Abstract
Purpose: :
Bacterial contamination of the contact lens surface has been shown to cause corneal infiltrative events (CIE). A reduction in the rate of bacterially-driven CIE during lens wear is one of the major goals of the contact lens industry. The aim of this pilot trial was to investigate safety of prophylactic topical antibiotic (AB) instillation during continuous wear (CW) of silicone hydrogel (SH) lenses with the eventual aim of conducting a large scale proof-of-principle efficacy trial to determine if AB drop use reduces AE rate during CW.
Methods: :
To detect difference of 0.5±0.5 grade units in bulbar/limbal redness, 42 subjects were dispensed with SH lenses (lotrafilcon A) for a 3 month, 30-night CW, monthly replacement trial. Subjects were randomised into either AB drop (tobramycin 0.3%) or saline drop group. Two drops were instilled into each eye on waking and prior to sleep. Routine clinical examination was performed at scheduled visits. Any CIE at scheduled or unscheduled visits was recorded. At monthly visits, lenses were collected aseptically and ocular and throat swabs were performed.
Results: :
AB group had less corneal staining superiorly (p=0.025) but increased overall bulbar redness (p<0.001) at 3-month visit only compared to saline group. Numbers of microbes recovered from eye swabs from AB group was significantly lower than from saline group (p = 0.01). Gram-positive cocci were less frequently recovered from AB group (p = 0.001). More eye swabs from AB group were culture-negative than swabs from saline group. There were no significant difference in CIEs, the numbers and types of microbes recovered from lens samples, or the contamination rate of the lenses between the two groups. There were no changes in the numbers and rate of fungal recoveries. Microbes recovered from throat swabs showed no resistance to tobramycin.
Conclusions: :
Overall there appeared to be minimal health risk from daily use of antibiotic drops over a 3 month period in this sample group. The AB drops group did, however, induce mild to moderate bulbar redness by the 3-month time-point. Prolonged use of antibiotic eye drops did not induce an increase of specific bacterial or fungal species.
Clinical Trial: :
www.anzctr.org.au ACTRN12608000626369
Keywords: contact lens • antibiotics/antifungals/antiparasitics • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials