VOL. LXXXVII."] PHILOSOPHICAL TRANSACTIONS. 75 



degree of contraction usually exerted by them, it puts the fibres into a very uneasy 

 state ; which while in health they support with the utmost difficulty, and when 

 affected by disease are unable to sustain : under these last circumstances near ob- 

 jects cannot be seen at all without considerable pain, and never distinctly, the eye 

 not remaining a sufficient time adjusted for that purpose. I cannot better explain 

 the nature of this disease, than by giving an account of the symptoms which oc- 

 curred in the following case. 



A gentleman 40 years of age, naturally short-sighted, of a delicate irritable habit 

 from his infancy, being always soon tired by exercises that required muscular exer- 

 tion, had the following affection of his eyes. His sight had fjeen very perfect till 

 he was 1 Q. years of age ; at that time he resided in a part of the country where the 

 ground consisted chiefly of white chalk, which produced an unpleasant glare ; and 

 his constant amusement both by day-light and candle-light was drawing, which he 

 frequently pursued so far as to fatigue his eyes*. While thus employed his com- 

 plaints had their origin. The first symptoms were that of being unable to look 

 long at any object without pain, and feeling uneasiness when exposed to strong 

 light. The eyes were apparently free from disease, having no unusual redness, nor 

 any purulent, or watery discharge. The plan that was first adopted for his relief 

 consisted in lowering the system, both constitutionally and locally ; but this treat- 

 ment rendered him more irritable, and made his eyes rather worse than before ; he 

 therefore, after a trial of 8 years, in different means of this kind, gave them entirely 

 up. For the next 5 years, in which nothing was done to the eyes, the symptoms 

 appeared to have been stationary ; but at the end of that period, his mind suffering 

 from an uncommon degree of anxiety, the complaints in his eyes were evidently 

 rendered worse ; this effect however depended solely on the state of mind, for as 

 soon as he recovered from his distress, the eyes also returned to their former state. 

 In this condition I first saw him in 17Q5, when his eyes had no external mark of 

 disease, and were moved by the muscles in every direction without the smallest 

 uneasiness. He could look at any thing at some distance, as the furniture in the 

 room, the passing objects, &c. with perfect ease ; but whenever he attempted to 

 adjust the eyes to near objects, the effort gave so much pain, that though he suc- 

 ceeded in seeing them, he was almost immediately obliged to desist. Every attempt 

 to write or read gave so much pain, that he became unable to do either ; but as 

 soon as the strain produced by such an effort was taken off, he was at ease. His 

 disease therefore consisted in a want of power to adjust the eyes to near objects, for 

 a sufficient length of time to render them distinct, which of course incapacitated 

 him from reading or writing. The cause of this disease appears to be a morbid 

 affection of the straight muscles of the eyes, which allows them to perform all their 

 intermediate contractions as usual, but not the extreme degrees of contraction with- 

 out considerable pain. 



As these symptoms have not, I believe, been before accounted for in this way, it 



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