June 2015
Volume 56, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2015
Pitfalls in the Use of Stereopsis for the Diagnosis of Non-organic Visual Loss
Author Affiliations & Notes
  • Kevin Sitko
    Ophthalmology, Emory University, Atlanta, GA
  • Jason Peragallo
    Ophthalmology, Emory University, Atlanta, GA
    Pediatrics, Emory University, Atlanta, GA
  • Samuel Bidot
    Ophthalmology, Emory University, Atlanta, GA
  • Valerie Biousse
    Ophthalmology, Emory University, Atlanta, GA
    Neurology, Emory University, Atlanta, GA
  • Nancy J. Newman
    Ophthalmology, Emory University, Atlanta, GA
    Neurology and Neurosurgery, Emory University, Atlanta, GA
  • Beau B Bruce
    Ophthalmology and Neurology, Emory University, Atlanta, GA
    Epidemiology, Emory University, Atlanta, GA
  • Footnotes
    Commercial Relationships Kevin Sitko, None; Jason Peragallo, None; Samuel Bidot, None; Valerie Biousse, None; Nancy Newman, None; Beau Bruce, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2015, Vol.56, 554. doi:
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      Kevin Sitko, Jason Peragallo, Samuel Bidot, Valerie Biousse, Nancy J. Newman, Beau B Bruce; Pitfalls in the Use of Stereopsis for the Diagnosis of Non-organic Visual Loss. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):554.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: Titmus stereoacuity testing is used to estimate visual acuity (VA) in the diagnosis of non-organic visual loss (NOVL), but only predicts mean VA and doesn’t account for normal inter-subject variability. These predictions were derived from optical degradation of VA in normal subjects and may not account for the variability seen in patients with neuro-ophthalmic pathologies included in the differential diagnosis of NOVL. The purpose of this study was to evaluate the relationship between Titmus stereoacuity and minimal visual acuity based on a real-world testing environment.

Methods: All patients presenting to our service between 4/25/2014 and 6/26/2014 underwent routine neuro-ophthalmic examination, including Titmus stereoacuity measurements. A compound Bayesian logit-lognormal model accounting for heteroskedasticity was used to determine 95% and 99% prediction intervals of the worse eye’s near visual acuity (VA) based on stereoacuity. LogMAR acuity and log stereoacuity were analyzed.

Results: Of 561 patients, 28 were excluded for missing stereoacuity or VA measurements, 4 for cognitive issues, 3 for suspected NOVL, and 119 for heterotropia or history of strabismus/amblyopia. Patients who correctly identified zero circles (43) were also excluded from the calculation. 364 subjects were analyzed [median age: 45-yo (range: 11-91); 258 (71%) women; median worse-eye VA 20/25; median Titmus: 7 circles correct]. Titmus stereoacuity was positively associated with VA: 9 circles correct (40 seconds of arc) indicated VA of at least 20/41 with 95% confidence and 20/88 with 99% confidence; 6 circles correct (80 seconds of arc): 20/63 and 20/197; and 4 circles correct (140 seconds of arc): 20/106 and 20/582, respectively.

Conclusions: When fully accounting for individual variation and the full spectrum of neuro-ophthalmic diseases affecting VA, stereoacuity remains associated with VA, but commonly-used VA estimates based on stereoacuity overestimate VA. Our results more accurately predict minimum VA from Titmus stereoacuity and should be preferentially used when evaluating patients with suspected non-organic visual loss. We demonstrate that Titmus stereoacuity cannot establish definitively normal VA, and therefore can only suggest, but not establish, the diagnosis of NOVL.

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