Macropsia

Macropsia is a neurological and perceptual condition in which objects within part or all of the visual field appear abnormally large to the affected individual. As a result of this distortion, the person may feel physically smaller in relation to their surroundings. Macropsia is classified under the broader category of dysmetropsia, which refers to disorders of perceived size or distance of visual objects. Its opposite condition is micropsia, in which objects appear smaller than normal.
Macropsia is closely related to other visual perception disorders, including aniseikonia and Alice in Wonderland syndrome (AIWS), also known as Todd’s syndrome. Although the perceptual experience can be dramatic and distressing, individuals experiencing macropsia typically remain conscious, oriented, and capable of accurately describing their symptoms.

Definition and Classification

Macropsia refers specifically to an enlargement of perceived object size without a corresponding enlargement in the actual visual stimulus. It may affect the entire visual field or be restricted to a particular region. When the distortion affects only one eye and causes a size discrepancy between the images perceived by each eye, the condition is classified as aniseikonia.
Within dysmetropsia, macropsia represents a positive size distortion, whereas micropsia represents a negative distortion. These perceptual anomalies may arise from retinal, neurological, or functional causes and can be transient or persistent depending on the underlying condition.

Physiological Basis

From a physiological perspective, retinal macropsia is believed to result from compression or abnormal displacement of photoreceptor cells, particularly cones, within the retina. When cone receptors are compressed into a smaller retinal area, a given image stimulates a greater number of receptors than normal. This increased receptor activation leads to the perception of a larger-than-normal image.
Such receptor redistribution may occur in retinal disorders that physically alter the macula or adjacent retinal structures. In contrast, central or cortical macropsia arises from dysfunction in higher visual processing areas of the brain, particularly along the ventral occipitotemporal visual pathway, which is involved in object recognition and size perception.

Signs and Symptoms

The hallmark symptom of macropsia is the perception of abnormally enlarged objects. Everyday items may appear disproportionately large, and in some cases, people or parts of the body may appear gigantic. This distortion can lead to a strong subjective feeling of being undersized or overwhelmed by the surrounding environment.
Additional symptoms reported by patients include:

• A sensation of bodily shrinkage relative to surroundings
• Transient auditory disturbances, including buzzing or temporary hearing loss prior to visual distortion
• Visual hallucination-like experiences without loss of insight
• Difficulty judging distance or spatial relationships

Importantly, individuals experiencing macropsia generally remain lucid and alert, retaining full awareness that their perception is abnormal. Episodes are often vividly recalled and described in detail.
Some patients report partial relief when attempting to physically touch the enlarged object, suggesting an interaction between tactile and visual sensory integration.

Visual and Binocular Effects

When macropsia affects only one eye, binocular vision may be disrupted. This unilateral dysmetropsia can lead to symptoms such as:

• Headaches and eye strain (asthenopia)
• Reading difficulties
• Impaired depth perception
• Diplopia (double vision)

These effects arise because the brain receives mismatched image sizes from each eye, making image fusion difficult. Without suppression of one image, binocular rivalry may occur, ranging from mild visual discomfort to intolerable perceptual conflict.

Psychological and Emotional Effects

Macropsia can be accompanied by a wide range of psychological and emotional responses, although it is not considered a psychiatric disorder in itself. Anxiety is common, both during and after episodes, due to the overwhelming and unfamiliar nature of the perceptual distortion.
Some individuals experience:

• Fear or panic during episodes
• Irritability or agitation
• Transient euphoria
• Feelings of detachment or dissociation from the environment or from other people

In children and adolescents, macropsia has been associated with strong feelings of vulnerability and perceived hostility from the environment, given the exaggerated size of surrounding objects. Defensive behaviour may manifest verbally, with attempts to compensate psychologically for perceived physical smallness.
Despite these effects, there is broad consensus that psychological conditions do not cause macropsia, although psychological distress may arise as a secondary consequence. Most patients show no evidence of underlying psychiatric illness, and psychiatric treatment is usually unnecessary unless anxiety becomes persistent.

Causes and Aetiology

Macropsia has a diverse range of causes, which can be broadly grouped into neurological, retinal, pharmacological, and systemic categories.

Neurological Causes

Neurological macropsia may occur in association with:

• Migraine, particularly migraine with aura
• Alice in Wonderland syndrome, often linked to migraine or viral illness
• Complex partial (focal) epilepsy, where macropsia may precede or follow seizure activity
• Cerebral infarction, particularly lesions affecting the posterior cerebral artery and ventral occipitotemporal cortex

In such cases, macropsia reflects altered cortical processing of visual information rather than primary eye disease.

Retinal and Structural Causes

Several retinal conditions are known to produce macropsia, often through mechanical displacement or compression of photoreceptors. These include:

• Epiretinal membrane, frequently associated with metamorphopsia and aniseikonia
• Vitreomacular traction, causing abnormal adhesion between vitreous and retina
• Macular oedema, leading to altered photoreceptor spacing
• Retinal detachment and surgical reattachment, particularly macula-off detachments
• Retinoschisis, involving splitting of retinal layers

In these cases, the physical reorganisation of retinal cells directly alters image scaling.

Pharmacological Causes

Macropsia has been reported as a rare adverse effect of certain medications and psychoactive substances. Notable examples include:

• Zolpidem, a hypnotic drug used for insomnia
• Citalopram, a selective serotonin reuptake inhibitor antidepressant
• Cannabis, psilocybin (magic mushrooms), and cocaine

Drug-induced macropsia is typically transient and resolves after the substance is metabolised or discontinued. Reported cases suggest a higher prevalence among women, possibly related to differences in drug metabolism and plasma concentration.

Infectious and Systemic Causes

Macropsia may occur during or after viral infections, particularly in children, and is commonly associated with Alice in Wonderland syndrome. In such cases, full recovery of normal visual perception is the rule.

Diagnosis and Clinical Considerations

Diagnosis of macropsia is primarily clinical, based on patient history and symptom description. Ophthalmological examination is essential to identify retinal causes, while neuroimaging may be required when a central neurological origin is suspected.
Because patients retain insight and awareness, macropsia must be distinguished from psychotic visual hallucinations. The absence of delusions, disorganisation, and impaired reality testing is a key diagnostic feature.