Changes in myopia with low-Dk hydrogel and high-Dk silicone hydrogel extended wear.
OBJECTIVE
This study compared changes in myopia between wearers of high-oxygen permeability (Dk) silicone hydrogel lenses and low-Dk hydrogel lenses after 1 year of extended wear (EW).


METHODS
Ninety-two adult subjects were randomly assigned to a lens type. Subjective refraction and autokeratometry were performed at baseline and at 6 and 12 months.


RESULTS
After 6 months of EW, myopia (spherical equivalent) regressed by 0.18 +/- 0.33 D (p < 0.001) in the high-Dk silicone hydrogel group and progressed by -0.23 +/- 0.36 D (p < 0.001) in the low-Dk hydrogel group. There were no further changes after 12 months. Previous lens wear history, baseline refractive error, and age and gender did not have an impact on the change in myopia, and only 35% of the variation could be accounted for by changes in corneal curvature and lens type.


CONCLUSIONS
Soft contact lens type significantly affects the direction of change in myopia during EW. We hypothesize that these changes are driven by pressure-related redistribution of corneal tissue in high-Dk silicone hydrogel lens wearers and by hypoxia-associated corneal thinning in low-Dk hydrogel wearers. More long-term studies are required to confirm whether the effects of high-Dk silicone hydrogel lens wear on myopia are permanent.
The Cooperative Research Centre for Eye Research and Technology, School of Optometry and Vision Science, University of New South Wales, Sydney, NSW 2052, Australia. i.jalbert@visioncrc.org
Isabelle
I
Jalbert
Serina
S
Stretton
Thomas
T
Naduvilath
Brien
B
Holden
Lisa
L
Keay
Deborah
D
Sweeney
D000328:Adult; D003262:Contact Lenses, Extended-Wear / Q000706:statistics & numerical data*; D003315:Cornea / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D009216:Myopia / Q000503:physiopathology*; D010100:Oxygen / Q000378:metabolism; D010539:Permeability; D012189:Retrospective Studies; D012826:Silicone Elastomers
D012826:Silicone Elastomers; D010100:Oxygen