Abstract
Purpose:
To study inter- and intraindividual variability in volume of retinal layers in subjects over 60 years-of-age without macular pathology.
Methods:
In fifty randomly chosen individuals without macular pathology from the Eugenda (European Genetic Database) spectral domain optical coherence tomography was performed (HRA Spectralis+OCT, Heidelberg Engineering, Heidelberg, Germany). The following retinal layers were delineated manually and volumes calculated using the ImageJ software (developed by Wayne Rasband, NIH, Bethesda, Maryland, USA): RNFL=retinal nerve fiber layer, GCLIPL=ganglion cell layer and inner plexiform layer, INL=inner nuclear layer, OPLONLPIS=outer plexiform, outer nuclear, Henle’s fiber layer and inner part of the photoreceptor layers, POSRPEBM=outer part of the photoreceptor layer, retinal pigment epithelium and Bruch’s membrane. In 20 eyes of 10 subjects the measurements were done twice to evaluate the test-retest reliability of the ImageJ measurement algorithm.
Results:
Mean age was 67 ± 5 years. Twenty-one men and 29 women were analyzed. Mean volumes of the retinal layers were RNFL=0.291±0.023 mm3, GCLIPL=0.742±0.057 mm3, INL=0.310±0.024 mm3, OPLONLPIS=1.105±0.069 mm3, POSRPEBM=0.647±0.028 mm3. There was a moderate to high concordance for all retinal layers between the right and the left eyes (RNFL r=0.734, p<0.001; GCLIPL r=0.918, p<0.001; INL r=0.759, p<0.001; OPLONLPIS r=0.946, p<0.001; POSRPEBM r=0.855, p<0.001). In the test-retest reliability testing there was a correlation between the volume of two different measurements (RNFL r=0.905, p<0.001; GCLIPL r=0.966, p<0.001, INL r=0.808, p<0.05; OPLONLPIS r=0.999, p<0.001; POSRPEBM r=0.870, p<0.05). The concurrent validity showed a high correlation between macular volume measured using ImageJ and Heidelberg Eye Explorer software (right eye r=0.961, p<0.001; left eye r=0.969, p<0.001).
Conclusions:
We developed an algorithm to measure retinal layers using public domain software ImageJ. Overall there is a good reliability and validity of the algorithm used. In this study we described the normal value of measured retinal layers.
Keywords: 688 retina •
550 imaging/image analysis: clinical