ABSTRACT
Objective To evaluate the feature of meibomian glands and tear film lipid layer thickness (LLT) in dry eye of children with long-term visual display terminals (VDTs) exposure.Methods Cross-sectional case control observation was performed.Eighty-four 6-14 years old children (149 eyes) with long or short time VDTs exposure from January to August 2017 in Tianjin Medical University Eye Hospital were enrolled,including 29 children 56 eyes for long time VDTs group and 55 children 93 eyes for short time VDTs group.Questionnaires were designed to detect disease history and ocular surface disease index (OSDI).Slit lamp microscopy,Keratograph 5 M,lipiview ocular surface interometry examination,corneal-conjunctival fluorescence staining,tear film break-up time (BUT) and Schirmer test (S I t) were performed on all the subjects.The subjective OSDI and clinical signs were compared between long time VDTs group and short time VDTs group and correlation between OSDI and clinical signs were analyzed in each group.This study followed the declaration of Helsinki.Informed consent was obtained from each subject or the guardian prior to any medical examination.Results Compared with the short time VDTs group,high OSDI value and long average noninvasive BUT (NIBUTav) were observed in the long time VDTs group,the differences were statistically significant (OSDI:t =-2.662,P =0.009;NIBUTav:Z =2.315,P =0.021).The meibomian gland dropout score was significantly different between the 2 group (x2 =11.779,P =0.008).In long time VDTs group,OSDI was negatively correlated with S I t (rs =-0.598,P =0.050) and positively correlated with meibomian gland dropout score and NIBUTav (rs =0.522,P =0.022;rs =0.597,P =0.011).In short time VDTs group,OSDI was positively correlated with first time noninvasive BUT (NIBUTf),NITBUTav and partial blink rate (rs =0.372,P =0.030;rs =0.408,P =0.008;rs =0.426,P =0.050).Conclusions Compared with short time VDTs exposure,the value of subjective OSDI was high and meibomian gland dropout was serious in long term VDTs exposure dry eye children.The OSDI value is associated with NIBUTf and partial blink ratio in short time VDTs dry eye children.
ABSTRACT
Objective To design a VDT operation related upper extremities fatigue detection system using keying duration (KD)as an indicator of fatigue and to execute experimental verification.Methods The system included the software part able to calculate,compare and analyze KD and hardware part able to support normal VDT operations.Subjects finished typing task under controlled condition while the system was running. The flexor digitorum superficialis (FDS), extensor digitorum communis(EDC),extensor carpi radialis(ECR),extensor carpi ulnaris(ECU)muscle fatigue were retrieved by sEMG method and standardized questionnaire. Results As the number of keystrokes increased, KD shortened by 1.3%, FDS MVC% dropped by 22.9%,and EDC MVC% decreased by 47.9%.The perceived level of typing fatigue also increased.Conclusion Results revealed KD's change with fatigue,showing the possibility of using KD as an indicator of fatigue and validating the feasibility and effectiveness of the system design.
ABSTRACT
Objective To analyze the musculoskeletal injuries related to touch screen VDT operation and design implications.Methods The effects of touch screen size and angles on touch-screen-VDT-operation-related muscle load and fatigue were explored using thorough experiment and EMG acquisition method,and the independent variables included the size and angle and the dependant variables consisted of the load and fatigue of flexor digitorum superficialis (FDS),extensor digitorum communis (EDC),extensor carpi radialis (ECR) and extensor carpi ulnaris (ECU).Results No significant difference was found with regard to pointing success rate and accuracy at all screen sizes and angles levels.FDS and EDC MVC％ increased with increasing touch screen size at all levels of angles.FDS MVC％ decreased while EDC MVC％ increased with inclining angles at all levels of touch screen sizes.All measured muscles' MF did not decrease with time.Conclusion This study helps to provide basis for the optimization of equipment design,reduce exposure to musculoskeletal injuries risks and implement primary prevention.