Photophobia can be described as an abnormal physical intolerance to the visual perception of light. As a medical symptom, photophobia is not a morbid fear or psychological phobia, but an experience of discomfort or pain to the eyes due to light exposure.
Photophobia is almost always accompanied by other coinciding effects such as pupil dilation which may trigger this effect by disabling the eye's ability to adjust itself accordingly depending on current levels of light exposure. It is most commonly induced under the influence of heavy dosages of psychedelics compounds, such as LSD, psilocybin, and mescaline. However, it can also occur to a lesser extent under the influence of certain stimulants.