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Hess screen test for ocular deviations

Simplified free Hess screen test for ocular deviations!

Try this and check your eyes!

It is a free Lancaster test, it is actually a simplified Hess screen. It really works on your PC, you could also use a video projector to achieve better results. It is an ideal device for measurement and documentation of all comitant and incomitant deviations in 9 cardinal gaze positions i.e. an standard deviometry chart could be derived easily. It is useful in evaluating patients with paretic or paralytic strabismus who have normal retinal correspondence.


1. Download and install the program. Simply follow the instructions.

2. First of all you need two optical filters, a pure Red and a pure Green filter. Check the purity of the filters by placing them over each other, you should see nothing with the combination resultant black filter.

3. Set your PC security setting allowing the Java scripts to run.

4. You should be familiar with the basics of strabismus and retinal correspondence and dissimilar target tests.

5. Wear red-green goggles and click the link below to lunch the program. place circles over each other using the mouse and write down the result, click anywhere to continue to the next gaze position.

6. Reverse the red and green filters and repeat the test.

7. Close the test just touching the mouse in the first page left and down. Do not click!

Download now!

Important terms of use: Before utilizing any content on this page, in any manner, you agree that you have read & understood the following.

This software is developed by Dr. Alireza Peyman. The material  is intended only for the educational and personal use of health care students and professionals. It is not intended for persons who have not received appropriate medical training, and should not be used for making clinical decisions pertaining to patient diagnosis, care, or management. No warranties, implicit or otherwise, are being made as to the accuracy and completeness of the material.

The software at this web site may be freely downloaded and used for non-commercial purposes. Due acknowledgement is required if results using the software are published in any form. Any commercial use or re-distribution requires prior written consent from Dr. Alireza Peyman.

Please contact me if you encounter any problem or there was any inconvenience using this test