Relationship Between Neurological Disability and Visual Impairment in Patients With ALS or Friedreich's Ataxia

Inclusion Criteria: * Older than 18 years. * Best corrected visual acuity more than 0.4 (20/50 Snellen = 0.4 logMAR = 65 ETDRS letters). * Refractive defect less than 5 diopters of spherical equivalent and / or cylinder less than 2 diopters. * Transparent optical media: Opacity of crystalline \<1 according to Lens Opacities Classification System (LOCS) III. * Open anterior chamber angle assessed by gonioscopy with Goldmann lens (grade\> III). * Availability and collaboration to carry out the tests of the exploratory protocol. * Acceptance of informed consent. Exclusion Criteria: * Previous intraocular surgeries of less than 6 months of evolution. Patients with refractive surgery using the LASIK or LASEK technique will not be excluded. * Physical or mental difficulties to perform reliable and reproducible perimeters. * Pathology and / or ocular malformations, angular or optic nerve anomalies. * Any retinopathy or maculopathy. * Intraocular pressure (IOP)\> 21 mmHg. * Signal-to-noise ratio in OCT less than 5/10. * Failure to meet any inclusion criteria. * Mental retardation or any other limitation in obtaining informed consent.