Pitfalls in the Use of Stereoacuity in the Diagnosis of Nonorganic Visual Loss

• Type of Material: Article
• Authors: Kevin R. Sitko, Emory University; Jason Peragallo, Emory University; Samuel Bidot, Emory University; Valerie Biousse, Emory University; Nancy Newman, Emory University; Beau Bruce, Emory University
• Language: English
• Date: 2016-01-01
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.
• Final Published Version (URL): http://dx.doi.org/10.1016/j.ophtha.2015.09.024
• Title of Journal or Parent Work: Ophthalmology (Section 12 EMBASE)
• ISSN: 0014-4169
• Volume: 123
• Issue: 1
• Start Page: 198
• End Page: 202
• Grant/Funding Information: Financial Support: Supported in part by an unrestricted departmental grant (Department of Ophthalmology) from Research to Prevent Blindness, Inc., New York and by NIH/NEI core grant P30-EY006360 (Department of Ophthalmology) and NEI grant K23-EY019341 (Bruce).
• Keywords: Ophthalmology; Life Sciences & Biomedicine; STEREOSCOPIC ACUITY; CONTRAST; Science & Technology; VERNIER

Abstract

Purpose: Titmus stereoacuity testing has been used to estimate visual acuity in the evaluation of non-organic visual loss. Previous predictions were derived from optical degradation of visual acuity in normal subjects and may not account for the variability seen in patients with neuro-ophthalmic pathologies included in the differential diagnosis of non-organic visual loss. The purpose of this study was to evaluate the relationship between Titmus stereoacuity and minimal visual acuity based on a real-world testing environment. Design: Cross-sectional, observational study. Subjects: All patients presenting to our neuro-ophthalmology service between 4/25/2014 and 7/31/2014. Methods: All subjects 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 based on stereoacuity. LogMAR acuity and log stereoacuity were analyzed. Main Outcome Measures: Titmus stereoacuity and worse eye visual acuity. Results: Of 561 patients, 364 subjects aged 11 to 91 years were included. Titmus stereoacuity was positively associated with VA: 9 circles correct (40 seconds of arc) indicated visual acuity of at least 20/40 with 95% confidence and 20/79 with 99% confidence; 6 circles correct (80 seconds of arc): 20/62 and 20/180, respectively; and 4 circles correct (140 seconds of arc): 20/110 and 20/570, respectively. Conclusions: When fully accounting for individual variation and the full spectrum of neuro-ophthalmic diseases affecting visual acuity, stereoacuity remains associated with visual acuity, but previous commonly-used visual acuity estimates based on stereoacuity overestimated visual acuity. Our results more accurately predict minimum visual acuity from Titmus stereoacuity and should be preferentially used when evaluating patients with suspected non-organic visual loss. We demonstrate that Titmus stereoacuity cannot definitively prove normal visual acuity, and therefore can suggest, but not fully establish, the diagnosis of non-organic visual loss.