Quantitative Assessment of Photoreceptor Layer in Eyes with Resolved Edema after Pars Plana Vitrectomy with Internal Limiting Membrane Removal for Diabetic Macular Edema

Abstract

Background/Aims: To evaluate the correlation between visual acuity (VA) and photoreceptor integrity in eyes with resolved diabetic macular edema (DME) after pars plana vitrectomy (PPV). Methods: Eleven eyes with resolved macular edema following PPV with internal limiting membrane removal for DME were included in this retrospective study. The integrity of the external limiting membrane (ELM) and inner and outer segments (IS/OS) of the photoreceptor junction was evaluated by spectral domain optical coherence tomography. The main outcome measures were percentage of disrupted ELM and IS/OS lines, and correlation between VA and photoreceptor integrity. Results: The mean time after PPV was 78 ± 17 months. The mean lengths of the disrupted ELM and IS/OS lines were 223 ± 167 µm (63%) and 189 ± 175 µm (54%) in the foveola, and 900 ± 522 µm (60%) and 835 ± 582 µm (55%) in the fovea, respectively. Intact ELM and IS/OS lines were positively correlated with VA in both the fovea (p = 0.09 and p = 0.02, respectively) and foveola (p = 0.004 and p = 0.03, respectively). Linear regression analysis showed a statistically significant association of intact ELM and IS/OS lines with VA in the fovea. Disrupted ELM and IS/OS lines had a strong correlation with each other in both the fovea (r = –0.71, p = 0.013) and foveola (r = 0.81, p = 0.02). Conclusions: The integrity of the ELM and IS/OS lines was positively correlated with VA in eyes with resolved DME after PPV.