Purpose:
To observe the 3-dimensional images of vitreo-retinal interface using spectral-domain OCT, and to investigate the pathogenesis of diabetic macular edema (DME).
Methods:
Retrospective non-comparative case series.Twenty-six eyes of 21 DME patients, 2 eyes of epiretinal membrane(ERM)patients, and the control 2 eyes of macular hole(MH)patients who underwent pars plana vitrectomy (PPV) from July 2008 through November 2010 were observed.The changes of vitreoretinal interface status before and after PPV were compared by the segmentation analysis equipped with spectral-domain OCT (Cirrus HD-OCTTM).In 14 patients, the specimens of the removed inner limiting membrane (ILM) and/or ERM were observed immunohistrochemically, and compared among the cases of DME, ERM, and MH.This study was approved by Ethical Committee of Yamagata University Faculty of Medicine.
Results:
In DME patients, the segmentation findings were classified into 3 patterns.Group1: Fine folds were detected by the segmentation analysis,not by tomography on the retinal surfaces in 11 eyes (42%).The fold disappeared after the removal of ILM(Figure), which was confirmed by type IV collagen expression immunohistochemically.Group2: Uneven surface without fine folds was observed in 11 eyes (42%). Tomography revealed the ERM with fine fold of ILM underneath it (containing type II collagen corresponding to vitreous cortex).Group3: Smooth surface was observed both by segmentation analysis and by tomography in 4 eyes (16%). Central retinal thickness reduced significantly by 35% (Group 1), 53% (Group 2) or 50% (Group 3). ILM/ERM specimens from DME and ERM eyes cotained more astro-grial cells(GFAP+), and IL-6 expressing cells in comparison with MH eyes.
Conclusions:
The fine folds of ILM were detected by the segmentation analysis, not by tomography.The fine fold findings were caused by the cells containing astro-glial cells and expressing IL-6. The tangential tractional force may be exterted on ILM by the surface cells and ERM in DME.
Keywords: diabetic retinopathy • edema • imaging/image analysis: clinical