Choroidal blood flow and thickness measurements

Most of the ocular blood supply goes into the choroidal circulation. Intensive research has been directed towards choroidal structure and function in health and disease. Indeed, choroidal blood flow and its regulation has been found to be altered in several ocular diseases, such as age-related macular degeneration. Several techniques for the assessment of choroidal blood flow have been developed including laser Doppler flowmetry, laser speckle flowgraphy, laser interferometric measurement of fundus pulsation amplitude or pneumotonometric measurement of pulsatile ocular blood flow. All these techniques have significant limitations and currently no gold standard method for the assessment of choroidal blood flow exists.

With the introduction of enhanced depth imaging optical coherence tomography (OCT) systems, it is now possible to image choroidal thickness in vivo. Alterations in choroidal thickness have been observed in several ocular diseases. The correlation between functional and structural choroidal parameters is, however, weak. Further research is required to better understand the results obtained in patients with ocular pathologies and to investigate whether choroidal thickness is a good biomarker for choroidal disease.