Thickness of individual layers at the macula and associated factors: the Beijing Eye Study 2011.

Background: Diagnosis and follow-up of retinal diseases may be improved if the thickness of the various retinal layers, in addition to the total retinal thickness, is taken into account. Here we measured the thickness of the macular retinal layers in a population-based study group to assess the normative values and their associations.
Methods: Using spectral-domain optical coherence tomographic images (Spectralis®, wavelength: 870 nm; Heidelberg Engineering Co, Heidelberg, Germany), we measured the thickness of the macular retinal layers in participants of the population-based Beijing Eye Study without ocular diseases and without systematic diseases, such as arterial hypertension, hyperlipidemia, diabetes mellitus, cardiovascular diseases, previous myocardial infarction, cerebral trauma and stroke. Segmentation and measurement of the retinal layers was performed automatically in each of the horizontal scans.
Results: The study included 384 subjects (mean age:60.0 ± 8.0 years). The mean thickness of the whole retina, outer plexiform layer, outer nuclear layer,retinal pigment epithelium, inner retinal layer and photoreceptor layer was 259.8 ± 18.9 μm, 19.4 ± 3.9 μm, 93.4 ± 9.6 μm, 17.6 ± 1.9 μm, 169.8 ± 18.6 μm, and 90.0 ± 4.2 μm, respectively. In multivariable analysis, the thickness of the foveola and of all retinal layers in the foveal, parafoveal and perifoveal region decreased with older age (all P < 0.05), except for the thickness of the parafoveal outer plexiform layer which increased with age. Men as compared to women had higher thickness measurements of the photoreceptor layer and outer nuclear layer in all areas, and of all layers between the retinal nerve fiber layer and inner nuclear layer in the parafoveal area (all P < 0.05). The associations between the macular retinal layers thickness and axial length were not consistent. The inner plexiform layer was thicker, and the ganglion cell layer and inner nuclear layer were thinner, in the temporal areas than in the nasal areas, CONCLUSIONS: The associations between decreasing thickness of most retinal layers with older age and the correlation of a higher thickness of some retinal layers with male gender may clinically be taken into account.