Abstract
Purpose :
The stability of the precorneal tear film is essential for maintaining the optical quality of the eye between blinks.Changes in ocular aberrations over time occur, during the postblink period, in healthy individuals of all ages.However, tear film function decreases with age causing tear film irregularities in older individuals, and thus poorer image quality of the retina during the postblink period.Contact lens wear also changes the retinal image quality after a blink, as it alters the tear film characteristics and along with the drying of the contact lens surface can lead to further changes in aberrations.To understand the issue, we conducted a preliminary study on the changes in higher ocular aberrations (HOAs) during the postblink period in different age groups with and without multifocal contact lens wear.
Methods :
Three different age groups (i.e. group I: 18-29 years, group II: 30-39 years and group III: > 40 years) comprised of 8 eyes each group were included in this study.Eyes with astigmatism less than 1D, corrected visual acuity 20/20 (feet) or better and normal non-invasive tear break-up time (NIBUT) findings were enrolled.Total ocular aberrations were measured in the left eye sequentially for 12 seconds (sec) after a blink, using a Hartmann-Shack wavefront aberrometer (irx-3, Imagine Eyes).Dynamic tear meniscus measurements were obtained during 12 sec postblink period, employing optical coherence tomography (OCT).All measurements were performed initially without contact lenses and then with contact lenses.
Results :
Systematic changes in the HOAs significantly increased with time after a blink for the young subjects tested and included in group I (p< 0.002).In this group, a positive relationship was identified between time and spherical aberration (p<0.002) during the postblink period, with the curves to be coalesced 3 sec after a blink, due to tear film consolidation.The tear meniscus height and its area did not change significantly (p>0.79) over the postblink period.A large amount of inter-subject variability was also observed within any of the groups.While, contact lens wear significantly changed the aberration profile during the post blink period (p<0.05).
Conclusions :
The optical quality of the human eye varies considerably over time after a blink, due to changes in the tear film characteristics.Age and contact lens wear also influence on the dynamics postblink changes in aberrations.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.