The Freiburg Vision Test before and after cataract operation

Abstract

Especially in aged patients testing the visual acuity can be most time consuming. An automatic test could therefore be of great help. The recently introduced "Freiburg Visual Acuity Test' (FVT) using a forced-choice determination of Landolt orientation has proved a reliable method of automatic visual acuity testing in younger patients. To learn about practicability and ease of this self-administered test, we tried this test in 87 patients (mean age 73) before and after cataract surgery. The Landolt ring was presented in 8 different positions on a monitor. A keyboard of 8 buttons, depicting the possible orientation of the Landolt C, allowed the patients to run through the test by themselves. With each patient's correct response, the size of the Landolt ring decreased accordingly. Although near vision of all patients was grossly impaired and accommodation power zero, handling of the keyboard for the subject's response was generally reported as easy. The reliability and reproducibility of the obtained values were good and close to acuity values obtained using projected test figures according to DIN. Prior to cataract surgery we found DIN values statistically significantly lower than FVT values. This difference did not persist after surgery. Although the tested patients were definitely no computer freaks, the procedure of the test was rapidly understood. The average testing time was 4.5 min, thus prolonged by 40% in comparison to assisted DIN testing, however consuming only 1.0 min of personnel's time. The test proved to be equally reliable in the elderly patient.