Volumetric assessment of the space between the posterior hyaloid and internal limiting membrane using SD-OCT

The purpose of this study was to measure, for clinical and surgical utility, the distance between the posterior hyaloid and the internal limiting membrane using a spectral domain optical-coherence tomography (SD-OCT) device. Eight eyes of eight patients with subclinical partial posterior vitreous detachment (PPVD) with vitreomacular traction syndrome were examined with SD-OCT. To quantify the vitreoretinal distance, the basic applications of SD-OCT (Spectralis HRA+OCT Heidelberg Engineering) were modified. We conducted a topographic study of the entire posterior pole by defining new maps, each generated from 19 raster scans. We obtained maps that represent the space between the residual vitreous and retina, expressed numerically and on a colour spectrum, and overlapped them on a posterior pole photograph. We also created a single map of the entire posterior pole. The mean PPVD volume in the eight eyes was 104.87 +/- 5.25 mm(3). This study produced detailed maps of the vitreoretinal distance, which may facilitate the study of the clinical progression of PPVD. In case of surgery the maps may help to accurately determine where surgical manipulation is needed safely apart from the retina. These maps could also assist in the assessment of pharmacological vitreolysis efficacy.