416 OPHTHALMOLOGY 



In the eye we have admirable examples of inflammation due to 

 nonbacterial causes, like the retinitis following the excessive use of 

 the eyes, or exposure to excessive light; the choroiditis attending 

 myopia; and the inflammations of the conjunctiva and lids due to 

 eye-strain. Have such pathologic processes any necessary relation to 

 bacteria whatever? What other processes resembling reactions to 

 microorganisms may be reactions to unknown causes quite unrelated 

 to bacterial invasion? It may be suggested that certain forms of 

 ocular disease, such as "Parinaud's conjunctivitis" and "vernal 

 conjunctivitis" ought to be carefully studied for a possible connec- 

 tion with microorganisms other than bacteria. 



Neurology. The relations of neurology with ophthalmology are 

 so extensive and so intimate that the boundary between them 

 would vary enormously with the taste or training of the individual 

 who undertook to delineate it. Die Neurologic des Auges, of Wil- 

 brand and Saenger, has already reached some 1500 pages and 

 promises to extend indefinitely. Of the twelve pairs of cranial nerves, 

 six are distributed partly or entirely to the eye and its appendages. 

 Peculiarly intimate relations and analogies existing between the retina 

 and the brain give to observations made upon the former a unique 

 scientific interest and value. Then, too, the dependence placed upon 

 the visual function in nearly all occupations and amusements gives it 

 a predominant influence upon the general condition of the nervous 

 system. 



Fatigue, neurasthenia, excessive irritability, sluggish and defective 

 development of the higher centres are likely to be very closely con- 

 nected with abuse or defect of the visual function. The term eye- 

 strain may be loose, indefinite, and faulty, but behind it stands an 

 entity of enormous scientific and sociologic importance. Those who 

 have most strongly emphasized its importance may sometimes have 

 betrayed narrowness of view, and a disposition to reason from mere 

 plausible hypotheses; but the known facts with regard to the in- 

 fluence of abnormal use of the eyes upon the functions of the general 

 nervous system justify more general attention than has yet been paid 

 to them. 



Psychology. In the motor and sensory phenomena attending 

 eye-use and eye-strain, we have an open path to intimate experi- 

 mental knowledge of the general nature and relations of nerve actions 

 and states, both normal and pathologic; and may make the closest 

 approach to objective knowledge of the phenomena of consciousness. 

 One need have but a limited knowledge of ophthalmology and neur- 

 ology to travel this path and bring back results of great value, as did 

 Joseph Le Conte. Other similar investigations would yield additional 

 matter of high interest for its relations to psychology. Close obser- 

 vations of form, as modified by lenses and prisms; and of color as 



