PURPOSE: To investigate if there is any difference in volume and drop weight of prostaglandin analogs when adopting drip angles of 45º and 90º, regarding a horizontal line. METHODS: An experimental study was conducted using the follow ophthalmic solutions: latanoprost, travoprost and bimatoprost. In this study the ophthalmic solutions were dripped according to an angle of 45º or 90º. Prostaglandin analogs were chosen due to their common use in ophthalmology and their cost. The first drop and other ten drops were weighed, alternating the drip angle (45º or 90º). Statistical analysis was done with SPSS® 12.0 (Microsoft), using quantitative comparisons with the ANOVA test. An odds value (P) below 0.001 was considered a statistical significant difference. RESULTS: We verified differences in weight and size of the travoprost and bimatoprost drops instilled at 45º and 90º. The drip at 45º produces a smaller drop of travoprost (P<0.001), and the inverse occurs for bimatoprost. There were no statistical significant differences in weight of latanoprost drops according to the instillation angle. CONCLUSIONS: Once there was statistical difference in weight - which has direct relationship with size - of the drops of two kinds of prostaglandin analogs and in another one we did not observe this variation, we infer that cost and therapy duration estimates should be analyzed carefully, especially if this kind of drip measure is used.
Glaucoma; Drug price; Ophthalmic Solutions; Ophthalmic solutions; Instillationm, drug; Prostaglandins F, synthetic; Health care costs; Health expenditures; Comparative study
