Comparative mydriatic efficacy between mixture containing 0.8% tropicamide 5% phenylephrine and 0.4% and tropicamide 2.5% phenylephrine: A prospective analytical study

This study is conducted to know the efficacy of mydriasis of diluted commercially available combination drop of tropicamide and phenylephrine. The pupillary dilation achieved with 0.8% tropicamide and 5% phenylephrine is compared with that of 0.4% tropicamide and 2.5% phenylephrine.

In this prospective analytical study conducted in 100 patients, one eye of each patient was dilated with combination drop of 0.8% and 5% phenylephrine and the other eye was dilated with a diluted concentration of the same eye drops. The drops were instilled at an interval of 10 minutes for 3 times. Mydriasis was recorded at 10, 20, 30, 40 and 60 minutes and difference between the two eyes was observed.

The combination of 0.4% Tropicamide and 2.5% phenylephrine has produced an adequate mydriasis (8mm) at 30 and 40 minutes interval with a statistically significant p value of 0.045 and 0.042 respectively. The proportion of patients who required an additional application of drops after 60 minutes interval was statistically insignificant (p= 0.498). The progression of the pupil dilation at 20, 30and 40 minutes was found to be statistically significant with p values of 0.020, 0.003 and 0.022 respectively. A statistically significant difference was found in the dilation between the diabetic group and non-diabetic group at 40 and 60 minutes (p<0.001).

The diluted mixture was effective enough to produce an adequate mydriasis for intraocular examination. During the process of attaining an adequate mydriasis it also showed a significant progression in the pupillary dilation. The use of this mixture would possibly reduce the occasional adverse effects of the combination drops of higher concentrations especially in patients with co-morbid systemic conditions.