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Focke Ziemssen, Martin Leitritz, Ditta Zobor, Michael Voelker, Karl-Ulrich Bartz-Schmidt, Faik Gelisken; Semi-automated Contour Analysis of SD-OCT images after Epiretinal Membrane Peeling using either air tamponade or balanced salt solution. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5506.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the morphological changes after macular surgery for epiretinal membranes (ERM) in transconjunktival 23G surgery using air or balanced salt solution (BSS) by spectral domain optical coherence tomography (SD-OCT) and standardized contour analysis.
Consecutive patients (80 eyes) with ERM were included in the retrospective analysis after receiving BSS (41) or air tamponade (39) at the end of surgery. Ophthalmic examination included best corrected visual acuity (BVCA) and SD-OCT. The OCT was performed preoperative and three months postoperatively. The analysis of the images was made with image processing ImageJ software. The binary images were processed in a masked fashion. Automated threshold algorithm was used to detect and measure the retinal area. The inner and outer borders of the binary picture were outlined and analyzed on the basis of their coordinates. Further geometric parameters were calculated with the JMP 10.0 software package (SAS Institute, Cary, NC, USA). For the regularity assessment, the rotational symmetry of the foveal depression was tested. The group differences were detected by using Wilcoxon Signed-Rank test (α=0.05).
Preoperative best-corrected visual acuity (BCVA) after air tamponade (0.6 logMAR; median; range: 0.2 to 1.3) did not significantly differ from the BSS group (median: 0.4 logMAR; range: 0.1 to 1.3). Three months after surgery, the median BCVA of the air group increased significantly to 0.3 logMAR, similar to the BCVA in the BSS group. The measured retinal area showed a similar distribution in both groups (air: 976.919 µm2, range: 524.955µm2-2.656.249µm2; BSS: 937.370 µm2, range: 622.763µm2-1.540.951µm2). After three months, the area significantly decreased in both groups (air: 749.002µm2, BSS: 749.038µm2). Foveal symmetry (±100µm) were significantly more common seen when using BSS (median 10.44µm, range 0-41.24µm) in comparison to air (median 10.99µm, range 0-65.93µm).
Interestingly, comparable functional and anatomical results were seen for both groups. At the 3-months examination, the changes of retinal thickness were slightly more pronounced in the air group, while foveal symmetry was more frequently seen in the BSS group. Semi-automated contour analysis is able to describe the gradient of the foveal surface and provides objective parameters of local thickness development.
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