Figure 1.

Retinal images of point light sources (PSFs) simulating the combined effects of diffraction from the pupil, longitudinal chromatic aberration³⁰ and higher order monochromatic aberrations (3^rd to 6^th order Zernike polynomials)²⁹. The effect of longitudinal chromatic aberration was calculated every 10 nm, for wavelengths from 400 to 700nm, including the effect of V_λ and assuming 555 nm is in focus on the retina. The PSFs were then summed to demonstrate the size of the white light PSF, but not the chromatic content. The age appropriate photoreceptor inner segment diameters are illustrated in the top left corner of panels A and B, to demonstrate the spacing at which the PSF would be neurally sampled (neonate = 2.6 arcmin³³, ³⁴ & adult = 0.49 arcmin⁶⁸). PANEL A: a young infant with a pupil size of 3mm²⁹ (average monochromatic aberrations of a six-week-old & average chromatic aberration of a three-month-old). PANEL B: an adult with a pupil size of 4.5mm²⁹. PANEL C: the infant with an additional 2D of hyperopic defocus. PANEL D: the infant with 0.5D of astigmatism and one meridian in focus. At three months of age, approximately 50% of infants have more than 0.75 D of astigmatism⁶⁹ and therefore it has the potential to disrupt the retinal image in significant cases.