Purchase this article with an account.
A.E. Partal, E.E. Manche; Functional Optical Zone Measurements versus Programmed Ablation Zone Settings in Myopic LASIK using the VISX S2 Excimer Laser . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2624.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: To compare the functional optical zones of eyes treated with myopic LASIK using the VISX S2 excimer laser to the programmed ablation zone settings. Methods: 204 eyes treated with LASIK using the VISX S2 excimer laser were retrospectively evaluated to determine the size of the functional topographic optical zone, defined as the zone creating the major refractive change. The functional optical zone was measured at the edge of the midperipheral flattening on subtraction topography (yellow) on the pre-operative and 3-6 month post-operative topographies. No blend zones were used, and only 6.5 mm ablation zones were included in the study. The eyes were divided into four groups A-D in order of increasing myopia. Results: When the subtraction topography optical zone was compared to the programmed ablation zone, an optical zone reduction of 1.5 +/- 0.1 mm and 1.2 +/- 0.1 mm was found for the longest and shortest diameters, respectively. For eyes with spherical ablation zones, this reduction was 1.6 +/- 0.1 mm and 1.4 +/- 0.1 mm shorter than the programmed horizontal and vertical dimensions. Groups A, B, C, and D, in order of increasing myopia, showed reductions of approximately 1.5 +/- 0.1 mm and 1.2 +/- 0.1 mm for the longest and shortest diameters of the optical zone. Conclusions: The functional topographic optical zone was significantly reduced from the programmed ablation zone. This reduction was clinically significant for both elliptical and spherical ablations, and seemed to be independent of the degree of myopia.
This PDF is available to Subscribers Only