Treatise on the Diseases of the Eye. 



203 



of sensibility of the retina varies with the age of the person. In 

 infancy and youth it is great, but gradually declines to maturity, 

 from which period the diminution of sensibility proceeds more rapidly. 

 It is probably in consequence of this rapid decrease of sensibility in 

 the retina and other appendages of the organ of vision which have 

 been exposed to the powerful sun, that the eyesight fails so early in 

 tropical climates. In addition to exposure to a strong light, the 

 character of the ordinary food of the natives is not sufficiently 

 nourishing for the youth who is increasing in stature, which weakens 

 the system, and produces a debilitating effect on the retina. Such 

 is the influence of these combined causes, that there are not many 

 natives of Bengal who have reached the age of 30 years, who can 

 read a book by candlelight. The weakness of sight is with them 

 greatly aggravated by writing at night with the aid of a dim lamp. 

 In this way a defect of vision often proves the precursor, and lays the 

 foundation of many other diseases. The progress of the complaint 

 is very gradual, and is unattended with symptoms of particular 

 severity. It commences with occasional pain in the eye-balls and 

 head, and is attended with some degree of dimness of vision. At 

 first these symptoms only occur after exposure to the sun, and during 

 the heat of the day, but the defect of vision slowly increases, and 

 manifests itself particularly on the occurrence of any derangement of 

 the system. At length it becomes so great, as to prove a hindrance 

 to the performance of the patient's customary avocations ; or termi- 

 nates in amaurosis, which, if in his power, necessitates an application 

 to the hospital for relief. This is so very common a complaint, that 

 when officiating as Surgeon of the Eye Infirmary at Calcutta, I 

 prepared the following Table, showing the number of applications for 

 impaired vision and amaurosis, in the year 1841 : — 





Total. 



Ages. 



Total. 



Ages. 





Males. 



from 



20 to 



30 



30 



to 



40 



40 

 to 

 50 



50 



to 



7«> 



10 







2 



Females. 



from 



20 to 



30 



30 



to 

 40 



7 

 1 

 3 



11 



40 

 to 

 50 



4 

 1 

 3 



8 



50 



to 

 70 



Impaired vision, 



Amaurosis, j P arti f» »• 

 ' ( complete, 



81 

 15 



22 



29 

 6 

 6 



"IT 



26 

 6 



7 



5 



17 

 3 



7 



5 



17 

 3 



7 



4 

 1 

 1 



2 

 



o 



Total, 



118 



12 



27 



6 



2 



