Abstract
Purpose :
There is agreement on pathological loss rate of nerve fiber layer (NFL) in the optic nerve head (ONH) in glaucomatous individuals, as well as non-pathological due to aging. Morphometric measures of the NFL allow for assessment of the loss rate. Previous studies of non-glaucomatous individuals have reported a normal loss rate ranging from -1 to -2 µm/year. So far, a fully automatic method has never been used in studies for morphometrical measurement of the NFL.
Our clinical experimental study was performed with the use of an in-house developed AI-algorithm for automatical annotation and measurement of the NFL waist along the ONH, to investigate whether there is an age-related NFL loss rate in non-glaucomatous subjects.
Methods :
Altogether 16 non-glaucomatous individuals were enrolled and equally stratified according to sex and age in four age groups of [30 39], [40 49], [50 59], [60 69] years. Three left-eye volumes were obtained from each participant. In each volume 500 annotations of the central limit of pigmental epithelium and their shortest distances to the inner limit of the retina were detected by the AI algorithm. The average distance was calculated in each volume. Then, all three volumes were averaged for each subject.
ANOVA and simple linear regression analysis were performed to evaluate the obtained data.
Results :
Automatic measurement of one volume took approximately 1 minute. The 95% CI for the mean in age groups of [30 39], [40 49], [50 59], [60 69] years were estimated as 376.0±33.5, 292.3±51.4, 364.6±61.6 and 344.3±49.9 µm.
Variation among volumes and subjects was 7.7 µm2 (d.f.= 32) and 2758 µm2 (d.f.= 12) respectively. In a linear regression graph a negative trend was found, equivalent to a NFL loss of -2.43 µm/year.
Conclusions :
Our automatical algorithm successfully annotated and computed the NFL waist thickness and produced results in line with current research, although general conclusions about normal loss rate in the population are difficult to draw due to our small sample size.
A fully automated approach to track changes in NFL thickness over time for glaucoma follow-up is possible. Comparison of loss rate in the glaucomatous and non-glaucomatous population enables new glaucoma follow-up method to detect pathological changes earlier than current clinical perimetry.
This is a 2021 ARVO Annual Meeting abstract.