Influence of accommodative response and visual symptoms on visual display terminal adult operators with asthenopia through adequately corrected refractive errors

PURPOSE: Application of adequate correction of refractory errors for the treatment of asthenopia of young visual display terminal (VDT) workers was evaluated from subjective complaints and the effect on accommodation dynamics (step response) before and after 6 months. METHODS: Young VDT workers who visited the clinic because of eye strain were consecutively selected. Fifteen workers who were under-corrected for myopia and three workers who were over-corrected for myopia were treated by "adequate correction of refractory errors" with spectacles or soft contact lenses. The adequate correction was defined as minimum convex lenses which could obtain visual acuity of 1.2 or better, similar to daily life conditions, without cyclopegia or fogging. The workers were in their 20's. Accommodative responses to step stimuli were recorded by infrared optometer, and questionnaires were filled out by the VDT workers concerning the severity (a severity rating in percent in five steps) of subjective symptoms (headache, dry eye, eye strain, and eye irritation). Spectacles or disposable contact lenses were prescribed for the workers for "adequate correction". Six months later, accommodative responses and subjective symptoms were evaluated and compared with under-or over-corrected conditions and adequate correction. RESULTS: In under-corrected workers, the adequate correction significantly improved complains i.e. headache, eye strain, eye tiredness (p < 0.005). Accommodative responses also improved in gain (%), maximum velocity (D/sec), and time of accommodation and relaxation (p < 0.05). Three over-corrected workers showed improvement of complains and also accommodative response in gain, maximum velocity, and time of accommodation and relaxation. CONCLUSIONS: Application of "adequate correction" to young VDT workers with asthenopia by using adequately corrected spectacles or soft contact lenses improved the asthenopia and accommodative dynamics.