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F. Lu, T.L. Simpson, L. Sorbara, D. Fonn; The Relationship Between the Treatment Zone Diameter With Visual and Optical Performance in Hyperopic Corneal Refractive Therapy Lens Wearers . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2057.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate the stability of the treatment zone (TZ) after one night of hyperopic Corneal Refractive Therapy (CRT®H) lens wear and to determine the association between the TZ with visual and optical performance. Methods: Paragon CRT®H lenses (Dk=100) were fit on one eye of 20 ametropes (mean±SD spherical equivalent: –2.09±2.53D) with no lens on the contralateral eye (randomly selected). High/Low contrast visual acuity (HCVA/LCVA), refractive error, aberrations (LADARWaveTM), and corneal topography were measured at baseline, and immediately after lens removal and 1, 3, 6, 12 hours later on the following day. The TZ was defined by the change in curvature from negative to positive and vice versa, using the tangential difference map from the Atlas TM and Orbscan II TM corneal topographers. Root mean square (RMS) wavefront errors and zernike coefficients of spherical aberration (SA) were collected using 4.5mm pupils. Results: During the day, the central steepened zone (CSZ, ±SE) was statistically constant (both p≥0.118) and was 2.50±0.11mm using the Atlas and 3.30±0.18mm using the Orbscan. During the same period, the total treatment zone (TTZ) ranged from 7.18±0.13mm to 6.65±0.24mm using Atlas, from 6.11±0.10mm to 5.82±0.13mm using the Orbscan (both p≤0.011). There was a positive correlation between CSZ and signed SA using Orbscan (r=0.676, p=0.002); there were negative correlations between TTZ and RMS SA using Atlas and CSZ and HCVA/LCVA using Orbscan (r =–0.480∼–0.584, all p≤0.044). There were also marginal correlations between TTZ and signed SA and LCVA using Orbscan (r=0.432, p=0.073; r=–0.441, p=0.067). Conclusions: CSZ was approximately constant after one night of CRT®H lens wear, while TTZ reduced. The treatment zone concept (both central and total) is a useful indicator of visual and optical performance of CRT®H lens wear.
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