Evaluation of Anatomical and Tomographic Biomarkers as Predictive Visual Acuity Factors in Eyes with Retinal Vein Occlusion Treated with Dexamethasone Implant

Abstract

Background: This prospective study evaluated the impact of anatomical and tomographic biomarkers on clinical outcomes of intravitreal dexamethasone implants in patients with macular edema secondary to retinal vein occlusion (RVO). Methods: The study included 46 patients (28 with branch RVO (BRVO) and 18 with central RVO (CRVO)). Best corrected visual acuity (BCVA) significantly improved from a mean baseline of 0.817 ± 0.220 logMAR to 0.663 ± 0.267 logMAR at six months and 0.639 ± 0.321 logMAR at twelve months (p < 0.05). Central retinal thickness (CRT) showed a significant reduction from 666.2 ± 212.2 µm to 471.1 ± 215.6 µm at six months and 467 ± 175.7 µm at twelve months (p < 0.05). No significant differences were found in OCT biomarkers between baseline and follow-ups. Results: The study analysed improvements in visual acuity relative to baseline biomarkers. At six months, ellipsoid zone disruption (EZD) was significant for all subgroups. Disorganization of retinal inner layers (DRIL), external limiting membrane (ELM) disruption, macular ischemia (MI), CRT, and BRVO showed significance for any improvement, while DRIL and ELM were significant for changes greater than 0.3 logMAR (p < 0.05). At twelve months, EZD remained significant for all subgroups. ELM, MI, CRT, and BRVO were significant for any improvement, while MI and BRVO were significant for changes greater than 0.3 logMAR (p < 0.05). Hyperreflective foci were not statistically significant at either time point (p > 0.05). Conclusions: The regression model suggested that MI and CRVO could be negative predictive factors for visual outcomes, while ELM and EZD were associated with BCVA improvement one-year post-treatment.

Keywords: DRIL; ELM; EZD; MI; OCT; macular edema; retinal vein occlusion.

Figure 1

A case of CRVO at baseline and six months after treatment. FA and SD-OCT of a patient before and after treatment. (a) FA shows a non-ischemic (*) central retinal vein occlusion (CRVO) with marked delay in arteriovenous transit time, masked by retinal haemorrhages, and vessel wall staining. (b) The SD-OCT shows ME with considerable central thickness, absence of DRIL (+), and incomplete disruption of ELM and EZ. (c) After six months of treatment, FA shows resolution of the RVO with late staining of optic disc. (d) The SD-OCT highlights the reduction in retinal thickness, the presence of HRF ($), resolution of photoreceptor layers (#), and absence of DRIL (+). FA: Fluorescein angiograms; SD-OCT: spectral domain–optical coherence tomography; ME: macula edema; DRIL: disorganization of retinal inner layers; ELM: external limiting membrane disruption; HRF: hyperreflective foci; EZD: ellipsoid zone disruption.