Efficacy of A Mydriatic Mixture of 0.5% Tropicamide and 5% Phenylephrine at Thammasat University Hospital
Purpose: To compare the effectiveness of mydriasis between mydriatic mixtures of 0.5% tropicamide and 5% phenylephrine versus 1% tropicamide and 10% phenylephrine.
Design: Prospective randomized controlled trial
Methods: In this study, 30 Asian patients with dark irides were randomized to receive topical 1% tropicamide and 10% phenylephrine (conventional regimen), and 30 patients to receive a
fixed combination of 0.5% tropicamide and 5% phenylephrine (mixed regimen). The vertical pupillary dilatation, blood pressure, and pulses were studied.
Results: Sixty patients were equally randomized into conventional and mixed regimens. For the conventional and mixed regimen groups; the mean baseline pupil diameter was 1.49 ± 0.62
mm and 1.84 ± 0.64 mm, respectively. The mean pupil diameter at 15 minutes was statistically significant difference between both groups, 3.79 ± 0.90 mm in the conventional regimen group and 4.30 ± 1.05 mm in the mixed regimen group with mean difference 0.5133 mm (95%CI 0.0076 - 1.0191, P = 0.047). Whereas the mean pupil diameter at 30, 45, and 60 minutes showed no significant difference between groups. In the first 30 minutes, the proportion of eyes that achieved 7 mm pupil size between both groups was significant difference, 36.7% in the conventional regimen group, and 63.3% mixed regimen group (P = 0.039). At 60 minutes, the proportion was 86.7% and 96.7% respectively (P = 0.353). There was no significant difference in arterial blood pressure and pulse rate between groups.
Conclusion: The mixture of 0.5% tropicamide and 5% phenylephrine showed comparable efficacy to a conventional regimen and resulted in greater pupillary dilatation within the first 15 minutes,
allowing for more rapid achievement of desired mydriasis.
2. Rengstorff RH, Doughty CB. Mydriatic and cycloplegic drugs: a review of ocular and systemic complications. Am J Optom Physiol Opt. 1982;59:162-177.
3. Obianwu HO, Rand MJ. The relationship between the mydriatic action of ephredine and the colour of the iris. The British Journal of Ophthalmology. 1965;49(5):264–270.
4. Yospaiboon Y, Luanratanakorn P, Noppawinyoowong C. Randomized double-blind study of phenylephrine 2.5% vs 10% on pupillary dilation. Journal of the Medical Association of Thailand. 2004:1380-1384.
5. Trinavarat A, Pituksung A. Effective pupil dilatation with a mixture of 0.75% tropicamide and 2.5% phenylephrine: A randomized controlled trial. Indian J Ophthalmol. 2009;57:351-354.
6. Bartlett DK. Dilatation of the pupil. In: Bartlett JD, Jaanus SD. Clinical Ocular Pharmacology. 4th ed. Boston: Butterworth-Heinmann;2001:405-411.
7. Alcon Canada Inc. Mydriacyl: prescribing information and consumer information. Canada: Alcon; 2018 May. https://www.alcon.ca/sites/www.alcon.ca/files/Mydriacyl-PM-16-May-2018-e.pdf.Accessed April 16, 2019.
8. Bhurayanontachai P, Saengkaew S, Apiromruck P. Efficacy of an eye drop mixture for pupillary dilatation: A randomized comparative study. Journal of Optometry. 2017;10(2):111-116.
9. Yamazaki T, Shimada Y, Taenaka N, Oshumi H, Takezawa J, Yoshiya I. Circulatory responses to after loading with phenylephrine in hyperdynamic sepsis. Crit. Care Med. Jul 1982;10(7):432-435.