European Academy of Optometry and Optics

Sunday 19 May 2019; Open Paper Session 6: Binocular Vision, 11:30-13:00

Presenter: Dinah Paritzky

Authors: DINAH PARITZKY, NADAV WOLF, INBAR WUNCH, LIAT GANTZ; Hadassah Academic College

Keywords: VA, dynamic acuity, Dyop

Optometrists test VA using the Snellen or LogMar charts developed in 1862 and 1976. The LogMar chart lacks many of the problems of the Snellen chart, such as non-linear crowding, optotypes of varying difficulty, non-geometrical changes between the lines, and varying numbers of optotypes per line. However, both charts are limited because they measure static acuity, whereas everyday tasks involve moving and static objects. Furthermore, two patients may have the same quantitative VA whilst having different qualitative VA.

In addition, the end-point is often difficult to ascertain, with a patient able to identify some optotypes on several different lines. A new type of test for VA has been designed to overcome these problems: The DYOP® is a dynamic segmented optotype that can rotate clockwise or anticlockwise. VA threshold is measured by using DYOPs of constant colour, contrast, and speed rotation and decreasing the diameter of the DYOPs until the direction of motion can no longer be recognised. This method solves the problems of literacy, memorising, and crowding while enabling a more precise endpoint. In addition, there is no limit to the number of DYOPs that can be shown for a given line of VA.

Methods: VA measurements with the DYOP have been compared with Landolt C, with the DYOP yielding a clearer endpoint. The DYOP correlates highly with a standard Sloan LogMAR and Sloan acuity chart. It has also been found to obtain similar VA scores for the same refraction values compared with the LogMAR E chart in adults. We are currently carrying out a study of the repeatability, reproducibility and speed of exams and also assessing the subjective experience of the patients.

Recommendations/Conclusions: Initial results indicate that the DYOP gives good results and is well tolerated by patients. Given its advantages over Snellen/LogMAR, the DYOP may be a superior VA test. It is possible that after 150 years, the time has come to change how we measure VA in the clinic.

The DYOP, a new test of visual acuity