262 PROBLEMS OF HUMAN EVOLUTION 



Indian Civil Service must not fall, Dr Carter concluded that only 

 2*8 per cent, of the children examined had excessive short sight. 



Before we attempt to analyse the figures, it must be observed 

 that what normal vision really is has never been ascertained ; it 

 is explained to mean *' the power of sight commonly possessed 

 by healthy people in civilised countries, and the definition of the 

 term is that the person to whom it is applied is able to see an 

 object of given magnitude at a given distance." 1 But inequality 

 of vision in the right and left eyes is a question of fact, indepen- 

 dent of any arbitrary standard, and it was found that 12*5 per 

 cent, had normal vision in the right eye and subnormal in the 

 left ; 8'6 had normal vision in the left eye and subnormal in the 

 right. 2 From this we may fairly infer that "normal vision" 

 does not represent an absurdly high standard. 



We must, further, be careful not to lump together all kinds 

 of abnormal vision. The common causes of bad sight are hyper- 

 metropia (where the axis of the eyeball is too short, so that a 

 clear image is never obtained without the effort of focussing) 

 and myopia (where the length of the eyeball is excessive, with 

 the result that when parallel rays fall upon the eye they focus in 

 front of the retina). This is properly called "short sight," "a 

 condition," as Dr Carter puts it, "in which the eyes have good 

 vision 'within but not beyond some specified distance, according to 

 the degree of the defect." In England some small degree of 

 hypermetropia is almost universal in childhood. "As the eye- 

 ball grows in the course of natural development, it often attains 

 more correct proportions, and the hypermetropia may conse- 

 quently diminish, but it seldom entirely disappears." 3 As to 

 short sight, "Ophthalmologists are more and more coming to 

 regard myopia as a state which may often be aggravated by 

 injudicious methods of using the eyes, but which, in the great 

 majority of instances, depends greatly on predisposing causes, 

 and which, when these are in active operation, is liable to 

 increase, notwithstanding all the precautions which can be 

 employed." 4 



i Dr Carter's Report, p. 3. 2 Lie. cit. p. 4. 



3 Loc. cit. p. 6. 4 Loc. dt. p. 7. 



