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Refractive error shift with continuous use (Rescu) lenses

Merchea, Mohinder Mohan
http://rave.ohiolink.edu/etdc/view?acc_num=osu1054652868

Abstract Details

2003, Doctor of Philosophy, Ohio State University, Physiological Optics.
Low Dk hydrogel contact lenses have been associated with minimal but measurable progression of myopia although evidence to the contrary exists. This so called “myopic creep” has been shown to decrease or reverse when hydrogel lens wearers switch to 30 night and day silicone hydrogel lens wear. To assess the mechanisms contributing to changes in refractive error associated with the refitting of extended wear hydrogel contact lens users with 30-night continuous use silicone hydrogel contact lenses a prospective clinical trial was completed. Fifteen adapted extended wear low-Dk contact lens patients and five non-contact lens wearers were enrolled and followed for 3-months after fitting with 30-night continuous wear lenses. Patients were examined at 1-day, 1-week, 1-month, 2-months and 3-months. Refractive error evaluation included subjective and automated refractions and wavefront derived measurements. Ocular biometric measurements included topography, pachymetry, axial length, anterior chamber depth and phakometry. A hyperopic shift of 0.40 diopters was observed in previous myopic low-Dk extended wear hydrogel contact lens users after 3-months of continuous wear of a silicone hydrogel contact lens. Hyperopic shifts are predicted in those subjects with the greatest baseline myopic refractive error. The occurrence of hyperopic shifts are associated with corneas that experience larger amounts of anterior curvature flattening and are associated with large changes towards more positive values in ocular 4th order spherical aberration Zernike term. Corneal thinning (Orbscan I pachymetry) was also associated with the hyperopic shift. Low Dk hydrogel contact lenses have been associated with minimal but measurable progression of myopia although evidence to the contrary exists. This so called “myopic creep” has been shown to decrease or reverse when hydrogel lens wearers switch to 30 night and day silicone hydrogel lens wear. To assess the mechanisms contributing to changes in refractive error associated with the refitting of extended wear hydrogel contact lens users with 30-night continuous use silicone hydrogel contact lenses a prospective clinical trial was completed. Fifteen adapted extended wear low-Dk contact lens patients and five non-contact lens wearers were enrolled and followed for 3-months after fitting with 30-night continuous wear lenses. Patients were examined at 1-day, 1-week, 1-month, 2-months and 3-months. Refractive error evaluation included subjective and automated refractions and wavefront derived measurements. Ocular biometric measurements included topography, pachymetry, axial length, anterior chamber depth and phakometry. A hyperopic shift of 0.40 diopters was observed in previous myopic low-Dk extended wear hydrogel contact lens users after 3-months of continuous wear of a silicone hydrogel contact lens. Hyperopic shifts are predicted in those subjects with the greatest baseline myopic refractive error. The occurrence of hyperopic shifts are associated with corneas that experience larger amounts of anterior curvature flattening and are associated with large changes towards more positive values in ocular 4th order spherical aberration Zernike term. Corneal thinning (Orbscan I pachymetry) was also associated with the hyperopic shift.
Joseph Barr (Advisor)
Health Sciences, Ophthalmology
Corneal; REFRACTIVE ERROR; contact lens; contact lenses; hydrogel; extended wear; LENSES

Recommended Citations

Citations

  • Merchea, M. M. (2003). Refractive error shift with continuous use (Rescu) lenses [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1054652868

    APA Style (7th edition)

  • Merchea, Mohinder. Refractive error shift with continuous use (Rescu) lenses. 2003. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1054652868.

    MLA Style (8th edition)

  • Merchea, Mohinder. "Refractive error shift with continuous use (Rescu) lenses." Doctoral dissertation, Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1054652868

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.