Micropsia can be caused by optical factors (such as wearing glasses), by distortion of images in the eye (such as optically, via swelling of the cornea or from changes in the shape of the retina such as from retinal edema, macular degeneration, or central serous retinopathy), by changes in the brain (such as from traumatic brain injury, epilepsy, migraines, or drugs), and from psychological factors.

[citation needed][1] Micropsia is also commonly reported when the eyes are fixating at (convergence), or focusing at (accommodation), a distance closer than that of the object[2] in accord with Emmert's law.

Micropsia causes affected individuals to perceive objects as being smaller or more distant than they actually are.

It is common for patients with micropsia to be able to indicate true size and distance despite their inability to perceive objects as they actually are.

Epileptiform abnormalities including spikes and sharp waves in the medial temporal lobe of the brain can diagnose this condition, which can in turn be the cause of an epileptic patient's micropsia.

After a set of trials, the overall pattern of responses should display a normal distance effect where the more similar the two circles, the higher the number of errors.

Computed tomography (CT) and magnetic resonance imaging (MRI) may find lesions and hypodense areas in the temporal and occipital lobes.

Micropsia, along with hemianopsia, quadrantopsia, scotoma, phosphene, teicopsia, metamorphopsia, macropsia, teleopsia, diplopia, dischromatopsia, and hallucination disturbances, is a type of aura that occurs immediately before or during the onset of a migraine headache.

[4] Although drug-induced changes in perception usually subside as the chemical leaves the body, long-term cocaine use can result in the chronic residual effect of micropsia.

[18] Micropsia may also be a symptom of psychological conditions in which patients visualize people as small objects as a way to control others in response to their insecurities and feelings of weakness.

In some adults who experienced loneliness as children, micropsia may arise as a mirror of prior feelings of separation from people and objects.

[22] Macular degeneration typically produces micropsia due to the swelling or bulging of the macula, an oval-shaped yellow spot near the center of the retina in the human eye.

Some studies show that consuming spinach or collard greens five times a week cuts the risk of macular degeneration by 43%.

[23] CSCR is a disease in which a serous detachment of the neurosensory retina occurs over an area of leakage from the choriocapillaris through the retinal pigment epithelium (RPE).

[citation needed] Treatments involving the occlusion of one eye and the use of a prism fitted over an eyeglass lens have both been shown to provide relief from micropsia.

Speculation has arisen that Carroll may have written the story using his own direct experience with episodes of micropsia resulting from the numerous migraines he was known to have.

[31] Current experimental evidence focuses on the involvement of the occipitotemporal pathway in both the perceptual equivalence of objects across translations of retinal position and also across size modifications.

A variety of drugs that block vascular endothelial growth factors (VEGFs) are being evaluated as a treatment option.