Erratum in: “Choroidal Structure in Normal Eyes and After Photodynamic Therapy Determined by Binarization of Optical Coherence Tomographic Images” by Shozo Sonoda, Taiji Sakamoto, Takehiro Yamashita, Makoto Shirasawa, Eisuke Uchino, Hiroto Terasaki, and Masatoshi Tomita (
Invest Ophthalmol Vis Sci. 2014;55:3893-3899) doi:
10.1167/iovs.14-14447
During the course of our recent experiment, we found an error that affected the values presented in our publication titled “Choroidal Structure in Normal Eyes and After Photodynamic Therapy Determined by Binarization of Optical Coherence Tomographic Images.”
The purpose of that study was to determine the changes in the luminal and interstitial areas of the choroid before and after photodynamic therapy. To accomplish this, we recorded choroidal images by enhanced depth imaging-optical coherence tomography (EDI-OCT), and the subfoveal luminal and interstitial areas were converted to binary images by the Niblack method using an open access software, ImageJ (
http://imagej.nih.gov/ij/; provided in the public domain by the National Institutes of Health, Bethesda, MD, USA). To quantify the luminal and interstitial areas of the choroid, the luminal areas were determined by using the threshold tool. The light pixels were defined as the interstitial choroid and the dark pixels were defined as the luminal area. After entering the distance of each pixel, the choroidal area, luminal area, and interstitial area were automatically calculated. A more detailed description of the method can be found in the Supplementary Material of the paper.
The error occurred when we entered the distance between the pixels in the x- and z-directions. We used our program to enter the conversion factor to scale the OCT image to the ImageJ software, and the value entered for the z-axis was approximately 50% larger than the actual distance. As a result, the value of the choroidal area was calculated to be uniformly larger by approximately 50% than the actual size. But this error was made for both the luminal and interstitial areas, and so the ratios of these two areas did not change. Thus, the statistical results and the conclusions are not affected by this error, but we believe it is important to present the corrected values of the choroidal areas in the text, Table 2, and Figure 3. The following are the changes that should be made.
In the Results section, under the subheading, “Binarization of Subfoveal Choroid of Healthy Eyes of Volunteers,” the second to last sentence should be replaced with: “The subfoveal choroidal area was 457,669.2 ± 128,223.7 μm2 (average ± SD); the luminal area was 301,868.3 ± 94,025.3 μm2; and the interstitial area was 155,800.9 ± 38,304.7 μm2.”
In the Results, under the heading, “Subfoveal Choroid in AMD Eyes,” the first sentence of the third paragraph should be replaced with: “The baseline choroidal area of eyes with AMD was 426,539.6 ± 110,544.6 μm2; the luminal area was 280,785.7 ± 79,207.3 μm2; and the interstitial area was 145,753.9 ± 33,259.4 μm2.
The first sentence of the fourth paragraph should be replaced with: “The baseline choroidal area of the fellow eyes with no AMD was 459,791.8 ± 111,196.3 μm2; the luminal area was 303,310.0 ± 75,956.2 μm2; and the interstitial area was 156,481.8 ± 36,144.0 μm2.”
The first sentence of the fifth paragraph should be replaced with: “Six months after the PDT, the choroidal area was reduced to 339,277.2 ± 108,503.1 μm2.”
The third sentence of the fifth paragraph should be replaced with: “Both the luminal area of 216,036.0 ± 78,858.1 μm2 and the interstitial area of 123,241.2 ± 31,687.6 μm2.”
The first and second sentences of the sixth paragraph should be replaced with: “On the other hand, the choroidal area of the fellow eyes was 453,825.3 ± 116,459.3 μm2, which was not significantly different from the baseline choroidal area. Both the luminal area, 301,153.3 ± 82,383.1 μm2, and the interstitial area, 152,672.0 ± 35,283.7 μm2, were not changed significantly relative to the baseline (65.8% vs. 66.4%, P = 0.20, Wilcoxon signed-rank test; Figs. 3, 4).”
In Table 2, the values of Examiner 1 should be “452,345.2 ± 128,254.6, 299,340.4 ± 94,047.0, and 153,004.7 ± 38,543.6,” for the choroid, luminal area, and interstitial area, respectively. The values of Examiner 2 should be “462,993.1 ± 128,946.9, 304,396.1 ± 94,520.5, and 158,597.0 ± 38,366.6,” for the choroid, luminal area, and interstitial area, respectively.
The new Figure 3 has the scale axis corrected.
Citation: Sonoda S, Sakamoto T, Yamashita T, Shirasawa M, Uchino E, Terasaki H, Tomita M. Erratum in: Choroidal structure in normal eyes and after photodynamic therapy determined by binarization of optical coherence tomographic images.
Invest Ophthalmol Vis Sci. 2014;55:3893-3899. DOI:
10.1167/iovs.14-14447a