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The digital revolution, which has been underway since the 1980's, is disrupting our daily routines with an exponential increase in the use of screens, which has not been without consequence to our visual system. Digital eye strain (DES), or computer vision syndrome (CVS), includes all the visual symptoms secondary to the use of digital devices. DES is present in at least 50% of regular users of digital media and is defined by blurred vision, difficulty focusing, ocular irritation or burning, dry eye, visual fatigue, headaches and increased sensitivity to light. Exposure time, age, female gender, and work environment are the main factors increasing its prevalence. Its pathophysiology, still poorly understood, is felt to be multifactorial and includes disturbances in the accommodative-convergence balance and changes in the ocular surface. Regarding accommodation and convergence, the studies are mostly old and their results heterogeneous. Conversely, many studies have shown an increase in the prevalence of dry eye in screen users. Although the retinal toxicity of blue light has been proven in in vitro models, the low level of evidence in the available studies does not allow it to be clearly correlated with the symptoms of DES. The objective of this review is to condense the knowledge available in the literature on the symptoms, prevalence, pathophysiology and management of DES.

To study the prevalence of hyperopia in school-aged children and to analyze the factors that increase the risk of squint or amblyopia in a retrospective study.Three hundred eyes of 150 children with hyperopia who did not have anisometropiaor =1.5 D were selected. Complete ophthalmological examination was performed for all children. Hyperopia was defined when spherical equivalent was +0.5 D or greater. Amblyopia was screened and treated by patching therapy and then penalisation. Complete spectacle correction was achieved in children with high hyperopia (+3.5 D or greater) or in presence of squint or amblyopia. A statistical analysis compared the results using the Mann-Whitney test and the chi square test.The mean age was 9.5+/-2.7 years. Girls were statistically more represented than boys. The mean sphere measured overall was +2 D (+/-1.65). Severe hyperopia was detected in 19% of the children; it was latent in 35% of children. Strabismus was detected in 7% and was accommodative in 25%. Esotropia was the most prevalent deviation (72.8%). The prevalence of amblyopia was 12%. The mean sphere measured in amblyopic children was 5.66 D (+/-1.64 D). Initial depth of amblyopia was mild to moderate and 98% of the children achieved iso-acuity after patching therapy. The correlation between severe hyperopia, amblyopia, and squint was statistically significant. Indeed, the risk ratios of squint and amblyopia, 5.2 and 3.70, respectively, were significantly high in children with severe hypermetropia. Complete spectacle correction improved final visual acuity and reduced the angle deviation in accommodative esotropia.Children with hyperopia of +3.5 D or greater have an increased risk of amblyopia and squint that threatens their visual function. Hyperopic correction should be prescribed even if no strabismus or amblyopia is detected in order to prevent this risk. Screening programs should also be promoted to detect these children at an early age.

To report the relative frequency of the asthenopic complaints in an african black population.Data from 184 records of African black subjects with asthenopic complaints and a normal ocular examination between January 1996 and December 1998 were considered.There were 87 males (47.3%) and 97 females (52.7%). The mean age was 24.6 +/- 9.2 years with a sex ratio of 1:1. Asthenopic symptoms were: headache (47.0%), ocular pain (37.0%), tearing (24.5%), blurred vision (23.4%), photophobia (20.1%), burning sensation (12.5%), foreign-body sensation (8.7%), red eyes (4.3%) and diplopia (4.3%). Asthenopic subjects with headache had more associated symptoms. Headache was 2-3 times more frequently associated with the presence of tearing, foreign-body sensation and burning complaints than others.African black people seem to present the same asthenopic symptoms as in other races. Headache is the main symptom. Tearing, foreign-body and burning sensation are the most common complaints associated with asthenopic headache.

The vertebral cervical syndrome is a clinical entity defined as a dysfunction of the cranio-cervical junction of traumatic or non traumatic cause. The authors report on asthenopic disorders occurring in such a syndrome. The fusion amplitude and the accommodation power were reduced in all patients and were a cause of delayed job recurrence. The treatment of fusion was long, painful and, in some cases, not successful. A depressive status associated with a prolonged job interruption were bad prognosis factors. A differential diagnosis has to be made with the so-called insurance neurotic reaction.

This study provides the first description of a test of fixation disparity that can be used in daily clinical practice. Exploration of this problem lays a basis for understanding, and allows rational prescription of the use of small prisms for the treatment of asthenopia associated with horizontal heterophoria. The fixation disparity is opposite to the heterophoria in almost 30% of cases. The test has a specificity of 71,5% for a study population of 55 patients. When the disparity test was abnormal, use of this examination demonstrated that the prescription of an adapted prism was effective in all cases in eliminating the disparity. This prescription usually involved asymmetric prisms. We also found that complaints of non-specific neck and back pains tended to improve in parallel to the improvement in the asthenopia and the elimination of the disparity. We feel that these postural pains ares part of the asthenopia related to symptomatic heterophoria. The ability to study disparity in daily clinical practice will also provide the physician with a means to study the genetic relationships underlying tropias and phorias when disparity is abnormal.

An epidemiological survey on 30,000VDT operators has been carried out to evaluate the relationship between asthenopia and monitor characteristics. A VDU operator has been classified as asthenopeic if he complained about at least two of the following ten symptoms: headache, tearing, eye smarting, blurred vision, double vision, ocular itching, photophobia, blinking, nausea, eye heaviness. Visual discomfort has been related to 1) the presence of flicker; the possibility to regulate, 2) brightness, 3) height; and 4) inclination of monitor. Asthenopia has resulted statistically correlated to the presence of flicker and to the impossibility of regulating height and inclination of monitor for both sexes. The possibility to regulate monitor brightness has not determined a reduction of visual discomfort either in men or in women.

Insufficiency of accommodation in children is often misdiagnosed, and particularly in preschool age. Subject if symptoms are unspecific, asthenopia, difficulties in nearwork, and for concentration. Differential diagnosis must be done between dyslexia, non refractive accommodative esotropia with high AC/A. In some cases we can't exclude the possibility of myasthenia even if this subject is still in discussion. The authors report two clinical cases of hypoaccommodation in children.

Description of interocular accommodative disparities about 3 cases of young patients, whose occupations require an excellent stereopsis in near vision. Is is a paresis, an asynergy or a constitutional asymmetry? In order to delimit this pathology, the accommodative power of each eye has been measured on a reference population including 100 subjects aged 20 to 35 years. The suitable correction of this anomaly, allows an exact compensation and the recovery of a normal functional comfort.