Pitfalls in the Use of Stereoacuity in the Diagnosis of Nonorganic Visual Loss.
OBJECTIVE
The Titmus Stereotest (Stereo Optical Co., Inc., Chicago, IL) has been used to estimate visual acuity (VA) in the evaluation of nonorganic visual loss. Previous 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 nonorganic visual loss. The purpose of this study was to evaluate the relationship between Titmus stereoacuity and minimal VA based on a real-world testing environment.


METHODS
Cross-sectional observational study.


METHODS
All patients treated at the authors' neuro-ophthalmology service between April 25, 2014, and July 31, 2014.


METHODS
All subjects underwent routine neuro-ophthalmic examination, including Titmus stereoacuity measurements. A compound Bayesian logit-lognormal model accounting for heteroscedasticity was used to determine 95% and 99% prediction intervals of the worse eye's near VA based on stereoacuity. Logarithm of the minimum angle of resolution VA and log stereoacuity were analyzed.


METHODS
Titmus stereoacuity and worse eye VA.


RESULTS
Of 561 patients, 364 subjects 11 to 91 years of age were included. Titmus stereoacuity was associated positively with VA: 9 circles correct (40 seconds of arc) indicated VA of at least 20/40 with 95% confidence and VA of at least 20/79 with 99% confidence; 6 circles correct (80 seconds of arc) indicated VA of at least 20/62 and 20/180, respectively; and 4 circles correct (140 seconds of arc) indicated VA of at least 20/110 and 20/570, respectively.


CONCLUSIONS
When fully accounting for individual variation and the full spectrum of neuro-ophthalmic diseases affecting VA, stereoacuity remains associated with VA, but previous commonly used VA estimates based on stereoacuity overestimated VA. Our results more accurately predict minimum VA from Titmus stereoacuity and should be used preferentially when evaluating patients with suspected nonorganic visual loss. We demonstrated that Titmus stereoacuity cannot definitively establish normal VA, and therefore can suggest, but not fully establish, the diagnosis of nonorganic visual loss.
Department of Ophthalmology, Emory University, Atlanta, Georgia.
Kevin R
KR
Sitko
Department of Ophthalmology, Emory University, Atlanta, Georgia; Department of Pediatrics, Emory University, Atlanta, Georgia.
Jason H
JH
Peragallo
Department of Ophthalmology, Emory University, Atlanta, Georgia.
Samuel
S
Bidot
Department of Ophthalmology, Emory University, Atlanta, Georgia; Department of Neurology, Emory University, Atlanta, Georgia.
Valerie
V
Biousse
Department of Ophthalmology, Emory University, Atlanta, Georgia; Department of Neurology, Emory University, Atlanta, Georgia; Department of Neurological Surgery, Emory University, Atlanta, Georgia.
Nancy J
NJ
Newman
Department of Ophthalmology, Emory University, Atlanta, Georgia; Department of Neurology, Emory University, Atlanta, Georgia; Department of Epidemiology, Emory University, Atlanta, Georgia. Electronic address: bbbruce@emory.edu.
Beau B
BB
Bruce
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003430:Cross-Sectional Studies; D003867:Depth Perception; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014786:Vision Disorders / Q000175:diagnosis* / Q000503:physiopathology; D014787:Vision Tests / Q000379:methods*; D015348:Vision, Binocular / Q000502:physiology*; D014792:Visual Acuity; D055815:Young Adult