近视患者角膜的非线性回归拟合曲面方程VIP免费

第9卷第3期2007年5月眼视光学杂志ChineseJournalofOptometry&OphthalmologyV0J．9No．3May．2007近视患者角膜的非线性回归拟合曲面方程包芳军，王晓幸，王勤美，陈世豪，符爱存温州医学院附属眼视光医院，浙江温州325027AnonlinearregressionequationtodescribethecornealsurfaceofmyopesBAOFangjun，WANGXiaoxing，WANGOinmei，eta1．TheAffiliatedEyeHospital，WenzhouMedicalCollege，WenzhouChina，325027[Abstract]ObjectiveToobtainmoreaccuratecornealsurfaceequa—tionsformyoposthroughsurfacemeshingofboththeanteriorandpos—teriorsurfacesofthecornea，3Dcoordinatemeasurements，acquisitionandanalysis．Thisresearchlaysthefoundationforfollow-upresearchonbiomechanicalfiniteelementmodels．Me~odsAnOrbscan—．1IZcornealtopographysystemwasusedtomeasurecentralcornealthick—nessinthe”Pachymetry”mapandtheradialdistance(diferenceval—ues)ofthespecificpoints(0．2mm×0．2mmgridofvertices)betweenthecentralcornealsurface(anteriorcornealsurface7mm×7mm，pos—teriorcornealsurface6mm×6mm1andthebestfitsphereinthe”Ele—vationBFS”map．TheCartesianCordinatesystemwasestablishedbyusingthehorizontalaxisfortheX—axis，theverticalaxisfortheY—axis，andtheopticalaxisfortheZ—-axis．Thecordinateoftheanteriorcornealsurfaceapexwassetupto(0，0，O)，theanteriorandposteriorcornealsurfaceapexesweleonthesameaxis，andthecoordinateoftheposteriorcornealsurfaceapexWaSsetupto(0，0，-0．536)．DifferencevaluesofthespecificpointsweroexportedtoExcel2003andincorpo—ratedintothe3Dcoordinatesaccordingtothefollowingmathematicalformula：=z0一(r_[(r蝴一胡．Sixtyrandomlyselectedcorneasfrom64eyeswereusedforcalculatingthegeneralcornealsurfaceequationusingthefollowingmathematicalformula：①Ellipsoid：／+／b+0+c)／c=1O，b>0，c>o】．@)Hyperboloidoftwosheets：x2／Ⅱ2+／6一0一c)Vc：-1(a>O，b>0，c>o】．(EllipticParaboloid：+)刀g=2z(P