Computer has become one of the main tools in educational operation requiring prolonged daily usage. The use of computer device has increased throughout the developed countries ranging from five minutes a day to eight  hours  a  day  depending  on  the  type  of  job  a person does. The extent to which an individual experiences computer usage related symptoms is largely dependent upon visual demands of the task being performed.

According to Gupta et al. (2014), 70 to 75% of computer workers have eye problems which are the most frequently related health problems. Up to 90% of computer users report visual problems and eye irritation which are associated with tasks that require repetitive motions occurring over long period of time. Various degrees of eye dysfunctions appear to suggest that it originates from prolonged and protracted working before computer (Sauter, 2001; Ellahi et al., 2011).

The human visual system is responsible for acquiring and processing the visual information.  Eye condition such as irritation, allergic conjunctivitis, blurred vision, eye aches, glaucoma and refractive errors represents a group of undesirable hazards to health that form a recognizable pattern, especially of something undesirable that have been linked to prolonged sitting before computers under operation (Amalia et al., 2010; Ellahi et al., 2011; Akinbinu and Mashalla, 2013).

Visual acuity is the measurement of acuteness of central vision. Visual acuity is a complex phenomenon influenced by many factors; some of which are the state of the image forming mechanism of the eye, the state of the cones and stimulus factors including illumination, brightness of the stimulus, contrast between stimulus and background.

Accommodation is an active process that requires muscular effort. The degree to which the lens curvature can be increased is, of course limited and light rays from a very near object cannot be brought to focus on the retina even with the greatest effort. The nearest point to the eye at which an object can be brought into clear focus by accommodation is called the near point of vision. The near point recedes throughout life, slowly at first and then rapidly with advancing age, from approximately 90 cm at age 10 to approximately 83 cm at age 60. By the time a normal individual reaches age 40, the loss of accommodation is usually sufficient to make reading and close work difficult (Ganong, 2007).

Competitiveness in today’s world requires the use of computers for problem solving. At the National Open University of Nigeria (NOUN), there is no resident staff and student on the campuses/study centres, while the bulk of activities in NOUN are the production and provision of instructional materials to learners (students). The learning activity of the institution is predicated on effective system of communication which takes the advantage of the existence of computers and associated devices in carrying out the function of teaching.

The shift to almost 100% computer use by many companies and institutions was alluded to by Abdelaziz et al. (2009) and Ellahi et al (2011) whose work observed that health complaints are often found predominantly in computer users. Investigation of these health concerns gave birth to the emergence of what has been described as Computer Vision Syndrome. These syndromes include complaints such as eye irritation, eye strain, eye ache, lacrimation,  blurred  vision,  hypermetropia,  photophobia and carpal tunnel syndrome.

In view of the boundless structure of the NOUN, the use of Information and Communication Technologies (ICT) has greatly influenced performance of tasks of staff which requires the use of computer and keeps them on this device for prolonged hours. Literatures were reviewed on human visual system, visual acuity, eye and vision related complaints, visual demands of computer workers, computer usage in Nigeria and eye health problems as well as the mechanism and operation of open and distance learning.

This research was a cross sectional descriptive survey of the staff of National Open University of Nigeria (NOUN). The study comprised of 297 staff randomly selected from the 902 staff (using Fischer’s minimum sample size determination formular). Multi-staged random sampling method was used to select 17 study centres from the 44 existing study centers of NOUN. The subjects included in the survey were devoid of any visual related problems and procedures were guided by the standard ethical practice of the University of Ilorin and NOUN.

A self-constructed questionnaire and Snellens chart were the tools used to obtain information from the subjects. Visual acuity was conducted with the help of 4 trained Ophthalmic Nurses at near similar conditions in the various centres of investigation. Visual acuity were graded as “very desirable”, “desirable” and “not so desirable” acuities (Table 1).

Data obtained were expressed in means, frequencies and percentages. Chi square statistic and correlation analysis were used to test for the relationship among computer usage, pattern of usage and visual acuity at 5% level of significance using Statistical Package for Social Sciences (SPSS) version 16.

Descriptive analyses in frequencies and percentages were used to describe the pattern of computer usage among the subjects (Figure 1). The respondents were first divided by whether or not they use computer; hence, Chi square analysis was used to measure the association between computer use and visual acuity (Tables 2 and 3). The patterns of computer use among computer users were further correlated with their visual acuities (right and left eye visual acuities). Also, some of the results were presented based on three staff categories of NOUN which are actively involved in computer use. These are the academic, administrative and support staff (e.g. technicians, counsellors, drivers, etc). Males, subjects in the lesser age groups, those with less than 4 years of experience and academic staff, use computers more than their other counterparts. Subjects who are in their late 50s account for the majority of non computer users (Table 4).

The Chi square analysis showed that computer usage is significantly associated with visual acuity. Subjects who do not use computer have  more  desirable  acuities  than their counterparts (Table 3).

Frequency of computer use (occasionally, weekly and daily) significantly correlates with visual acuity of the subject (Table 5). The scatter plots (Figures 2 and 3) showed that less desirable acuity is significantly associated with daily computer use.

The application of computers in institutions of higher learning is best exemplified by Open University system that depends largely on computer use for distance learning activities.

The bulk of activities at the NOUN are the production and provision of instructional materials to learners (students). The learning activity is predicated on effective system of communication which takes the advantage of the existence of computers and associated devices in carrying out the function of teaching.

The findings of this study revealed that less desired visual acuity exist more among the academics (89%), the group whose roles make the highest demand on the use of computers. Strongly implicated is the prolonged use of computer as a risk factor for visual dysfunctions even if some environmental and genetic  factors  may  be  contributing to this as observed by Sanchez et al. (2010) and Tatemichi et al. (2004).

The findings on the investigation of pattern of computer usage further established the association between computer usage and visual acuity; less desirable acuity were found in staff with daily computer users compared to their counterparts with weekly and occasional use. The length of time spent daily was also identified to be a contributing factor with not so desirable acuity. Staff who spent more than 8 h on daily computer use had less desirable acuity than their counterparts who spent less.

The findings showed a continuous increase in the percentage of staff with visual dysfunctions as daily duration of exposure to computer increases agreed with the previous study by Abdelaziz et al. (2009) who affirmed that duration of computer usage may have effect on visual acuity. Since near point recedes throughout life starts slowly at first and then rapidly as an individual advances in age from approximately 90 cm at age 10 to about 83 cm at age 60. This recession has been attributed primarily to increasing hardness of the lens consequently leading to loss of accommodation precipitated by steady decrease in the degree to which the curvature of the lens has been increased.

 Institute of Electrical and Electronics Engineers (IEEE, 2003) reported that concentrating on the screen for long period could reduce the blink rate and allow the tear film on the surface of the eye to dry which can result into dry and sore eyes. Suzuki et al. (2006) in a study conducted by the Department of Human Factor Engineering, University of Occupational and Environmental Health, Japan, revealed that visual strain occurred after merely 60 min of video terminal work, which further resulted in lower productivity.

Seybert (2007) examined the differences in the regular use of ICT among women and men in the different members States European Union. In nearly all European countries and in all age groups, however, men are more regular users of both computers and the internet than women and many more men than women are employed in computing jobs throughout the European Union.

Tomte (2011) also noted that the overall picture of the situation relating to gender and ICT has so far been that men have been dominant and left the women behind.

The continuous steady decrease in the percentage of computer users with normal visual acuity as the number of years of computer usage increases, testifies to the fact that years of  usage  is  a  risk  factor  to  visual  acuity  of computer users.

This study has attempted to investigate the pattern of computer usage and visual acuity among computer users at the NOUN. This study therefore concludes that prolonged computer usage over a long period of time without interaction of activity may lead to the propagation of poor vision and lower productivity. Hence, it is suggested that that periodic eye examination and public health campaign should be adopted as preventive strategies in order to maintain vision integrity among computer users. Sensitization of staff on the effective use of computer with necessary precautions to limit the dangers of job hazards should be frequently organized for staff in the institution. 

Authors have none to declare.