gms | German Medical Science

Introduction: New volume mode of the Spectralis-OCT (Heidelberg Engineering, Dossenheim) allows a distance as little as 11 µm between adjacent b-scans. So far, there is no experience regarding interpretation of c-scans that can be acquired using this technique.

Methods: OCT volume scans were acquired in 52 Patients with AMD and choroidal neovascularizations (CNV) with horizontal orientation of the RPE line. Virtual cross-sections through the volume dataset parallel to the retinal layers were reconstructed. Corresponding b-scans were shown separately and compared to the c-scans.

Results: Shadows of retinal vessels showed minimal offset between b-scans, allowing accurate acquisition of volume scans sufficient for c-scan visualization. Three different patterns were observed regarding retinal layers when scrolling through the volume (from inner towards outer retina): a) straight pattern: lines representing retinal layers moving from one side towards the other. b) concave pattern: lines on one side were mirrored on the opposite side and moving towards image center. c) convex pattern: lines running from center outwards. Considering these patterns, vessels of CNV or fibrovascular membranes, drusen and cystic alterations were detectable and could be correlated to other structures in 40/52 patients.

Conclusion: Volume scans with 11 µm lateral resolution provide improved images of pathologies in AMD. The planar visualization improves the assessment of the extent of pathologies in comparison to b-scans. However, interpretation of corresponding b-scans is still necessary to avoid misinterpretations of structures in c-scans.