Eyestrain and progressive myopia: A minus lens induces asthenopia at the near range by interfering with the development of the eye

Abstract

Introduction This paper suggests that asthenopia, or eye strain, initiates a process that can lead to detachment. Asthenopia can be induced in the myopic eye at the near range with a minus lens; and under those conditions, it creates the tendency for one's myopia to become worse. Progressive myopia, past a certain stage, is attributed mainly to the eyeball (or sclera). An excessive elongation of the sclera can lead to detachment. The Hypothesis Asthenopia is often thought to be prevalent in cases of hyperopia when performing close-up work, but it can also be induced in the myopic eye at the near range with a minus lens. A minus lens projects the focal point from a close-up object farther behind the retina. The crystalline lens would have to "bulge" more to bring it into focus-more than how much it would normally "bulge" for near focusing. Under those conditions the myopic eye becomes susceptible to progressive myopia. Evaluation of Hypothesis This means the ciliary muscle, which controls the shape of the crystalline lens, would have to tighten up more. If the ciliary muscle tightens up excessively, the oblique muscles would also tighten up more in response. (The oblique muscles are already tense since the eye is myopic.) The excess tension of the oblique muscles can force the sclera to elongate and thereby reduce the distance between the retina and the focal point. This alleviates some of the strain on the ciliary muscle. The crystalline lens would not have to "bulge" to its maximum-although it would still "bulge" more than how much it would normally "bulge" for near focusing. Conclusion It can be demonstrated that if the eye was continuously subjected to such a condition for an extended period of time, near-point asthenopia can promote progressive myopia. It is attributed to asthenopia because more than the normally required "effort to see" is generated, before a near image could be brought into focus. Not only will the crystalline lens "bulge" excessively, but the sclera will also elongate progressively. Detachment tends to occur at the area where the retina has thinned out due to the continuous elongation of the eye.