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Visual function in human ocular toxoplasmosis
  1. Janine Scherrer1,*,
  2. Milko E Iliev1,*,
  3. Markus Halberstadt3,
  4. Laurent Kodjikian4,
  5. Justus G Garweg2
  1. 1Department of Ophthalmology, University of Bern, Bern, Switzerland
  2. 2Swiss Eye Institute, Bern, Switzerland
  3. 3Department of Ophthalmology, Med University, Hannover, Germany
  4. 4Department of Ophthalmology, Croix-Rousse Hospital, University of Lyon I Claude Bernard, Lyon, France
  1. Correspondence to: Dr J G Garweg Swiss Eye Institute, Bremgartenstr 119, CH-3012 Bern, Switzerland; justus.garweg{at}eye-institute.ch

Abstract

Aim: To assess functional impairment in terms of visual acuity reduction and visual field defects in inactive ocular toxoplasmosis.

Methods: 61 patients with known ocular toxoplasmosis in a quiescent state were included in this prospective, cross-sectional study. A complete ophthalmic examination, retinal photodocumentation and standard automated perimetry (Octopus perimeter, program G2) were performed. Visual acuity was classified on the basis of the World Health Organization definition of visual impairment and blindness: normal (⩾20/25), mild (20/25 to 20/60), moderate (20/60 to 20/400) and severe (<20/400). Visual field damage was correspondingly graded as mild (mean defect <4 dB), moderate (mean defect 4–12 dB) or severe (mean defect >12 dB).

Results: 8 (13%) patients presented with bilateral ocular toxoplasmosis. Thus, a total of 69 eyes was evaluated. Visual field damage was encountered in 65 (94%) eyes, whereas only 28 (41%) eyes had reduced visual acuity, showing perimetric findings to be more sensitive in detecting chorioretinal damage (p<0.001). Correlation with the clinical localisation of chorioretinal scars was better for visual field (in 70% of the instances) than for visual acuity (33%). Moderate to severe functional impairment was registered in 65.2% for visual field, and in 27.5% for visual acuity.

Conclusion: In its quiescent stage, ocular toxoplasmosis was associated with permanent visual field defects in >94% of the eyes studied. Hence, standard automated perimetry may better reflect the functional damage encountered by ocular toxoplasmosis than visual acuity.

  • BCVA, best-corrected visual acuity
  • WHO, World Health Organization

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Footnotes

  • * These authors contributed equally to this paper.

  • Published Online First 20 September 2006

  • Funding: None.

  • Competing interests: None declared.

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