Enhanced depth imaging-OCT of the choroid: a review of the current literature

Background: With the advent of enhanced depth imaging optical coherence tomography (EDI-OCT), detailed visualisation of the choroid in vivo is now possible. Measurements of choroidal thickness (CT) have also enabled new directions in research to study normal and pathological processes within the choroid. The aim of the present study is to review the current literature on choroidal imaging using EDI-OCT. Methods: Studies were identified by a systematic search using Medline (http://www.ncbi.nlm.nih.gov/pubmed). Papers were also identified based on the reference lists of relevant publications. Papers were included in the review if the focus of the study involved imaging of the choroid using EDI-OCT. Results: Recent studies have demonstrated successful imaging of the choroid and high reproducibility of measurements of CT using EDI-OCT. There are much data confirming that abnormalities in choroidal structure and function contribute to major ocular diseases and patterns of CT variation may be observed in certain disease states and may be influenced by treatment. However, it is not clear whether these variations are a contributing factor or a consequence of the disease. Conclusion: While more invasive methods such as indocyanine green (ICG) angiography remain the gold standard for detecting abnormalities of the choroidal vasculature in normal eyes and disease states, EDI-OCT has become an important adjunctive clinical tool in providing three-dimensional anatomical information of the choroid.