Abstract: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that damages the motor neurons, the spinal cord, the cerebellum, and some areas of the brain. However, more recent studies show that it can also affect the visual system, for example, through oculomotor and visual pathways. ALS patients do not usually complain of visual problems, so studies focusing on the visual pathway are scarce. Early work on ALS and the eye was related to oculomotor function and visual pathway analysis, with visually evoked potentials being used to study the disease. Subsequently, some works have appeared that analyze visual function, with tests such as visual acuity, visual field, and contrast sensitivity. Furthermore, in neurodegenerative diseases, it is observed that the changes that occur in the brain also occur in the retina, with this nervous tissue being considered as a “window to the brain” (MacCormick et al., 2015). The changes in the retina can be detected by a widely used diagnostic test in ophthalmology, namely optical coherence tomography (OCT). Recently, this technique has been used for the analysis of the retinal and optic nerve changes that occur in various neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, and even ALS, and can serve to help in their diagnosis and follow-up (Salobrar-García et al., 2016; Rojas et al., 2019). In the retina of ALS patients, OCT has demonstrated retinal thinning in the peripapillary retinal nerve fiber layer, inner nuclear layer, and outer nuclear layer, which may be related to neurodegenerative processes (Volpe et al., 2015; Rohani et al., 2018; Rojas et al., 2019). This fact has been confirmed by histopathological studies performed by Volpe et al. on retinas of ALS patients and they observed a loss of retinal ganglion cell axons, which would explain the macular thinning observed by OCT (Volpe et al., 2015). In addition, a study in early spinal-onset ALS patients without ocular disease demonstrated retinal thickening, through significant increases in the macular thickness in the temporal and inferior areas of the inner macular ring, suggesting that the thickening may be due to microglial activation during the neuroinflammatory process (Rojas et al., 2019).