For Visual acuity levels beyond the limit of the letter charts, the common practice is for clinicians to categorize vision according to whether the patient can count fingers (CF) or detect hand motion (HM), but there is no recognized or standard procedures for doing this.
The Berkeley Rudimentary Vision Test (BRVT) was developed to enable efficient and easy measurement of visual acuity beyond the limits of the letter chart. It becomes necessary to make the test task simpler than the letter chart task and, in order to achieve very large angular sizes, very close viewing distances may be required. In the interests of simplicity and flexibility of use, the BRVT has 3 card-pairs. Each card pair consists of two 25 cm square hinged cards so each card-pair has 4 target surfaces.