Diabetic retinopathy is one of the further most common reasons of visual loss. It mainly caused by neovascularization, macular
edema and ischemic macular changes. Due to the limitations of conventional therapies for macular edema, the propensity for other
therapies, such as intravitreal injection of triamcinolone and anti-VEGF agents, has increased. Tetracyclines have recently suggested
as complementary drugs in the treatment of clinically significant macular edema (CSME). In addition to the known bacteriostatic
properties of tetracyclines, especially doxycycline and minocycline, these drugs can influence the regulation of inflammation,
immunization, cell proliferation, and angiogenesis. Accordingly we have aimed to evaluate the efficacy of using oral Doxycycline on
the number of intravitreal Bevacizumab injection in diabetic patients with CSME. In this clinical trial pilot study, 60 patients with
CSME, referred to the ophthalmology clinic of Imam Khomeini Hospital in Ahvaz, were studied. Patients were randomly divided into
two equal groups; Group A receiving 1.25 mg bevacizumab intra vitreal (IV) injection and group B receiving 1.25 mg IV injection
bevacizumab in combination with 200 mg per day doxycycline for 4 months. Pre and post-treatment variations in evaluated
parameters including best corrected visual acuity (BCVA) and optical coherence tomography (OCT) were assessed. Results showed
that the mean age of patients was 67.7 years, ranging from 49 to 72 years. The demographic characteristics of patients included age
(p=0.35) and gender (p=0.43) were parallel among the two groups. Number of bevacizumab IV injection was not different in study
groups. It was shown that central macular thickness (CMT) and macular volume decreased significantly in both groups. However, the
percentage of reduction was higher in patients receiving doxycycline. BCVA in both groups showed a significant improvement which
was more in doxycycline group. In conclusion the findings of this study, in line with previous studies, showed that the use of
doxycycline in addition to intravitreal injection of bevacizumab significantly increased visual acuity and reduced the macular
thickness, and volume. We suggest further studies with more patients in study groups and more detailed evaluation of changes
using new diagnostic modalities and longer duration of follow up.
Keywords: Doxycycline, Bevacizumab, Macular edema