Measurement of visual acuity on TE / O will be carried out on an ETDRS AV scale, the size of the letters having been adapted to the reading distance (80 cm by 0.40 cm on the tablet). An ETDRS intermediate vision (EVI) or meadow vision (TEU) score according to the group will be established in the same way. The VA measurement will be supervised by a CRA trained to the extent of the VA, without the orthoptist or ophthalmologist being informed of the results obtained.