The LEA-distance book with 4 symbols is used for testing visual acuity of young children around the age of 3. Visual acuity range from 0.1 to 2.5. 

Within this book, there are 4 symbols on each chart. They are in a logharhythmic order through the book. The Lea symbols make testing of children and illiterates easy. With an L-shaped occluding device, all other 3 symbols can be covered. This way, the test person cannot exclude certain Lea symbols, as he/she has no comparison. Testing distance is 3 meters. The included answer cards (1 symbol each) are for the children to show the doctor non-verbally, what symbol they saw. The larger transparent answer chart can be used by the children to show with a finger, which symbol they saw. It is transparent, so that the examiner can see the finger from the other side.