BLINK RATE

Lidocaine HCl 1.0%, is a local anaesthetic which is commonly used in the eye care profession during certain diagnostic tests and examinations to produce numbness or loss of sensation on or around the eye to aid certain diagnostic tests and procedures such as tonometry, pachymetry, gonioscopy, foreign body removal etc. It is also the drug of choice for certain ocular surgical procedures such as cataract surgery, pterygium excision, trabeculectomy and other procedures involving periocular structures. This study was carried out to examine and determine the effect of topical lidocaine HCl 1.0% on blink rate, tear stability and tear flow rate. This was an experimental study which was carried out on 36 randomly selected healthy young adults (18 males and 18 females) with mean age 22.61 ± 2.66 years, with no history of contact lens wear, ocular surface disorders, and current use of topical ocular medications. The blink rate, tear stability and tear flow rate of the various participants were obtained before and after the application of lidocaine HCl 1.0% ophthalmic solution. The blink rate per minute was measured with the use of a stopwatch, tear stability was determined through NonInvasive Tear Break Up Time (NITBUT) with a keratometer. The results obtained showed that the mean value of the blink rate, tear stability and tear flow rate decreased after the instillation of lidocaine. There was no significant relationship between gender and the value of the blink rate, tear stability and tear flow rate; there was also no significant relationship between age and the blink rate and tear flow rate but it was observed there was an inverse relationship between age and tear stability. Thus, the use of topical lidocaine HCl 1.0 % is safe for use in the eye care profession but screening for dry eye disease should be carried out before administration of this anaesthetic.