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Douglas Kenneth Sigford, Amir Reza Hajrasouliha, Andrea Breaux, Laurie Conrad, Shlomit Schaal; A novel normalized reflection scale reveals occult optical coherence tomography changes in retina structures with aging. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2802. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To introduce a novel scale which objectively quantifies optical coherence tomography (OCT) reflectivity and to use this scale to study occult progressive retinal structural changes that occur with age in normal subjects.
A total of 179 normal subjects underwent complete ophthalmic examination and SD-OCT (Spectralis SLO-OCT, Heidelberg) with horizontal line scans through the fovea. Raw data from the SD-OCT was imported for further analysis in ImageJ. A novel normalized reflectivity scale (NRS) was established for OCT reflectivity ranging from 0 units (vitreous) to 1000 units (RPE). Raw reflectivity in the nasal and temporal parafovea was then extracted, converted to NRS, and compared for all retinal layers. Subjects were grouped by decade of life to assess reflectivity changes in different retinal layers as a function of age.
A total of 310 eyes of 179 subjects (87 males and 92 females) were included. The subjects mean age was (60.3+/-19.6). NRS of the nerve fiber layer (NFL) showed significantly higher reflectivity in the nasal parafoveal retina as compared to temporal side (843 vs 559 units; P<0.001). None of the other retinal layers demonstrated a statistically significant difference between the nasal and temporal sides. The NRS-NFL decreased throughout life and became significantly different from baseline (age group 10-19) in age group 30-39 in nasal side (1168 vs 882 units; P<0.001) and in age group 70-79 in temporal side (673 vs 483 units; P= 0.02). There were statistically significant correlations with aging in NFL and ellipsoid layers (P<0.001). All other layers demonstrated non-significant changes in NRS with aging.
A novel normalized reflectivity scale provides additional quantitative measurements of SD-OCT images. This scale reveals that the normal aging process results in significant changes in the reflectivity of the ellipsoid and nerve fiber layers as measured by OCT. This adds to our understanding of the normal vision decline that occurs in normal human aging. The novel scale may also prove beneficial in diagnosing, quantifying, or tracking pathologic disease processes affecting the retina.
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