Purpose: To predict future glaucomatous sensitivity loss using a perimetric color saturation test (PCST) that measures the color saturation discrimination threshold for six hues (red, yellow, green, green-blue, blue, and purple) at 9 degrees in horizontal and 3 degrees in vertical extrafoveal points.
Methods: This new test was carried out on 31 patients (31 eyes) with early glaucoma or ocular hypertension. The sensitivity loss at the four points approximately 9.5 degrees apart from the fixation point was prospectively evaluated annually for 3 years using the Humphrey Field Analyzer (HFA) program central 30-2. The initial results of PCST and the total deviation (TD) in the follow-up HFA results were compared.
Results: Twenty-seven patients (27 eyes) were followed up for 3 years. The color saturation threshold for six hues was correlated with the TD of HFA results at 108 points in the 27 eyes. The TD was -4 dB or better at the baseline measurement in 91 out of the 108 points. The averaged TD in the second and the third year in the follow-up period decreased below -4 dB in 10 of these 91 points, which were categorized as progression points in relation to the 81 nonprogression points. In the initial PCST, only the saturation threshold for purple was higher in the progression points when compared with the nonprogression points (P=.0004, Mann-Whitney U-test).
Conclusion: Future sensitivity loss is most likely at the points where the threshold of color saturation discrimination is increased for purple in eyes with early glaucoma or ocular hypertension.