HOMOTROPINE — METHYL ATROPINE 213 



Atropine. Atropine causes mydriasis by paralyzing the nerve 

 endings of the oculomotor nerve and destroys accommodation by 

 paralysis of the nerve ends in the ciliary muscle. Intraocular ten- 

 sion is also increased. With a solution of 4 gr. to 1 ounce of water 

 (practically 1 per cent.), mydriasis will begin in from 15 to 20 

 minutes, reach its maximum in one-half hour, and persist for 8 to 10 

 days. Loss of accommodation is not produced so quickly and is less 

 persistent than mydriasis. 



Therapeutics. 



1. Atropine may be used as a simple mydriatic for examination 

 of the interior of the eye, but for this purpose euphthalmine, cocaine 

 and homatropine are just as serviceable and less disagreeable because 

 their action is less persistent. 



2. It is valuable to paralyze accommodation for refractive work 

 (in man), but others of less persistent action are often preferred. 



3. It is unequaled in iritis to break down and prevent adhesions 

 between the capsule and lens. 



4. It is useful in acute keratitis to allay ciliary irritation. 

 Strengths of Solution. As a mydriatic use one fourth grain 



to ounce of water, in iritis four grains to the ounce and keratitis one- 

 half grain to the ounce. 



Homatropine. This is an artificial alkaloid of atropine. The 

 hydrobromide is the salt most used and is freely soluble in water. 



Its action is similar to atropine but does not last more than two 

 0* three days. Stronger solutions are required than in the case of 

 atropine, a solution of 8 to 12 grains to the ounce being required to 

 paralyze accommodation. For examination of the interior of the eye 

 a solution of one-half grain to the ounce is sufficient. Homatropine 

 is expensive and rarely used in veterinary medicine. 



Methyl Atropine or eumydrin is similar in action to atropine 

 but is less toxic, more prompt and less persistent. Used in 1 to 2 

 per cent, solution. 



Hyoscyamine. Very similar to atropine but less persistent. 

 Use 2 grains to the ounce. 



Hyoscine or Scapolamiue is more powerful and less persistent 

 than atropine. 



Cocaine Hydrochloride. A four per cent, solution will pro- 

 duce complete anesthesia and mydriasis in 15 minutes. The my- 

 driasis will reach its maximum in about one hour and last for 10 to 

 12 hours. The action is due to peripheral origin. Accommodation 

 is but slightly impaired. On account of its prompt and short action, 

 and because it so slightly disturbs accommodation, it is very suitable 

 for examination of the interior of the eye. In cases of iritis, how- 

 ever atropine is to be recommended for just the opposite reasons. 

 Cocaine mydriasis may be easily overcome by a one per cent, solu- 



