evaluating and improving functional driving vision of patients with astigmatism

Conditions: Astigmatism

Summary: small amounts of astigmatism are often uncorrected in contact lens wearers. the effect with respect to driving is unknown, but it could threaten safe operation of a motor vehicle, especially under conditions such as nighttime driving when visual abilities are highly challenged. this study measures driving-specific visual abilities and simulated driving performance in participants with astigmatism who either have or do not have their astigmatism corrected. the primary hypothesis is that at a tactical level, contact lenses correcting for astigmatism will result in safer driving performance overall. the secondary hypothesis is that at an operational level, contact lenses correcting for astigmatism will result in better driving-specific visual performance.

safe driving relies heavily on "good vision." good vision while driving relates to multiple abilities, such as dynamic visual acuity, contrast sensitivity, management of glare and peripheral vision, etc. while spherical contact lenses address issues of correction of visual acuity as determined by forward static vision tests, if they do not provide visual acuity both immediately and smoothly with eye movement then vision can be compromised. glare can be a problem as well when contact lenses are off center. fluctuating vision as a result of lens movement on the eye could be especially problematic and frustrating for patients who have astigmatism. furthermore, experiencing moments of blurred vision no matter how brief can be potentially hazardous while driving. the 1\*day acuvue® moist for astigmatism contact lenses have a unique blink-activated stabilization system to prevent rotation of the lens on the eye, and may have significant visual advantages for drivers with astigmatism. these lenses provide continuous corrected acuity compared to non-ballasted contact lenses, and thus are potentially safer for driving. contact comparison will consist of 1\*day acuvue® moist (spherical control) versus 1\*day acuvue® moist for astigmatism (the daily disposable astigmatism alternative). the study will investigate the potential advantages of contact lenses specifically designed to correct for astigmatism, compared to similar correction with spherical contacts, for adult licensed drivers with astigmatism, employing a double-blind (subjects and research assistant blind to hypotheses), randomized, cross-over design (spherical, vs. astigmatism contacts). this will be a multi-stage study comprised of the following: preliminary study to determine the likelihood of detecting a significant difference between the standard spherical and astigmatism contacts in a full randomize clinical trial (n=12; data and power analysis)

Eligibility criteria:
inclusion criteria: * adult licensed drivers between the ages of 18-39, similar number of males and females will be studied who meet the following inclusion criteria: * bilateral corrected vision of 20/40 or better * bilateral astigmatism between 0.75 to 2.0 diopters, with spherical correction from -1 to -6 * no active eye infection * no defective peripheral vision * do not have correction for bifocals * routinely wear contact lenses more than 4 times per week * routinely drive a car more than 4 times week * do not have a history of motion, sea or big screen (e.g. imax) sickness or experience persistent simulation adaptation syndrome exclusion criteria: * bilateral corrected vision of worse than 20/40 * no astigmatism * active eye infection * defective peripheral vision * wear bifocals * wears contact lenses less than 4 times per week * drives infrequently (less than 4 times per week)

Keywords: astigmatism, contact lens, driving