Normal macular thickness measurements in healthy eyes using Stratus optical coherence tomography

Abstract

Objective: To report normal macular thickness measurements in healthy eyes using the latest commercially available optical coherence tomography (OCT) mapping software, version 3.0, from the Stratus OCT (OCT3).

Methods: Thirty-seven eyes from 37 healthy subjects underwent a complete ophthalmologic examination, including OCT. Six radial scans, 6 mm in length and centered on the fovea, were obtained using the OCT3. Retinal thickness was automatically calculated by OCT mapping software. Measurements were displayed as the mean and standard deviation for each of the 9 regions defined in the Early Treatment Diabetic Retinopathy Study.

Results: Foveal thickness (mean thickness in the central 1000-microm diameter area) and central foveal thickness (mean thickness at the point of intersection of 6 radial scans) on the OCT3 were 212 +/- 20 and 182 +/- 23 microm, respectively. Macular thickness measurements were thinnest at the center of the fovea, thickest within 3-mm diameter of the center, and diminished toward the periphery of the macula. The temporal quadrant was thinner than the nasal quadrant. Central foveal thickness was also manually determined as 170 +/- 18 microm, approximately 12 microm less than the value automatically obtained from the OCT3 software. There was no correlation between age and foveal thickness (P = .80).

Conclusions: Mean foveal thickness measurements were 38 to 62 microm thicker than previously reported values, while mean central foveal thickness measurements were 20 to 49 microm thicker than previously published values. This discrepancy should be considered when interpreting OCT scans.

Figure 1

Foveal thickness (A) and central foveal thickness (B). In A, foveal thickness is defined as the mean thickness within the central 1000-μm diameter area (the central blue circle on the Early Treatment Diabetic Retinopathy Study map). In B, central foveal thickness is defined as the mean thickness measured at the point of intersection of the 6 radial scans on optical coherence tomography. The mean foveal thickness is approximately 30 μm greater than the mean central foveal thickness.

Figure 2

Macular thickness measurements for a healthy eye population in this study, displayed as the mean and standard deviation in 9 regions, as defined in the Early Treatment Diabetic Retinopathy Study (A) and a false-color map for a prototypical healthy eye (B). I indicates inferior; N, nasal; S, superior; and T, temporal.

Figure 3

Regression plot of foveal thickness vs age. There is no relationship between foveal thickness and age (P = .80).

Figure 4

The optical coherence tomographic (OCT) image (A), the fundus image (B), and the false-color map and numeric printout (C) for the right eye of a healthy patient who did not have well-aligned scans. In C, the central blue area corresponding to the fovea is off center superiorly. The OCT software determined the center (mean ± SD central foveal thickness) to be 207 ± 18 μm. Misaligned scans may give falsely elevated values. I indicates inferior; N, nasal; S, superior; and T, temporal.