Horizontal Lang two-pencil test as a screening test for stereopsis and binocularity.
OBJECTIVE
To assess the horizontal Lang two-pencil test as a bedside test to detect gross stereopsis.


METHODS
Eighty-four strabismic subjects divided into two groups based on the amount of deviation, and 40 normal subjects were studied. Sensory status examination including binocularity and stereopsis were evaluated with Bagolini, Titmus test and The Netherlands organisation for applied scientific research (TNO), Randot, synoptophore and horizontal Lang two-pencil test.


RESULTS
The subjects in the group with smaller deviation showed better performance on all the four stereo tests and over 90% demonstrated presence of fusion. When compared to TNO and Randot for determining presence of stereopsis, the horizontal Lang two-pencil test demonstrated sensitivity of 100% and 83.9%, specificity of 77.8% and 73.7%, and negative predictive value of 100% and 100% respectively. It also showed 100% specificity as a test for binocularity when compared with the Bagolini striated glass test.


CONCLUSIONS
Horizontal Lang two-pencil test, an easily performed test with a high sensitivity and negative predictive value can be used as a screening test to detect gross stereopsis and binocularity.
Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India.
Monisha E
ME
Nongpiur
Pradeep
P
Sharma
D000293:Adolescent; D002648:Child; D003430:Cross-Sectional Studies; D003867:Depth Perception / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods; D011237:Predictive Value of Tests; D012016:Reference Values; D012680:Sensitivity and Specificity; D013285:Strabismus / Q000175:diagnosis* / Q000503:physiopathology; D015348:Vision, Binocular / Q000502:physiology*; D014792:Visual Acuity / Q000502:physiology