"Intravitreal Dexamethasone implant effective for postoperative macular oedema": Study

Guglielmo Parisi et al systematically reviewed the scientific evidence on the intravitreal dexamethasone implant (DEX) for the treatment of macular oedema secondary to vitrectomy for epiretinal membrane (ERM) and retinal detachment (RD) and performed meta-analyses on visual and anatomical outcomes. The study was published in Journal of Ophthalmology, Hindawi publication.

Studies reporting clinical outcomes of DEX use for the treatment of macular oedema secondary to ERM and RD vitrectomy were searched on PubMed and Embase databases. The primary outcome was best-corrected visual acuity (BCVA) change between baseline and post-DEX treatment, reported as mean difference (MD) with 95% confidence interval (CI). Mean central macular thickness (CMT) change was assessed as a secondary outcome. Postimplant adverse events, including intraocular pressure rise and cataract development, were reported as well.

Five uncontrolled studies, 1 nonrandomized controlled study, and 1 randomized controlled study were included, with a total of 5 cohorts and 3 cohorts in the ERM group and RD group, respectively. Considering the last available follow-up, a significant improvement in postimplant BCVA was found in the overall population, irrespective of the indication for vitrectomy but with significant heterogeneity. In either group, mean BCVA significantly improved following the implant with no difference between the two groups.

Considering the last available follow-up, a significant CMT reduction was found in the overall population, irrespective of the indication for vitrectomy . In the ERM group, a significant CMT reduction was shown following DEX ,with no heterogeneity. In the RD group, mean CMT reduction was borderline significant with significant heterogeneity. No difference in CMT improvement was found between the two groups

The present meta-analysis showed favorable visual and anatomical outcomes following the use of dexamethasone implant for macular oedema secondary to ERM and RRD vitrectomy.

Postvitrectomy macular oedema is a sight-threatening condition which could affect visual recovery following a successful surgery. This complication has been reported in roughly 15% of cases following RRD vitrectomy, while its incidence ranges from 13% to 47% following ERM vitrectomy.

The causative mechanisms of postvitrectomy macular oedema have not been completely understood yet. It seems that inflammation plays a key role in this process. Indeed, macular oedema following RRD vitrectomy has been associated with the presence of proliferative vitreoretinopathy (PVR) and with longstanding RRD, which, in both cases, are likely to be linked with an inflammatory status . Furthermore, macula-off RRD has been associated with a higher rate of postvitrectomy macular oedema. In case of ERM vitrectomy, macular distortion due to the contractile membrane has been assumed to trigger the inflammatory condition.

In the above context, the use of the intravitreal 0.7 mg dexamethasone implant is being investigated. DEX is characterized by a potent anti-inflammatory activity and a good safety profile. A remarkable advantage of the slow release implant is its efficacy in vitrectomized eyes, which are less suitable to intravitreal antivascular endothelial growth factor (antiVEGF) therapy because of a faster washout.

"When considering the last available follow-up, our analyses revealed a significant visual gain following DEX administration in both the ERM and the RRD groups, and in the overall population as well. Similarly, a significant reduction in macular thickness was shown in the overall population. Such an anatomical improvement was evident in the ERM group, while it was borderline significant in the RRD group due to a wide confidence interval."

When considering the different follow-ups, significant visual and anatomical improvements were demonstrated in both groups at 1 and 6 months. At 12 months, significant visual and anatomical improvements were shown in the ERM group, while these were nonsignificant in the RRD group.

Most of the included studies reported on persistent postvitrectomy macular oedema, which proved unresponsive to topical nonsteroidal anti-inflammatory drugs (NSAIDs) and/or periocular or intravitreal triamcinolone acetonide.

Chronic postsurgical macular oedema is unlikely to resolve spontaneously and its treatment might prove challenging. The fact that DEX provided both a functional and anatomical improvement in vitrectomized eyes with, in most cases, persistent CMO is worth noting, in particular taking into account that a low number of implants (from 1 to 1.7) was administered over a follow-up ranging from 3 to 12 months. In this systematic review, DEX-related adverse events were collected as well.

In general, the main adverse events related to dexamethasone implant were IOP rise and cataract. Most eyes of the included studies were pseudophakic at the time of DEX implant. This could be explained by the fact that these eyes had undergone a previous vitrectomy and cataract surgery could have been performed at that time or before.

Limitations of the study included significant heterogeneity for BCVA analysis in both groups and for CMT analysis in the RRD group. The presence of high heterogeneity limits the quality of the evidence provided. Additionally, no analysis was conducted on potential adverse events, such as IOP rise and cataract, due to the limited number of cases reported. Finally, a relatively small number of studies was included. However, a metaanalysis is featured by a greater power and accurate confidence interval compared with an individual study.

The researchers concluded , "The use of intravitreal dexamethasone implant for macular oedema following vitrectomy for ERM and RRD allowed improving both visual and anatomical outcomes. The implant represents a valid therapeutic option for this sight-threatening condition."