214 MYOTICS 



tion of eserine. It is used in 4 per cent, solution. Stronger solu- 

 tions are said to irritate the cornea. 



Euphthalmine. This is a synthetic alkaloid derived from B. 

 Eucaine. It is soluble in cold water, staple in solution and may be 

 sterilized by boiling. After the installation of a few drops of a 4 

 per cent, solution, mydriasis takes place in a few minutes, reaches 

 its maximum in one-half hour, and lasts but a few hours. Accommo- 

 dation is not affected to any great extent. This drug is not irritant 

 to the cornea or conjunctiva, causes no systemic disturbances, but 

 does increase intraocular pressure. Since it interferes with accommo- 

 dation so slightly, it is recommended for examination of the interior 

 of the eye. A 4 to 6 per cent, solution is usually employed. 



MYOTICS 



Myotics are drugs that contract the pupil. Myosis or contrac- 

 tion of the pupil may be produced by conditions exactly opposite to 

 those of mydriasis. Pilocarpine and eserine applied locally contract 

 the pupil by stimulation of the circular muscle of the iris, or by 

 stimulation of the peripheral endings of the oculomotor nerve in this 

 muscle. Myotics lessen intraocular pressure by bringing about con- 

 ditions exactly opposite to those produced by the action of mydriatics. 

 Strong solutions of the myotics may bring about spasm of the iris. 

 Most important of myotics are : 



Physostigmine Pilocarpine Arecoline 



Physostigmine and Pilocarpine (Physostigmine or eserine) is 

 the one used most. A solution of one-eighth to one grain to the 

 ounce of water is sufficient for mild continuous action, but stronger 

 solutions (2 to 3 gr. to the ounce) are required where prompt action 

 is needed. Eserine produces its maximum effect in less than an 

 hour (30 to 40 minutes) and may persist several days. It is not 

 staple in solution or in tablet form. This is its chief disadvantage. 

 Pilocarpine is similar in action to eserine but weal^er. Usually em- 

 ployed in solution of 1 to 4 grains to the ounce. 



Arecoline Hydrobromide. This is a powerful myotic applied 

 locally, but causes mydriasis if given internally. Myosis starts 

 within a few minutes and is complete in about 15 minutes after in- 

 stallation of a few drops of a solution of 2 to 5 grains to the ounce. 

 It may also produce spasm of the iris. Its chief advantage is that 

 solutions are staple. In comparison to eserine its action is more 

 prompt but less persistent. 



