Classic eye charts do not have a logarithmic scale (LogMAR), as a required by now. However, this is far from the only requirement that is not being complied with. The situation is particularly serious with vision charts for children. They are often downright misleading and give far too favorable eye test results when screening children. In fact, the figures on a number of the eye charts used for children are up to 86% too large, and as a result many vision problems are not detected – until children are promoted to vision charts without figures, typically ETDRS letter charts, Landolt C or Tumbling E .

Since 2016, with ISO 8586, there have been international guidelines for vision testing in general medical practice and healthcare. But the guidelines have only been followed to an extremely limited extent.
In addition to logarithmic scale, the directions also set focus on uniform lighting of the eye chart within the lux spectrum as ISO standard 8596 specifies a brightness of between 700 and 1300 Lux, measured from the vision test distance used.

Being within this spectrum cannot be achieved with arbitrary daylight or ceiling light in the fitting room. The light can fluctuate a lot, but will usually be below the minimal 700 lux. Likewise with the color temperature, which with the glare of sunlight will most often be too. warm a candle (below 3000 kelvin), and too warm light degrades the vision test environment.

The arrangement of figures and letters on the eye charts in an inverted pyramid means that the lines with pictures and letters must be increasingly close together, with smaller and smaller line spacing for each logarithmic step. It will make demands  proper lighting.
The compressed (crowded) arrangement of rows requires an improved lighting environment.