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C. C. Teixeira, A. R. Rodrigues, L. C. L. Silveira; Spatial and Temporal Luminance Contrast Sensitivity Measurements Using Psychophysical Tests Developed for Personal Computers. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2535.
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© ARVO (1962-2015); The Authors (2016-present)
The aim of this work is to measure both spatial and temporal luminance contrast sensitivity using psychophysical tests developed for personal computers and to obtain statistical norms for normal young subjects.
We used a Pentium IV microcomputer (1.7 GHz, 512 MB RAM, 40 GB hard disk) and a software written with C++ Builder 3.0. Visual stimuli were generated using an Annihilator 2 graphic card (Creative) with 24 bits color pallet (8 bits / gun) and displayed on a Multiscan G420 CRTl (Sony), 19", 1024 x 768 pixels spatial resolution, and 120 Hz frame rate. The luminance output as a function of CRT input voltage was linearized by software. Luminance measurements were performed using Chroma Meter CS-100A colorimeter (Konica Minolta), 1o aperture, placed at 1 m from the monitor. A dithering routine was used to obtain 10 bits gray levels. We measured the luminance spatial contrast sensitivity of 30 subjects (15 men, 16-30 years old) and the luminance temporal contrast sensitivity of 34 subjects (16 men, 16-30 years old). Spatial contrast sensitivity was evaluated using sinusoidal black-and-white gratings of eleven spatial frequencies, 0,2, 0,5, 0,8, 1, 2, 4, 8, 10, 15, 20, and 30 cycles per degree (cpd). Temporal contrast sensitivity was measured using a flickering square field at seven frequencies, 0,5, 1, 2, 4, 8, 16, and 32 Hertz (Hz). Mean luminance was kept at 42 cd/m2 for all stimulus conditions. Subjects were monocularly tested at 3 m from the CRT monitor.
Spatial contrast sensitivity curves had the expected band-pass shape, peaking at 300 in the 2-4 cpd range and having a spatial frequency cut-off at 30-40 cpd. Temporal contrast sensitivity curve had a low-pass shape, peaking at 100 in 8 Hz. Statistical tolerance and confidence intervals were calculated for both data set.
These results suggest that psychophysical tests developed for low cost personal computers can be useful to measure spatial and temporal contrast sensitivities of normal subjects and has potential applications on clinical evaluations.
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