The D-OCT image of a normal subject illustrates the method of retinal layer segmentation using the multipoint selection tool of ImageJ. The ONL thickness was defined as the distance between the inner edge of the ELM (4) to the outer edge of the HFL (3). 1, ILM; 2, the transition between the OPL and the HFL; 3, the transition between the HFL and the ONL; 4, ELM; 5, the outer edge of the RPE.