Outcome of Intravitreal Bevacizumab (Avastin®) vs Triamcinolone in Treating Diabetic Macular Edema. A Retrospective Study.

Introduction: The 2011 World Health Organization (WHO) Step Survey reported that Fiji had a Diabetes Mellitus (DM) prevalence of 15.6%. Lin et al also showed an increased trend of DM and obesity in Fiji over the past 30 years among both major ethnic groups, iTaukei and Fijians of Indian decent. Increasing numbers of people living with DM would also mean increasing numbers of people with Diabetic Retinopathy (DR). Damato et al had noted that 40% of diabetic patients who reported to retinal screening had DR on the first screening visit and 27% had Sight Threatening DR (STDR) including Diabetic Macular Edema (DME). Treatment for DME includes laser photocoagulation and intravitreal injections.
The aim of this study was to compare two different intravitreal injections, intravitreal Avastin® (IVA) and intravitreal Triamcinolone (IVTA). These were compared, using before and after measures of Central Macular Thickness (CMT), in patients with DME.
Method(s): This was a retrospective comparative study with a single injection of IVA or IVTA and a short follow-up period (less than 3 months). A total of 417 eyes had intravitreal injections in the year 2017 and only 71 of those eyes were eligible for this study. Of those 71 eyes, 35 eyes received IVA while IVTA was injected into 36 eyes. The paired t-test was used to compare central macular thickness (CMT) and best corrected visual acuity (BCVA) before and after treatment within the same group. The unpaired t-test was used to compare CMT and BCVA after treatment between each group.
Results: Both groups showed significant changes in CMT post-treatment, with a p-value of 0.02 for IVA and <0.01 for IVTA. However, improvements in BCVA post-treatment were not statistically significant in either group. When these two groups were divided into two sub-groups of Improved and Worsened CMT, there were improvements in BCVA. In the IVA and IVTA groups with Improved CMT, it was noted that there was a statistically significant improvement in BCVA, with a p-value of 0.02 and 0.05 respectively. Side effects, such as cataract (22%), raised Intraocular Pressure (IOP) (62%), and raised IOP requiring medical treatment (16%) were observed in the IVTA group. Both groups showed relatively uncontrolled blood pressure (BP) and capillary blood glucose (CBG).
Conclusion: Both IVA and IVTA were found to be equally effective in treating DME with a single injection and short follow-up. However, side effects such as cataract and raised IOP were observed at higher rates in the IVTA group. Triamcinolone should be used judiciously because of the increased side effects. This was a study with a small sample and a short follow-up, a further large study with a longer follow-up period is needed.