top of page

Hallucinogen-persisting perception disorder (HPPD) is a disorder characterized by a continual presence of sensory disturbances, most commonly visual, that are reminiscent of those generated by the use of hallucinogenic substances. Many of the characteristics of this disorder can be mistaken for anxiety or panic-related disorders by physicians.


Visual Stress is a neurological disorder characterized by visual sensory processing difficulties when viewing patterned high contrast images. This leads to symptoms of physical discomfort and perceptual distortions that are alleviated by individually prescribed coloured filters. [1] Common symptoms include blurring, doubling, and the appearance of movement, flickering and colour in the visual field. Visual Stress is often associated with migraines and anxiety, and is also frequently misdiagnosed.  


Referrals usually come from Clinical Psychologists and Psychiatrists for patients who are experiencing “not yet diagnosed” symptoms of visual discomfort and perceptual distortions, including some with reported hallucinogenic episodes and anxiety.  We help these patients with individually prescribed coloured filter lenses that alter the visual triggers in their environment, neutralizing the effect of the images and removing the perceptual distortions.  

All of our patients are pre-screened for symptoms and report perceptual distortions of some sort to varying degrees. Whether we call these perceptual distortions, or illusions, or hallucinations, it is all the same thing – they are seeing (in fact perceiving) things that are not there.  Fortunately, we are helping them to perceive correctly, and no longer “see” these things.  Visual stress, while studied primarily for the misperceptions experienced with looking at patterned images in text – can also cause perceptual distortions, illusion and hallucinations in the general visual environment.  


We have heard the following examples:

  • "There are things that I see coming at me that my husband tells me are not there."


  • "Rows of trees fall down and then get up again."

  • "I see a blue glow around everything — it makes reading hard, but looks cool around other things."

  • "Patterned tile floors or stripy hardwood floors look like they are wobbling and are hard to walk on without feeling dizzy."


It is fair to say that these visions, whether you call them perceptual distortions, illusions or hallucinations, are not pleasant. It could easily lead to stress, depression, anxiety and other adverse reactions, especially if they are thought to be made-up or malingering as is often the case with these types of reported symptoms that have no apparent cause. 


We recommend a full investigation with a specialist optometrist, in particular, a neuro-optometrist, to rule out any eye health, refractive error or binocular issues that may be contributing to visual symptoms. Since Visual Stress can also be present, we recommend investigating for Visual Stress if any perceptual problems are present.

bottom of page