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U. C. Christensen, K. Kroyer, J. Thomadsen, T. M. Joergensen, M. la Cour, B. Sander; Normative Data of Outer Photoreceptor Layer Thickness Obtained by Software Image Enhancing Based on Stratus Optical Coherence Tomography Images. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1890. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To present normative data of outer photoreceptor layer thickness obtained by a newly developed image analysis algorithm operating on software enhanced optical coherence tomography (OCT) images.
Eight high-quality Stratus OCT3 scans from identical retinal locations from 25 normal eyes were registered and combined to form an enhanced average image. Utilizing the vertical intensity gradients of the enhanced OCT images to demarcate retinal layers, thickness measurements from the outer border of the retinal pigment epithelium to the photoreceptor inner- and outer segment junction (RPE-OScomplex) were obtained. Additionally the backscattered light within the outer nuclear layer (ONL) in the fovea was registered and compared to the backscattered light within ONL in the peripheral part of the macula (Iratio-ONL).
In healthy subjects, the mean RPE-OScomplex thickness in the foveal centre was 77.2 µm (SD = 3.95). RPE-OScomplex thickness in corresponding locations 1 mm inferior and 1 mm superior of the centre was 63.76 µm and 67.84 µm respectively. RPE-OScomplex thickness in corresponding locations 2 mm inferior and 2 mm superior of the centre was 62.16 µm and 65.36 µm respectively. The RPE-OScomplex thickness in the superior macula 0.5 mm to 3 mm of the centre was significantly increased as compared to the corresponding inferior retina (p < 0.001). In healthy subjects the intensity of backscattered light within the outer nuclear layer was identical in the central part of the retina as compared to the peripheral part ( Iratio-ONL = 1.06).
Contrast enhanced OCT images enable quantification of outer photoreceptor layer thickness. We have presented normative values of outer photoreceptor layer thickness and demonstrated a difference in outer photoreceptor layer thickness between corresponding areas of inferior and superior macula. The normative values are of potential value for objectively assessing the relationship between the functional outcome and photoreceptor morphology after resolution of macular diseases.
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