August 31^ 1916] 



NATURE 



553 



glasses, and the War Office has, up to the present, 

 set its face against the wearing of glasses. The 

 reasons which existed formerly, although, of course, 

 quite inadequate now, were that we had a very small 

 Armv, and a sufficiency of officers and men could 

 alwavs be counted on, besides which, this small Army 

 was mostly employed abroad, and then chiefly in the 

 tropics, and lost or broken spectacles could not easily 

 be replaced. 



Not only must a myope wear glasses for distance, 

 but he must wear them for near work — that is, always. 

 It was the old treatment of wearing them for distance 

 only (because he could see so well without them for 

 near work) that we now know was the cause of the 

 increase of the myopia, an increase which sometimes 

 led to complete blindness. 



When a myope does any near work without glasses 

 he converges unduly ; this means excessive pull on the 

 internal recti muscles, which in their turn pull on the 

 tunics of the eye, which leads to the eyes lengthening 

 antero-posteriorly, which means that the eye becomes 

 more short-sighted. This increase of myopia again 

 causes more convergence, and so a vicious circle is 

 produced. 



(Lantern slides were here exhibited showing the 

 harmful changes produced in high myopia, viz. atrophy 

 of the choroid and retina, haemorrhages at the macula, 

 and retinal detachment.) 



If the eyes are thoroughly tested under atropine or 

 homatropine and the full correction given to be worn 

 always they are thus made normal, undue convergence 

 ceases, as the work can be held further from the 

 eyes, and the ciliary muscle is made to work normally, 

 and the progress of the myopia is stayed. Out of 

 532 myopes watched by me over a period of five years, 

 ail of whom were fully corrected, only four progressed 

 to any appreciable extent. 



In the Army we can get rid of the difficulty of 

 replacing lost or broken glasses by having an oculist 

 and one or more working opticians attached to ever>' 

 "centre" with a register of the glasses worn in that 

 centre, and once we have this as part of the Army 

 equipment we can replace an effete sight test, which 

 judges only the uncorrected vision, by the Continental 

 plan of estimating the value of a man's vision when 

 corrected. 



By the accompanying table we see that the highest 

 amount of myopia we allow is about 25 D., whereas 

 abroad 6 or 7 D. pass easily. 



A strong argument showing the inadequacy of our 

 present system is that men will pass in easily who, 

 from the visual point of view, may be far worse than 

 those rejected. A high hypermetrope, for instance, at 

 twenty, will pass the present test easily, but some 

 years later he has to use up the whole of his accom- 

 modative power in correcting his distant vision, and 

 later still he even loses the power of correcting- this, 

 and so he must have glasses for distant and near 

 vision, whereas the myope of 5 or 6 D., or more, will 

 be able to read without glasses when he is a hundred 

 years old ! 



It is true that at present a jxjrtion of the scheme 

 suggested above is being adopted, but we want to see 

 it in its entirety and for all time, and that in future 

 the wearing of glasses will never be considered a 

 disability in the Army. 



Although mj'opia is the chief visual cause that keeps 

 men out of the Army, high hypermetropia and 

 astigmatism also do so, and the maiorit>' of cases can 

 be made absolutely normal with suitable glasses. 



(2) Eyestrain. 



We now pass to the important subject of eyestrain 

 as it affects our soldiers. 



There are three chief causes of eyestrain : — (i) Low- 

 errors of astigmatism ; (2) low anisometropia ; (3) . 

 small want of balance in the external muscles of the 

 eye. 



(i) Astigmatism. — Large errors take care of them- 

 selves. The craving for distinct vision leads the 

 possessor to have the error properly corrected, but he 

 is generally totally unconscious of the presence of a 

 small error, as the ciliary muscle, by producing an . 

 astigmatism of the lens — the inverse of that of the 

 cornea — corrects it, with the result that his vision is 

 so perfect that he is quite annoved with the physician 

 he is consulting for some functional nerve trouble, if 

 he suggests that the eves are at fault. It should be 

 remembered that there is not a single functional nerve 

 trouble that may not be caused bv eyestrain. The 

 great prevalence of astigmatism is shown in the 



Table showing the Visual Standards for Recruits in the Chief European Armies. 



(Paterson and Traquair.) 



Amount of short-sight (myopia) allowed. 



Standard of corrected vision. 



Remarks. 



Combatants. 



Germany 



Austria. . 



Franxe . 



6'5 D. For Landsturm 

 no limit if standard of 

 corrected vision attained. 



Non-combatants. 



Combatants. 



Non-combataots. 



1/2 in better eye. Other [ 

 eye may have minimal 

 vision. For Landsturm 

 vision = 1/4. If one eye , 

 bas\-ision — 1.2 the other 

 may be blind. 



Virion with glasses (corrected 

 vistoo) comits. 



6 D. 



7D. 



Abo\-e 6 D. no limit if 

 standard of corrected 

 vision is attained. 



Above 7 P. no limit if 

 standard of cfxmeted 

 vi^on is attained. 



Italy . 



7D. 



Gre.\t 

 Brit.\in 



No amount specified, but 

 according to vision re- 

 quired highest amount 

 possible is about 2*5 D. 



No amount specified, but 

 according to vision re- 

 quired highest amount 

 possible is about 2*5 D. 

 in better eye and. 3*5 D. 

 in worse eye. 



Group I, 1/2 in each eye. 

 Group 2, 1/2 in one ; 

 1/4 in other. 



1/4 in one ; i/io in the 

 other. 



1/2 in one eye ; i/zo ia 

 the other. 



1/4 in one eye ; i/ao ia 

 the other. 



1/3 iu each eye, or 1/12 in one eye if the other has 

 i/i (full vision). 



No correction allowed for ( Uncorrected vision 



general service. Un- must be 1/4 in better 

 corrected \-ision most be 

 1/4 in each eye, or 1/4 in 

 the right eye with i/io 

 in the left. 



eye, i/io m worse eye. 

 The better eve may be 

 the left. 



Visioa with glasses counts. 



Vision ^th glasses counts. 



Vision with glasses counts. 



Vision without glasses counts. 

 For home service, garrison 

 ser\ice, and garrison service 

 abroad glasses are allowcff 

 within un.«pccified limits. 



NO. 2444, VOL. 97] 



