Study of effect of mydriatic and myotic drugs on pupillary size by card pupillometer

Introduction: Pupillometers used for demonstration of drugs on pupillary size are available in the form of digital instruments which are expensive. The Medical Council of India mandates use of pupillometer for demonstration in Department of Pharmacology and therapeutics. Card pupillometer, which is a cheaper alternative for digital pupillometer may be used for the same purpose. The present study was aimed to demonstrate the ability of card pupillometer to measure difference in pupillary diameter using mydriatic and myotic drugs. Material and methods: Volunteers with healthy eyes, of age more than 14 years of either gender, with or without refraction errors (myopia and hypermetropia) willing to give written informed consent were included in the study. All volunteers were subjected to use of Pilocarpine (0.5%), Tropicamide (1%) and Carboxymethylcellulose (0.5%) eye drop randomly and pupillary size was recorded at baseline, 15, 30, 60 and 120 minutes. Results:15 volunteers were included in the study. With instillation of Tropicamide, there was a trend of increase in pupillary diameter, with largest diameter (5.38 mm) at sixty minutes. There was statistically significant increase in pupillary diameter when the diameter at Zero was compared with the diameter at Fifteen, Thirty, Sixty and Hundred & twenty minutes (P<0.001, ANOVA with post hoc Tukey-Kramer Multiple Comparisons Test). There was a decreasing trend of pupillary size after instillation of Pilocarpine, with significant reduction in pupillary diameter when the diameter at Zero was compared with that of Thirty min, One hour and Two hour (P<0.001). There was no significant change in pupillary diameters after instillation of Carboxymethylcellulose. Conclusion: Card pupillometer can differentiate between changing pupillary sizes of eyes with use of Pilocarpine and Tropicamide in comparison with Carboxymethylcellulose. Card pupillometer is a useful tool for the purpose of demonstration of effects of drugs on pupillary size.