosuppression, where it is used to treat persisting UME after the associated inflammation has been largely controlled with systemic steroid sparing agents. Once the clinical decision is made to use an injectable steroid, our options are either periocular steroid injection or intravitreal therapy where preparations include triamcinolone or Ozudex (Allergan plc, Dublin, Ireland). Ozurdex is a dexamethasone implant containing 700 μg of preserverative-free dexamethasone. TGA-approved for non-infectious posterior uveitis. Its use is funded by Medicare and accessible in Australia through the PBS for the indication of non-infectious posterior uveitis, as well as diabetic macular oedema and branch retinal vein occlusion. It uses a 23 gauge injector, with a shelved approach used to enter the sclera. So which is the best option for the local treatment of UME? This was recently addressed by the POINT trial, a prospective randomized clinical trial with three arms: periocular triamcinolone acetonide (Kenalog, BristolMyers Squibb Company, Princeton, New Jersey), intravitreal triamicinolone (4 mg/0.1 mL triamcinolone—Triesence, Alcon Pharmaceuticals, Fort Worth, Texas) and Ozudex. This study showed that either of the intravitreal steroids were more effective than periocular steroids in reducing macular thickness: 39% in the intravitreal triamicinolone group, 46% in the implant group vs 23% in the periocular group. Visual acuity gains were also better in the intravitreal groups, where the difference was not regained by the periocular group after they were switched to intravitreal therapy. DOI: 10.1111/ceo.13694