Editorial
Issueswith Silicone Hydrogel Lens Wear Silicone hydrogel (SH) materials have allowedclinicians to fit their patients with hydrogel lenses that supply sufficientoxygen to eliminate hypoxia. > more
Quick Vote:
Have you noticed refractive changes after refitting patients with silicone hydrogel lenses who were long term wearers of hydrogel lenses? >click
Would you like to subscribe to our monthly newsletter? > click
Posters
REFRACTIVE AND KERATOMETRIC CHANGES FOLLOWING EXTENDED WEAR
Kathy Dumbleton, MCOptom, MSc, Doris Richter, OD, MASc, Desmond
Fonn,
DipOptom MOptom, Centre for Contact Lens Research, UW;
Robin Chalmers, OD, CIBA Vision, Atlanta, GA
Purpose:
A small but significant increase in myopia following extended wear of low DK hydrogel lenses has been previously reported, however the specific impact of hypoxia on refractive status and corneal curvature with extended wear are not well documented. The purpose of this study was to compare that over a period of 6 months extended wear with experimental high DK (HDK, 140) and lower DK (LDK, 28) hydrogel lenses.
Method:
Ninety-one contact lens wearers were enrolled in the study and randomly assigned to one of two groups. The LDK group wore etafilcon A (DK=28) for up to 7 days and 6 nights (n=32) and the HDK group wore lotrafilcon A (DK=140) for up to 30 days and 29 nights (n=59). Refractive error and corneal curvature (Nikon AutoRef Keratometer) and corneal topography (Alcon eyemap) were measured at 3 monthly intervals over 6 months of extended wear.
Results:
The LDK group demonstrated an average increase in myopic correction of 0.50D over the 6 month period (p=0.000). No increase was measured in the HDK group (p=0.200). The cylindrical component was unchanged in both groups. A stratified analysis revealed no difference in degree of myopic change for low (less than -3.00, n=53) to moderate (-3.00 to -6.00, n=23) myopes in either group (LDK p=0.071, HDK p=0.204). Keratometric analysis revealed an average central corneal flattening in both major meridians of 0.40D in the HDK group (p=0.000, 0.000), but no change in the LDK group (p=0.426, 0.516)
Conclusions:
Hypoxia from 6 months of extended wear of lower DK lenses is associated with myopic progression in adult myopes. Wearing lenses of high DK had no impact on refractive error and may be associated with a small degree of central corneal flattening. Supported by a grant from CIBA Vision, Atlanta, GA
Posters
