The Research On Spatial Contrast Sensitivity Measurements Based On B/S Structure

Background: Contrast sensitivity(CS) is an important parameter to examine and assess the visual function. There are a great variety of methods and indexes to evaluate human’s visual function, i.e. visual acuity, view, photaesthesia. Among them, visual chart is the most common method on clinic. The diagnosis is through distinguishing the direction of black letter E in white background. In fact, this method is based on vision which uses visual acuity and visual field as quantitative standard of visual function.Visual chart is efficient under high-contrast, but it can not work well under low-contrast. With the further researches of visual function, ophthalmologists found visual chart can’t satisfy the needs of ophthalmology fully on clinic. The method about visual acuity cannot evaluate the visual function comprehensively and accurately, especially to amblyopia, maculopathy and other ophthalmic diseases. Using this traditional method may miss the early diagnosis about visual diseases and delay the treatment, which would bury curses for the later visual function. The researchers and ophthalmologists have found that the CS is a very accurate and comprehensive index to visual function. CS could not only examine the visual function under the high-contrast background, but also assess it under the low-contrast one. More and more ophthalmologists are realizing the importance of CS. Unfortunately, the measuring methods of CS are confined, so that CS isn’t applied extensively on clinic. Currently, there are some measuring instruments in the markets, but they are too expensive to be widely applied. Taking advantage of “ Internet + ”, we propose a spatial contrast sensitivity measurement method based on B/S. Objective: To simplify and optimize the measurement of CS by designing a software based on B / S. Methods: The design of this project is to combine HTML5 and Javascript coupled with CSS. The measurement based on the keyboard is that participants use direction buttons to judge the position of the grating with 57 cm distance from the displayer. The grating will appear on the both sides of sighting target randomly, meanwhile the other side will present a gray picture without color difference with the background. Spatial frequency(SF) content in accordance with the abscissa, the ordinate CS for CSF curve for result analysis. The measurement based on the mouse is that participants use onMouseWheel to adjust the contrast of grating. Under the default contrast, moving the onMouseWheel can adjust the contrast till the threshold of just recognizing or unrecognizing the grating, at the same time pressing the mouse can complete once measurement. Plot the CSF curve which the abscissa and ordinate same with the measurement based on keyboard. Results: The measurement based on the keyboard can measure the CS of three participants under the different SF of 0.5, 1, 2, 4, 8, 16 c/d. Finishing the six groups of SF to every participant costs 0.5h for the method based on the keyboard, and 10 mins for the mouse. Conclusion: The project of contrast sensitivity measurement based on B/S is feasible. The results are in accord with other methods. The measurement based on the keyboard is more accurate, while the method based on the mouse is faster and not accurate enough.