PC Hess Screen

 Ocular motility testing on your PC …


Establishing the cause of binocular vision problems is one of the most challenging aspects of clinical practice. The PC Hess Screen provides the clinician with a powerful new PC-based tool for assessing such patients, without having to invest in bulky and expensive equipment.


  • Rapid and accurate assessment of the size and direction of phoria / tropia in up to 25 directions of gaze
  • Results plotted in conventional Hess screen format allowing the clinician to establish whether a deviation is concomitant or incomitant and which muscle is affected
  • A variety of analytical tools to help the clinician form a diagnosis
  • Built in database allows results to be archived for future reference
  • Results can be printed or pasted into referral letters and reports
  • Runs on a standard PC
  • Voice instructions.

£250.00 £300.00 (incl.VAT) Add to cart

A more detailed look at the features …


The PC Hess Screen is a computer program which is designed to run on any computer operating under Windows, with a 19’’ (or larger) monitor.When the program is run for the first time, the user is required to calibrate the size of the screen (by measuring the dimensions of a box displayed on the screen) and to enter the preferred viewing distance (usually 25-50 cm).The patient wears red and green goggles and is positioned in front of the computer screen at the appropriate distance.  The room lights are extinguished and a red and a blue circle are displayed on the screen (the right eye sees the red circle and the left the blue). Initially the red circle is placed in the top left of the screen and the patient is instructed to move the blue circle using the mouse until it appears to be centred on the red circle. HessTest
HesStimCircle As the eyes are dissociated, any deviation in this direction of gaze will result in a misalignment of the circles. This is repeated for either 9 or 25 directions of gaze (depending on the option selected). The colour of the circles is then reversed and measurements repeated with the left eye fixating. The nine point test takes approximately 4 minutes to complete.Results are then displayed in the conventional format on the screen. A number of analytical tools can then be applied to the data to help the clinician establish a diagnosis. For example, the program will automatically calculate the relative areas of the plots for the left and right eyes, helping the clinician to determine which eye has a palsied muscle and providing an index for monitoring the progression of an incomitant deviation.
Multiple plots can be superimposed to assess longitudinal changes and the exact amplitude of any deviation can be displayed at any point on the chart. HessScreenMultiple
 HessDataBase  The charts can be printed or exported to other Windows programs for inclusion in a referral report or for further analysis. The program also incorporates a database to allow records to be stored and retrieved.