The Snellen eye chart

The Snellen visual acuity test is probably what you're picturing if you think of a vision test. It's a wall chart with rows of letters printed on it. The letters are big at the top, and each row gets increasingly smaller the farther down on the chart you look. Your eye care specialist will ask you to read rows until you can't make out the letters. Some eye care specialists use Snellen charts projected on a wall or displayed on a screen.

The random E chart

The random E visual acuity test is similar to the Snellen eye chart. It's a wall chart, but instead of rows of different letters, it only has E printed on it. As the E gets smaller, it's also rotated, flipped and positioned differently. You'll read down the chart until you can't tell which way the E is facing.

Dynamic visual acuity test

Your eye care specialist will hold your head and move it back and forth while you perform a visual acuity test. This can test how well your eyes stabilize during motion without affecting your vision (your vestibulo-ocular reflex).

Pinhole visual acuity test

Pinhole visual acuity tests are specifically for diagnosing myopia (nearsightedness). Your eye care specialist will ask you to cover one of your eyes with a paddle similar to one you'd use during a typical visual acuity test. However, the paddle for a pinhole test has one (or a few) tiny holes in it. Instead of using the uncovered eye to read a Snellen or random E chart, you'll use the covered eye by looking through the pinhole.

Visual acuity tests for children

There are few versions of pediatric visual acuity tests for kids of different ages. You might see a visual acuity for kids referred to as a Cardiff visual acuity test. Some tests use symbols or pictures instead of rows of letters. Your eye care specialist might also give your child a “cheat sheet” with the letters on a Snellen eye chart and ask them to match the letters they see on the sheet to their location on the wall chart.