Assessment of visual function and the neuroretina in subjects diagnosed with colour blindness

Purpose: To assess whether the existence of colour vision deficiency or colour blindness involves impairment of visual acuity, contrast sensitivity and colour vision and results in variations in retinal nerve fibre layer (RNFL) thickness, macular area, retinal ganglion cell complex and retinal layers that contain photoreceptors (bastons and cones) versus subjects with normal colour vision within the same age and gender distribution. Methods: Cross‐sectional and observational study including 50 eyes of subjects with colour blindness and 50 eyes of control subjects. Visual function (visual acuity, contrast sensitivity and colour vision) and neuroretinal structure were assessed in all subjects using optical coherence tomography (OCT). Results: Significant thinning of the retinal nerve fibre layer, ganglion cell layer and retina were observed in the colour blindness group. Significant thinning was also recorded in layers that involve photoreceptor nuclei (between the outer limiting layer and the Bruch membrane and between the outer plexiform layer and the outer limiting membrane). Conclusions: Significantly reduced thicknesses in the RNFL and several retinal layers (ganglion cell and photoreceptor layers) were found, demonstrating that colour blindness is associated with thinning in retinal and RNFL thickness, and in the retinal layers that involve photoreceptor nuclei. OCT study with retinal segmentation therefore seems to be a marker of colour blindness of utility in clinical practice in the case of doubt regarding diagnosis. This analysis could be useful in evaluating the effectiveness of potential therapies such as gene treatment.