Abstract
The action of blinking can cause considerable disruption of vision, and this disruption may be greater with contact lenses than with spectacles. Patients often complain that their vision is more variable and of poorer quality with hydrogel contact lenses than with spectacles, a qualitative difference that is difficult to demonstrate. Previous investigators may have failed to fully define the nature of the subjective difference because unlimited stimulus viewing paradigms were employed. In this study, we attempted to determine if transient fluctuations in vision following a blink occurred with hydrogel contact lenses and spectacles. Two hydrogel contact lens wearers with optimally fitted lenses were the subjects. A modified Optronix CS 2000 was employed to measure contrast thresholds for vertically oriented sine-wave gratings (square-wave onset, 16 msec duration) at 11.4 and 22.8 c/deg (using a yes/no detection task). Twenty trials were run at each contrast level (a minimum of five contrast levels centered around threshold were employed). Measurements were taken at eight stimulus onset times (starting at 25 msec after the blink, increasing in I octave steps to 3200 msec). Psychometric functions were produced from the data for each onset time and a Weibull equation was fit to the data to determine threshold. For onset times greater than 100 msec after the blink, the spectacle and contact lens thresholds were identical and did not change with longer onset times (consistent with previous reports). For shorter postblink stimulus onset times, the thresholds for both conditions were higher and greater with contact lenses.
Original language | English |
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Pages (from-to) | 231-237 |
Number of pages | 7 |
Journal | International Contact Lens Clinic |
Volume | 18 |
Issue number | 11-12 |
DOIs | |
Publication status | Published - Nov 1991 |
ASJC Scopus subject areas
- Ophthalmology