Asthenopia

ASTHENOPIA (from Greek asthenes - weak and ops - vision), weakness of vision. By asthenopia, unlike amblyopia, is understood not poor vision in general, but difficulty and rapid fatigue of vision. With asthenopia, characteristic phenomena occur—aching and pain in the eyes and head, blurring of vision, and general malaise. At the present time, several types of asthenopia are distinguished. This is, first of all, accommodative asthenopia, developing in cases where there are disturbances of accommodation (due to senile changes of the lens in presbyopes, in cases of paralysis of accommodation) or where there are excessively high demands on accommodation (in hypermetropes, in cases of opacities of the media, when patients have to bring the objects being viewed too close to the eyes to increase the angle of vision and, consequently, strain accommodation extremely). A very common form of asthenopia is also, so-called, muscular asthenopia, developing, predominantly, in eyes with latent divergence. In these cases, due to the overpowering of the external rectus muscles, the eyes tend to assume a divergent position. When working at a near distance, an extreme strain of convergence is required in order to give the axes of the eyes the converging direction necessary for fixing near objects. Muscular asthenopia develops especially often in uncorrected myopia, since myopes do not strain accommodation when working at a near distance, but by virtue of their very myopia, they perform work at a very close distance from the eye, which causes the need for increased convergence. The resulting dissociation between accommodation and convergence leads to a particularly acute development of asthenopic phenomena. Often one has to observe asthenopic phenomena also in people with inflammatory phenomena of the conjunctiva and the edges of the eyelids. When working at a near distance, all such conjunctival phenomena are often intensified to a significant degree. This form of asthenopia is called conjunctival asthenopia. Finally, in some cases, asthenopic phenomena develop without any connection with any functional disturbance of the eye. Often such phenomena develop in nervous, hysterical subjects and are in a certain dependence on the general state of the nervous system. This is so-called nervous asthenopia. A combination of individual forms of asthenopia is often observed. To combat asthenopia, correction of refractive anomalies is necessary, the prescription of prismatic glasses (in cases of latent strabismus), and, mainly, paying special attention to the observance of hygienic conditions of work—good lighting, and when reading—clear and sufficiently large print. Non-observance of these conditions quickly leads to the development of severe asthenopic phenomena; the latter in some professions (stenographers, draftsmen, typists) take on the character of an occupational eye disease.

A. Ya. Samoylov.