Purchase this article with an account.
P. Walker, G. W. Ousler, III, D. A. Workman, M. Hankin, M. B. Abelson; Visual Function in Normals Compared to Patients Diagnosed With Dry Eye as Measured by the Inter-Blink Interval Visual Acuity Decay (IVAD) Test. Invest. Ophthalmol. Vis. Sci. 2007;48(13):422.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Dry eye patients often complain of blurriness when performing activities such as reading, watching television, or driving at night. Tear film break up time (TFBUT) between blinks is thought to be the primary cause for this decay in visual acuity. To better understand this relationship a method of measuring functional visual acuity between blinks has been developed. The inter-blink interval visual acuity decay (IVAD) test is used in this study to determine whether there is a difference in visual function between normals and patients diagnosed with dry eye.
Eighteen (18) dry eye patients and 17 age-matched controls underwent ophthalmic examinations including BCVA, slit lamp biomicroscopy, TFBUT assessment, and functional visual acuity between blinks as measured by the IVAD test. IVAD is a real-time, computer-based measure of visual acuity decay which involves the identification of images at the patients’ BCVA. A rotating ‘c’ is presented at the response pace of each patient so that the decay in visual acuity between blinks can be measured. The IVAD test is conducted without the use of an anesthetic.
The age-matched controls were able to maintain their BCVA for significantly longer than dry eye patients, p=.0001. Additionally, controls had a longer inter-blink interval while performing the task than the dry eye subjects, p=.002. TFBUT was also significantly longer in control subjects than dry eye patients, p=.0001, and this effect significantly correlated with the subjects’ time at best corrected visual acuity on the IVAD test, p=.0001.
The data show that the dry eye patients were significantly less able to maintain their BCVA during the inter-blink interval. This finding may account for the visual disturbances reported by dry eye patients.
This PDF is available to Subscribers Only