Novel OCT-Based Method to Measure Volumes of Retinal Specific Entities

Abstract

Objectives- The aim of the study is to describe and validate an optical-coherence-tomography (OCT) based method to easily calculate specific volumes, overcoming the inability of current OCT software to automate a volumetric analysis for specific entities in retinal pathologies. Methods- After manual drawing with caliper of the specific entity on linear OCT scans and consequent automated measurement of its area, the following formula was used for volumetric calculation: Volume [mm³] = ∑area [mm²] x OCT-scan distance [mm]. Two independent observers calculated the retinal volume (RV) in eyes with normal foveal profile (NFP) and compared it with the automated measurements performed by the OCT software; as well as the volume of the foveal cavity (FC) or foveoschisis (FS) in eyes with lamellar macular hole (LMH). The measurements were re-acquired after six weeks. Intra- and inter-observer variability and variability with automated RV calculations were analysed. Results- The study included 62 eyes: 30 NFP and 32 LMH eyes. High degree of agreement was determined for inter-observer and intra-observer variability between the two observers or singular observer with Spectralis for RV in NFP eyes; as well as between the two observers for FC/FS volume in LMH eyes. Conclusions- We describe and validate, showing excellent inter- and intra-observer agreement, an easy, reliable and widely applicable method to calculate volumes which can be applied to any entity requiring a specific study in the context of retinal pathologies.