Comparison of imo and Humphrey field analyzer perimeters in glaucomatous eyes

Abstract

Aim: To compare the imo perimeter, a new portable head-mounted perimeter unit that enables both eyes to be examined quickly and simultaneously, with the Humphrey field analyzer (HFA) perimeter to investigate correlations and their diagnostic ability in glaucomatous eyes.

Methods: The performance of the equipment in 128 glaucomatous eyes and 40 normal eyes were tested. We investigated the correlations of mean deviation, pattern standard deviation, visual field index, and the sensitivity.

Results: Measurements of mean deviation (r=0.886, P<0.001), pattern standard deviation (r=0.814, P<0.001), and visual field index (r=0.871, P<0.001) in both perimeters were strongly and positively correlated. The sensitivities in the imo perimeter were 80.5% for mean deviation, 81.2% for pattern standard deviation, and 80.5% in visual field index; those in the HFA were 63.3% for mean deviation, 74.5% for pattern standard deviation, and 80.5% for visual field index. Both perimeters demonstrated high diagnostic ability.

Conclusion: The parameters by the imo and HFA in glaucomatous eyes show strong positive correlations with favorable sensitivity, specificity, and diagnostic ability. However, the difference between imo and HFA results increases with the increase in visual field disturbance.

Keywords: diagnostic validation; imo perimeter; visual field diagnosis.

International Journal of Ophthalmology Press.

Figures

Figure 1. Head-mounted imo perimeter weighing 1.8 kg

It can be used in a well-lit room, and it enables both eyes to be examined quickly and simultaneously.

Figure 2. Simultaneous monitoring of binocular fixation by imo perimeter, with automatic tracking correction (from side to side and up and down), and pupil diameter measurement.

Figure 3. The test target was presented randomly to either eye under a nonocclusion condition, and the patient was not aware of which eye was being tested.

Figure 4. In 128 glaucomatous eyes, the imo perimeter and the HFA perimeter's measurements of MD (r=0.886, P<0.001), PSD (r=0.814, P<0.001), and VFI (r=0.871, P<0.001) were strongly and positively correlated.

Figure 5. Displays of the visual field by the HFA and imo perimeters

In case 1 (mild glaucoma), there was no difference in the displays; in case 2, 3 and 4 (advanced glaucoma), however, the differences were obvious.

Figure 6. Bland-Altman analysis was used to compare MD, PSD, and VFI measurements by the HFA perimeter and the imo perimeter

For glaucoma eye a proportional error was observed. The results show the fan-shaped distribution, where the worse is the glaucoma (horizontal axis), the greater is the difference between imo and HFA results.

Figure 7. The diagnostic abilities of both the HFA and the imo perimeters were significant; AUC was 0.8 or greater in the MD, PSD, and VFI measurements, and the maximum value of the AUC was 0.911 for the MD measurement by the imo perimeter.