Short-Term Assessment of Intravitreal Dexamethasone Implant Using Enhanced-Depth Image Optical Coherence Tomography and Optical Coherence Tomography Angiography in Patients with Retinal Vascular Diseases

Abstract

Introduction: To evaluate the short-term efficacy and safety of intravitreal dexamethasone implant (IDI) in patients with macular oedema associated with diabetic retinopathy (DR) and retinal vein occlusion (RVO) using enhanced-depth image optical coherence tomography (EDI-OCT) and to estimate the effect of dexamethasone on the choroid and the retinal vascular network using OCT angiography (OCTA).

Methods: Fifteen eyes in 15 patients with macular oedema secondary to diabetes (DR, n = 8) or retinal vein occlusion (RVO, n = 7) were treated with intravitreal injection of sustained-release IDI. Primary efficacy end points were changes in best corrected visual acuity and central macular thickness (CMT). Secondary end points were changes in choroidal thickness and choroidal and retinal vascular networks as determined by OCTA.

Results: CMT was significantly reduced from baseline by 3 h after injection (p < 0.01) and improved further during the 3-month follow-up. Visual acuity improvement was consistent with CMT reduction. No alterations in IOP or systemic side effects were observed. OCTA showed improvement from baseline in terms of decreased number and size of cysts and restoration of the retinal vascular network; flow choroidal thickness did not change significantly. CMT and visual acuity variations were similar in the two groups.

Conclusions: CMT reduced as early as 3 h after the injection of IDI, with further reduction during follow-up. Choroidal thickness was unchanged, whereas the vascular retinal network improved from baseline to the end of study. Both EDI-OCT and OCTA were useful in demonstrating the early beneficial effects of IDI on the macula and the perifoveal vascular network.

Funding: The article processing charges, the open access fee and the medical writing and editorial assistance was funded by Allergan.

Keywords: Central retinal thickness; Diabetic macular oedema; Enhanced-depth image optical coherence tomography; Innovative biotechnology; Macular oedema; OCT angiography; Ophthalmology; Retinal vein occlusion; Spectral domain OCT; Sustained release intravitreal dexamethasone implant.

Fig. 1

Graph showing the linear regression of central macular thickness (CMT) as a function of time. Analysis of the early effect of dexamethasone from 3 h to 3 months after intravitreal injection. The single asterisk is related to a P value < 0.05, whereas the double asterisk corresponds to a P value < 0.001, representing the maximum level of statistical significance

Fig. 2

Figure showing the trend of action of the drug as a function of time. Specifically, the reduction of central macular thickness is statistically significant after 3 h, and it continues after 80 h, reaching the half-life of the drug

Fig. 3

Example of an enhanced-depth image-optical coherence tomography (EDI-OCT) of a diabetic macular oedema eye in a patient (#5) who underwent an intravitreal injection of long-release dexamethasone 700 µg at baseline (T0). The sequences of the structural OCT B-scan represent the timing of follow-up starting from 3 h (T1) to 3 months (5). T2 = 24 h; T3 = 1 week; T4 = 1 month

Fig. 4

Figure showing the modification of the superficial and deep capillary plexuses of patient #10 at baseline (T0) and T5 (3 months after dexamethasone injection). In the deep network, the reduction of the central macular no-flow aspect connected to cystic space (arrow) is shown together with the decrease of the no-ischaemic area (asterisk) regarding the foveal avascular zone (FAZ) and the remodelling of the hyperreflective spot connected to microaneurysm (arrowhead). The reduction of central macular cysts is shown in C′

Fig. 5

Optical coherence tomography angiography (OCTA) showing the effects of intravitreal dexamethasone implant (IDI) on retinal vascularisation in the eyes of two patients with diabetic macular oedema. Cystoid macular oedema and microaneurysms can be seen on OCTA images of the deep capillary plexus, obtained during the baseline examination (a, a′). OCTA scans acquired 1 day after the injection (b, b′) show a reduction in the number and size of the cysts. The decrease progresses further and is even more evident 1 week after the administration of IDI (c, c′) concurrently with a partial vascular restoration