Visual hallucinosis in patients with Parkinson’s disease

Aim. To determine the effect of visual impairment on the formation of visual hallucinosis.

Materials and methods. We studied 87 patients with Parkinson’s disease (PD). The average age of the patients was 65.16 ± 8.22 years. The patients underwent a comprehensive neurological and ophthalmological examination, including optical coherence tomography of the retina.

Results. The presence of visual hallucinosis was reported by 50.6 % of patients with PD. Extracampine hallucinations (ECH) are the most common. ECH was detected at all stages of PD and in patients with different forms of the disease and patients with ECH have no cognitive impairment. In patients with ECH, there was no decrease in visual acuity, impaired color perception, contrast sensitivity, as well as ophthalmic diseases such as cataracts, glaucoma, etc. An important difference between patients with ECH and patients without ECH was a statistically significant thinning of the retinal layers. Complaints about the presence of illusions were detected in 18.4 % of patients with PD. According to the results of our study, patients with illusions were characterized by a marked decrease in visual acuity, impaired color perception and contrast sensitivity, and, apparently, the presence of illusions in patients with PD can be explained by impaired visual perception and amblyopia. According to the results of neuropsychological testing, patients with illusions have impaired visual-spatial functions. Visual hallucinationsis appeared in the late-stages of PD, patients over 65 years of age with mild cognitive impairment.

Сonclusion. As a result of our study, it was revealed that the development of visual hallucinosis in patients with PD is associated not only with central (cortical) mechanisms, but the peripheral part of the visual analyzer is also of considerable importance, primarily retinal damage and loss of visual afferentation.