We thank Dr Oh for his interest and comments on our manuscript. In this study, we reported the frequent occurrence of outer foveolar defects after surgery for small macular holes (MHs) and described their process and period of disappearance. Dr Oh pointed out that hidden photoreceptor defects, which were not detected in time-domain (Stratus OCT; Carl Zeiss Meditec, Dublin, California, USA) optical coherence tomography (OCT) because of the poor resolution, may remain long after surgery. We partly agree with his comment and already have discussed the limitations of using time-domain OCT. However, because of the innate limitations of OCT, which depends on tissue reflectance, even high-resolution OCT cannot replace histologic study. Because a histologic result is required to confirm the integrity of photoreceptors, the term outer foveolar (or foveal ) defect has been used instead of photoreceptor defect in the description of OCT results not only in this study, but also in some previous studies. The histologic results that Dr Oh cited were from the eye that seemed a poor candidate to show a full recovery of photoreceptors after MH sealing. That was a large and chronic MH. As we suggested in the Discussion, full recovery of photoreceptors in the eye is not anticipated.

The main results of our study were obtained using Stratus OCT in all subjects to create a consistent data set. We also collected extra spectral-domain (SD) OCT images from some of the subjects. Although the number of cases was not sufficient to reach any conclusion, the development and complete extinction of outer foveolar defects also were noted in the SD OCT examination. Our observation also is in line with previous studies using SD OCT, which documented the disappearance of outer foveolar defects and the restoration of the inner segment and outer segment junctions in 9 of 28 cases after 6 months. However, we also agree that there may be tiny outer foveolar defects that may not be detected by Stratus OCT, but could be detected by SD OCT. The transverse resolutions of Stratus OCT and SD OCT are reported as 20 and 10 μm, respectively. Thus, with SD OCT it is possible that the mean period for the disappearance of the defects is longer than the 6 months of our study.

In Figure 2, we intended to show a schematic drawing of the MH sealing process. Each illustration is consistent with time-based changes of the fovea on OCTs from different patients. Dr Oh’s comment regarding the process of resolution of outer foveolar defects in Figure 1 is not actually different from the description in the legend of Figure 2 and in the Discussion.

There have been many reports about MH development, but research on MH sealing has been hindered by certain limitations so far. In this regard, this study suggests meaningful observations. However, the sealing mechanism hypothesis provided in this study is based on the inference of the authors. This requires further investigation to be proven. We expect that further studies on the MH sealing process may shed light on the development of more efficient means to induce MH sealing.

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Jan 16, 2017 | Posted by in OPHTHALMOLOGY | Comments Off on Reply

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