Abstract
Purpose: :
To determine if natural aging has an effect on retinal nerve fiber layer (RNFL) thickness.
Methods: :
After approval by the Institutional Review Board, the RTVue Fourier-domain OCT from Optovue, Inc. (Fremont, California) was employed on a series of 25 normal individuals without previous history of eye disease except for refractive error. Specifically, no diabetes, hypertension, macular degeneration, glaucoma, retinal or optic nerve degenerative diseases existed in these subjects. Forty-one eyes of 25 patients were examined using the OCT with the MM4 and MM7 protocols. The outcome measures assessed by the OCT included superior RNFL thickness, inferior RNFL thickness and cup to disc ratio (c/d).
Results: :
The superior and inferior RNFL thickness when assessed with age had a pearson correlation coefficient of -0.39 (p=0.013) and -0.31 (p=0.049). There was no significant correlation between age and c/d ratio (r=0.216, p=0.212). The age variable was stratified into three categories, =< 35, 36-59, =>60. Two ANOVA tests were performed for each outcome measure, 1) test of group means, and 2) test of linear relationship between the group means. For the outcome measure of superior RNFL thickness, there was a significant difference between group means (F=4.71, p = .015). The linear relationship between the group means for superior RNFL thickness (F=9.16, p = .004) and inferior RNFL thickness (F=5.194, p=0.029) was significant, but c/d (F=1.125, p=0.297) was not significant.
Conclusions: :
Advanced age itself may result in thinning of the superior RNFL, independent of eye diseases such as glaucoma. This should be taken into consideration when evaluating RNFL thickness.
Keywords: nerve fiber layer • aging • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)