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Contrast sensitivity and visual hallucinations in patients referred to a low vision rehabilitation clinic
  1. M L Jackson1,
  2. K Bassett2,
  3. P V Nirmalan3,
  4. E C Sayre4
  1. 1Vision Rehabilitation Center, Massachusetts Eye and Ear Infirmary, Harvard Department of Ophthalmology, Boston, Massachusetts, USA Vancouver Island Health Authority, Victoria, BC, Canada
  2. 2British Columbia Centre for Epidemiologic and International Ophthalmology, UBC, Vancouver, BC, Canada
  3. 3LV Prasad Eye Institute, Hyderabad, India
  4. 4Arthritis Research Center of Canada, Department of Statistics and Actuarial Science, Simon Fraser University, Vancouver, BC, Canada
  1. Correspondence to: M L Jackson c/o Vision Rehabilitation, MEEI, 243 Charles Street, Boston, MA, USA, 02114; Marylou_jackson{at}


Aim: To examine the association of reported visual hallucinations and measured visual parameters in adult patients referred for low vision rehabilitation.

Methods: All patients (N = 225) referred to a low vision rehabilitation clinic for a calendar year were asked a standardised question about symptoms of formed visual hallucinations. Best corrected visual acuity and contrast sensitivity using the Pelli-Robson chart were measured. We conducted multiple logistic regression analysis of the association between visual hallucinations and visual parameters.

Results: Of the total cohort, 78 (35%) reported visual hallucinations. Visual acuity and contrast sensitivity were considered in four quartiles. In multiple logistic regression controlling for contrast sensitivity, age, gender, report of depression and independence, measured acuity in each of the poorer three categories (compared to the best) was not associated with reported hallucinations. Contrast sensitivity in the three poorer quartiles (compared to the best) was strongly associated with the report of hallucinations (OR 4.1, CI 1.1, 15.9; OR 10.5, CI 2.6, 42.1; OR 28.1, CI 5.6, 140.9) after controlling for acuity, age, sex, depression and independence.

Conclusions: Lowest contrast sensitivity was the strongest predictor of reported hallucinations after adjusting for visual acuity.

  • Charles Bonnet hallucinations
  • contrast sensitivity

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  • Funding: This study was funded by a CNIB EA Baker Applied Research Grant.

  • Competing interests: none.

  • Published Online First 11 October 2006

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