Abstract
Purpose:
To compare different Spectral-Domain Optical Coherence Tomographers (SD-OCTs) and different scan widths in the evaluation of posterior vitreous detachment.
Methods:
Retrospective analysis of SD-OCT scans acquired the same day from sixty-nine consecutive patients using: OCT RS-3000 Advance by Nidek (12 millimeters horizontal macula scan); OCT Avanti RtVue XR by Optovue (12 millimeters horizontal macula scan) and OCT Spectralis by Heidelberg Engineering (6 and 9 millimeters horizontal scans through the fovea and a “composite” image, approximately 15 millimeters wide, obtained by composing horizontal overlapping scans from the macula and the periphery).<br /> Images were randomized and reviewed separately by two vitreo-retinal experts, who evaluated the degree of posterior vitreous detachment (PVD) and whether the Bursa Premacularis (BP) could be detected. To test the agreement between the two examiners for PVD grading, Cohen’s kappa was computed; smaller weights were post-hoc assigned to grades corresponding to no PVD and complete PVD as they were the primary source of disagreement.
Results:
345 images were evaluated. Interobserver agreement for PVD was found to be fair to moderate with OCT Spectralis scans, with the highest agreement obtained with composite scans (κ = 0,569). With 12 millimeters scans, agreement was found to be substantial with both OCT RS-3000 Advance (κ = 0,654) and OCT Avanti RtVue XR scans (κ = 0,758). Weighted Cohen’s kappa shows interobserver agreement to be almost perfect (κ = 0,808 to 0,913) for all SD-OCT instruments and scans. With OCT Spectralis, the BP was observed in up to 29,0% of 6 and 9 mm scans and 39,1% of composite scans (χ² = 2,5; P = 0,3). The BP was detected in up to 55,1% of OCT Avanti RtVue XR scans and 63,8% of OCT RS-3000 Advance scans (χ² = 19,6; P = 0,0006).
Conclusions:
SD-OCT grading of PVD guarantees high interobserver reproducibility when applied to the first stages of PVD. The distinction between no PVD and complete PVD is subject to higher interobserver variability. In this study, the best results were obtained using 12 mm scans, which also allow for better visualization of posterior vitreous structures. Prevalence of the BP (both overall and corrected by degree of PVD) with 12millimeters scans is consistent with previously reported data.