DISORDERS IN RELATION TO THE EYE 787 



ical symptoms. The typical pathological extreme is presented by exoph- 

 thalmic goiter and from this to practically normal conditions with a hyper- 

 thyroid tendency there is a logical and regular gradation. The local, 

 ocular, effect of sympathetic irritation will, of course, depend on the 

 amount, plus or minus, of inherent vagotonia, and on the final balance 

 between the two vegetative influences. It follows that minor degrees of 

 sympathetic irritation depending on hyperthyroidism will impress the 

 observer, clinically, as a defect of vagus tone, and be expressed ophthal- 

 mologically as accommodative defect, insufficiencies of the external ocular 

 muscles, or fatigability of the retina, or hypersensitiveness to light, or 

 tendency to hyperemias, all of which, as we have seen, are included in 

 the categories of asthenopia, retinal, accommodative, or conjunctival. 



Emotional stimuli and sensory irritation cause, largely, sympathetico- 

 tonic ocular reactions, such as mydriasis, dilatation of vessels in the -con- 

 junctiva and possibly in the retina, lowering of accommodation and fixa- 

 tion energy, and lachrymation. 



When unaffected by external stimuli the eye seems to be under vagus 

 control, as indicated by the contraction of the pupil in sleep and in nar- 

 cosis. 



Hyperthyroidism. For clinical purposes, the ophthalmic signs and 

 symptoms of this condition, as far as we know at present, are summed up 

 in the term sympathetico-tonia. Under approximately normal conditions 

 in health we note characteristic reactions accompanying emotional ex- 

 citement, notably rage and sexual erethism. Such' are, dilatation of the 

 pupil, flushing of conjunctiva and lids, enlarged lid-fissure and promi- 

 nence of the globe, with infrequent winking. 



The individual reaction, vagotonic or sympathetico-tonic, to strong emo- 

 tion, particularly anger, may depend on whether there is a basic, pituitary- 

 adrenal or thyroid dominance, indicated by stature and complexion as well 

 as by other features such as hair distribution. The very dark types would 

 react with pallor, bradycardia, muscular contractions, narrowing of the 

 pupil and lids ; the blonde types, with flushing, exophthalmos, rapid heart 

 action, and a dilated pupil. The English novelist Meredith says some- 

 where that there are only two kinds of human beings, those who turn 

 white and those who turn red when enraged. 



With subsidence of the emotion, all these reactions pass away. Where 

 the emotion or similar sympathetico-irritant factors are repeated or be- 

 come habitual or chronic, we may say that the ocular reactions border on 

 the pathological. From this point there are easy and regular stages to the 

 milder types and formes frustes, and finally to the typical cases of exoph- 

 thalmic goiter. 



Akin to the formes frustes of exophthalmic goiter is the ocular syn- 

 drome described by Lamb and ascribed by him to thyroid hypersecretion. 



