25-Gauge Vitrectomy with Epiretinal Membrane and Internal Limiting Membrane Peeling in Eyes with Very Good Visual Acuity – Author Reply

We thank Dr. Kaya for his interest in our recent article “25Gauge Vitrectomy with Epiretinal Membrane and Internal Limiting Membrane Peeling in Eyes with Very Good Visual Acuity”, in which we described our experience with performing surgery in a relatively large series of patients with a preoperative visual acuity (VA) of 20/40 or better. We would like to take this opportunity to make a few clarifications. First, although it is true that the progression of epiretinal membranes (ERMs) is slow, one must remember that it is not a static condition, and that even a slight change in the quality of vision can be bothersome for a patient whose baseline is 20/20 or close to it. In the cited study by Sidd et al., the stability reported in 90% of patients was in regard to their appearance on fundus exam. There was no optical coherence tomography (OCT) at the time that study was performed, and it is likely quite possible that OCT could detect more change in that cohort of patients. Moreover, in the same series it is reported that 71% of patients had final VA within one line of that recorded at the first examination, meaning that quality of vision can decrease even if the fundus appearance is the same. Another important aspect is that ERMs often cause metamorphopsia, which is a bothersome symptom not necessarily correlated with the VA of the patients. Our study included only patients who had a documented decrease in VA or subjective reports of a decrease in quality of vision. We do not advocate offering surgery to asymptomatic patients with ERMwith very good and stable VA.However, once symptomatic progression starts, we believe surgery may be offered at an earlier stage than reported in the majority of the literature. Second, we emphasize that there is an essential difference between vitreomacular traction and partial posterior vitreous detachment (PVD). It has been well established that in the majority of cases, ERMs develop after PVD, and this has also been noted in 92% of patients in the above-mentioned study by Sidd et al. Third, we agree that OCT must be a part of the preoperative evaluation of any patient with ERM. It is also a valuable tool to detect progression. We note that although OCT data were reported for only 38% of patients in our study, they were was obtained prior to surgery in all of them, but since it was done in different institutions the images were unavailable for us to include at the time of the analysis. Additionally, we note that although the vitreoretinal interface is important to evaluate in patients with ERM, it is more important to focus on changes in the outer retinal layers, which has been established as key prognostic factor in these patients. This has also been corroborated by the OCT analysis in our study, which demonstrated high rates of outer retinal layer preservation in our patients with very good VA. Also, a major point in our study is that the very good VA of our patients was not compromised by pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling, and that about 30% of the series improved to 20/20. ILM peeling has been implicated in several studies to reduce the possible vision gains from ERM peeling, and our series supports the approach that ILM peeling is a safe procedure. In conclusion, our results demonstrate that 25-gauge PPV and membrane peeling is safe and effective in patients with ERM with very good preoperative VA. We do not advocate early intervention in all cases, and emphasize that all included patients had progression of symptoms and sought surgical intervention in order to improve their vision. OCT should certainly be included in the monitoring of patients with ERM and in their preoperative evaluation, focused primarily on the condition of the outer retinal layers. Our results show that timely intervention in progressing symptomatic patients with ERM is an effective means to achieve excellent final VA and improvement of metamorphopsia, even in eyes with preoperative VA of 20/40 or better. We hope that the readers of this journal find our experience clinically valuable to their practice. Thank you very much, Elad Moisseiev, MD Joseph Moisseiev, MD