Prognostic value of multifocal electroretinography and central visual field test in the evaluation of macular function improvement in patients with diabetic macular edema after treatment with ranibizumab

Purpose This study aims to assess the prognostic value of multifocal electroretinography (mfERG) and central visual field tests in evaluating macular function improvement in patients with diabetic macular edema (DME) following treatment with Ranibizumab. Design A prospective interventional cohort study Methods This study included 30 eyes from 20 diabetic patients with DME and central subfield thickness exceeding 300 µm. Treatment was done with 3 monthly injections of intravitreal Ranibizumab. OCT, mfERG and central visual field were done before treatment and 1 month after the last injection. Results: Central visual field test revealed that mean pre-operative MD was −10.13 ± 7.46 dB compared to −7.26 ± 4.93 dB post-operatively ( p =0.039). Similarly, pre-operative PSD was 4.73 ± 2.23 dB and postoperative PSD was 3.77 ± 2.23 dB ( p =0.017). Multifocal ERG showed that P1 implicit time showed significant reduction in rings 2, 4, and 5 after treatment ( p =0.009, p < 0.001, and p =0.021, respectively). Conversely, there was a statistically significant decrease in P1 amplitude post-operatively within rings 3 and 5 ( p =0.002 and p < 0.001, respectively). Negative moderate correlation was found between LogMar BCVA change on one hand and R1P1 amplitude change ( p = 0.035, r =−0.387) and R5P1 amplitude change ( p = 0.021, r =−0.421) on the other hand. Similarly, statistically significant negative correlation was found between central subfield thickness change and R2P1 amplitude change ( p =0.002, r =−0.543). On the contrary, there was a positive moderate correlation between central subfield thickness change on one hand and R3P1 implicit time change ( p =0.025, r =0.407) and R5P1 implicit time change ( p =0.032, r =−0.391) on the other hand. Our study identified a statistically significant negative correlation between postoperative LogMAR BCVA and postoperative mean sensitivity in the central part of the visual field. Conclusion This study demonstrated a significant improvement in central visual field recordings after Ranibizumab injection in DME patients and good correlation of foveal mean sensitivity with BCVA showing the potential role of central visual field in assessment of macular function in these cases which is more accurate than mfERG which showed a significant improvement in some recordings, so it did not completely reflect the improvement in BCVA and CST in 3 months duration follow up.