CenterVue’s Compass points perimetry in a new direction.
The methods to perform a visual field test and engage the patient have changed little, until now with the introduction of the Compass Fundus Automated Perimeter (FAP) from CenterVue, Inc. The perimeter has been a staple of diagnostic testing, used in the evaluation of a host of ocular conditions, including glaucoma. The automated static perimeter was introduced in the late 1970s with the Octopus perimeter from Interzeag, Inc., which was soon followed by the Humphrey Field Analyzer (HFA) from Carl Zeiss Meditec. These perimeters were a major advance over manual Goldmann perimetry, primarily by reducing the need for a skilled technician to administer the test. Since the introduction of the automated perimeter almost 40 years ago, little has
|The Compass provides both standard 24-2 visual field results and true color confocal images of the retina.|
changed in regards to the hardware, though significant changes have taken place in regards to the software.
Software improvements include new operating systems such as in the HFA with the Swedish Interactive Testing Algorithm and analysis package (Guided Progression Analysis). Now, the Compass FAP from CenterVue brings several major improvements.
The Compass FAP is a combined confocal imaging system and real time tracking perimeter. At the start of testing, an infrared 600 picture is taken that is used as the “baseline” for real-time tracking and for the refraction compensation, eliminating the need for trial lenses.
In essence, the target is focused onto the retina. Using the infrared image of the back of the eye, a spot is placed over the optic nerve which represents the location of the blind spot. A 10-2 or 24-2 test pattern is then laid out onto the back of the eye, using the position of the optic nerve as the point of reference. A Zest algorithm is used as the points are projected onto the back of the eye, with the perimeter’s background and luminance similar to the HFA perimeter. A 25Hz retinal tracker is used to make sure the target is placed in the correct location of the test pattern, even when eye movement occurs.
RETINAL TRACKING RESULTS
Still, a patient who is clicking randomly (false positives) or is not paying attention (false negatives) will contaminate the results. At the completion of the test, the results are provided using a normative database. The printout includes a gray scale, total deviation and pattern deviation plots along with measurements of global metrics (mean deviation, pattern standard deviation). A confocal color retinal photograph is taken after the field is completed with the printout showing a close-up view of the optic nerve along with a 600 retinal image. The red-free image is shown with the field results placed over it. This allows a qualitative structure-function type assessment. There is also retinal tracking performance results that show the extent of fixation during the test and the resultant percentage of stimulus presentations within 0.5Â° and 1.0Â° of the projected retinal location.
In summary, Compass is a combination confocal imaging system and perimeter which employs real-time tracking to ensure a reliable visual field test and a 60Â° confocal image for retinal imaging through small pupils and media capacities.
Murray Fingeret, OD, Department of Veterans Affairs, is on the Optometric Office Editorial Advisory Board.
WHERE TO FIND IT:
408.988.8404 | centervue.com