In 1910 phenylephrine hydrochloride was introduced first by Barger and Dale. Phenylephrine hydrochloride is a synthetic sympathomimetic compound structurally similar to epinephrine and ephedrine. Synthetic phenylephrine hydrochloride is clinically used as a nasal decongestant, vasopressor and mydriatic, etc.. The use of phenylephrine hydrochloride in ophthalmological practice is based on its action of vasoconstriction and mydriasis. Phenylephrine hyddochloride has been introduced in U.S.A. as 10% neosynephrine (U.S.P.) and in Japan as 5 % neosynesine.
It´s usufulness in therapy and examination is due to the following characteristics; (1) Rapid effect, (2) No influence on intraocular pressure nor on accommodation, (3) No undesirable side reaction.
In many countries including U.S.A. and Japan, they reported experimentally and clinically in detail about the mydriatic action of phenylephrine hydrochloride but unfortunately there is no data concerning mydriatic action of phenylephrine hydrochloride in Koreans in spite of its wide use in ophthalmology.
The study was performed for dilatation of the pupil, influence on intraocular pressure and accommodation, antagonistic action to pilocarpine, and side reaction after instillation of 10 neosynephrine (U.S.P.) by the following method.
Method and Material
Material; 10% Neosynephrine hydrochloride (U.S.P.) 2 % Pilocarpine
Subjects; 228 Korean normal eyes (6-84 yrs. old) Method;
1. Dilatation of the pupil (176 eyes)
Group 1; One drop of 10% neosynephrine instilled into 75 eyes. Over 60 yrs. old 10 eyes
36-59 yrs. old 17 eyes Under 35 yrs. old-48 eyes
Group 2; Two drops of 10% neosynephrine instilled into 59 eyes. Over 60 yrs, old 2 eyes
39-59 yrs. old 17 eyes
Under 35 yrs, old 40 eyes
Group 3; Three drops of 10% neosynephrine instilled into 42 eyes. Over 60 yrs. old 7 eyes
36-59 yrs. old 14 eyes
Under 35 yrs. old 21 eyes
Interval between each instillation was two or three minutes. After instillation of JA J into the eyes, the diameter of the pupils was measured frequently till maximum dilatation.
2. Influence on the intraocular pressure (25 eyes).
After measurement of the intraocular pressure and diameter of the pupil in each eyes, one drop of 10% neosynephrine was instilled into 9 eyes and two drops into 10 eyes, and three drops into 6 eyes. After that measurement of intraocular pressure and diameter of the pupil was done every 10 minutes for 90 minutes and 2 and 3 hrs. later.
3. Influence on accommodation.
The diameter of the pupil and distance of N.P.C. were measured before instillation of neosynephrine and every 10 minutes interval for 90 minutes and at 2 and 3 hrs. after instillationn of .10% neosynephrine into 23 eyes (one drop into 8 eyes, two drops into 10, eyes, three drops into 5 eyes).
4. Antagonistic action of 2 % pilocarpine to mydriatic action of 10 % neosynephrine.
In two eyes of a 26 yrs: old man, diameter of the pupil was measured and compared in both eyes before instillation of one drop of 10 % neosynephrine and in 10 minutes interval to 90 minutes, at 2 and 3 hrs. after instillation of one drop of 10% neosynephrine into both eyes. Then one drop of 2 % pilocarpine was instilled into only the right eye at 50 minutes, after first instillation of neosynephrine.
One drop of 10% neosynephrine was instilled into both eyes of a 23 yrs. old man, two drops into both eyes of a 20 yrs. old man, and three drops into both eyes of a man aged 22- yrs:,.. One drop of 2 % pilocarpine was instilled into only the right eye of each person, respectively at 40 minutes (22 yrs. old eye), 50 minutes (20 yrs. old eye), and 60 minutes(23 yrs. old eye) after first instillation of neosynephrine.
The diameter of the pupil, the distance of N. P. C., and the intraocular pressure were measured and compared in both eyes of each person before instillation and at 10 minutes, intervals for 90 minutes, and at two. and three hrs. after first instillation.
Results and Conclusion
1. In most of 176 eyes, the diameter of the pupils reached more than 7.5mm (maximum dilatation) and they took an average of 42 minutes to reach their maximum dilatation
Among them, the shortest was 26 minutes and the longest 75 minutes.
2. The time the pupil takes to reach its maximum dilatation is a little difference between group (one drop of neosynephrne instilled) and group 2 (two drops of neosynephrine instilled) but definitely shorter in group 3 (three drops of neosynepphrine instilled).
3. 10% neosynephrine has little influence on intraocular pressure.
4. 10%, neosynephrine has slight influence on accommodation (slight paresis of accommodation) in about half of 26 eyes but they have no disturbance at near work (Table 2 and 3). 5. 2% pilocarpine constricts the dilated pupil more quickly than if not used (Table 4.). 6. Age has no effect on , dilatation of the pupil due to instillation of 10% neosynephrine. 7. No undesirable side reaction was noted.
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