Abstract
Purpose To evaluate the effectiveness of intravitreal bevacizumab treatment in patients with diabetic macular edema (DME) by assessing retinal changes using optical coherence tomography angiography (OCT-A). Methods This prospective study was performed in patients with treatment-naïve DME. The eyes of patients were imaged using a swept-source OCT system with a scan area of 6 × 6 mm. The DME patients with a central macular thickness (CMT) of ≥300 μm received nine bevacizumab injections within 12 months. The demographic, systemic, and ocular parameters, including the best-corrected visual acuity (BCVA), CMT, microaneurysm (MA) count, and foveal avascular zone (FAZ) area in both superficial capillary plexus (SCP) and deep capillary plexus (DCP), as well as vessel density in SCP, were assessed in the patients. In addition, the response (good or poor) of the DME eyes to bevacizumab treatment and the final visual acuity (BCVA of 75 letters) were analyzed. Results Seventy-seven eyes of DME patients were subjected to the final analysis. Bevacizumab treatment reduced CMT from 425.06 μm (±77.15) to 350.25 μm (±82.04) and improved BCVA by about 8.61 letters (from 64.73 to 73.34) in the patients. The mean number of MAs in SCP decreased from 3.51 ± 2.07 to 2.31 ± 1.15 (p < 0.001) and in DCP from 17.12 ± 11.56 to 12.21 ± 6.99 (p < 0.001), whereas the area of FAZ increased in SCP from 328.22 ± 131.38 to 399.70 ± 156.98 (p < 0.001) and in DCP from 571.13 ± 396.01 to 665.89 ± 412.77 (p = 0.001). The final BCVA letter score and CMT were statistically significant in both poor and good responders, as well as in BCVA < 75 and BCVA ≥ 75 groups. Conclusion The fixed-regimen intravitreal bevacizumab therapy was effective in treating DME. Apart from noninvasive visualization of microvascular damage, OCT-A showed limited usefulness in predicting treatment response. Although the study showed that the number of MAs was significantly reduced during treatment, which is an OCT-A predictor of a good response to bevacizumab treatment at a 12-month visit, commonly observed artifacts may reduce the usefulness of OCT-A.
Highlights
Diabetic retinopathy (DR) is identified as one of the leading causes of preventable visual impairment and blindness worldwide [1–3]
We found that the mean number of MAs decreased in both superficial capillary plexus (SCP) and deep capillary plexus (DCP), apart from the response to bevacizumab treatment
We found that the foveal avascular zone (FAZ) area was larger in DCP than in SCP, apart from the response to the treatment, which is in line with the results of Lee et al poor responders showed a larger FAZ area in DCP compared to good responders
Summary
Diabetic retinopathy (DR) is identified as one of the leading causes of preventable visual impairment and blindness worldwide [1–3]. The breakdown of the blood-retinal barrier caused by a high concentration of inflammatory mediators and the leakage of MAs lead to the development of diabetic macular edema (DME), which is identified as a leading cause of vision impairment in patients with diabetes mellitus type 2 [1, 8–11]. Is the dominant factor of retinal vascular hyperpermeability, DME is mainly treated using anti-VEGF inhibitors [3, 9, 12, 13]. Bevacizumab is a monoclonal, humanized VEGFinhibiting antibody which is a common, off-label medication used for the treatment of DME [14–16] [17]. It is not approved for ophthalmology [16, 17], bevacizumab is often used as a first-line treatment in many countries. As the efficacy and safety of this drug have been less documented than approved drugs, even small-scale prospective studies may broaden the knowledge about optimal treatment regimens with bevacizumab for DME
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