1916] on Eyesight and the War 689 



diagrams that in the normal eje, the emmetropic eye, parallel rays 

 focus, by means of the dioptric apparatus in the eye, on to the 

 retina. In the hypermetropic eye they focus behind the retina. 

 The hypermetropic eye has the power, by the focussing arrange- 

 ments in the eye, of making the rays converge on the retina ; or, 

 what is better still, these parallel rays may be made to converge 

 and focus on to the back of the eye by a suitable convex glass. 

 In the myopic, or short-sighted eye, the parallel rays are focussed 

 in front of the retina, and when they meet the retina they are out of 

 focus. The myope has no power of focussing as the hypermetrope 

 has, and only rays coming from a near point in front of the eye, 

 that is, divergent rays, or parallel rays made divergent with a con- 

 cave glass, focus on the back of the eye. 



Xow myopia has been the hete noire of the War Office for a great 

 many years. Thousands of eligible young men, keen on getting a 

 commission, have been refused because of myopia. We hear con- 

 stantly the same tale — a well-set-up young man, with muscles of iron, 

 keen and intellig^ent, but a myope, and lost to the country as a good 

 officer. Why this fear of myopia ? It is bound up with another 

 question — Why has the War Office always set its face against the 

 wearing of glasses ? The answer is not far to seek. Hitherto our 

 small army was chiefly employed abroad, and mostly in the tropics, 

 and it was difficult to replace lost or broken glasses. That has all 

 changed now. There was a very good reason for fearing myopia in 

 the old days, but there is no fear now. The reason was that when 

 myopia was not properly treated it tended to progress. The tunics 

 of the eye stretched more and more, and so much damage was done 

 to the back of the eye, either by rupture or atrophy of the retina, or 

 hemorrhage, that the person often became blind. [Lantern slides 

 were here exhibited, showing the changes occurring in high myopia.] 



Apart from the changes at the back of the eye, we may get rup- 

 ture and detachment of the retina. In high myopia the vitreous 

 becomes liquefied and fails to support the retina sufficiently, some 

 jar takes place through taking a false step, jumping, etc., and 

 a small rent takes place in the retina, the fluid vitreous then passes 

 behind it and separates it from the choroid, and the person becomes 

 Wind. 



The cause of progressive myopia is undue or excessive convergence. 

 The old treatment for myopia was to give glasses for distance, but 

 not for near work because the individual could see well without them. 

 The result was that the individual liad to come nearer his work than 

 was necessary. This extra pull on the internal recti muscles caused 

 the eye to be stretched antero-posteriorily. This meant more short- 

 sight, which meant bringing the work nearer still, and so a vicious 

 circle was introduced. This shows how important it is even in the 

 nursery to prevent undue convergence. The soft eye of the child is 

 especially prone to the ill-effects of this nndue convergence, and such 

 Vol. XXI. (Xo. 110) 2 z 



