Abstract
Purpose::
Glare light deteriorates central vision but the effects on the peripheral vision remain unclear. Contrast sensitivity function (CSF) is a comprehensive measure of vision. This study compared the effects of glare on the central and peripheral CSF.
Methods::
Twenty subjects (gender matched) with a mean age of 21.8 (± 1.2) years participated. Central CSF was taken at 5 spatial frequencies (1.5, 2.9, 5.8, 12.5 and 18.8 cycle per degree; cpd) through a 4 mm artificial pupil (OD only) using a vertical grating of 1.4° with two longitudinal glare light sources fixed on both sides at 2.5°, 5° or 7.5°. In addition, peripheral CSF was taken from 3 retinal positions (5°, 10° and 15° from the fovea). The glare sources were placed at 2.5° from the gratings when the peripheral CSF was taken. Control CSF was also taken without the glare.
Results::
The effects of glare were significant for the central and 5° retinal eccentricity at low spatial frequencies (p<0.05). CS decreased by 25% - 40% at 1.5 to 5.8 cpd. Peripheral CSF was reduced significantly in all spatial frequencies with or without the glare (p<0.05). The reductions in CSF increased with retinal eccentricity. Glare within the central 5° significantly reduced the central CSF of low spatial frequencies (p<0.05). When the glare was fixed at 2.5°, central CS was reduced by 35% and 25% at 1.5 cpd and 2.9 cpd respectively. Similar observations were obtained when the glare was fixed at 5°.
Conclusions::
Glare light deteriorates the central and peripheral CSF differently. The reduction in central CSF is more apparent in low spatial frequencies. Peripheral CSF deteriorates with retinal eccentricity and the effect is enhanced by glare. The significance will be discussed with regard to dynamic tasks involving the detection of object and motion. Further investigations are being conducted in the aged population.
Keywords: contrast sensitivity • detection