Color Vision Testing: New Methodologies

Dr. Bernard Blais was kind enough to share with us a recent set of slides from a presentation he delivered to a group of occupational health professionals. Such fundemantal concepts and technologies are at the core of every eyecare professional's training. But new exciting technologies like pachymeters, the latest hand-held tonometers, digital fundus imaging or electronic medical records can sometimes overshadow the basic essentials like color vision testing. How old and tattered are your Ishihara plates? -Ed.

Eye and vision issues are not taught thoroughly enough in general medicine, nursing, or PA training. The goal of this presentation is to provide a refresher on the importance of color vision testing throughout a patient's lifetime. This update should provide essentials required for medical personnel to adequately diagnose hereditary color vision issues and evaluate the aging patient population and treat appropriately. Emphasis is on the use of the examination for the clinical condition. New color vision testing modalities are also presented. How to handle the patient who has just received refractive surgery, or an intraocular lens will be discussed. Current color vision tests are reviewed to assist with screening and ultimate diagnostic evaluation of the patient.

The HRR (Hardy Rand and Rittler) Pseudoisochromatic Plate Test 4th Edition supports very efficient color deficiency screening. The first four plates (demo series) are used to show the patient how the test works. The fourth plate in this demonstration series has no figure and serves to alleviate anxiety if the patient does not see any figures in the real plates. The next six plates (screening series) present the most difficult yellow, blue, red, and green colors. Success with these plates defines the subject as having ‘normal color vision’ and completes the test for that person. The subsequent 14 plates (diagnostic series) cover all four colors and provides diagnostic as to the extent (mild, medium or strong) and type of defect (Protan, Deutan, Tritan). More than six different clinical trials (to date) has attested to the effectiveness of the HRR 4 Edition. The HRR test uses simple figures which can be located in any quadrant on each plate. This combination is virtually impossible to memorize, unlike Ishihara type numbers based tests. A wide range of options are available including laminated, combination with Amsler Grid, and instructions in multiple languages.

Below are just a few of the new systems mentioned in the above presentation. In many ways, it's difficult to replace the standard time-tested methods like Ishihara plates, but some of the newer methods are more interactive and can detect more subtile aquired color vision defects like one would expect in cataract patients. Clinical color-vision tests that use pseudoisochromatic vanishing designs on neutral gray backgrounds such as the Hardy-Rand-Rittler (HRR) pseudoisochromatic plates and the Neitz Test of Color Vision (NTCV) are becoming a standard.