Comparative pupil dilation using phenylephrine alone or in combination with tropicamide.
OBJECTIVE
A prevalence survey of actinic and other eye diseases was conducted in Nambour, Queensland, Australia, in 1992. Pupils were dilated with phenylephrine alone for cataract identification because there were concerns that patient discomfort, due to cycloplegia occurring with the usual dilating agents of tropicamide and phenylephrine, may influence future compliance in an associated intervention study. This validation study was undertaken to measure the possible underestimation of cataract prevalence in this community study, which may have occurred because of inadequate dilation from phenylephrine alone.


METHODS
The study design was a repeated measures experimental design.


METHODS
Forty-seven normal subjects participated in the study. Both eyes were tested.


METHODS
Pupil diameter after dilation with three drops of 10% phenylephrine alone was compared with pupil diameter after dilation with three drops of 10% phenylephrine together with three drops of 1% tropicamide. The two regimens were given to the same subjects 1 week apart. Reversal was attempted with thymoxamine hydrochloride 0.5%.


METHODS
Pupil diameter was assessed using a Neitz cataract camera, and accommodation reserve also was measured. Subjects' subjective appreciation of return of ocular function was assessed by a questionnaire. Repeated measures analysis of variance, paired t test, McNemar's test, and Wilcoxon signed rank test were used to analyze outcomes.


RESULTS
Mean maximum pupil size with 10% phenylephrine and 1% tropicamide was significantly larger than pupil size after the use of 10% phenylephrine alone (F1,19 = 18.99, P = 0.0003). However, there was no significant difference between the two dilation regimens when comparing the proportion of subjects who dilated to 6 mm or more (McNemar's X(2)1 = 2.7, P > 0.1). Compared with 10% phenylephrine and 1% tropicamide, pupil diameters were significantly smaller (t46 = 16.77, P = 0.0001), and accommodation reserve greater (t46 = 4.14, P = 0.0001), 40 minutes after reversal with thymoxamine in the group dilated with 10% phenylephrine alone.


CONCLUSIONS
Pupil dilation with 10% phenylephrine alone, if allowed at least 40 minutes to act, will be as satisfactory for the identification of cataracts in a normal population as 10% phenylephrine and 1% tropicamide and is more acceptable because of reduced problems with glare and accommodation.
Eyeson-Annan
M L
ML
West Moreton Public Health Unit, Queensland Health, Ipswich, Australia.
Hirst
L W
LW
Battistutta
D
D
Green
A
A
D000065:Accommodation, Ocular / Q000187:drug effects; D000328:Adult; D000368:Aged; D002386:Cataract / Q000175:diagnosis / Q000453:epidemiology; D004338:Drug Combinations; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008916:Miotics / Q000008:administration & dosage; D013948:Moxisylyte / Q000008:administration & dosage; D009184:Mydriatics / Q000008:administration & dosage*; D009883:Ophthalmic Solutions; D010656:Phenylephrine / Q000008:administration & dosage*; D015995:Prevalence; D011680:Pupil / Q000187:drug effects*; D011793:Queensland / Q000453:epidemiology; D014331:Tropicamide / Q000008:administration & dosage*
D004338:Drug Combinations; D008916:Miotics; D009184:Mydriatics; D009883:Ophthalmic Solutions; D010656:Phenylephrine; D014331:Tropicamide; D013948:Moxisylyte