Stereo Tower Vision Test                                                                        View Shopping Cart

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Without the use of any instruments, viewers, filters or glasses, The Stereo Tower offers a comprehensive and thorough vision testing system for evaluating binocular vision, stereopsis and depth perception. The Stereo Tower® uses a quick, easy and effective format for testing and screening for amblyopia, strabismus, suppression, and a wide range of other binocular vision and neurological disorders.

The testing system utilizes a combination of both random dot and line stereogram technology. The Stereo Tower® presents a superb collection and extensive series of stereo targets ideal in helping to assess various degrees of binocular function. Random Dot Stereograms are the proven fool-proof testing tools for determining basic binocular status, as well as for evaluating gross and medium stereopsis capabilities for a given patient. Line stereograms offer advantages in testing for quantifying fines levels of stereopsis.

Patients simply view the test plates directly with nothing in front of their eyes (except their own eyeglasses when needed). The ability to perceive these stereo 3-D images without wearing any ŗ-D glasses" is accomplished by a special printing process. A special prismatic effect is created whereby two different sets of images are separated, so that one set is presented to and perceived only by the left eye and the other only by the right eye. This allows the two sets of images to be fused binocularly resulting in stereo depth perceptions.

Correct viewing of the test requires the plates to be presented directly and symmetrically in front of the patient eyes at the proper distance. The test plate can be held wither by the patient or the examiner, but care must be taken to hold the test plate still and not tilt it. Restricting patient head movements will eliminate any monocular cues. Assymetrical viewing of the test plate may cause the images to appear in reverse depths.

The series of tests are presented on each of the four side panels of the Stereo Tower®. The tope nameplate containing one number from 1-4 along each of its edges serves to identify the test below it.

Beneath #1 is the Random Dot Butterfly.

The Random Dot Butterfly serves as an excellent tool for evaluating medium and gross stereopsis. If and only if, both eyes are open and working properly together, a butterfly will emerge in beautiful life-like depth and appear to float in space off the background. A simple verbal identification by the patient as to the presence of the butterfly will instantly provide the examiner with a wealth of information about the patient's binocular visual status. The L which is seen by the left eye and the R which is seen by the right eye serve as suppression checks and may indicate which eye is responsible for poor visual function. The Random Dot Butterfly is designed to be viewed at a distance of 10" – 12".

Random Dot Butterfly – Disparities for 12" viewing distance in seconds of arc:

Top of Top Wing – 2350 seconds

Tip of Bottom Wing – 1350 seconds

Body/Antenna – 820 seconds

Beneath #2 are the Stereo Circles and Animals.

The Stereo Circles and Animals are designed to test for finer levels of stereopsis. The patient should identify the circles and animals which appear elevated above the background. The Stereo Circles and Animals should be viewed at 12" – 16".

Stereo Circles and Animals – Disparities for 13.3" viewing distance in seconds of arc:

Bottom – 800 seconds 6. Left – 80 seconds

Left – 400 seconds 7. Right – 60 seconds

Bottom – 200 seconds 8. Left – 50 seconds

Top 140 seconds 9. Right – 40 seconds

5. Top – 100 seconds

Row A Cat – 400 Sec., Row B Rabbit – 200 Sec., Row C Monkey – 100 Sec.

Beneath #3 is the Random Dot Figures

The Random Dot Figures Test serves as an excellent tool for evaluating medium and gross stereopsis. If and only if both eyes are open and working properly together, figures normally hidden will appear to rise and float in space off the background. A simple identification of each figure, either a square, the letter E or a circle, will instantly provide the examiner with a wealth of information about the patient's binocular visual status. The L which is seen by the left eye and the R which is seen by the right eye serve as suppression checks and may indicate which eye is responsible for poor visual function. The middle right is a blank. It contains no figure and serves as a control. The Random Dot Figures test is designed to be viewed at a distance of 12"-16".

Random Dot Figures – Disparities for 15.7" viewing distance in seconds of arc:

Upper Left - Square - 170 seconds

Upper Right - Letter E - 127 seconds

Middle Left - Circle - 85 seconds

Middle Right - Blank

Lower Left - Square - 535 seconds

Lower Right - Circle - 410 seconds

For non-verbal patients, the figures perceived can be matched against the corresponding simulated 3-D perspective drawing of each of the Random Dot Figures presented below.

Beneath # 4 is the Stereo Numbers.

The Stereo Numbers are designed to test for finer levels of stereopsis. The patient should identify the numbers in each row which appear elevated above the background. Below the numbers is an additional stereo target and suppression check. The Stereo Numbers are designed to be viewed at a distance of 12" – 16".

Stereo Numbers -  Disparities for 15.7" viewing distance in seconds of arc.

Row A –   4  -  526 seconds

Row B –   2  -  227 seconds

Row C –   5  -  128 seconds

Row D –   3  -   66 seconds

Row E –   4  -   41 seconds

Row F –   2  -   28 seconds

If the tests are properly administered at the correct viewing distance then accurate and reliable stereopsis measures can be obtained.

Clean and remove fingerprints with a soft damp cloth

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