Correlation between photoreceptors status using Spectral Domain Optical Coherence Tomography(SD-OCT) and Visual outcome after injection of intravitreal Bevacizumab in Diabetic Macular oedema(DMO)

Abstract

Purpose: : To investigate the correlation between photoreceptor status and final visual acuity (VA) following intravitreal injection of Bevacizumab in eyes with Diabetic Macular oedema (DMO).

Methods: : We retrospectively reviewed 35 eyes of 33 patients with Diabetic Macular oedema (DMO) who were treated with intravitreal injection of Bevacizumab. Using Spectral Domain Optical Coherence Tomography(SD-OCT) the following specific features were assessed :1. Condition of external limiting membrane (ELM) at the fovea.2. Integrity of photoreceptor inner segment/outer segment (IS/OS) junction.The main outcome measures were percentage of disrupted ELM and IS/OS lines and correlation between visual acuity (VA) and photoreceptor integrity. All patients had modified macular grid laser treatment and two of them had triamcinolone injection before intravitreal injection of Bevacizumab. Central Macular Thickness (CMT) was also assessed with SD-OCT.Treatment consisted of intravitreal injection of Bevacizumab 1.25mg/0.05ml once every 4 weeks for the first three months and retreatment was given depending on OCT findings at monthly follow up visit. Minimum follow up was for a period of 12 months.

Results: : Mean improvement in visual acuity was 4.86 letters with 55 microns reduction in central macular thickness. 29.45% had no disruption in IS/OS junction and ELM lines achieving more than 10 letter gain. 53.10% had stability in vision showed disruption of the IS/OS junction and ELM. 17.45% had loss of more than 15 letters and showed absence of ELM and IS/OS lines. Mean number of injections during this period was 6.4. No ocular or systemic adverse events were noted.

Conclusions: : Integrity of external limiting membrane and the inner segment/outer segment line is a reliable indicator of favourable visual outcome following treatment of Diabetic Macular oedema with intravitreal injection of Bevacizumab.

Keywords: diabetic retinopathy • vascular endothelial growth factor • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)