Evaluation of Retinal Nerve Fiber Layer Thickness Parameters in Myopic Population Using Scanning Laser Polarimetry (GDxVCC)

Abstract

 

Methods:

 

100 eyes of emmetropes, 30 eyes of low myopes (0 to -4 D spherical equivalent), 50 eyes with moderate myopia (-4 to -8D spherical equivalent), and 30 eyes with high myopia (-8 to -15D spherical equivalent). All subjects were normal subjects without any features of glaucoma. The retinal nerve fiber layer assessment was performed using the Scanning Laser Polarimetry (GDxVCC) in all subjects using standard protocol. The TSNIT global average, superior & inferior average, and NFI were noted.

 

Results:

 

There was no significant difference in the mean age between the myopes and emmetropes. There was no statistically significant difference in the NFI and TSNIT values between emmetropes and low myopes. The TSNIT average, superior and inferior average was significantly lower (p=0.0097), while the NFI was higher (P < 0.0001) in moderate myopes as compared to emmetropes. In high myopia the RNFL showed supranormal values, the TSNIT average, superior and inferior average was significantly higher (p < 0.0001) as compared to emmetropes. (Table 1)

 

Conclusions:

 

The RNFL measurements on scanning laser polarimetry are affected by myopic refractive error. Moderate myopes show a significant thinning of the RNFL. In high myopia due to peripapillary chorioretinal atrophy and contribution of scleral birefringence, the RNFL thickness values are abnormally high. These findings need to be taken into account while assessing and monitoring glaucoma damage in moderate-high myopes on GDxVCC.  

 

Keywords: myopia • nerve fiber layer • imaging/image analysis: clinical