Abstract
Purpose :
To study the effect of long-term intravitreal ranibizumab on the retinal microarchitecture in patients with diabetic macular edema (DME).
Methods :
For this retrospective study 31 patients, with a history of at least 20 intravitreal ranibizumab injections (IVI, n=31), were selected from our database comprising 383 patients treated for DME. Spectral domain optical coherence tomography (SD-OCT) images were evaluated at baseline (BL,prior to first ranibizumab injection) and after 20 IVI for disorganization of retinal inner layers (DRIL), retinal atrophy (RA), disruption of retinal pigment epithelium/bruch complex (RPE/BR) and integrity of external limiting membrane/ ellipsoid zone (ELM/EZ), as well as alterations at the outer plexiform layer/henle fiber layer junction (OPL/HE). Primary outcome was the amount of patients with above mentioned alterations at BL versus after 20 IVI. Best corrected visual acuity (BCVA) and degree of DME were defined as secondary outcome measures. Patients with further degenerative or vascular retinal diseases, ischemic maculopathy and focal laser treatments during the observation period were excluded from the analysis. Graders were masked as to clinical data and to the number of injections. Statistical analyses were performed using SPSS. The Wilcoxon signed ranks test was applied to study statistical differences.
Results :
At BL all included patients showed retinal microstructural alterations (DRIL 100%, RA 54.9%, RPE/BR 93.6%, ELM/EZ 83.9%, OPL/HE 100%). Between BL and IVI 20 no significant microstructural retinal changes were encountered (DRIL p=0.19, RA p=0.13, RPE/BR p=0.26, ELM/EZ p=1.0, OPL/HE p=1.0). The amount of patients with CME differed significantly (p=0.01). 9 patients (29%) were pretreated with other intravitreal agents, 14 patients (45.2%) underwent focal laser coagulation prior BL. The treatment period with ranibizumab ranged from 14 to 47 months (mean=29, SD±7). Mean BCVA at baseline (BL) was 69.3±12.5 letters, after IVI 20 69.9±14.9.
Conclusions :
No effect on pre-existing retinal alterations was encountered following long-term IVI. Thus, intravitreal ranibizumab appears to represent a “neutral” treatment option with the known effect on DME, but without impact on the restoration of retinal layer disruption. Alterations of the retinal microarchitecture may be causative for the functional outcome in patients with DME.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.