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Horizontal Lang two-pencil test as a screening test for stereopsis and binocularity
Monisha E Nongpiur1, Pradeep Sharma
1Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India.
Indian Journal of Ophthalmology
|June 11, 2010
Summary
The horizontal Lang two-pencil test effectively screens for gross stereopsis (3D vision) and binocularity (two-eyed vision). This simple bedside test demonstrates high sensitivity and negative predictive value in strabismic patients.
Area of Science:
- Ophthalmology
- Neuroscience
- Vision Science
Background:
- Stereopsis and binocularity are crucial for visual function.
- Assessing these in clinical settings can be challenging.
- Bedside tests offer a practical solution for rapid evaluation.
Purpose of the Study:
- To evaluate the horizontal Lang two-pencil test's utility.
- To determine its accuracy in detecting gross stereopsis.
- To assess its role as a bedside screening tool.
Main Methods:
- Studied 84 strabismic and 40 normal subjects.
- Utilized multiple sensory status examinations.
- Included Bagolini, Titmus, TNO, Randot, synoptophore, and horizontal Lang two-pencil tests.
Main Results:
- The horizontal Lang two-pencil test showed 100% sensitivity and 83.9% specificity for stereopsis detection (vs. Randot).
- It demonstrated 100% specificity for binocularity (vs. Bagolini).
- Patients with smaller deviations performed better on stereo tests.
Conclusions:
- The horizontal Lang two-pencil test is a valuable screening tool.
- It is easy to perform and has high sensitivity and negative predictive value.
- It can reliably detect gross stereopsis and binocularity at the bedside.
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