MultiModal approaches to Managing ocular pathology

November/December 2013 SupplemeNt to retiNa toDay 1 The word “choroid” is derived from the Greek words for “forms” and “membrane.” The choroid is a highly vascular and pigmented tissue that lies between the retina and sclera and that has a histologic thickness between 0.10 mm (anterior) and 0.22 mm (posterior pole). The vascular supply of the outer retina is maintained by the choroid, and changes to this structure can result in photoreceptor death; choroidal changes are also associated with diseases such as central serous chorioretinopathy (CSC), age-related macular degeneration (AMD), and Vogt-Koyanagi-Harada syndrome. The in vivo thickness of the choroid has been understood via B-scan and Doppler imaging, but until spectraldomain optical coherence tomography (SD-OCT) imaging became available, very little was known about its in vivo structure. The first time-domain (TD) OCT system, the Stratus (Carl Zeiss Meditec), provided little information about the choroid because most of the light emitted could not penetrate the retinal pigment epithelium (RPE); however, SD-OCT frequency settings improved upon the wavelengths used in TD-OCT to allow imaging deeper into the retina. The most recent advance in OCT technology, known as swept-source OCT (SS-OCT), further improves upon the precision with which we can determine the inner and outer boundaries of the choroid, while also allowing examination of the choriocapillaris and larger choroidal vessels.