Examples of macular hole of different sizes, as measured by the size of the aperture. The aperture is defined as the smallest distance between the 2 borders of the macular hole seeing on spectral-domain optical coherence tomography (SD-OCT), as measured by a line parallel to the retinal pigment epithelium. a–d. Variable sizes of macular hole. e, f. Measurement of the macular hole aperture size using the SD-OCT built-in software.