Repeatability of an automated Landolt C tet, compared with the early treatment of diabetic retinopathy tudy (ETDR) chart teting

Purpoe To evaluate the repeatability of viual acuity core from the automated tet and compare them with the Early Treatment of Diabetic Retinopathy tudy (ETDR) chart. Deign Intrument validation tudy baed on a model of repeatability tudy in two obervation. Method etting: a propective, clinic-baed, comparative tudy. A total of 206 participant without ocular dieae and refractive error in their right eye were randomly enrolled in the automated group in which 107 participant performed the automated tet and the ETDR group in which 99 participant read the ETDR chart. All participant were teted with only their right eye without correction at 4 meter and came back to have the ame tet 1 week later. The automated tet ued the Landolt ring a optotype and wa conducted by a low-ended peronal computer with a 15-inch monitor and a wirele keyboard. The “letter” core calculated by counting every correct repone to optotype, and the “threhold curve” core interpreted from the optotype ize at the midpoint of a viual acuity threhold curve. Reult The 95% confidence interval of tet–retet of viual acuity core from the automated tet are comparable to the ETDR chart (.143 compared with .125 for letter core, .145 compared with .122 for threhold curve core). The core repeatabilitie, calculated from the tandard deviation of tet-retet, from the automated tet are alo comparable to the ETDR chart (.201 compared with .177 for letter core, .206 compared with .172 for threhold curve core). All comparion demontrated no tatitical difference (P > .05). Concluion The automated teting ytem in thi tudy enable practical meauring viual acuity by the Landolt ring. The ytem’ repeatability, which i comparable to the ETDR chart, upport it role a an alternative tool for meauring outcome in new clinical reearch. It ability to practically generate viual acuity threhold curve may alo be ueful in future clinical reearch tudie.