title: Ocular Tonometry and Sporadic Creutzfeldt - Jakob Disease (sCJD): A Confirmatory Case-Control Study.
abstract: OBJECTIVE
  To evaluate the hypothesis that sporadic Creutzfeldt-Jakob disease (sCJD) may be transmitted through ocular tonometry.
  
  
  BACKGROUND
  The infectious agent of sCJD may be present in the cornea prior to clinical symptoms. Cornea infectiousness has been documented by cornea transplants in guinea pigs and humans. sCJD is resistant to complete inactivity by conventional sterilization techniques. Thus contact tonometry equipment is not disinfected sufficiently to kill sCJD. We previously hypothesized that contact tonometry is a sCJD risk factor.
  
  
  METHODS
  Population-based case-control study.
  
  
  METHODS
  Department of Neurology, School of Medicine, Loma Linda University, Loma Linda, CA, USA; 4 years.
  
  
  METHODS
  An 11-state case-control study of pathologically confirmed definite sCJD cases, individually matched controls, and a sample of control surrogates was conducted. Ocular tonometry histories were obtained from case-surrogates, controls, and a sample of control-surrogates.
  
  
  RESULTS
  The odds ratio (OR) for ever vs never having had an ocular tonometry test was statistically significant for matched and unmatched analyses for 15 through 3 years prior to disease onset, using both control self-responses and control surrogates: ORs were ∞ and 19.4 with 1-sided P-values <0.0001 and 0.003 and ORs=∞ and 11.1 with 1-sided P-values <0.003 and 0.02, respectively. ORs increased as the number of tonometry tests increased during this age period: trend test, 2-sided P-value < 0.0001. For ≥5 vs <5 tonometry tests, the OR was 5.8 (unmatched) and 3.7 (matched), 2-sided P-value<0.00005. Respondents generally could not specify the type of tonometry. There was no indication of increased tonometry testing among cases within 2 years of disease onset.
  
  
  CONCLUSIONS
  Thea priorihypothesis was supported. Contact tonometry, preferred by ophthalmologists, may be capable of transmitting sCJD. Consideration should be given to using disposable instrument covers after each use. The use the disposable covers or non-contact tonometry is preferable in the absence of effective disinfectant processes at this time.
authors.affiliation: Department of Neurology, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
authors.forename: Zoreh
authors.initials: Z
authors.lastname: Davanipour
authors.affiliation: Department of Neurology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA ; Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.
authors.forename: Eugene
authors.initials: E
authors.lastname: Sobel
authors.affiliation: Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.
authors.forename: Argyrios
authors.initials: A
authors.lastname: Ziogas
authors.affiliation: Department of Neurology, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
authors.forename: Carey
authors.initials: C
authors.lastname: Smoak
authors.affiliation: Department of Neurology, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Bohr
authors.affiliation: Department of Internal Medicine, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
authors.forename: Keith
authors.initials: K
authors.lastname: Doram
authors.affiliation: Department of Pathology, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
authors.forename: Boleslaw
authors.initials: B
authors.lastname: Liwnicz
keywords: Sporadic Creutzfeldt-Jakob disease (sCJD); case-control study; eyes; iatrogenic transmission; intraocular pressure (IOP) test; neuroepidemiology; ophthalmology; prion diseases; risk factors
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