Visual Acuity Charts: Analytical Review, Basic Terms

Maria A. Gracheva, Anna A. Kazakova, Dmitry F. Pokrovskiy, Igor B. Medvedev
2019 Rossiiskaya Akademiya Meditsinskikh Nauk. Vestnik  
The review is dedicated to the visual acuity charts for assessment vision at far. The first part of the review provides definitions of basic terms: optotypes, step of the chart (change in the sign size from line to line), chart design; also, termination rules for measurement procedure and the main measuring units (logMAR, decimal units) are discussed. The second part of the paper provides historical review of charts development, starting from the beginning of the XIX century. The most wide
more » ... d visual acuity charts are described: Snellen chart, Sivtsev-Golovin chart, ETDRS chart, Lea chart, etc. The features of their structure and the optotypes used are discussed, taking into account their usefulness, practicality and feasibility in children vision assessment. Charts compliance with the standard in view of recommendations about optotypes properties and optotypes distribution on the chart field are reviewed. A special attention is drawn to the modern tendencies in optotypes development in order to obtain better repeatability of visual acuity assessment.
doi:10.15690/vramn1142 fatcat:mz5kmk4jurdmjd3th3a23ncqty