Abstract
Optical coherence tomography (OCT) has facilitated an understanding of the pathogenesis of various retinal diseases. It also enables measurement of the thickness of the total retina and nerve fiber layer that aids in the diagnosis of early glaucoma, the monitoring of disease progression, and the evaluation of treatment effects. Recently, the acquisition speed and sensitivity of OCT have been dramatically improved with a novel detection technique known as Fourier-, spectral-, or frequency-domain detection that increases the imaging speed by ∼25- to 100-fold compared to that yielded by standard-resolution time-domain OCT (TD-OCT). Spectral-domain OCT (SD-OCT) enables three-dimensional (3D) analysis of retinal pathologies, 3D visualization of the vitreoretinal interface, and comprehensive observation of intraretinal structural changes. It allows the segmentation of some retinal layers such as the nerve fiber layer, inner retina, and photoreceptor outer segment, and this in turn enables the monitoring of the thickening or thinning of these structures. SD-OCT also allows the segmentation of 3D pathological lesions such as soft drusen, pigment epithelial detachment, and serous retinal detachment. Thus, disease progression can be monitored and the effects of treatment can be evaluated more precisely using SD-OCT than TD-OCT. Further, SD-OCT enables the registration of 3D volume images with other standard ophthalmic images such as color fundus photographs and angiograms. Thus, SD-OCT dramatically expands the potential use of OCT in the analysis of retinal diseases and glaucomas.
