Original Article Simplified Method to Measure the Peripapillary Choroidal Thickness Using Three-dimensional Optical Coherence Tomography

Advances in spectral domain optical coherence tomog-raphy (SD-OCT) and enhanced depth-imaging techniques have allowed for measurement of the deep layers of the retina and choroid [1]. Recently, some studies have been published regarding the configuration of choroidal thick-ness on the macula and the peripapillary area of normal controls, as well as those of patients with various macular and optic disc diseases [1-6]. However, the method used to measure choroidal thickness has varied among studies and could be dependent on the observers and the location of the scans used to measure choroidal thickness. In previous optical coherence tomography (OCT) stud-ies, line scanning was used to investigate choroidal thick-ness around the optic disc [4,5]. In these studies, choroidal thickness was determined between two boundaries set by the observers. Although they found excellent inter-observ-er agreement for the measurements, variations between observers were still present. Choroidal thickness was de-termined at a specific point on the line scans of the optic disc, rather than the entire line scan. More time and effort may be needed to manually measure the thickness of the entire area of the line scan. They topographically related choroidal thickness with those of the overlying retina or retinal nerve fiber layer (RNFL). While a relationship be-tween choroidal thickness and overlying RNFL thickness was found, the comparison was not based on the normative database of peripapillary RNFL thickness. In contrast to measurements taken from line scans of the optic disc, measurement of peripapillary RNFL thickness by OCT circle scan has been widely used for the diagnosis and monitoring of optic disc disorders, such as glaucoma and anterior ischemic optic neuropathy [7-10]. The circl