The scale method as a spectral analysis for accommodative fluctuation.

Abstract

ABSTRACf A scale method of computer analysis was developed as an automatic spectral analysis system of the accommodative fluctuations. The scale approach employed a computer to identify wave peaks. Using this new system. spectral analysis of the fluctuations in accommodation measured by an infrared optometer was performed. Both the power spectrum method and the scale method were used to perform a spectral analysis and a wave form analysis. The spectrum peaks obtained by both methods were virtually coincidental. Twenty sec was adequate for the measuring time examined from the viewpoint of data stability. Fluctuations in accommodation were measured in 17 adult males. The mean peak frequency band range in 18 eyes of the young group was 2.5-3.15 Hz, in contrast to 1.25-1.6 Hz in 16 eyes of the middle-aged group. The newly developed system was considered effective as a criterion for visual load in VDT (visual display terminal) work and other high-level visual tasks. INTRODUCfION Present workplace conditions are undergoing rather sudden changes with the advance in modern microelectronics. Heavy physical work is on the wane, and work using the upper extremities, sensory organs, and sophisticated visual functions are on the increase. With this change in overall working conditions, a new examination method is needed which can determine objectively and easily the effects on visual functioning. The items measured in relation to visual work load included amplitude of accommodation, accommodative near point, accommodative far point, accommoda­ tion time, critical flicker fusion frequency, blinking, accommodative fluctuation of the crystalline lens, and convergence, among others. The accommodation-related measurement is likely the most promising method l ). As the result of efforts to obtain an objective measuring procedure, two methods have been developed: one is the observation of the accommodative wave form measured by infrared optometer, from which it was noted that frequency lowered with fatigue 2 ). The other is a new method to measure objectively the accommodation time using a dynamic refractometer 3 ). Both of these approaches can be said to measure the feedback function of the accommodation system via 11~~. ~.~+..~.~. ~m.~, ~~~. #D~~. ~~.~, ~m~., ~ffiK~. Wffi~~