Ocular Straylight Visual Cortical Processing and the Lived Experience of Visual Stress: Exploring a Potential Neuro-Optical Contribution

Visual stress is characterised by visual discomfort and perceptual disturbance in response to particular visual stimuli and environments. Although its symptoms are increasingly recognised, the mechanisms underlying individual differences in susceptibility remain to yet be fully explored. Research has traditionally focused on the characteristics of visually stressful stimuli, including repetitive patterns and particular spatial frequencies, and on the possibility that these stimuli may trigger overstimulation of visual cortical processing. More recent research has broadened this perspective, identifying distinct dimensions of visual hypersensitivity that include brightness, repeating patterns, strobing and visually intense environments.Ocular straylight represents a potentially relevant but perhaps less investigated aspect of this wider phenomenon. Straylight results from the scattering of light within the eye and produces a diffuse luminance over the retinal image, reducing contrast and contributing to disability glare. It is a well-established determinant of visual quality and can vary independently of visual acuity. However, the author has not been able to find existing research which has directly examined whether individual differences in ocular straylight are associated with visual stress or with the cortical responses associated with visual discomfort.This narrative review considers the potential relationship between ocular straylight, visual cortical processing and the lived experience of visual stress. Existing evidence is examined across three related domains: the optical effects of intraocular light scatter, the neural mechanisms associated with visual discomfort and sensitivity to glare, and the phenomenology of visual stress and visual hypersensitivity. Although available evidence does not support the conclusion that straylight causes visual stress, it does, however, provide a plausible basis for investigating whether optical degradation of the retinal image may interact with individual differences in cortical processing to influence visual stress and the severity of the symptoms linked to this condition.A neuro-optical model is proposed in which the experience of visual stress may arise from interactions between properties of the visual environment, optical characteristics of the eye and individual characteristics of visual cortical processing. This framework places the lived experience of visual stress at the centre of investigation while recognising that similar symptoms may arise through different combinations of optical and neurological factors. Future research should therefore examine ocular straylight alongside measures of visual hypersensitivity, the intensity of symptoms related to visual stress and cortical response rather than treating these phenomena as unconnected areas.