Background
To determine the value of the distance doubling visual acuity test in the diagnosis of nonorganic visual loss in a comparative
observational case series.
Methods
Twenty-one consecutive patients with nonorganic visual acuity loss and 21 subjects with organic visual loss as controls were
included. Best corrected visual acuity was tested at the normal distance of 5 meters using Landolt Cs. The patient was then
repositioned and best corrected visual acuity was tested with the previous optotypes at double the distance via a mirror.
Results
Nonorganic visual acuity loss was identified in 21 of 21 patients. Sensitivity and specificity of distance-doubling visual
acuity test in functional visual loss were found to be 100% (CI; 83%–100%) and 100% (CI; 82%–100%), respectively.
Conclusion
Distance doubling visual acuity test is widely used to detect nonorganic visual loss. Our results show that this test has
a high specificity and sensitivity to detect nonorganic visual impairment.
Keywords Nonorganic visual loss - Distance-doubling visual acuity test - Malingering - Psychogenic visual loss - Vision chart - Diagnostic techniques - Visual acuity