Retinal Ganglion Cell Complex Thickness after Internal Limiting Membrane Peeling for Idiopathic Macular Hole

Abstract

Comment on: “Analysis of retinal ganglion cell complex thickness after Brilliant Blue--assisted vitrectemy for idiopathic macular holes.”

To the editor,

We have read Sevim and Sanisoglu’s recent article on the analysis of retinal ganglion cell complex thickness after Brilliant Blue-assisted vitrectomy for idiopathic macular holes.1 The primary purpose of their study was to evaluate the effect of brilliant blue G (BBG)-assisted internal limiting membrane (ILM) peeling on retinal ganglion cell complex (GCC) thickness changes. GCC was measured using RTVue-100 FD-OCT within 7 mm × 7 mm square centered 1 mm temporal to the fovea. The conclusion was that ILM peeling had no significant effect on GCC and RNFL thickness values in the patients who underwent BBG-assisted PPV. We think the authors’ study is interesting, while some points of their observations and conclusions are worth considering.

Potential negative effect of ILM peeling on retinal structure and function has been observed for almost 10 years. It has been reported and was partly cited in the authors’ article that ILM peeling may lead to damage to the Müller cells’ processes and endfeet, and may delay the recovery of the b-waves of the focal macular electroretinograms.2–4 Ohta et al. previously reported that the temporal macula was significantly thinner and the nasal macula was significantly thicker on Spectralis® HRA-OCT after vitrectomy with ILM peeling for macular hole treatment.5 They recently further demonstrated that changes in the inner retinal layer thicknesses contributed to the decreased temporal and increased nasal sectors. They believed that these changes were associated with the ILM peeling, which may result a weakening of longitudinal support of the Müller cells.6 Similarly, using Cirrus HD-OCT, Kumagai et al. found that the temporal retina was significantly thinner in eyes that had undergone vitrectomy with ILM peeling compared to those of their fellow eyes, and to those eyes without ILM peeling. Their study also suggested that ILM peeling leads to a thickening of the nasal macula.7 Later on, they even noted that a progressive macular thinning occurs for at least 2 years with different patterns of the changes in the macular regions after successful MH surgery with ILM peeling, although the mechanism by which the retina became progressively thinner after successful macular hole surgery with ILM peeling remains unclear.8 Nevertheless, Sevim and Sanisoglu’s did not compare temporal and nasal GCC thickness in their article. GCC thickness after macular hole surgery was also studied recently by Baba et al. Using SD-OCT (RTVue-100) measurement within a 6 mm × 6 mm square centered slightly temporal to the fovea, they found that the GCC thickness was significantly reduced at 3 and 6 months after indocyanine green (ICG)-assisted ILM peeling during MH surgery.9 It was also showed by Baba et al. that the GCC thickness was significantly reduced postoperatively in both the BBG group and the ICG group, however, the GCC thickness were not significantly different between the two groups at 3 and 6 months.10 The above-mentioned studies differ in the measurement methods, but all supports an observation that ILM peeling may cause changes of retina, including GCC, thickness, which is apparently inconsistent with Sevim and Sanisoglu’s observation.

Furthermore, BBG-staining and ILM peeling represents two surgical factors distinct from one another, which means that their effects on the retina are different and one likely affects the other. In order to evaluate accurately the effect of BBG-assisted ILM peeling on GCC thickness, it would be more appropriate for a prospective study to involve a control group of patient underwent ILM peeling without staining, or even, a control group of BBG-staining without ILM peeling, rather than a control group of patient with neither BBG-staining nor ILM peeling.

To sum up, we feel that Sevim and Sanisoglu’s viewpoint as “that this surgery does not cause any damage that can adversely affect anatomical structure and visual function” should be cautiously interpreted.

Declaration of interest

The authors report no conflicts of interest.