Abstract
Purpose :
To date there are no markers detectable in biological fluids that allow diagnosis and evaluation of axonal degeneration in patients with glaucoma. An open-label, cross-sectional study was performed to evaluate the clinical relevance of neurofilament light chain (NfL) levels as marker of axonal damage in glaucomatous patients.
Methods :
Forty-five subjects (mean 60.27 years, SD 11.77, range 30-86) were included, of which 15 affected with advanced glaucoma (stage 3-4-5 according to Glaucoma Staging System 2, GSS2), 15 with initial glaucoma (stage 1-2 according to GSS2) and 15 healthy subjects (stage 0 according to GSS2). All included cases underwent an overall eye examination, Humphrey 24-2 visual field test to obtain the mean defect value (MD) and optic coherence tomography of the retinal nerve fiber layer (OCT RNFL) to obtain the global thickness value (G). Blood sampling was performed in each included subject and serum NfL values were subsequently analysed using Quanterix, Single Molecule Array (SIMOA) technology.
Results :
We observed a significant increase (p=0.038) of NfL values in patients with advanced (mean 16.23 pg/mL, SD 13.04) and initial (mean 14.20 pg/mL, SD 7.76) glaucoma in comparison to healthy subjects (mean 9.37 pg/mL, SD 2.36). This difference was still evident but no more significant (p=0.184) after adjusting for age. As expected, both the incidence of glaucoma and NfL values increased in correlation with age in the analysed cohort. In addition, a weak global correlation was found between MD and NfL values (r=0.262, p=0.012). We found a moderate statistically significant correlation between NfL levels and the G values (r=-0.421, p<0.001). This correlation was stronger in the group of healthy subjects (r=-0.635, p<0.001), weaker in the group affected with initial glaucoma (r=-0.231, p=0.123) and weakest in the group affected with advanced glaucoma (r=-0.011, p=0.958). We calculated that 13 pg/mL is the best threshold of serum NfL value in terms of sensitivity and specificity for distinguishing healthy subjects from glaucomatous patients.
Conclusions :
The correlation observed between serum NfL levels and OCT RNFL values supports the use of this biomarker as an indicator of axonal damage in glaucomatous patients. Moreover, NfL values might be a feasible non-invasive and repeatable biomarker able to track disease activity and progression in subjects with glaucoma.
This is a 2020 ARVO Annual Meeting abstract.