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.
Supported by the Medical Research Charities Group in Ireland; Fighting Blindness, Ireland; and the Health Research Board, Ireland.
Submitted for publication June 26, 2008; revised August 6, 2008; accepted January 21, 2009.
Disclosure:
M.L. Kirby, None;
M. Galea, None;
E. Loane, None;
J. Stack, None;
S. Beatty, Bausch & Lomb (C), Alcon (C), MacuVision Europe Ltd. (C);
J.M. Nolan, Bausch & Lomb (C), Alcon (C), MacuVision Europe Ltd. (C)
The publication costs of this article were defrayed in part by page charge payment. This article must therefore be marked “
advertisement” in accordance with 18 U.S.C. §1734 solely to indicate this fact.
Corresponding author: Mark Kirby, Waterford Institute of Technology, Cork Road, Waterford, Ireland;
mlkirby@wit.ie
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 |
| 1° | 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 |
| 7° | 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 |
| 1° | 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 |
| 7° | 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 |
| 1° | 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 |
| 7° | 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 |
| 1° | 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 |
| 7° | 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 |
| 1° | 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 |
| 7° | 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 |
| 1° | 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 |
| 7° | 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 |
| 1° | 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 |
| 7° | 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 |
| 1° | 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 |
| 7° | 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 |
| 1° | 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 |
| 7° | 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 |
| 1° | 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 |
| 7° | 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 |
| 1° | 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 |
| 7° | 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 |
| 1° | 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 |
| 7° | 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 |
| 1° | 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 |
| 7° | 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 |
| 1° | 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 |
| 7° | 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 |
| 1° | 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 |
| 7° | 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 |
| 1° | 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 |
| 7° | 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 | 1° | | | 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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