OCT-Angiography Changes in Patients with Diabetic Macular Edema Treated with Intravitreal Dexamethasone Implant

Abstract

To evaluate, using optical coherence tomography angiography (OCTA), the impact of intravitreal dexamethasone (DEX) implant on quantitative vascular measurements in patients with diabetic macular edema (DME). Methods: Prospective, randomized, and open-label study. Primary endpoints were mean changes in vessel density (VD) and vascular perfusion (VP) in superficial capillary plexus (SCP) and VP in deep capillary plexus (DCP) and peripapillary capillary plexus (PCP). Results: Thirty-four eyes from 19 patients were included. Mean age was 67.4±7.3 years and 24 (76.5%) were men. VD in SCP in the 6 mm × 6 mm perifoveal ring was significantly decreased from 15.2±2.7 mm/mm 2 at baseline to 13.5±3.1 at month-2, p, 0.0029. VP in SCP in the 6 mm × 6 mm perifoveal ring decreased significantly from baseline to month-2 (mean change −3.8%; 95% confidenceinterval: −7.7% to −1.7%, p, 0.0028). Compared to baseline, the VP in DCP was significantly reduced at month 2 in the perifoveal ring of the 6 mm × 6 mm scan (p, 0.0063), and in the parafoveal ring of the 6 mm × 6 mm scan (p, 0.0048). Foveal avascular zone (FAZ) area did not change throughout the study. Central macular thickness significantly decreased from baseline in 210.3 µm (149.9-270.8 µm) and 201.8 µm (140.4-263.3 µm), p < 0.0001 each at month-2 and month-3, respectively. Conclusions: Besides functional and anatomical improvements, DEX implant significantly reduced VD and VP in DME patients.

Retinal Microvascular Changes after Intravitreal Triamcinolone Acetonide in Diabetic Macular Edema

“…Similar to some previous studies, we found in the present study that there was no significant change in the vessel density of the SCP and DCP, with the exception of two quadrants of the superior and inferior SCP. In contrast, the present study did show that there was significant enlargement of the FAZ area after the administration of TA (before: 0.29 ± 0.10 mm 2 , after: 0.32 ± 0.13 mm 2 p < 0.041), which is not consistent with the previous report on the intravitreal dexamethasone implant [23][24][25]. To the best of our knowledge, at the present time, there have been no data reported on OCTA parameters that include information on microaneurysms after the intravitreal injection of TA.…”

“…However, there are other studies that found that there were no significant changes in the vessel density (SCP and DCP) [22][23][24] and that there was a decrease in the FAZ area after an intravitreal dexamethasone implant [23,24]. In contrast, Carnota-Méndez et al reported finding that there was a reduction in the vessel density and vascular perfusion in the absence of any changes in the FAZ area after the administration of dexamethasone [25]. Similar to some previous studies, we found in the present study that there was no significant change in the vessel density of the SCP and DCP, with the exception of two quadrants of the superior and inferior SCP.…”

Changes in vessel density patterns assessed with OCTA in patients with diabetic macular edema treated with anti-VEGF therapy

“…Carnota-Méndez P et al [31] evaluated VD by quadrants, similarly to us, in 34 eyes treated with a single injection of dexamethasone, and found a significant reduction in VD at months 2 and 3 post-injection, mainly in the nasal quadrant, a finding that is in line with our results. Moreover, Toto L et al [21] and Sugimoto M et al [32] both found that vessels in the peripapillary area appear to be especially sensitive to anti-VEGF levels, causing a reduction in blood flow and However, this variation in VD values could also be caused by changes in suspended scattering particles in motion (SSPiM) [33] SSPiM has been defined as an unusual extravascular signal on OCTA associated with the presence of hyperreflective material at the border of fluid spaces.…”

Quantitative Parameters Relevant for Diabetic Macular Edema Evaluation by Optical Coherence Tomography Angiography

“…Another study found that, at the second month of follow-up after an intravitreal dexamethasone implant (IDI), the vascular density in the perifoveal ring in the SCP on a 6 × 6 mm scan was significantly decreased [ 25 ]. Furthermore, in patients with previously treatment-naïve DME, after subthreshold micropulse yellow laser (SMYL) treatment, it resulted that there were no significant differences regarding the VD in the SCP, DCP and choriocapillary plexus (CCP) after the procedure [ 26 ].…”

“…In the same study, the choriocapillary density tended to increase after treatment, but the explanation was that, in the setting of edema, the OCT signal could have been attenuated, this being the reason why the choriocapillaris could have seemed reduced before the dexamethasone implant [ 32 ]. On the other hand, another study found that, at the second month of follow-up after IDI, vascular perfusion in the perifoveal ring in the SCP on a 6x6 mm scan was significantly decreased, and also reported a reduction in the vascular perfusion in the perifoveal ring in the DCP at months 2 and 3, and parafoveal ring at month 2, suggesting the importance of permanent capillary occlusion in DME [ 25 ].…”