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J. C. Rabin, B. Davies, J. Gooch, C. Reilly, R. Rubin, S. Linnemeyer, M. Foxworth; Super Vision: Quantification of Exceptional Acuity and Contrast Detection. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2000.
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© ARVO (1962-2015); The Authors (2016-present)
Optical correction of higher order aberrations make it possible to achieve exceptional ("super") vision (e.g., 3X better than "20/20"). However, no clinical tests quantify superior resolution or contrast detection. We describe design, validation results, and application of a new approach to quantify super vision in a clinical setting.
The Super Vision Test (SVT, Prevision-Vision®) includes high contrast visual acuity (VA; 20/32 to 20/5; 4X smaller than 20/20) and small letter contrast sensitivity (CS; 20/25 letters) on a single, back-illuminated letter chart viewed photopically (100 cd/m2) or through dark green filters (4 and 1 cd/m2) simulating color and brightness of a night vision goggle (NVG) display. SVT VA and CS were assessed in 20 subjects tested with best correction and Izon® high resolution lenses under photopic and low luminance-NVG conditions; and in patients with various conditions (n=129; PRK, LASIK, IOL, early keratoconus, glaucoma).
Photopic SVT VA (mean 20/14 ± 3 letters; 20/19 to 20/11) and log CS (1.05 ± 3 letters; 0.8 to 1.5) agree with established values, and both decrease non-monotonically with luminance (p<0.0001; gradual decrease from 100 to 4 cd/m2; steep square-root decline from 4 to 1 cd/m2). While neither VA (p>0.7) or CS (p>0.5) show consistent improvement with Izon® vs. standard lenses, photopic CS improved >1SD in nine eyes while only two decreased by the same amount. In clinical conditions SVT VA and CS are correlated (r=0.7, p<0.0001), but the likelihood of detecting enhanced vision or decrements >2SD from normal is 3X greater with CS than with VA.
The SVT quantifies exceptional acuity and contrast detection as well as subtle decrements from normal. As predicted for targets of comparable spatial frequency, SVT VA and CS are correlated and potentially redundant; but departures from normal vision are more often detected with SVT CS and at low luminance, perhaps due to lesser stimulus redundancy and/or a more robust (less saturated) contrast response function at threshold levels. In practice SVT VA and CS complement each other providing a precise metric of spatial vision.
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