The Lang-Stereotest® II is an easy-to-use examination instrument designed for screening, i.e. early detection of spatial vision problems in children.
The Lang-Stereotest® II is a supplement to the proven Lang-Stereotest® I (Star, Cat, Car) and is also used to test binocular vision according to the same principle. In addition to three figures that are only visible binocularly (crescent moon, car and elephant), there is also a contoured star that can be seen with one eye. The individual figures appear to be set off from the background at different distances.
Many users had requested another stereoscopic examination card as an alternative to the Lang stereo test® I. In version II, the random dots are smaller and less dense. The disparities are chosen a little finer, namely 200 arc seconds for the moon, 400″ for the car and 600″ for the elephant at an observation distance of 40 cm. The star, which is also visible monocularly and has a disparity of 200″, is intended to improve diagnostics in young children by increasing attention and reaction. In addition, subjects without binocular vision remain less disappointed.
Note: the LANG-STEREOTEST does not measure visual acuity and does not substitute for an ophthalmologic examination. A negative test result indicates only a lack of stereoscopic vision at the time of examination.
Examination & Application
Application and purpose of the examination
The Lang-Stereotest® II is an orthoptic product for binocular diagnostics and screening of stereo vision disorders, for medical professionals. The test is used for rapid screening of stereo vision in all age groups from 6 months of age. As loss of stereopsis is considered a key symptom of amblyopia (weak eye), failure to recognise random dot stereograms may indicate a previously undetected, treatable disorder of binocularity (e.g. microstrabismus, anisometropia). The Lang stereo test® has proven to be highly specific and highly sensitive for stereo vision. Thanks to the unique combination of random dots and lenticular, special glasses are not required and the gaze behaviour remains observable.
Examination of children:
- Position yourself in front of the examinee, so that you can easily observe his/her eye movements.
- Show the test plate exactly at right angles at a distance of about 40 cm (16 inches).
- Ask the child if he/she sees something on the plate and watch the searching movements of his/her eyes.
- When a 3D object has been detected, ask the child to look for additional objects and also to describe them. The examinee may then also point at the figures and should be able to tell which of them sticks out most.
- Positive: Correct localization and naming of all hidden objects, typically jumping eye movements from one object to the next. No further examination of stereoscopic vision is needed.
- Negative: no object can be detected, and eye movements also do not indicate the recognition of the 3D objects. Eyes are scanning the test plate and then shift away from it. Refer family to specialist for further examination of stereoscopic vision and visual acuity.
- Doubtful: only one hidden object is localized and named correctly, eyes are scanning the plate for objects. Refer to specialist for further examination of stereoscopic vision and visual acuity.
Refining the examination:
- The child already knows the correct results and might try to cheat. Use the test card upside-down or use two tests, one in the correct horizontal position, the other one in a vertical position in which the 3D objects cannot be detected. Change between versions of LANG-STEREOTEST when retesting.
- To confirm a positive result, ask the person to close one eye while looking at the stereoscopic figures. Immediate disappearance of the figures will be noted.
- Do not let the examinee hold the test card in order to prevent flip-flop-movements. The child may be permitted however, to adjust to the best viewing position by small movements of the head.
- Do not try to help the examinee by suggesting what he/she might recognize. Continue to observe the child’s eye movements while performing the task.
- Do not expose the test card to heat or sunlight, which may cause deformation. If it has been deformed convexly, not all 3D objects may be seen simultaneously.
Important note: Information about clinical data and evaluations can be found on the literature page (Features of the Lang-Stereotest® II, scientific articles). All contents refer exclusively to the original Lang-Stereotest® and may lead to false statements when applied to other similar or copied products.
3D Objects and Disparities of Lang-Stereotest® II
- ELEPHANT 600’’
- TRUCK 400’’
- MOON 200’’
- STAR 200’’ (2D, always visible)
- Reading distance: 30-40 cm (10-15 Inches)
- REF 102, CE Medical Device Class I, compliant with EU RL 93/42/EEC
- Format: 145 x 95 mm | Thickness 1,5 mm
- (5,71 x 3,75 Inches | 0,08 Inches)
- Weight without cover: 20 g
- Comes with red hard cover
- Operating instructions are in the envelope
No longer manufactured, but still available until further notice. The revised test successor will appear in April 2023 under the name Lang-Stereotest® II-R.
Manufactured in Switzerland, developed by Lang-Stereotest AG. All rights reserved.