Eyestrain (commonly called asthenopia) / by Ernest Clarke.

  • Ernest Clarke
Date:
1892
Catalogue details

Licence: Public Domain Mark

Credit: Eyestrain (commonly called asthenopia) / by Ernest Clarke. Source: Wellcome Collection.

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    can' understand that headache should result from vascular repletion,^ Everyone knows from experience the in- creased severity of a headache caused by the stooping position. Sometimes the headache in eyestrain is purely reflex. Lauder Brunton says, in writing of the headache caused by carious teeth, The mechanism of the headache here is that the irritation in a tooth, for example, acting through the vaso-motor nerves, causes vascular spasm, and this vascular spasm causes the pain of headache.^ In the same way the eyestrain may through the sympathetic also produce the same effect, Hewetson says sick-headaches occur in neurotic sub- jects, the sympathetic system of whose brain is irritated by the eye attempting to overcome its defect ; this irritation and pain apparently depresses the individual, and reflects its influence to the heart and stomach by the pneumo- gastric nerve. ^ IV. Vertigo and Sickness.—Diplopia is the chief cause of these symptoms, and consequently it is mostly found in muscular asthenopia. If the internal recti are subjected to excessive strain, they will break down from stress of work, and will relax suddenly or gradually, and their opponents, the external recti, that have been in a passive state of tension, actively contract and pull over the eyes causing diplopia. Schiotz,* of Christiania, writing of the symptoms of muscular asthenopia, says, We rarely hear complaints of 1 op. at., p. 797. 2 op. cit., p. 333. The Relation between Sick-headaches and defective Sight chiefly resulting from Astigmatism : their pathology and treatment by glasses Medical Times and Gazette, 1885, vol. i., p. 375. ■' Kjtapfs Arch. o f Oph., vol. xix„ p., 176.
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