Abstract
Purpose: :
Jansonius et al. developed a mathematical model for the description of retinal nerve fiber bundle trajectories in the human eye (Vision Res 2009;49:2157). This model was based on traced trajectories extracted from randomly collected fundus photographs and described the wiring of the superior-temporal and inferior-temporal parts of the retina. Aims of the current study were (i) to expand the model to the entire retina and (ii) to determine the influence of refraction on the trajectories.
Methods: :
A new dataset of high-quality fundus photographs was taken from 28 eyes of 28 subjects. Eyes were stratified according to spherical equivalent refraction (SE) in myopia (SE less than or equal to -1.00 D), emmetropia, and hyperopia (SE greater than or equal to +1.00 D). This resulted in 9 myopic (median SE -4.00 D; range -8.75 to -1.25 D), 10 emmetropic (0.00 D; -0.75 to +0.50 D) and 9 hyperopic (+1.50 D; +1.00 to +6.25 D) eyes. For inclusion, at least 12 trajectories had to be traceable with no more than one per semi clock hour and at least one in every quadrant; trajectories had to start within 5 deg from the center of the optic disc and had to have a minimum length depending on the clock hour. All trajectories in the superior-temporal and inferior-temporal parts of the retina were fitted by the previously published model; the model was extended to the nasal part of the retina.
Results: :
625 trajectories were included. In the superior-temporal and inferior-temporal parts of the retina (401 trajectories), 349 of 401 trajectories (87%) were within the 95% central range of the previously published model. After stratification for SE, this was the case in 104 of 118 (88%) for myopia, 131 of 151 (87%) for emmetropia and 114 of 132 (86%) for hyperopia (P=0.91; Chi-square test). In the nasal part, we found two "singularities", located roughly at the one and five o'clock positions for the right optic disc. In these singularities, trajectories from relatively large areas of the retina converge.
Conclusions: :
The wiring of the human retina displays a considerable variability. Refraction is not a major reason for this variability. The variability depends on the location at the disc margin to where the trajectories converge. Two singularities exist where the spatial relationship between structure and function is poorly defined.
Keywords: perimetry • nerve fiber layer • optic disc