Abstract

1.1.Purpose: To evaluate the feasibility of the TNO chart for the assessment of distance stereo-acuity using an inverted telescope in normal subjects.

1.2.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.

1.3.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

Keywords

Stereoacuity, Stereopsis, Strabismus, Telescope, TNO test, Ocular alignment, Intermittent exotropia, Amblyopia, Squint, Stereo-test