Short-term, low-contrast visual acuity reduction associated with in vivo contact lens drying.
Hydrogel contact lens surfaces partially desiccate during extended interblink intervals, producing a microscopically rough and irregular surface that scatters light. Such light scattering could reduce retinal image contrast, elevating thresholds for target perception. To test this idea, we measured low (7%)-contrast visual acuity of subjects who wore: (1) hydrogel contact lenses, (2) rigid gas permeable (RGP) lenses, and (3) no contact lenses when the subjects blinked normally and when they suppressed blinking. Acuity thresholds were determined using computer-generated acuity stimuli and a staircase psychophysical procedure. Cessation of blinking resulted in small reductions in low-contrast acuity for subjects wearing RGP lenses (mean loss: 0.1 line) or no lenses (mean loss: 0.3 lines). Subjects wearing hydrogel lenses, however, generally exhibited substantial reduction of acuity (mean loss: 4.1 lines) when blinking was suppressed.
Timberlake
G T
GT
Department of Ophthalmology, University of Kansas Medical Center, Kansas City.
Doane
M G
MG
Bertera
J H
JH
D000328:Adult; D001767:Blinking; D003261:Contact Lenses / Q000009:adverse effects*; D015350:Contrast Sensitivity; D003890:Desiccation; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D008027:Light; D008875:Middle Aged; D011092:Polyethylene Glycols; D012542:Scattering, Radiation; D014786:Vision Disorders / Q000209:etiology; D014792:Visual Acuity
D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D011092:Polyethylene Glycols