Purpose It is important to evaluate the atypical birefringence pattern of GDx VCC and GDx ECC in myopic subjects. The purpose of the present study was to evaluate and compare the atypical birefringence pattern using GDx VCC and GDx ECC in myopic eyes.
Methods A total of 149 myopia subjects were included in the study. Scanning laser polarimetry (SLP) was performed using GDx VCC and GDxECC (Carl Zeiss Meditec, Dublin, CA, USA), and analyzed with software version 5.5.0.14.Atypical birefringence pattern (ABP) was defined as having a TSS＜80. The raw data was exported from the instrument. The parameters of superior, inferior, and TSNIT average RNFL thickness were collected.Comparison of GDx VCC and GDx ECC parameters were performed with paired t-test. Prevalence of ABP in both GDx VCC and GDx ECC was calculated and compared by using the likelihood ratio chi-square test.
Results The GDx VCC measured significantly thickner RNFL than that of GDx ECC. The TSS measured by GDx ECC (96.0+/-10.6) was significantly greater than that measured by the GDx VCC (84.7+/-24.8) (p<0.001).26 eyes (18.4%) were found to have ABP using GDx VCC, while only one eye had ABP using GDx ECC. More eyes were found to have ABP in high myopia group than that of low to moderate group by using GDx VCC.
Conclusion ABP was frequently observed in myopia eyes especially in high myopia eyes. ECC appears to yield improved SLP images of the RNFL, compared with VCC, which may allow clinicians a more accurate assessment of the retinal nerve fiber layer with the GDx VCC for diagnosing and monitoring glaucoma.