Forty-seven 47 patients (20 normal, 27 with macular disease) with a mean age of 59.0 ± 19.0 years (range, 24–88) were enrolled; one eye of each was examined. Macular disease consisted of 12 eyes with age-related macular degeneration (AMD), 7 eyes with epiretinal membrane (ERM), 4 eyes with cystoid macular edema (CME), 2 eyes with central serous retinopathy (CSR), and 2 eyes with pattern dystrophy. Five eyes with maculopathy had coexisting glaucomatous optic neuropathy (average visual field mean defect −4.2 ± 1.9 dB). The demographics of the patients are listed in
Table 1 .
Among normal eyes, macular bow-tie patterns were classified as well defined in 19 (95%) of 20 eyes, weak in 1 (5%) of 20 eyes, and indeterminate in none of the eyes. Among eyes with maculopathy
(Table 2) , macular bow-tie patterns were characterized as well defined in 15 (55%) of 27 eyes, weak in 4 (15%) of 27 eyes, and indeterminate in 8 (30%) of 27 eyes. Normal eyes had significantly (
P = 0.003) more well-defined macular bow ties than eyes with maculopathy; eyes with maculopathy had significantly (
P = 0.007) more indeterminate bow ties
(Fig. 6) . We evaluated the variance of CPA measurements
(Table 2) derived by corneal polarimetry (P
IV) and SLP-VCC. Mean variance (SD
2) of CPA by P
IV measurements was similar (
P = 0.84) in normal eyes (1.9 ± 2.8; range, 0–11.5) and eyes with maculopathy (1.8 ± 2.4; range 0–11.5). Mean variance of CPA measurements derived using SLP-VCC was similar (
P = 0.39) in normal eyes (2.9 ± 2.4; range, 0–9) and eyes with maculopathy (4.7 ± 8.9; range, 0–47).
Among normal eyes, there was no difference (
P = 0.97, paired
t-test) between mean CPA by P
IV (27° ± 14°, range 0–59°) compared with mean CPA derived by SLP-VCC (mean, 23 ± 14°; range, 5–45°). Among eyes with maculopathy, there was a difference that did not achieve statistical significance (
P = 0.08, paired
t-test) between mean P
IV (19° ± 18°; range, 20–61°) and mean CPA derived by SLP-VCC (25° ± 22°; range, −15–86°).
Figure 7 shows scatterplots comparing the CPA by P
IV with CPA derived by SLP-VCC (bow-tie method) and comparing CPA by P
IV with CPA derived by SLP-VCC (screen method) in normal eyes and eyes with maculopathy. With the bow-tie method, eyes with maculopathy had a weaker correlation (
R 2 = 0.22,
P = 0.024) than normal eyes (
R 2 = 0.72,
P < 0.0001). With the screen method, eyes with maculopathy demonstrated similar correlation (
R 2 = 0.83,
P < 0.0001) as normal eyes (
R 2 = 0.73,
P < 0.0001). The magnitude of difference between the CPA by P
IV and CPA by SLP-VCC was significantly greater (
P = 0.0007) in eyes with indeterminate bow-tie patterns (mean, 26° ± 25°) than in eyes with weak (mean, 14.0° ± 14°) and well-defined (mean, 7.0° ± 4.6°) bow-tie patterns. There was no association between the magnitude of difference in CPA derived by both methods and the subtype of maculopathy (
P = 0.22).
To determine whether complete neutralization of corneal birefringence was accomplished by using SLP-VCC in normal eyes and eyes with maculopathy, we evaluated the statistical associations between 12 SLP retardation parameters and the CPA derived with SLP-VCC. No relationship was observed in normal eyes (
P > 0.05 for all parameters). Eyes with macular disease showed a significant association between CPA and average thickness (
R 2 = 0.27,
P = 0.005), ellipse average (
R 2 = 0.24,
P = 0.008), superior average (
R 2 = 0.24,
P = 0.009), inferior average (
R 2 = 0.28,
P = 0.004), and superior integral (
R 2 = 0.37,
P = 0.0008), suggesting incomplete corneal compensation
(Table 3) .
A subgroup of five eyes with macular disease comprising two cases of exudative AMD, two cases of ERM, and one case of CSR were also imaged with the corneal compensator axis set to the CPA by P
IV measurements rather than the CPA derived by SLP-VCC, and the correlation with the 12 SLP retardation parameters was recalculated. Using the CPA derived by SLP-VCC, we noted a significant association between CPA and symmetry (
R 2 = 0.8,
P = 0.027), average thickness (
R 2 = 0.9,
P = 0.017), and ellipse average (
R 2 = 0.9,
P = 0.021). After substitution of the CPA by P
IV axis, there was no significant association between CPA and any retardation parameters (
P > 0.05 for all parameters), suggesting complete neutralization of corneal birefringence
(Table 4) .
Figure 8 illustrates a macular polarimetry image obtained with SLP-VCC in an eye with exudative macular degeneration and an indeterminate macular bow-tie pattern. After corneal compensation, persistence of the macular bow tie suggested incomplete corneal compensation. After substitution of the CPA derived by SLP-VCC (54° nasally downward) with the CPA by P
IV (4° nasally downward), a uniform pattern of retardation appeared, suggesting complete corneal compensation.