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T. Kuyk, L. McLin, J. Kent, L. Barnes, J. Dykes, P. Garcia; Evaluation of Prescription Lenses That Correct Higher Order Optical Aberrations. Invest. Ophthalmol. Vis. Sci. 2008;49(13):992.
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To determine if prescription lenses that incorporate a correction for higher order optical aberrations in addition to lower order aberrations provide wearers visual advantages over traditional prescription eyewear.
Using a within-subjects experimental design and a blind randomized treatment order, visual performance of 20 subjects (mean age = 30.5) was compared while wearing iZon® wavefront-corrected lenses (Ophthonix, Inc.) and traditional prescription lenses (plano lenses if the subject was emmetropic). Visual acuity was assessed with high (96%) and low (11%) contrast letter charts (Regan charts) at mean luminance (white portion) of 100 and 3 cd•m-². In addition contrast sensitivity was assessed at 5 spatial frequencies (0.9, 3, 6, 12, 18 cpd) using a staircase procedure at grating mean luminance (5o gabor patches) of 30 and 3 cd•m-². Subjects were tested twice, when the lenses were issued and at a minimum of 2 weeks later.
Average acuity for the high contrast letters with the traditional lenses (plano for emmetropes) was 20/11.5 and 20/14.8 at 100 and 3 cd•m-² compared with 20/11.4 and 20/15.1 with the Izon® lenses. None of the differences were significant. With the low contrast letter charts, acuity was reduced (approximately 20/18 and 20/30 at 100 and 3 cd•m-²) but like the high contrast condition no differences between the traditional and Izon® lenses were found. Similarly, in the contrast sensitivity data no significant differences between the traditional and Izon® lenses were found at any spatial frequency at either 30 or 3 cd•m-² (Figure 1).
When assessed with standard techniques, the Izon® lenses did not provide wearers any visual advantage over traditional lenses. One caveat in generalizing these results is that the sample tested consisted of a significant number of young US Air Force personnel who had exceptionally good corrected or uncorrected acuities even under low light test conditions and thus there may have been little room for measurable improvement.
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