March 2009
Volume 50, Issue 3
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Retina  |   March 2009
Foveal Anatomic Associations with the Secondary Peak and the Slope of the Macular Pigment Spatial Profile
Author Affiliations
  • Mark L. Kirby
    From the Macular Pigment Research Group, Department of Chemical and Life Sciences, and the
  • Martin Galea
    Department of Ophthalmology, Waterford Regional Hospital, Waterford, Ireland.
  • Edward Loane
    From the Macular Pigment Research Group, Department of Chemical and Life Sciences, and the
  • Jim Stack
    Department of Physical and Quantitative Sciences, Waterford Institute of Technology, Waterford, Ireland; and the
  • Stephen Beatty
    From the Macular Pigment Research Group, Department of Chemical and Life Sciences, and the
    Department of Ophthalmology, Waterford Regional Hospital, Waterford, Ireland.
  • John M. Nolan
    From the Macular Pigment Research Group, Department of Chemical and Life Sciences, and the
Investigative Ophthalmology & Visual Science March 2009, Vol.50, 1383-1391. doi:10.1167/iovs.08-2494
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    • Get Citation

      Mark L. Kirby, Martin Galea, Edward Loane, Jim Stack, Stephen Beatty, John M. Nolan; Foveal Anatomic Associations with the Secondary Peak and the Slope of the Macular Pigment Spatial Profile. Invest. Ophthalmol. Vis. Sci. 2009;50(3):1383-1391. doi: 10.1167/iovs.08-2494.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

purpose. To investigate the reproducibility of the macular pigment (MP) spatial profile by using heterochromatic flicker photometry (HFP) and to relate the MP spatial profile to foveal architecture.

methods. Sixteen healthy subjects (nine had the typical exponential MP spatial profile [group 1]; seven had a secondary peak MP spatial profile [group 2]) were recruited. The MP spatial profile was measured on three separate occasions. Six radiance measurements were obtained at each locus (0.25°, 0.5°, 1°, and 1.75° eccentricity; reference point, 7°). Foveal architecture was assessed by optical coherence tomography (OCT).

results. Subjects who had the typical decline profile, had this profile after averaging repeated measures (group 1). Subjects who had a secondary peak, displayed the secondary peak after repeated measures were averaged (group 2). Mean SD foveal width in group 1 was significantly narrower than mean SD foveal width in group 2 (1306 ± 240 μm and 1915 ± 161 μm, respectively; P < 0.01). This difference remained after adjustment for sex (P < 0.001). Foveal width was significantly related to mean foveal MP, with adjustment for sex (r = 0.588, P = 0.021). Foveal profile slope was significantly related to MP spatial profile slope, after removal of an outlier (r = 0.591, P = 0.020).

conclusions. HFP reproducibly measures MP spatial profile. Secondary peaks seen in the MP spatial profile cannot be attributed to measurement error and are associated with wider foveas. The slope of an individual’s MP spatial profile is related to foveal slope, with a steeper MP distribution associated with a steeper foveal depression.

The macula is the central region of the retina and is responsible for sharpest visual acuity. At the center of the macula, the carotenoids lutein (L), zeaxanthin (Z), and meso-Z, are concentrated, where they are collectively referred to as macular pigment (MP). 1 Although L and Z are of dietary origin, meso-Z is not found in a typical Western diet, but its high concentrations at the macula are attributed to L isomerization at the macula. 2 3 However, the mechanism of isomerization has yet to be elucidated. 
There are several techniques used to measure the spatial profile of MP, and these include: fundus autofluorescence, fundus reflectance, Raman spectroscopy, and heterochromatic flicker photometry (HFP). In this study, we used a customized (c)HFP technique to measure MP. This method has been validated against the absorption spectrum of MP in vitro. 4 5  
MP has been shown to peak at the center of the fovea and to decline in an exponential fashion with increasing retinal eccentricity, for most individuals. 6 Using HFP, we assume MP to be absent at approximately 7° eccentricity from the foveal center. 7 However, significant deviations from this typical distribution have been reported in some subjects. 6 8 9 Previous investigations into the spatial profile of MP have shown a secondary peak that occurs between 0.5° and 1° retinal eccentricity in some subjects. Indeed, Berendschot et al. 9 demonstrated a distinct ring pattern (representative of a secondary peak) in approximately half of their 53 subjects, with several subjects displaying a secondary peak with an even greater MP optical density (MPOD) than the primary peak. The first objective of our study was to determine whether such deviations from the typical spatial profile of MP were real or were a result of measurement error, when using cHFP. 
Snodderly et al. 7 and Delori 8 initially hypothesized that foveal architecture may contribute to the variability seen in MP distribution. More recently, Nolan et al. 10 found that MP was positively and significantly associated with a distinct feature of foveal architecture—namely, foveal width. The second objective of our study was to investigate the relationship between foveal architecture with respect to the spatial profile of MP and to try to identify whether a feature of foveal architecture (e.g., foveal width, foveal thickness, and foveal pit profile slope) was associated with MPOD, or indeed, with a specific type of MP spatial profile (i.e., typical versus secondary peak MP spatial profile). 
Methods
Subjects
A nested sample of 16 healthy subjects were recruited for the study, which was performed in the Macular Pigment Research Group (MPRG) laboratory at the Waterford Institute of Technology. After a detailed explanation of all aspects of the study by the study investigator (MLK), informed written consent was obtained from each subject. All experimental procedures adhered to the tenets of the Declaration of Helsinki. The study protocol was approved by the local Research Ethics Committee at Waterford Institute of Technology. 
Subjects were identified for recruitment into this multivisit study based on their MP spatial profile data, obtained during previous studies at the MPRG. Nine subjects who had a typical MP spatial profile were recruited from the MPRG database. A further seven subjects who had an atypical, or secondary peak, in their MP spatial profile were selected from the MPRG database. We use the term “typical” MP spatial profile to refer to the more commonly seen profile, previously referred to as an “exponential-like” decline in MPOD. We use the term “atypical” MP spatial profile to denote those profiles that display secondary peaks. 
All subjects were trained on the use of the custom-designed measuring equipment (Macular Densitometer, developed by Billy Wooten, Brown University, Providence, RI) before the study. Therefore, subjects recruited for the study were not considered naïve with respect to the technique. The inclusion criteria were absence of ocular disease as assessed by nonmydriatic fundus photography and a refractive error between −6 and +6 D. Fundus imaging and refractive error data were collected at Waterford Regional Hospital by an experienced ophthalmologist (MG). 
Measurement of MPOD
MP was measured psychophysically by cHFP with the Macular Densitometer. For the purpose of this study, we assume that flicker perception is dominated by the edges of the disc-shaped stimuli used in the Macular Densitometer, 11 although other research has suggested that this may not be the case. 12 HFP takes advantage of the fact that MP absorbs short-wavelength (blue) light, with absorption occurring maximally at a wavelength of 458 nm. The subject is required to observe a flickering target, which is alternating in square-wave counterphase between a blue light (460 nm; maximally absorbed by MP) and a green light (550 nm; not absorbed by MP). To generate a spatial profile of MP, we performed measurements at the following degrees of eccentricity—0.25°, 0.5°, 1°, 1.75° and a reference point at 7°—obtained using the following sized target diameters; 30 minute, 1°, 2°, 3.5°, and a reference 2°, respectively. Stimulus 5, our reference point, is a 2° disc located 7.5° from a fixation point. The subject is required to adjust the luminance of the blue light to achieve null flicker—in other words, until the target appears steady. At this point, the blue and green lights are perceived as isoluminant. The ratio of the amount of blue light required to achieve null flicker at the fovea is compared to that required in the parafovea (where MP is presumed to be 0), the logarithm of which is recorded as MPOD. 
Customized HFP describes a refined HFP technique. First, the luminance of the green and blue lights is adjusted in a yoked manner (i.e., as the luminance of the green light increases, the luminance of the blue light decreases, and vice versa). Second, the flicker frequency is calculated for each subject, to reduce variance in the luminance readings. The ability to adjust the flicker frequency is a major advantage of the Macular Densitometer. 13 Critical flicker frequency readings are taken before the test, from which the optimal flicker frequency for each subject is calculated. 13 Optimization of the flicker frequency for each subject corrects for variation in an individual’s flicker sensitivity, owing to factors such as age and disease. 14  
If necessary, further optimization of the flicker frequency may be achieved during the test by simply prompting the subject to indicate the width of the null zone to the examiner, while adjusting the radiance dial. If the null zone is excessively large for the subject to estimate its center, the flicker frequency is decreased by 1 Hz in a step-wise fashion. Conversely, if the null zone is too narrow (i.e., the target appears to flicker continuously), the flicker frequency is increased by 1 Hz in a step-wise fashion, until the subject can appreciate a null zone. Radiance values differing from each other by more than 10% indicate an unacceptably wide null zone. The benefits of individual customization of the HFP method are further discussed in recent publications by Nolan et al. 10 and Loane et al. 13  
At each study visit, six relative radiance measurements were taken at each locus (n = 18 radiance measurements). In the majority (n = 12) of cases there was only a 1-day rest period between sessions. In some cases (n = 4) the rest period was 2 to 3 days. A rest was essential to ensure that dietary changes did not affect the MP spatial profile during the study period. Average MPOD across the fovea was also calculated and is defined as follows; Mean MPOD refers to the average amount of MP across the fovea, calculated as the average for each visit 1, 2, and 3 at each eccentricity (0.25°, 0.5°, 1°, and 1.75°). 
Optical Coherence Tomography
Optical coherence tomography (OCT) is a noninvasive, optical technique that is used to measure specific aspects of retinal architecture, (e.g., foveal width, foveal thickness). A projected beam of light is split in two using a beam splitter (fiber optic coupler). One beam is projected onto the eye, while the other is projected onto a stationary reference mirror. Back-scattered light from each beam is combined by the coupler, creating an optical interference signal that is converted from light to an electrical current by a photodetector and processed electronically. The interference spectrum is measured by a spectrometer, and Fourier transformed to generate A-scans. The instrument used in this study (3-D OCT 1000; Topcon Corp., Tokyo, Japan) uses spectral/Fourier domain detection with a speed of 20,000 A-scans per second, with a resolving power of 20 μm horizontally and 5 μm in depth. From these A-scans, a 3-D image of the central retina (retinal B-scan), is generated. In this study, high-resolution OCT images were obtained. 
All OCT scans were taken in a dark room by the same operator (MG). Pupillary dilation was not performed, as it has been shown that reliable OCT scans are not dependent on pupil dilation in healthy subjects. 10 The disc and macula scanning protocol provided by the OCT software was chosen for all scans. To encourage stable fixation, each scan was taken using the smallest internal fixation target in the central fovea. Focus was adjusted using the built-in focusing split lines. Moreover, the unit was adjusted to the subject’s eye depth, using the automatic z-offset function (AZ function). 
We used OCT to obtain images of each subject’s fovea and, in particular, to acquire measurements of each individual’s foveal width, foveal thickness, and foveal pit profile slope (FPPS). Thus, a 3-D retinal map of the central 6-mm2 area of the macula, centered on the subject’s fixation point, was obtained for the right eye of each subject. Foveal width was defined as the straight line distance from nerve fiber layer to nerve fiber layer, on either side of the foveal depression, whereas foveal thickness was defined as the distance between the retinal pigment epithelium (RPE) and the vitreoretinal interface. Foveal width was measured subjectively, using the built-in caliper function, and foveal thickness was calculated automatically by the review software. This OCT review software was provided by Topcon Ltd., allowing for more detailed analysis of OCT images. 
FPPS and Macular Pigment Profile Slope (MPPS)
The calculation of FPPS between 0.25° and 1° retinal eccentricity is shown in Figure 1 . Given our strict inclusion criteria for refractive error (−6 to +6 D), we assume that, on average, 1° retinal eccentricity is 300 μm; however, a more precise conversion would have required axial length measurements on each study eye. The values, in micrometers, corresponding to these retinal eccentricities, are used as x-values. The foveal thickness values (caliper function-OCT) are taken as the perpendicular distance between the horizontal line drawn from the foveal center to the vitreoretinal interface. The thickness (micrometers) at both 0.25° and 1° retinal eccentricity are used as y-values. The slope equation m = (y2 − y1)/(x2 − x1) is then applied. Thus, the slope of the foveal pit profile curve is approximated with the slope of the line segment joining (x1, y1) and (x2, y2). 
The calculation of the MPPS between 0.25° and 1° retinal eccentricity is done in the same fashion, as shown in Figure 2 . The values, in micrometers, corresponding to these retinal eccentricities, are used as x-values. The average MPOD at both 0.25° and 1° retinal eccentricity are used as y-values. The slope equation m = (y2 − y1)/(x2 − x1) is applied, as before. 
In effect, piece-wise linear approximations to each subject’s foveal pit profile and macular pigment profile curves are used to investigate the relationships between the MP spatial profile and foveal pit profile. 
Statistical Analysis
A commercial statistical analysis software package (SPSS, ver. 14; SPSS, Chicago, IL) was used. Another commercial graphic software package (SigmaPlot, ver. 8.0; Systat, San Jose, CA) was used for graphic analysis. Independent samples t-test or paired t-test, as appropriate, were used to investigate the differences between various groups, depending on the analysis in question. The association between the MP spatial profile types and foveal widths, controlling for sex, was investigated using a general linear model approach. We used the linear model; y = b0 + b1 × 1 + b2 × 2; where y is foveal width, x1 is indicator for group (typical/secondary peak) and x2 is indicator for sex. This model tests whether group membership is related to foveal width, when adjusted for sex and vice versa, and whether sex is related to foveal width, when adjusted for group membership. Piece-wise linear approximations to each subject’s foveal pit profile, at eccentricities of 0.25°, 1°, and 1.75°, provided FPPS data, which were then used to investigate the relationships between subject’s MPOD and foveal pit profile. Pair-wise correlations between MPPS and FPPS were calculated, and differences in mean FPPS between group 1 (typical MP spatial profile subjects) and group 2 (secondary peak profile subjects) were assessed using the independent-samples t-test. 
Results
Macular Pigment Optical Density
Radiance values obtained for each subject, at each degree of retinal eccentricity, are presented in Table 1 . MPOD obtained for each subject, at each degree of retinal eccentricity, is presented in Table 2
Subjects 1 to 9 had a typical decline in their MP spatial profiles (Fig. 3A , group 1), and subjects 10 to 16 had a secondary peak in their MP spatial profile (Fig. 3B , group 2). Mean ± SD MPOD at 0.25° for group 1 was 0.58 ± 0.21, whereas mean ± SD. MPOD at 0.25° for group 2 was 0.38 ± 0.19 (P = 0.086). Mean ± SD MPOD at 0.5° for group 1 was 0.47 ± 0.21, whereas mean ± SD. MPOD at 0.5° for group 2 was 0.36 ± 0.21 (P = 0.304). 
Reproducibility of the Macular Pigment Spatial Profile
After averaging all 18 radiance values (six measurements repeated on three separate occasions), subjects who initially had the typical decline profile, still had the typical decline profile after averaging repeated measures (Fig. 3A) . Likewise, most subjects who had a secondary peak in their MP spatial profile, still had a secondary peak after averaging repeated measures (Fig. 3B) . The intraclass correlations (ICCs) were very high, in general, consistently in the range 0.93 to 0.96 at 0.25°, 0.5°, and 1° of retinal eccentricity. ICCs of this magnitude were found whether we combined data from all three visits (n = 18 repeated measures per subject), or when we analyzed within-visit data separately (n = 6 repeated measures per subject at each study visit). 
Included radiance values used to calculate MPOD varied by <10% for all subjects (Table 1) . Three radiance values (two for subject 11 at 0.25°, and one for subject 16 at 1.75°) were identified as obvious outliers, as these radiances were 3 SD or more above the mean and were therefore excluded from the study analysis. Also, three radiances were not recorded due to the subjects’ fatigue (subject 6 at 1.75°, subject 14, at 0.25°, and subject 15 at 0.25°). 
OCT: Test-Retest Reproducibility
Between session variability of OCT measurements was assessed in all subjects to assess the reproducibility of our foveal width measurements. Two scans were taken for each subject to examine scan reproducibility with respect to foveal width and foveal thickness (Tables 3 4 , respectively). As the data in Table 3show, strong agreement was found between foveal width readings recorded on the two separate occasions with a mean ± SD (%) difference (scan 1 – scan 2) of 1.87 ± 49 μm (0.12%) for foveal width measurements (P = 0.934, paired t-test). Intraclass correlation (ICC) is used to assess the reliability of foveal width measurements also (ICC, 0.975; 95% CI, 0.93–0.99). Table 4shows strong agreement between foveal thickness readings recorded on the two separate occasions with a mean ± SD (%) difference (scan 1 − scan 2) of 5 ± 6 μm (1.5%) for foveal width measurements (P = 0.218, paired t-test). 
Foveal Width with Respect to MP Spatial Profile
Mean ± SD foveal width for the entire study group was 1572 ± 381 μm. Mean ± SD foveal width for group 1 was 1306 ± 246 μm, whereas mean ± SD foveal width for group 2 was 1915 ± 161 μm, with a statistically significant difference between these groups (P < 0.01). Figure 4shows box plots of foveal width in both groups. As the plots illustrate, there was a significant difference in foveal width between the two groups, which remained even after adjustment for sex, by using a general linear model (P < 0.001). The relationship between foveal width and mean MPOD (the average MPOD of all four eccentricities measured, using the average of all three visits) across the fovea was positive but not statistically significant (r = 0.104, P > 0.05); however, after adjustment for sex, this correlation was positive and statistically significant (r = 0.588, P = 0.021). 
Central Foveal Thickness (CFT) with Respect to MP Spatial Profile
Mean CFT (±SD) for the entire study group was 194 ± 5 μm. CFT for group 1 was 203 ± 21 μm, whereas mean CFT for group 2 was 187 ± 40 μm, with no statistically significant difference between the groups (P = 0.376). There was no statistically significant relationship between CFT and mean MPOD at any degree of retinal eccentricity (P > 0.05, for all). 
FPPS with Respect to MP Spatial Profile
FPPS was found to be positively, but not significantly, correlated with the MPPS for all subjects (r = 0.303, P = 0.254). However, when data from one subject (identified as an outlier; i.e., >3 SD above the mean) were removed from the dataset, this relationship became both positive and significant (r = 0.591, P = 0.02; Fig. 5A ). 
The correlation between FPPS and MPPS was also investigated within the two MP spatial profile type groups. It was found to be positive and significant for group 2 (r = 0.821, P = 0.023; Fig. 5B ). Although the same relationship was also positive in group 1, it did not reach statistical significance (r = 0.124, P = 0.751). Group 1 contained the aforementioned outlier; after the outlier was removed, the correlation in group 1 was r = 0.137, P > 0.05). 
Discussion
This study was designed to investigate the reproducibility and test-retest variability of the MP spatial profile generated by cHFP and to relate the spatial profile of MP to foveal architecture, assessed by OCT. A detailed examination of MPOD across the fovea included six radiance measurements taken at four foveal loci on three separate study visits (n = 18 measurements in total). OCT measurements were assessed on two separate study visits. 
HFP has been validated against the absorption spectrum of MP in vitro. 4 5 For this reason, HFP was chosen to investigate the reproducibility of the spatial profile of MP. To our knowledge, this is the first and most detailed investigation into the reproducibility and test-retest variability of the spatial profile of MP, measured by HFP. Previous investigations have shown that secondary peaks occur at approximately 1° from the foveal center. 8 9 It has been suggested, however, that these secondary peaks may arise due to an artifact of the method of MP measurement used in those studies. 15 16 Inaccurate results in the measurement of MPOD with HFP may also occur because of subject fatigue. We took multiple radiance measurements, divided over multiple study visits, to eliminate this as a source of error. In addition, a customized version of the HFP technique was used in which the subject’s flicker rate is individually optimized to minimize the variance between subsequent radiance readings, and hence reduce measurement error. 
We have shown that the MP spatial profile is reproducible and robust to test-retest variability, in most cases (results in some subjects in group 2 were not as reproducible as those in subjects in group 1, with the secondary peak being less pronounced on one of the visits; Figs. 3A 3B ). Averaging the profiles from the three visits, however, showed that group 2 subjects consistently displayed an atypical MP spatial profile. Of interest, we found that MP at 0.25° was lower in the group with secondary peaks (group 2), when compared to those without secondary peaks (group 1). It is possible that the lack of MP at 0.25° in group 2, albeit not significantly less than group 1, may be due to the lack of a central peak in such subjects. It is possible that a lack of MP at the center in some individuals may be due to their inability to convert L to meso-Z in the retina. However, further study is necessary to venture such a provocative hypothesis. 
Other studies in which HFP was used to analyze MP spatial distribution have also reported secondary peak spatial profiles. 6 17 Consistent with this, investigations of the spatial profile of MP using fundus autofluorescence have reported “ring-like structures” or “bimodal distributions,” both representative of secondary peaks. 8 9 Also, and again consistent with suggestions by these investigators, our findings suggest that the spatial profile of MP is not always best described as a simple exponential decline with increasing retinal eccentricity. Our findings confirm that secondary peaks are real features of the MP spatial profile. Of importance, this relates to the way in which we categorize low, medium, and high MPOD levels, previously reported from a value at a single point (e.g., 0.5° eccentricity). Estimating overall MP levels in an individual with a secondary peak could, therefore, be better described by an “area under the curve” value. Such a value was calculated and described by Nolan et al. 10 as “integrated MP,” and they found it to be positively and significantly related to foveal width. 
Foveal architecture was assessed with respect to the spatial distribution of MP, as well as the average MPOD across the fovea. Specifically, foveal width, foveal thickness, and FPPS were assessed by using OCT. Consistent with a recent study by Nolan et al., 10 we found the relationship between foveal width and mean MPOD across the fovea to be positive and significant after controlling for sex. We concede that our finding is based on a smaller sample. However, it has been suggested that the greater levels of MPOD seen in subjects with wider foveas are attributable to the fact that the cone axons (fibers of Henle) are longer in wider foveas, and may therefore accumulate more MP; our findings are in agreement with this hypothesis. 10  
Foveal width was also shown to be significantly associated with MP spatial profile type, with those who had a secondary peak in their MP spatial profile having significantly wider foveas. It should be noted that group 2 in this study was predominantly female, and indeed, females have been shown to have wider foveas. 8 However, in the general linear model relating foveal width to sex and group 1/group 2 membership, it was the group membership variable which emerged significant. In other words, although females tend to have wider foveas and females also more frequently exhibit a secondary peak MP spatial profile, the association is between foveal width and MP spatial profile, not foveal width and sex. This is borne out by the fact that, in our study, males with a secondary peak in their MP spatial profile also tend to have wider foveas. We reiterate, however, that our sample size is small and verification of these findings in a larger study is warranted. 
In our study, foveal thickness was not found to be associated with mean MPOD. This finding is consistent with previous investigations in white subjects. 10 18 Of note, recent findings in a study by Liew et al., 19 which directly contradict our findings, may be explained by methodological alignment inconsistencies with respect to their OCT measurements. Further explanation of these alignment discrepancies are discussed in a recent publication by Nolan et al. 10  
Piece-wise linear approximations of subjects’ profile curves provided us with slope data (FPPS and MPPS) for investigating relationships between the shape of a subject’s foveal profile and the shape of the MP profile. We report a positive relationship between FPPS and MPPS, a relationship that becomes both positive and statistically significant for the entire study group when we exclude an obvious outlier from the analysis. This provocative finding suggests that the anatomic structure of a subject’s fovea plays an important role in the way MP is distributed within that fovea. Of the 10 distinct layers of the retina, MP is known to primarily accumulate in the inner plexiform layer and the cone receptor axons. 7 It is plausible that these layers are more compressed in a foveal depression with a steep slope, when compared to a shallow foveal depression (i.e., one with a gentle slope), resulting in a more rapid decline in MPOD from the foveal center. 
In conclusion, by incorporating multiple radiance measurements on separate occasions into the cHFP method, we can reproducibly measure the MP spatial profile. Our data strongly suggest that, to generalize all MP spatial profiles as a simple exponential decline with eccentricity, is inaccurate. With respect to MP spatial profile, secondary peaks are real features of the spatial profile of MP, existing between 0.5° and 1° retinal eccentricity, and are associated with wider foveas. We confirm previous findings that foveal architecture, in particular foveal width, is associated with MPOD across the fovea, after controlling for sex. Furthermore, we found that the slope of the foveal depression influences the MP spatial profile, with a steeper MP spatial profile being associated with a steeper foveal depression. Therefore, we suggest that further study using next-generation OCT focuses on the individual retinal layers, where MP is known to be concentrated (i.e., the fibers of Henle and the inner and outer plexiform layers). These investigations will allow us to further investigate the anatomic determinants of the spatial profile of MP. 
 
Figure 1.
 
The foveal pit, showing the FPPS calculation. The calculation of FPPS therefore, is as follows: m = (y2 − y1)/(x2 − x1); FPPS = (85 − 23)/(300 − 75) = 0.275.
Figure 1.
 
The foveal pit, showing the FPPS calculation. The calculation of FPPS therefore, is as follows: m = (y2 − y1)/(x2 − x1); FPPS = (85 − 23)/(300 − 75) = 0.275.
Figure 2.
 
A schematic of the MP spatial profile showing the calculation of the MP profile slope, between the eccentricities of 0.25° and 1° (i.e., 75 and 300 μm). The calculation of MP profile slope therefore, is as follows: m = (y2 − y1)/(x2 − x1); MP profile slope = (0.35 − 0.20)/(75 − 300) = −0.0007 μm−1.
Figure 2.
 
A schematic of the MP spatial profile showing the calculation of the MP profile slope, between the eccentricities of 0.25° and 1° (i.e., 75 and 300 μm). The calculation of MP profile slope therefore, is as follows: m = (y2 − y1)/(x2 − x1); MP profile slope = (0.35 − 0.20)/(75 − 300) = −0.0007 μm−1.
Table 1.
 
Radiance Values Obtained for Each Subject at Each Degree of Retinal Eccentricity
Table 1.
 
Radiance Values Obtained for Each Subject at Each Degree of Retinal Eccentricity
No. Ecc RV1 RV1 RV1 RV1 RV1 RV1 RV2 RV2 RV2 RV2 RV2 RV2 RV3 RV3 RV3 RV3 RV3 RV3 Mean SD % Diff
1 0.25° 1575 1643 1616 1504 1547 1452 1652 1652 1504 1723 1515 1607 1479 1677 1781 1744 1560 1725 1609 98.11 6.10
0.5° 1455 1415 1435 1463 1461 1430 1392 1483 1516 1616 1357 1369 1428 1405 1283 1409 1279 1356 1420 79.41 5.59
1310 1375 1358 1345 1299 1273 1391 1253 1292 1155 1263 1311 1099 1268 1341 1214 1284 1308 1286 73.54 5.72
1.75° 1151 958 1115 978 1083 1016 1029 1001 1006 953 944 945 904 970 1033 992 1020 997 1005 62.23 6.19
699 787 764 626 809 716 763 756 774 722 719 787 870 667 671 800 806 671 745 62.78 8.43
2 0.25° 1747 1700 1617 1629 1564 1562 1709 1676 1793 1611 1542 1549 1731 1611 1595 1580 1525 1502 1625 83.49 5.14
0.5° 1303 1407 1241 1338 1416 1246 1345 1321 1317 1357 1284 1340 1286 1353 1390 1438 1350 1242 1332 58.57 4.40
965 1032 896 1018 1068 1034 974 958 1115 906 1043 1065 934 1080 1011 919 1069 950 1002 66.14 6.60
1.75° 902 904 861 935 838 826 894 798 870 834 766 929 898 876 812 792 807 847 855 49.40 5.78
830 769 797 871 752 788 861 786 803 761 743 782 780 685 639 777 738 642 767 63.03 8.22
3 0.25° 2113 1948 1942 2080 2040 2003 1885 2053 1919 1902 1825 1908 1913 2018 1818 1914 1956 1965 1956 82.01 4.19
0.5° 1807 1761 1890 1817 1757 1882 1786 1673 1851 1776 1765 1827 1696 1762 1952 1761 1757 1699 1790 71.58 4.00
1515 1540 1417 1521 1440 1489 1507 1505 1497 1479 1523 1472 1527 1390 1620 1561 1512 1508 1501 51.93 3.46
1.75° 1092 1166 1145 1109 1070 966 1187 1183 1095 1176 1238 1224 1133 1111 1135 1262 1214 1133 1147 70.18 6.12
910 846 950 900 967 797 851 828 880 851 813 841 862 754 832 831 817 813 852 53.05 6.22
4 0.25° 1480 1542 1459 1477 1329 1370 1529 1450 1468 1484 1574 1435 1507 1554 1695 1578 1473 1492 1494 81.21 5.43
0.5° 1256 1266 1333 1393 1236 1330 1376 1272 1270 1294 1387 1362 1392 1386 1244 1363 1277 1353 1322 56.67 4.29
937 1033 1011 1015 1011 945 852 968 921 876 1031 901 939 989 908 851 879 959 946 60.38 6.38
1.75° 891 910 802 938 1017 866 935 941 800 868 863 804 743 818 882 818 798 818 862 68.53 7.95
817 809 746 788 810 880 816 736 784 749 729 754 759 841 797 702 658 897 782 59.84 7.65
5 0.25° 1423 1419 1428 1422 1404 1572 1579 1503 1442 1420 1340 1509 1428 1553 1387 1433 1417 1488 1454 65.79 4.53
0.5° 1346 1355 1288 1273 1232 1325 1379 1337 1223 1305 1252 1262 1331 1309 1265 1410 1266 1300 1303 50.82 3.90
1008 1073 1181 1064 1070 1096 963 1055 1012 992 1085 1154 1065 997 1183 1073 1160 1061 1072 64.87 6.05
1.75° 1000 916 1043 919 1024 1035 952 895 843 1003 1007 925 998 987 966 889 943 1017 965 57.14 5.92
911 941 815 822 938 937 951 952 853 1001 859 932 939 987 886 992 910 990 923 56.71 6.14
6 0.25° 1625 1498 1542 1587 1546 1668 1616 1551 1506 1641 1732 1673 1796 1821 1780 1621 1678 1840 1651 107.01 6.48
0.5° 1421 1366 1360 1361 1360 1346 1465 1417 1579 1562 1415 1426 1592 1574 1420 1458 1550 1370 1447 86.72 5.99
1263 1206 1289 1333 1294 1165 1288 1205 1198 1176 1049 1182 1153 1234 1133 1185 1287 1095 1208 75.46 6.25
1.75° 1117 1069 1048 1000 1026 1163 1050 953 959 998 905 982 937 944 1085 1088 1080 * 1024 71.86 7.02
771 762 769 874 759 777 846 732 800 776 810 833 779 864 868 831 719 797 798 46.06 5.77
7 0.25° 1359 1312 1314 1260 1372 1468 1453 1333 1475 1263 1331 1364 1468 1408 1399 1333 1373 1355 1369 66.02 4.82
0.5° 1234 1106 1108 1211 1265 1249 1347 1299 1365 1275 1259 1260 1250 1276 1264 1229 1300 1245 1252 65.30 5.21
984 961 1023 1058 925 1037 1139 1020 1163 979 972 996 1051 930 1072 1041 1033 1051 1024 63.12 6.16
1.75° 942 992 917 888 939 831 954 971 1001 956 955 914 953 895 917 925 918 862 929 42.96 4.62
903 870 893 827 820 836 924 840 863 893 843 988 899 965 853 785 820 804 868 54.42 6.27
8 0.25° 2307 2304 2256 2363 2260 2407 2262 2429 2252 2300 2441 2373 2285 2419 2426 2347 2387 2288 2339 67.35 2.88
0.5° 2120 2152 2160 2211 2205 2148 2301 2289 2284 2290 2130 2256 2140 2211 2206 2190 2108 2191 2200 62.72 2.85
1698 1819 1681 1790 1692 1639 1653 1696 1836 1787 1771 1782 1829 1753 1708 1806 1846 1646 1746 69.87 4.00
1.75° 1301 1317 1304 1240 1312 1245 1300 1265 1301 1318 1256 1300 1288 1162 1356 1365 1319 1273 1290 46.30 3.59
829 816 729 787 818 753 863 884 793 859 757 702 872 746 713 841 900 942 811 68.62 8.46
9 0.25° 1594 1623 1547 1530 1423 1634 1604 1618 1587 1549 1629 1636 1534 1432 1452 1425 1593 1653 1559 78.14 5.01
0.5° 1381 1433 1431 1409 1398 1418 1468 1495 1419 1446 1446 1430 1462 1463 1456 1438 1381 1441 1434 30.08 2.10
1319 1357 1363 1366 1346 1257 1286 1342 1267 1340 1325 1315 1408 1461 1309 1385 1295 1371 1340 50.41 3.76
1.75° 1146 1134 1095 1050 1109 1100 1139 1122 1064 1117 1073 1067 1054 1091 1054 1127 1051 1069 1092 33.11 3.03
755 808 830 776 773 715 776 816 735 762 766 718 730 884 752 892 822 741 781 51.92 6.65
10 0.25° 1978 1975 1897 1964 1690 1799 1839 1899 1704 1871 1822 1620 1948 2028 1852 1888 1811 1829 1856 107.75 5.80
0.5° 1909 1905 1857 1933 1908 1904 1790 1848 1909 1757 1781 1749 1776 1827 1820 1811 1723 1876 1838 65.55 3.57
1597 1623 1603 1634 1635 1608 1628 1672 1700 1769 1741 1759 1776 1640 1638 1749 1628 1640 1669 62.25 3.73
1.75° 1432 1414 1327 1302 1278 1303 1428 1344 1427 1410 1442 1410 1428 1352 1404 1341 1380 1444 1381 54.11 3.92
708 748 826 854 714 749 905 837 932 882 920 747 714 805 840 916 810 786 816 75.35 9.23
11 0.25° 1199 1123 1308 1151 , † , † 1329 1160 1245 1323 1362 1145 1130 1111 1124 1128 1189 1083 1194 90.09 7.54
0.5° 927 1032 1193 971 1161 1334 1016 1131 1084 1044 1161 1092 1124 1219 1164 1201 1223 1104 1121 99.89 8.91
1323 1094 1177 1101 1059 1058 1183 1279 1076 1281 1102 1040 1297 1227 1247 1309 1268 1236 1187 99.20 8.36
1.75° 1152 1127 998 947 1237 1074 1044 1100 1176 1273 1012 1038 994 1138 1168 1165 1127 1022 1100 89.26 8.12
843 1093 1022 931 1037 1061 986 1045 994 981 914 1084 1009 904 976 947 1083 977 994 68.64 6.91
12 0.25° 1285 1156 1285 1360 1283 1399 1258 1333 1327 1319 1283 1249 1345 1339 1224 1254 1212 1345 1292 60.28 4.67
0.5° 1294 1227 1140 1162 1238 1154 1283 1222 1228 1268 1259 1253 1350 1243 1252 1246 1266 1176 1237 52.62 4.25
1197 1340 1277 1299 1316 1295 1305 1261 1303 1247 1234 1220 1253 1284 1327 1275 1212 1245 1272 40.78 3.21
1.75° 1155 1162 1228 1199 1215 1133 1180 1232 1205 1192 1223 1258 1230 1172 1151 1125 1121 1118 1183 43.40 3.67
970 954 955 971 993 958 960 892 916 939 961 901 997 938 975 945 1065 916 956 39.72 4.16
13 0.25° 1383 1372 1383 1320 1457 1447 1389 1396 1401 1466 1416 1352 1472 1479 1473 1513 1512 1443 1426 55.15 3.87
0.5° 1343 1306 1349 1492 1475 1370 1494 1475 1464 1431 1466 1475 1445 1383 1435 1414 1409 1458 1427 56.01 3.93
1299 1193 1188 1292 1259 1271 1204 1307 1281 1288 1328 1223 1264 1289 1256 1269 1280 1241 1263 39.46 3.12
1.75° 1015 1060 1016 1085 1026 1030 1063 1074 1118 1009 1177 1124 1057 1068 1042 1037 1046 1166 1067 49.69 4.66
833 859 908 810 845 797 718 815 734 808 815 860 850 754 889 809 713 862 816 55.98 6.86
14 0.25° 1989 1870 1878 1849 2027 * 1883 2015 1982 2031 1904 1906 1876 1915 1901 1948 1830 1880 1923 63.84 3.32
0.5° 1660 1717 1684 1776 1634 1631 1704 1725 1716 1724 1665 1852 1717 1739 1716 1626 1698 1615 1700 58.21 3.42
1515 1560 1623 1595 1655 1650 1613 1618 1521 1580 1573 1647 1607 1784 1721 1670 1613 1788 1630 75.98 4.66
1.75° 1240 1215 1347 1298 1398 1323 1378 1372 1296 1347 1379 1398 1488 1451 1438 1402 1362 1349 1360 69.21 5.09
1010 1033 992 1032 1038 1015 1083 1164 1021 1165 1129 1127 1031 1127 1127 1115 1112 1125 1080 57.71 5.34
15 0.25° 1082 1195 1202 1110 1171 1203 1146 1165 1047 1170 1022 1141 1182 1081 1064 1043 1114 * 1126 60.13 5.34
0.5° 1116 1178 1201 1153 1149 1043 1042 1048 1034 1064 1035 1113 1072 1077 1050 1143 1012 1029 1087 57.57 5.30
996 967 1016 871 978 907 884 918 893 933 878 862 928 910 939 984 930 934 929 44.60 4.80
1.75° 936 1004 987 980 983 943 972 882 882 797 857 952 947 917 1003 1004 1042 946 946 61.06 6.45
666 841 718 761 761 784 815 786 827 924 800 782 739 846 882 730 869 875 800 66.13 8.26
16 0.25° 1273 1218 1242 1225 1193 1267 1235 1444 1359 1407 1359 1347 1329 1340 1300 1439 1428 1398 1322 81.63 6.17
0.5° 1340 1271 1379 1450 1373 1323 1387 1388 1234 1329 1422 1363 1316 1475 1302 1481 1426 1401 1370 67.70 4.94
1045 1120 1141 1159 1015 1020 1024 1086 970 1026 1047 934 989 1028 944 1179 1099 986 1045 71.86 6.88
1.75° 950 1045 1188 1098 1020 929 1013 962 995 921 1022 1055 960 , † 895 822 853 1158 993 98.87 9.95
615 603 658 686 526 622 575 612 728 709 660 680 650 688 609 720 683 653 649 52.96 8.16
Table 2.
 
MPOD Values Obtained for Each Subject at Each Degree of Retinal Eccentricity
Table 2.
 
MPOD Values Obtained for Each Subject at Each Degree of Retinal Eccentricity
No. 0.25° Mean SD 0.5° Mean SD Mean SD 1.75° Mean SD
MPV1 MPV2 MPV3 MPV1 MPV2 MPV3 MPV1 MPV2 MPV3 MPV1 MPV2 MPV3
1 0.56 0.57 0.62 0.58 0.03 0.49 0.48 0.43 0.47 0.03 0.42 0.37 0.36 0.38 0.03 0.24 0.17 0.19 0.20 0.04
2 0.56 0.57 0.61 0.58 0.03 0.36 0.38 0.45 0.40 0.05 0.15 0.17 0.22 0.18 0.04 0.06 0.05 0.11 0.07 0.03
3 0.73 0.7 0.73 0.72 0.02 0.6 0.61 0.63 0.61 0.02 0.39 0.44 0.47 0.43 0.04 0.14 0.24 0.25 0.21 0.06
4 0.43 0.52 0.5 0.48 0.05 0.34 0.39 0.4 0.38 0.03 0.14 0.11 0.13 0.13 0.02 0.07 0.03 0.09 0.06 0.03
5 0.37 0.36 0.33 0.35 0.02 0.28 0.25 0.24 0.26 0.02 0.13 0.08 0.1 0.10 0.03 0.07 0.01 0.01 0.03 0.03
6 0.53 0.55 0.61 0.56 0.04 0.41 0.46 0.46 0.44 0.03 0.34 0.28 0.28 0.30 0.03 0.21 0.13 0.15 0.16 0.04
7 0.33 0.32 0.36 0.34 0.02 0.24 0.28 0.28 0.27 0.02 0.1 0.11 0.13 0.11 0.02 0.05 0.05 0.04 0.05 0.01
8 1.03 1.04 1.05 1.04 0.01 0.92 0.97 0.91 0.93 0.03 0.62 0.62 0.63 0.62 0.01 0.35 0.34 0.33 0.34 0.01
9 0.57 0.48 0.53 0.53 0.05 0.47 0.43 0.42 0.44 0.03 0.39 0.39 0.39 0.39 0.00 0.25 0.2 0.24 0.23 0.03
10 0.6 0.71 0.71 0.67 0.06 0.61 0.75 0.65 0.67 0.07 0.55 0.57 0.57 0.56 0.01 0.36 0.4 0.4 0.39 0.02
11 0.07 0.17 0.1 0.11 0.05 0.07 0.06 0.13 0.09 0.04 0.09 0.11 0.19 0.13 0.05 0.06 0.1 0.08 0.08 0.02
12 0.21 0.25 0.22 0.23 0.02 0.19 0.22 0.16 0.19 0.03 0.2 0.23 0.21 0.21 0.02 0.12 0.2 0.15 0.16 0.04
13 0.37 0.42 0.45 0.41 0.04 0.37 0.46 0.42 0.42 0.05 0.28 0.34 0.32 0.31 0.03 0.14 0.22 0.19 0.18 0.04
14 0.57 0.53 0.49 0.53 0.04 0.42 0.39 0.36 0.39 0.03 0.37 0.27 0.37 0.34 0.06 0.19 0.16 0.2 0.18 0.02
15 0.3 0.2 0.21 0.24 0.06 0.28 0.18 0.17 0.21 0.06 0.16 0.09 0.06 0.10 0.05 0.17 0.12 0.05 0.11 0.06
16 0.47 0.51 0.53 0.50 0.03 0.55 0.51 0.51 0.52 0.02 0.37 0.28 0.29 0.31 0.0 0.34 0.27 0.21 0.27 0.07
Figure 3.
 
(A) Macular pigment spatial profile for each subject in group 1 at visits 1, 2, and 3. (B) Macular pigment spatial profile for each subject in group 2 at visits 1, 2, and 3.
Figure 3.
 
(A) Macular pigment spatial profile for each subject in group 1 at visits 1, 2, and 3. (B) Macular pigment spatial profile for each subject in group 2 at visits 1, 2, and 3.
Table 3.
 
Foveal Width in Scans 1 and 2
Table 3.
 
Foveal Width in Scans 1 and 2
No. Foveal Width (μm) Difference* SD of Difference, † Mean, ‡
Scan 1 Scan 2
1 1204 1290 −86 61 1247
2 1204 1125 79 56 1165
3 1571 1659 −88 62 1615
4 1607 1594 13 9 1601
5 1033 943 90 64 988
6 1075 1081 −6 4 1078
7 1044 1089 −45 32 1067
8 1521 1389 132 93 1455
9 1498 1381 117 83 1440
10 1995 2134 −139 98 2065
11 1826 1804 22 16 1815
12 1893 1807 86 61 1850
13 2223 2196 27 19 2210
14 1806 1814 −8 6 1810
15 1729 1722 7 5 1726
16 1938 2109 −171 121 2024
Average 1573 1571 1.88 49 1572
Table 4.
 
Central Foveal Thickness Scans 1 and 2
Table 4.
 
Central Foveal Thickness Scans 1 and 2
No. Central Foveal Thickness Difference* SD of Difference, † Mean, ‡
Scan 1 Scan 2
1 191 197 −6 4 194
2 227 228 −1 1 228
3 195 192 3 2 194
4 226 211 15 11 219
5 206 209 −3 2 208
6 188 188 0 0 188
7 231 231 0 0 231
8 179 177 2 1 178
9 181 179 2 1 180
10 222 224 −2 1 223
11 158 158 0 0 158
12 126 134 −8 6 130
13 210 192 18 13 201
14 169 163 6 4 166
15 181 186 −5 4 184
16 243 211 32 23 227
Average 196 193 5 6 194
Figure 4.
 
Foveal width in groups 1 and 2.
Figure 4.
 
Foveal width in groups 1 and 2.
Figure 5.
 
(A) The relationship between FPPS and the MPPS in 15 subjects (groups 1 and 2, one outlier excluded). (B) The relationship between FPPS and the MPPS in group 2.
Figure 5.
 
(A) The relationship between FPPS and the MPPS in 15 subjects (groups 1 and 2, one outlier excluded). (B) The relationship between FPPS and the MPPS in group 2.
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Figure 1.
 
The foveal pit, showing the FPPS calculation. The calculation of FPPS therefore, is as follows: m = (y2 − y1)/(x2 − x1); FPPS = (85 − 23)/(300 − 75) = 0.275.
Figure 1.
 
The foveal pit, showing the FPPS calculation. The calculation of FPPS therefore, is as follows: m = (y2 − y1)/(x2 − x1); FPPS = (85 − 23)/(300 − 75) = 0.275.
Figure 2.
 
A schematic of the MP spatial profile showing the calculation of the MP profile slope, between the eccentricities of 0.25° and 1° (i.e., 75 and 300 μm). The calculation of MP profile slope therefore, is as follows: m = (y2 − y1)/(x2 − x1); MP profile slope = (0.35 − 0.20)/(75 − 300) = −0.0007 μm−1.
Figure 2.
 
A schematic of the MP spatial profile showing the calculation of the MP profile slope, between the eccentricities of 0.25° and 1° (i.e., 75 and 300 μm). The calculation of MP profile slope therefore, is as follows: m = (y2 − y1)/(x2 − x1); MP profile slope = (0.35 − 0.20)/(75 − 300) = −0.0007 μm−1.
Figure 3.
 
(A) Macular pigment spatial profile for each subject in group 1 at visits 1, 2, and 3. (B) Macular pigment spatial profile for each subject in group 2 at visits 1, 2, and 3.
Figure 3.
 
(A) Macular pigment spatial profile for each subject in group 1 at visits 1, 2, and 3. (B) Macular pigment spatial profile for each subject in group 2 at visits 1, 2, and 3.
Figure 4.
 
Foveal width in groups 1 and 2.
Figure 4.
 
Foveal width in groups 1 and 2.
Figure 5.
 
(A) The relationship between FPPS and the MPPS in 15 subjects (groups 1 and 2, one outlier excluded). (B) The relationship between FPPS and the MPPS in group 2.
Figure 5.
 
(A) The relationship between FPPS and the MPPS in 15 subjects (groups 1 and 2, one outlier excluded). (B) The relationship between FPPS and the MPPS in group 2.
Table 1.
 
Radiance Values Obtained for Each Subject at Each Degree of Retinal Eccentricity
Table 1.
 
Radiance Values Obtained for Each Subject at Each Degree of Retinal Eccentricity
No. Ecc RV1 RV1 RV1 RV1 RV1 RV1 RV2 RV2 RV2 RV2 RV2 RV2 RV3 RV3 RV3 RV3 RV3 RV3 Mean SD % Diff
1 0.25° 1575 1643 1616 1504 1547 1452 1652 1652 1504 1723 1515 1607 1479 1677 1781 1744 1560 1725 1609 98.11 6.10
0.5° 1455 1415 1435 1463 1461 1430 1392 1483 1516 1616 1357 1369 1428 1405 1283 1409 1279 1356 1420 79.41 5.59
1310 1375 1358 1345 1299 1273 1391 1253 1292 1155 1263 1311 1099 1268 1341 1214 1284 1308 1286 73.54 5.72
1.75° 1151 958 1115 978 1083 1016 1029 1001 1006 953 944 945 904 970 1033 992 1020 997 1005 62.23 6.19
699 787 764 626 809 716 763 756 774 722 719 787 870 667 671 800 806 671 745 62.78 8.43
2 0.25° 1747 1700 1617 1629 1564 1562 1709 1676 1793 1611 1542 1549 1731 1611 1595 1580 1525 1502 1625 83.49 5.14
0.5° 1303 1407 1241 1338 1416 1246 1345 1321 1317 1357 1284 1340 1286 1353 1390 1438 1350 1242 1332 58.57 4.40
965 1032 896 1018 1068 1034 974 958 1115 906 1043 1065 934 1080 1011 919 1069 950 1002 66.14 6.60
1.75° 902 904 861 935 838 826 894 798 870 834 766 929 898 876 812 792 807 847 855 49.40 5.78
830 769 797 871 752 788 861 786 803 761 743 782 780 685 639 777 738 642 767 63.03 8.22
3 0.25° 2113 1948 1942 2080 2040 2003 1885 2053 1919 1902 1825 1908 1913 2018 1818 1914 1956 1965 1956 82.01 4.19
0.5° 1807 1761 1890 1817 1757 1882 1786 1673 1851 1776 1765 1827 1696 1762 1952 1761 1757 1699 1790 71.58 4.00
1515 1540 1417 1521 1440 1489 1507 1505 1497 1479 1523 1472 1527 1390 1620 1561 1512 1508 1501 51.93 3.46
1.75° 1092 1166 1145 1109 1070 966 1187 1183 1095 1176 1238 1224 1133 1111 1135 1262 1214 1133 1147 70.18 6.12
910 846 950 900 967 797 851 828 880 851 813 841 862 754 832 831 817 813 852 53.05 6.22
4 0.25° 1480 1542 1459 1477 1329 1370 1529 1450 1468 1484 1574 1435 1507 1554 1695 1578 1473 1492 1494 81.21 5.43
0.5° 1256 1266 1333 1393 1236 1330 1376 1272 1270 1294 1387 1362 1392 1386 1244 1363 1277 1353 1322 56.67 4.29
937 1033 1011 1015 1011 945 852 968 921 876 1031 901 939 989 908 851 879 959 946 60.38 6.38
1.75° 891 910 802 938 1017 866 935 941 800 868 863 804 743 818 882 818 798 818 862 68.53 7.95
817 809 746 788 810 880 816 736 784 749 729 754 759 841 797 702 658 897 782 59.84 7.65
5 0.25° 1423 1419 1428 1422 1404 1572 1579 1503 1442 1420 1340 1509 1428 1553 1387 1433 1417 1488 1454 65.79 4.53
0.5° 1346 1355 1288 1273 1232 1325 1379 1337 1223 1305 1252 1262 1331 1309 1265 1410 1266 1300 1303 50.82 3.90
1008 1073 1181 1064 1070 1096 963 1055 1012 992 1085 1154 1065 997 1183 1073 1160 1061 1072 64.87 6.05
1.75° 1000 916 1043 919 1024 1035 952 895 843 1003 1007 925 998 987 966 889 943 1017 965 57.14 5.92
911 941 815 822 938 937 951 952 853 1001 859 932 939 987 886 992 910 990 923 56.71 6.14
6 0.25° 1625 1498 1542 1587 1546 1668 1616 1551 1506 1641 1732 1673 1796 1821 1780 1621 1678 1840 1651 107.01 6.48
0.5° 1421 1366 1360 1361 1360 1346 1465 1417 1579 1562 1415 1426 1592 1574 1420 1458 1550 1370 1447 86.72 5.99
1263 1206 1289 1333 1294 1165 1288 1205 1198 1176 1049 1182 1153 1234 1133 1185 1287 1095 1208 75.46 6.25
1.75° 1117 1069 1048 1000 1026 1163 1050 953 959 998 905 982 937 944 1085 1088 1080 * 1024 71.86 7.02
771 762 769 874 759 777 846 732 800 776 810 833 779 864 868 831 719 797 798 46.06 5.77
7 0.25° 1359 1312 1314 1260 1372 1468 1453 1333 1475 1263 1331 1364 1468 1408 1399 1333 1373 1355 1369 66.02 4.82
0.5° 1234 1106 1108 1211 1265 1249 1347 1299 1365 1275 1259 1260 1250 1276 1264 1229 1300 1245 1252 65.30 5.21
984 961 1023 1058 925 1037 1139 1020 1163 979 972 996 1051 930 1072 1041 1033 1051 1024 63.12 6.16
1.75° 942 992 917 888 939 831 954 971 1001 956 955 914 953 895 917 925 918 862 929 42.96 4.62
903 870 893 827 820 836 924 840 863 893 843 988 899 965 853 785 820 804 868 54.42 6.27
8 0.25° 2307 2304 2256 2363 2260 2407 2262 2429 2252 2300 2441 2373 2285 2419 2426 2347 2387 2288 2339 67.35 2.88
0.5° 2120 2152 2160 2211 2205 2148 2301 2289 2284 2290 2130 2256 2140 2211 2206 2190 2108 2191 2200 62.72 2.85
1698 1819 1681 1790 1692 1639 1653 1696 1836 1787 1771 1782 1829 1753 1708 1806 1846 1646 1746 69.87 4.00
1.75° 1301 1317 1304 1240 1312 1245 1300 1265 1301 1318 1256 1300 1288 1162 1356 1365 1319 1273 1290 46.30 3.59
829 816 729 787 818 753 863 884 793 859 757 702 872 746 713 841 900 942 811 68.62 8.46
9 0.25° 1594 1623 1547 1530 1423 1634 1604 1618 1587 1549 1629 1636 1534 1432 1452 1425 1593 1653 1559 78.14 5.01
0.5° 1381 1433 1431 1409 1398 1418 1468 1495 1419 1446 1446 1430 1462 1463 1456 1438 1381 1441 1434 30.08 2.10
1319 1357 1363 1366 1346 1257 1286 1342 1267 1340 1325 1315 1408 1461 1309 1385 1295 1371 1340 50.41 3.76
1.75° 1146 1134 1095 1050 1109 1100 1139 1122 1064 1117 1073 1067 1054 1091 1054 1127 1051 1069 1092 33.11 3.03
755 808 830 776 773 715 776 816 735 762 766 718 730 884 752 892 822 741 781 51.92 6.65
10 0.25° 1978 1975 1897 1964 1690 1799 1839 1899 1704 1871 1822 1620 1948 2028 1852 1888 1811 1829 1856 107.75 5.80
0.5° 1909 1905 1857 1933 1908 1904 1790 1848 1909 1757 1781 1749 1776 1827 1820 1811 1723 1876 1838 65.55 3.57
1597 1623 1603 1634 1635 1608 1628 1672 1700 1769 1741 1759 1776 1640 1638 1749 1628 1640 1669 62.25 3.73
1.75° 1432 1414 1327 1302 1278 1303 1428 1344 1427 1410 1442 1410 1428 1352 1404 1341 1380 1444 1381 54.11 3.92
708 748 826 854 714 749 905 837 932 882 920 747 714 805 840 916 810 786 816 75.35 9.23
11 0.25° 1199 1123 1308 1151 , † , † 1329 1160 1245 1323 1362 1145 1130 1111 1124 1128 1189 1083 1194 90.09 7.54
0.5° 927 1032 1193 971 1161 1334 1016 1131 1084 1044 1161 1092 1124 1219 1164 1201 1223 1104 1121 99.89 8.91
1323 1094 1177 1101 1059 1058 1183 1279 1076 1281 1102 1040 1297 1227 1247 1309 1268 1236 1187 99.20 8.36
1.75° 1152 1127 998 947 1237 1074 1044 1100 1176 1273 1012 1038 994 1138 1168 1165 1127 1022 1100 89.26 8.12
843 1093 1022 931 1037 1061 986 1045 994 981 914 1084 1009 904 976 947 1083 977 994 68.64 6.91
12 0.25° 1285 1156 1285 1360 1283 1399 1258 1333 1327 1319 1283 1249 1345 1339 1224 1254 1212 1345 1292 60.28 4.67
0.5° 1294 1227 1140 1162 1238 1154 1283 1222 1228 1268 1259 1253 1350 1243 1252 1246 1266 1176 1237 52.62 4.25
1197 1340 1277 1299 1316 1295 1305 1261 1303 1247 1234 1220 1253 1284 1327 1275 1212 1245 1272 40.78 3.21
1.75° 1155 1162 1228 1199 1215 1133 1180 1232 1205 1192 1223 1258 1230 1172 1151 1125 1121 1118 1183 43.40 3.67
970 954 955 971 993 958 960 892 916 939 961 901 997 938 975 945 1065 916 956 39.72 4.16
13 0.25° 1383 1372 1383 1320 1457 1447 1389 1396 1401 1466 1416 1352 1472 1479 1473 1513 1512 1443 1426 55.15 3.87
0.5° 1343 1306 1349 1492 1475 1370 1494 1475 1464 1431 1466 1475 1445 1383 1435 1414 1409 1458 1427 56.01 3.93
1299 1193 1188 1292 1259 1271 1204 1307 1281 1288 1328 1223 1264 1289 1256 1269 1280 1241 1263 39.46 3.12
1.75° 1015 1060 1016 1085 1026 1030 1063 1074 1118 1009 1177 1124 1057 1068 1042 1037 1046 1166 1067 49.69 4.66
833 859 908 810 845 797 718 815 734 808 815 860 850 754 889 809 713 862 816 55.98 6.86
14 0.25° 1989 1870 1878 1849 2027 * 1883 2015 1982 2031 1904 1906 1876 1915 1901 1948 1830 1880 1923 63.84 3.32
0.5° 1660 1717 1684 1776 1634 1631 1704 1725 1716 1724 1665 1852 1717 1739 1716 1626 1698 1615 1700 58.21 3.42
1515 1560 1623 1595 1655 1650 1613 1618 1521 1580 1573 1647 1607 1784 1721 1670 1613 1788 1630 75.98 4.66
1.75° 1240 1215 1347 1298 1398 1323 1378 1372 1296 1347 1379 1398 1488 1451 1438 1402 1362 1349 1360 69.21 5.09
1010 1033 992 1032 1038 1015 1083 1164 1021 1165 1129 1127 1031 1127 1127 1115 1112 1125 1080 57.71 5.34
15 0.25° 1082 1195 1202 1110 1171 1203 1146 1165 1047 1170 1022 1141 1182 1081 1064 1043 1114 * 1126 60.13 5.34
0.5° 1116 1178 1201 1153 1149 1043 1042 1048 1034 1064 1035 1113 1072 1077 1050 1143 1012 1029 1087 57.57 5.30
996 967 1016 871 978 907 884 918 893 933 878 862 928 910 939 984 930 934 929 44.60 4.80
1.75° 936 1004 987 980 983 943 972 882 882 797 857 952 947 917 1003 1004 1042 946 946 61.06 6.45
666 841 718 761 761 784 815 786 827 924 800 782 739 846 882 730 869 875 800 66.13 8.26
16 0.25° 1273 1218 1242 1225 1193 1267 1235 1444 1359 1407 1359 1347 1329 1340 1300 1439 1428 1398 1322 81.63 6.17
0.5° 1340 1271 1379 1450 1373 1323 1387 1388 1234 1329 1422 1363 1316 1475 1302 1481 1426 1401 1370 67.70 4.94
1045 1120 1141 1159 1015 1020 1024 1086 970 1026 1047 934 989 1028 944 1179 1099 986 1045 71.86 6.88
1.75° 950 1045 1188 1098 1020 929 1013 962 995 921 1022 1055 960 , † 895 822 853 1158 993 98.87 9.95
615 603 658 686 526 622 575 612 728 709 660 680 650 688 609 720 683 653 649 52.96 8.16
Table 2.
 
MPOD Values Obtained for Each Subject at Each Degree of Retinal Eccentricity
Table 2.
 
MPOD Values Obtained for Each Subject at Each Degree of Retinal Eccentricity
No. 0.25° Mean SD 0.5° Mean SD Mean SD 1.75° Mean SD
MPV1 MPV2 MPV3 MPV1 MPV2 MPV3 MPV1 MPV2 MPV3 MPV1 MPV2 MPV3
1 0.56 0.57 0.62 0.58 0.03 0.49 0.48 0.43 0.47 0.03 0.42 0.37 0.36 0.38 0.03 0.24 0.17 0.19 0.20 0.04
2 0.56 0.57 0.61 0.58 0.03 0.36 0.38 0.45 0.40 0.05 0.15 0.17 0.22 0.18 0.04 0.06 0.05 0.11 0.07 0.03
3 0.73 0.7 0.73 0.72 0.02 0.6 0.61 0.63 0.61 0.02 0.39 0.44 0.47 0.43 0.04 0.14 0.24 0.25 0.21 0.06
4 0.43 0.52 0.5 0.48 0.05 0.34 0.39 0.4 0.38 0.03 0.14 0.11 0.13 0.13 0.02 0.07 0.03 0.09 0.06 0.03
5 0.37 0.36 0.33 0.35 0.02 0.28 0.25 0.24 0.26 0.02 0.13 0.08 0.1 0.10 0.03 0.07 0.01 0.01 0.03 0.03
6 0.53 0.55 0.61 0.56 0.04 0.41 0.46 0.46 0.44 0.03 0.34 0.28 0.28 0.30 0.03 0.21 0.13 0.15 0.16 0.04
7 0.33 0.32 0.36 0.34 0.02 0.24 0.28 0.28 0.27 0.02 0.1 0.11 0.13 0.11 0.02 0.05 0.05 0.04 0.05 0.01
8 1.03 1.04 1.05 1.04 0.01 0.92 0.97 0.91 0.93 0.03 0.62 0.62 0.63 0.62 0.01 0.35 0.34 0.33 0.34 0.01
9 0.57 0.48 0.53 0.53 0.05 0.47 0.43 0.42 0.44 0.03 0.39 0.39 0.39 0.39 0.00 0.25 0.2 0.24 0.23 0.03
10 0.6 0.71 0.71 0.67 0.06 0.61 0.75 0.65 0.67 0.07 0.55 0.57 0.57 0.56 0.01 0.36 0.4 0.4 0.39 0.02
11 0.07 0.17 0.1 0.11 0.05 0.07 0.06 0.13 0.09 0.04 0.09 0.11 0.19 0.13 0.05 0.06 0.1 0.08 0.08 0.02
12 0.21 0.25 0.22 0.23 0.02 0.19 0.22 0.16 0.19 0.03 0.2 0.23 0.21 0.21 0.02 0.12 0.2 0.15 0.16 0.04
13 0.37 0.42 0.45 0.41 0.04 0.37 0.46 0.42 0.42 0.05 0.28 0.34 0.32 0.31 0.03 0.14 0.22 0.19 0.18 0.04
14 0.57 0.53 0.49 0.53 0.04 0.42 0.39 0.36 0.39 0.03 0.37 0.27 0.37 0.34 0.06 0.19 0.16 0.2 0.18 0.02
15 0.3 0.2 0.21 0.24 0.06 0.28 0.18 0.17 0.21 0.06 0.16 0.09 0.06 0.10 0.05 0.17 0.12 0.05 0.11 0.06
16 0.47 0.51 0.53 0.50 0.03 0.55 0.51 0.51 0.52 0.02 0.37 0.28 0.29 0.31 0.0 0.34 0.27 0.21 0.27 0.07
Table 3.
 
Foveal Width in Scans 1 and 2
Table 3.
 
Foveal Width in Scans 1 and 2
No. Foveal Width (μm) Difference* SD of Difference, † Mean, ‡
Scan 1 Scan 2
1 1204 1290 −86 61 1247
2 1204 1125 79 56 1165
3 1571 1659 −88 62 1615
4 1607 1594 13 9 1601
5 1033 943 90 64 988
6 1075 1081 −6 4 1078
7 1044 1089 −45 32 1067
8 1521 1389 132 93 1455
9 1498 1381 117 83 1440
10 1995 2134 −139 98 2065
11 1826 1804 22 16 1815
12 1893 1807 86 61 1850
13 2223 2196 27 19 2210
14 1806 1814 −8 6 1810
15 1729 1722 7 5 1726
16 1938 2109 −171 121 2024
Average 1573 1571 1.88 49 1572
Table 4.
 
Central Foveal Thickness Scans 1 and 2
Table 4.
 
Central Foveal Thickness Scans 1 and 2
No. Central Foveal Thickness Difference* SD of Difference, † Mean, ‡
Scan 1 Scan 2
1 191 197 −6 4 194
2 227 228 −1 1 228
3 195 192 3 2 194
4 226 211 15 11 219
5 206 209 −3 2 208
6 188 188 0 0 188
7 231 231 0 0 231
8 179 177 2 1 178
9 181 179 2 1 180
10 222 224 −2 1 223
11 158 158 0 0 158
12 126 134 −8 6 130
13 210 192 18 13 201
14 169 163 6 4 166
15 181 186 −5 4 184
16 243 211 32 23 227
Average 196 193 5 6 194
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