Background Colircusi double anaesthetic eye drops (CAD) are mainly used in minor eye surgery and in diagnostic examination procedures in ophthalmology. Ocular tolerance for these eye drops is poor and it often causes weeping in the paediatric patient after instillation. Purpose The aim of this study was to present an ophthalmic anaesthetic compounded alternative to CAD, with suitable characteristics for its use in the paediatric population.

Material and methods Initially the composition, pH and osmolality of CAD were analysed. Next, a bibliographic research on the active ingredients with anaesthetic activity, potentially likely to be made as ophthalmic master formulas, was done (Martindale, Pubmed, Micromedex). Subsequently, anaesthetic eye drops with the chosen active ingredients were made and its pH (pHmeter- WTW Inolab) and osmolality (VAPRO 5520) were measured. Finally, after use of these eye drops for 3 months in paediatric patients, subjective perception of the paediatric ophthalmologist about ocular tolerance was recorded.

Results Every 1 mL of CAD contains 1 mg of tetracaine hydrochloride and 4 mg of oxybuprocaine hydrochloride, and also the excipients, chlorobutanol, monopotassium phosphate, disodium phosphate and purified water. It has an osmolality of 231 mmol/kg and a pH of 4.5. The active ingredient chosen to be formulated was lidocaine hydrochloride. Lidocaine eye drops at a concentration of 4% (CL4) were formulated—2 g of lidocaine hydrochloride were weighted in an analytical balance and, in a horizontal laminar flow cabin, the solid was solved in 50 mL of BSS, subsequently filtering it through a 0.22 µm filter to pack it in sterile amber glass bottles of 5 mm. The osmolality of CL4 was 594 mmol/kg and its pH was 7.0. The paediatric ophthalmologist had a positive perception about ocular tolerance and efficacy of these eye drops because they did not cause weeping of the patient’s eye after instillation and no significant adverse reactions were detected on the eye’s surface.

Conclusion CL4 as anaesthetic eye drops was safe and well tolerated in paediatric patients due to the pH and osmolality being similar to physiological values.

No conflict of interest.