Abstract
Purpose:
This study aimed to determine the onset and duration of action of 3 commercially available topical anesthetic solutions in Brazil, using the Cochet–Bonnet esthesiometer (Luneau®, Paris, France) and to quantitatively assess patient-reported discomfort during application.
Methods:
A prospective, randomized, masked, and double-blind study was conducted, involving 40 eyes from 21 patients. Patients were administered each one of the topical anesthetics weekly, and corneal sensitivity was measured using the Cochet–Bonnet esthesiometer's corneal touch threshold (CTT). Patients rated the burning sensation using a visual analogue scale (VAS).
Results:
Among the 21 patients (42.9% male), with a mean age of 31.95 years (±standard deviation = 10.17, range = 22.0–58.0), corneal sensitivity significantly decreased 30 s after application, returning to baseline after 30 min for all groups (P < 0.0001). Significant differences in CTT were observed at 5 min, with proparacaine exhibiting a superior anesthetic effect (P = 0.0003), at 10 min, where tetracaine displayed the most substantial anesthetic effect (P = 0.0135), and at 20 min, where tetracaine demonstrated the highest anesthetic efficacy (P < 0.0001). VAS scores indicated the most intense burning sensation with tetracaine (P < 0.0001). Men reported experiencing more discomfort during instillation compared with women (P = 0.0168).
Conclusions:
Proparacaine exhibited the fastest onset of action among the 3 topical anesthetics and provided a more comfortable eye sensation during instillation. However, tetracaine demonstrated the longest duration of action despite causing more discomfort.
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