A Novel Technique of Measuring Distance Stereo-Acuity Using TNO Chart and Inverted Telescope

Abstract

Purpose: To evaluate the feasibility of the TNO chart for the assessment of distance stereo-acuity using an inverted telescope in normal subjects.Methods: Stereoacuity of 30 emmetropic adult subjects was measured for near. The distance stereoacuity was measured using the TNO chart held at 40 cm and an inverted telescope (Galilean design, 26mm, 2X, Camma Inc. China) in front of the examinee's eyes. Results:The near stereopsis ranged from 60" (seconds of arc) -240" (Median 120"). Distance stereopsis ranged from 4.8" -38.4". Distance stereoacuity could be measured in 14 (47%) subjects. Conclusion:It is possible to measure the distance with an inverted telescope and a TNO chart. Further improvisation is required to design an optimal telescope system with larger field, gradable zoom and measurable inter pupillary distance.

Investigating the Link Between Subjective Depth Perception Deficits and Objective Stereoscopic Vision Deficits in Individuals With Acquired Brain Injury

“…Although the H-D–type stereoscopic vision test is the most widely used test for stereoscopic vision in Japan and has been considered to assess mainly stereoscopic vision from binocular disparity, there has been controversy as to whether it assesses stereoscopic vision from binocular disparity alone (Knight et al, 1998; Larson, 1985). Therefore, we also used the latest version of the TNO Stereo Test (MediSense, 2017), which is a more sophisticated tool for assessing stereoscopic vision from binocular disparity alone (Abd-Manan, 2000; Kothari, 2017; Schaadt et al, 2015).…”