Palinopsia

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Palinopsia
SpecialtyOphthalmology

Palinopsia (Greek: palin for "again" and opsia for "seeing") is the persistent recurrence of a visual image after the

symptoms with a wide variety of causes. Visual perseveration is synonymous with palinopsia.[dubious – discuss
]

In 2014, Gersztenkorn and Lee comprehensively reviewed all cases of palinopsia in the literature and subdivided it into two clinically relevant groups:

head trauma, prescription drugs, visual snow syndrome or hallucinogen persisting perception disorder
(HPPD), describes afterimages that are affected by ambient light and motion and are unformed, indistinct, or low resolution.

Presentation

People with palinopsia frequently report other visual illusions and hallucinations such as

entoptic phenomena, and cerebral polyopia.[citation needed
]

Cause

Further information: Hallucinatory palinopsia § Cause, and Illusory palinopsia § Cause

idiopathic seizures,[10] etc.) cause focal cortical hyperactivity or hyperexcitability, resulting in inappropriate, persistent activation of a visual memory
circuit.

Pathophysiology

clomiphene,[15] oral contraceptives, and risperidone[16] have been reported to cause illusory palinopsia. A patient frequently has multiple types of illusory palinopsia, which represent dysfunctions in both light and motion perception. Light and motion are processed via different pathways, suggesting diffuse or global excitability alterations.[citation needed
]

Diagnosis

Differentiation from physiological afterimages

Palinopsia is a

benign phenomenon.[1][3][17] Physiological afterimages appear when viewing a bright stimulus and shifting visual focus. For example, after staring at a computer screen and looking away, a vague afterimage of the screen remains in the visual field. A stimulus consistently produces the same afterimage, which is dependent on the stimulus intensity and contrast, the time of fixation, and the retinal adaptation state. Physiological afterimages are usually the complementary color of the original stimulus (negative afterimage), while palinoptic afterimages are usually the same color as the original stimulus (positive afterimage). There is some ambiguity between illusory palinopsia and physiological afterimages since there are not concrete symptomatic criteria which determines if an afterimage is pathological.[citation needed
]

Illusory versus hallucinatory

Further information: Illusory palinopsia and Hallucinatory palinopsia

Illusory palinopsia is due to an abnormality in the original perception of a stimulus and is similar to a visual illusion: the distorted perception of a real external stimulus. Hallucinatory palinopsia is due to an abnormality after a stimulus has been encoded in visual memory and is similar to a complex visual hallucination: the creation of a formed visual image where none exists.[citation needed]

External conditions such as stimulus intensity, background contrast, fixation, and movement typically affect the generation and severity of illusory palinopsia but not hallucinatory palinopsia. Illusory palinopsia consists of afterimages that are short-lived or unformed, occur in the same location in the visual field as the original stimulus, and are continuous or predictable. Hallucinatory palinopsia describes formed afterimages and scenes that are lifelike, high-resolution, long-lasting, occur anywhere in the visual field, and are unpredictable. Illusory palinopsia are caused by diffuse neuronal pathology such as global alterations in neurotransmitter receptors, while hallucinatory palinopsia is typically caused by focal cortical pathology.[citation needed]

The clinical characteristics that separate illusory from hallucinatory palinopsia also help differentiate and assess risk in visual illusions and hallucinations. Complex (formed) visual hallucinations are more worrisome than simple visual hallucinations or visual illusions.[citation needed]

Research

Research needs to be performed on the

dysmetropsia, and halos.[2]

Future advancements in

saccadic suppression).[citation needed
]

References

  1. ^
    PMID 5721933
    .
  2. ^
    PMID 25113609
    .
  3. ^
    PMID 10224677
    .
  4. PMID 11886369
    .
  5. S2CID 28424667
    .
  6. PMID 9604138
    .
  7. S2CID 219197116
    .
  8. PMID 18238797
    .
  9. PMID 2531161
    .
  10. S2CID 12737336
    .
  11. PMID 2310343
    .
  12. PMID 10770476
    .
  13. PMID 11411821
    .
  14. PMID 18451209
    .
  15. PMID 7710399
    .
  16. S2CID 9009335
    .
  17. PMID 24487436
    .

External links

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