ORIGINAL ARTICLES

Automatic segmentation in three-dimensional analysis of fibrovascular pigmentepithelial detachment using high-definition optical coherence tomography

C Ahlers¹, C Simader¹, W Geitzenauer¹, G Stock¹, P Stetson², S Dastmalchi² and U Schmidt-Erfurth¹

¹ Medical University of Vienna, Department of Ophthalmology, Vienna, Austria
² Carl Zeiss Meditec, Dublin, CA, USA

Correspondence to:
C Ahlers, Klinik für Optometrie und Augenheilkunde, der medizinschen Universität Wien, Waehringer Guertel 18–20, 1090 Vienna, Austria; christian.ahlers{at}meduniwien.ac.at

Background/aims: A limited number of scans compromise conventional optical coherence tomography (OCT) to track chorioretinal disease in its full extension. Failures in edge-detection algorithms falsify the results of retinal mapping even further. High-definition-OCT (HD-OCT) is based on raster scanning and was used to visualise the localisation and volume of intra- and sub-pigment-epithelial (RPE) changes in fibrovascular pigment epithelial detachments (fPED). Two different scanning patterns were evaluated.

Methods: 22 eyes with fPED were imaged using a frequency-domain, high-speed prototype of the Cirrus^TM HD-OCT. The axial resolution was 6 µm, and the scanning speed was 25 kA scans/s. Two different scanning patterns covering an area of 6x6 mm in the macular retina were compared. Three-dimensional topographic reconstructions and volume calculations were performed using MATLAB^TM-based automatic segmentation software.

Results: Detailed information about layer-specific distribution of fluid accumulation and volumetric measurements can be obtained for retinal- and sub-RPE volumes. Both raster scans show a high correlation (p<0.01; R²>0.89) of measured values, that is PED volume/area, retinal volume and mean retinal thickness. Quality control of the automatic segmentation revealed reasonable results in over 90% of the examinations.

Conclusion: Automatic segmentation allows for detailed quantitative and topographic analysis of the RPE and the overlying retina. In fPED, the 128x512 scanning-pattern shows mild advantages when compared with the 256x256 scan. Together with the ability for automatic segmentation, HD-OCT clearly improves the clinical monitoring of chorioretinal disease by adding relevant new parameters. HD-OCT is likely capable of enhancing the understanding of pathophysiology and benefits of treatment for current anti-CNV strategies in future.

Competing interests: Carl Zeiss Meditec provided an HD-OCT-System to support the scientific collaboration. Further commercial relations: None.

Ethics approval: The study complied with the declaration of Helsinki and was approved by the local ethics committee.

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