What you see while high depends entirely on the substance. Cannabis typically causes subtle shifts in color perception, depth, and night vision. Psychedelics like LSD and psilocybin produce vivid geometric patterns, color intensification, and complex visual scenes. Stimulants and dissociatives each create their own distinct visual profile. Here’s what happens to your vision under different substances and why.
Cannabis: Subtle Shifts, Not Hallucinations
Cannabis doesn’t usually make you “see things” in the way most people imagine. True visual hallucinations are rare, reported by only 3% to 27% of cannabis users during intoxication, and most of those are mild. What cannabis reliably does is alter how your eyes process what’s already in front of you.
Colors can look slightly different. Research on cannabis and visual function has found measurable deterioration in color vision, along with reduced visual acuity for both still and moving objects. Your ability to judge depth also takes a hit. Cannabis significantly impairs stereoacuity, the brain’s ability to construct three-dimensional images from the slightly different views each eye provides. Objects may look flatter or oddly layered, and distances can feel harder to gauge.
The most dramatic visual change from cannabis shows up at night. After smoking, people become more sensitive to glare, and light sources develop larger halos around them. Streetlights, headlights, and phone screens can appear to radiate outward, making it harder to see objects near those light sources. This happens because cannabis increases straylight in the eye and raises what researchers call the visual disturbance index. In practical terms, you lose the ability to discriminate details around anything bright.
Psychedelics: Geometry, Color, and Meaning
LSD, psilocybin mushrooms, and similar psychedelics produce the most well-known visual experiences of any drug class. These substances activate serotonin receptors in the brain’s visual processing areas, and the result is a two-layered visual experience: simple geometric patterns layered with complex, emotionally loaded imagery.
The geometric layer comes first. Users report brightly colored lattices, cobwebs, tunnels, and spirals, sometimes called “form constants” because they appear consistently across people and cultures. These patterns often appear with eyes closed but can also overlay open-eyed vision, making surfaces appear to ripple, breathe, or flow. Walls may seem to shift slowly inward and outward. Textures can look like they’re crawling or rearranging themselves.
At higher doses or later in the experience, the visuals become more complex. With eyes closed, people report progressing from abstract patterns to seeing recognizable objects, then animals or human figures, and eventually entire landscapes or scenes. This progression from simple to complex is consistent enough that researchers have documented it as a reliable sequence during hallucinogen use.
Colors become more saturated and vivid. Moving objects can leave trails behind them, sometimes called “tracers,” where an afterimage lingers in the visual field for a moment after the object has moved on. Halos may appear around people or objects. Some users experience micropsia (things looking smaller than they are) or macropsia (things looking larger), which can make a room feel like it’s expanding or shrinking around you.
One important distinction: most people on psychedelics know they’re hallucinating. Unlike visual hallucinations in psychotic disorders, psychedelic visuals come with preserved insight. You see the walls breathing, but you understand the walls aren’t actually moving.
Why Psychedelics Produce Visuals
The mechanism is surprisingly specific. Psychedelics activate serotonin 2A receptors, which are concentrated in the brain’s visual processing areas. When these receptors are stimulated, they increase the excitability of the visual network even when there’s nothing external to look at. Normally, your visual cortex produces a steady background rhythm (alpha oscillations) that keeps spontaneous activity in check. Psychedelics suppress this rhythm, essentially removing a filter that prevents the brain from generating images on its own.
At the same time, the brain’s response to actual visual input gets disrupted. The electrical signals your brain uses to organize what you see, the ones that help you recognize faces, edges, and shapes, become weaker. The result is a visual system that’s generating its own content while simultaneously scrambling the real information coming in through your eyes. That’s why psychedelic visuals feel like a mix of seeing new things and seeing familiar things strangely.
Stimulants: Shadow People and Crawling Things
Cocaine and methamphetamine create a very different visual experience than psychedelics, and it’s generally less pleasant. At moderate doses, stimulants may just make you more sensitive to light and movement. But during heavy use or prolonged sleeplessness, stimulant-induced psychosis can set in, bringing visual hallucinations that feel convincingly real.
The classic stimulant hallucination involves seeing movement in peripheral vision: dark shapes, figures, or “shadow people” that seem to dart away when you look directly at them. Research comparing hallucination content across different conditions found that people experiencing cocaine-induced psychosis frequently report seeing crawling insects, likely connected to the tactile disturbances (feeling things on the skin) that often accompany stimulant intoxication. Unlike psychedelic visuals, these hallucinations often come without insight, meaning the person genuinely believes what they’re seeing is real.
Dissociatives: Disconnection and Distortion
Ketamine and similar dissociative drugs create visual experiences defined by detachment rather than enhancement. Sight and sound become distorted, and users often describe feeling disconnected from their own body and surroundings. At lower doses, this might manifest as the environment looking slightly unreal, almost like watching your life on a screen. At higher doses, particularly in what’s called a “K-hole,” people report complete dissociation from their physical environment and immersion in internal visual experiences that can include vivid, dreamlike scenes.
The visual distortions from dissociatives tend to involve spatial perception more than color or pattern. Rooms may feel enormous or tiny. Perspectives can shift in ways that feel architecturally impossible. The experience is less about seeing new things and more about the familiar world looking fundamentally wrong.
The Pupil Factor
Many drugs cause your pupils to dilate significantly, a condition called mydriasis. This isn’t just a cosmetic side effect. Dilated pupils let in far more light than normal, which directly changes how everything looks. Bright environments become overwhelming. Light sources appear to glow or shimmer more intensely. This contributes to the “everything looks beautiful” quality that many people describe while high, as well as the discomfort of being in brightly lit spaces.
Pupil dilation from drugs can cause blurry vision, light sensitivity, and eye fatigue that lasts for hours. For psychedelics and MDMA, the dilation can persist for the full duration of the experience, which may be 6 to 12 hours. This is part of why lights at concerts or festivals look so spectacular to people on these substances, and why stepping into daylight can feel painful.
Visuals That Don’t Go Away
For a small number of people, visual disturbances persist long after the drug has worn off. Hallucinogen Persisting Perception Disorder (HPPD) is a recognized condition in which perceptual symptoms continue weeks or months after the last use. Symptoms include visual snow (a static-like overlay on your vision), trailing images behind moving objects, flashes of color, halos around objects, and the perception of movement in peripheral vision when nothing is there.
HPPD also includes micropsia and macropsia, persistent floaters, and in some cases difficulty reading. The condition has two subtypes ranging from mild to severe, and to be diagnosed, the symptoms must cause real distress or impair daily functioning. It has been reported after use of classic psychedelics, MDMA, and even ketamine. The condition is distinct from flashbacks, which are brief and intermittent. HPPD is ongoing, and for people who develop it, the visual artifacts become a constant feature of everyday sight.