Clinical value, normative retinal sensitivity values, and intrasession repeatability using a combined spectral domain optical coherence tomography/scanning laser ophthalmoscope microperimeter

Abstract

Purpose: To establish normative values for macular light sensitivity and to determine the intrasession fluctuation of perimetric responses using the OPKO/OTI microperimeter.

Methods: A total of 32 visually normal subjects participated in the study. A standardized grid pattern was used for testing, which consisted of 28 points arranged concentrically in three circles that occupied an area of 11° (in diameter) within the central macula. Each subject participated in at least two tests. Parameters evaluated included: overall mean macular sensitivity for test 1 and 2, overall difference in mean macular sensitivity between tests, and the mean sensitivity for each circle. The relationship between sensitivity and age was also examined.

Results: The overall median sensitivity for test 1 was 16.8 decibels (dB) and for test 2 was 16.9 dB. The median sensitivities for test 1 and test 2 were not significantly different (P = 0.72). The mean intrasession sensitivity difference was 0.13 dB. The variability of the sensitivity difference between tests decreased as mean sensitivity increased. The sensitivity values averaged across the two tests for inner, middle, and outer circles ranged from 14.3 to 18.8 dB (median value of 16.9 dB), 13.8-18.3 dB (median value of 17.2 dB), and 11.3-18.3 dB (median value of 16.6 dB), respectively. Linear regression analysis showed a 0.5 dB sensitivity loss for each decade of life.

Conclusion: We documented a narrow range of intrasession fluctuation using the OPKO/OTI microperimeter. The establishment of normative sensitivity values will facilitate monitoring the loss of macular visual function in patients with retinal disease.

Figure 1

Polar 3 test grid superimposed on the SLO infrared image of a normal subject. Each value represents the light sensitivity for the corresponding retinal area.

Figure 2

Sensitivity difference between tests 1 and 2 compared with the mean sensitivity for the two tests. The horizontal dashed line represents the overall mean sensitivity difference between the two tests, whereas the gray lines represent the 95% limits of repeatability.

Figure 3

Sensitivity difference between the two tests with the largest difference in sensitivity compared with the mean sensitivity for these two tests. The horizontal dashed line represents the overall mean sensitivity difference between the two tests, whereas the gray lines represent the 95% limits of repeatability.

Figure 4

Mean sensitivity for tests 1 and 2 as a function of age. The solid line is a linear regression line fit to the data.

Figure 5

Polar 3 test grid superimposed on the SLO infrared image of a patient with Stargardt disease. Each value represents sensitivity for the corresponding retinal area.