;T\'|[bY 人眼光学模型可用来设计眼科用设备,光学系统注定了要与人眼一起使用。本文演示了这样一个模型:Arizona眼睛模型,在Jim Schwiegerling教授的书中有详细描述:《Field Guide to Visual and Ophthalmic Optics》。AZ眼睛模型达到了基于平均临床数据所决定的轴上和轴外像差等级。FRED文件包含了此眼睛模型及几个用来分析它的光源,并包括一个基于想要的屈光度来调整模型的内嵌脚本。 p{W'[A{J . w[hT,$n 模型 Rw]lW;EN< Mcm%G# 模型的定义如表1种所示,由半径、圆锥常数、折射率、阿贝数、到下一面的距离等一系列表面组成。一些参数由屈光度(A)来决定。 DQyy">]Mh Table 1. AZ眼睛模型的定义 GQ])y ~pG,|\9 在FRED中使用0屈光度来创建的,光瞳加在了透镜的前面。材料是创建一个新的材料并选择类型“Model Material”,输入的参数是nd和vd. _6Qb 3tl dvPlKLp 光源 gf^XqTLs <)9dTOdd 多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 "fZWAGDBO\ ~%Xs"R1c, 图1. 光源和提示信息使用 xQ~N1Y2W ^rssZQKY[ 除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处,并增加了pre-propagation distance= -8。尽管光线在光瞳处创建,规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射,而不是在光瞳处入射。 =,G^GMi' -YJ4-]Z 在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 ?CO..l 图2. 字母F光源的设定方法光 ql2O%B.6? # "KaRh 图3. 字母F在视网膜上位置点列图 ,; k`N`#' >A
?{cbJ 视网膜的散射 1`v$R0`! vD3j(d 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 ,l7',@6Y B0dv_'L}L 图4. 视网膜朗伯散射设定 /@feY?glc ~%d* #Yxq 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 6hAMk<kx?i M~LYq 图5. 视网膜重点采样规格设定 X3l?
YA a`_w9r+v 脚本 wLOS,= P-)`FB 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: M TOZ:b 图6. 用户对话框的创建与编辑 ~?<VT
k 图7. 用户对话框编辑器 =5u;\b>* /6yH ,{(a 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 >@uF ye$ 余下的脚本计算与屈光度有关的所有参数。 = @n `5g m(p0)X),_i 分析 /\u1q< _ Y8jl,J 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 xY$@^(Q\ 图7. 字母F在视网膜上颜色分析 [$FiXH J +?bjP6w_g 脚本代码 :,1kSM%r Mv7=ZAm Option Explicit 'Remove this to enable non-dimensioned variables to be used. Q/ ^a( dA=T+u Dim entity As T_ENTITY %w#8t#[,6 Dim op As T_OPERATION 7xoq:oP-}N Dim mat As T_MODELMATERIAL %hV]vm Dim A As Double xay~fD Dim pupilDiam As Double `z~L0h Dim eID As Long $@@@</VbP Dim parID As Long 7]lUPLsl Dim count As Integer Tv /?-`Y Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double <)VNEy' Dim tlens As Double, nlens As Double $.T\dm- Dim curv As Double, conic As Double se`^g
,]P Dim ok As Long I6RF;m:Jw )F65sV{ Sub Main u]jvXPE6 eg(1kDMpn '用户输入对话框 /{FSG! Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 gN5;Uk TextBox 220,21,40,21,.TextBox1 'default: 0 B> V)6\ Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 rkWiGiisM OKButton 40,91,90,21 5[|ZceY CancelButton 190,91,90,21 $i"IOp Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 _8&a%?R@W TextBox 220,49,40,21,.TextBox2 'default: 4 (;cvLop End Dialog C jZIBMGc Dim dlg As UserDialog JE ''Th} lCiRvh1K ok = Dialog (dlg) [VY265)g RR[1mM If ok=0 Then 'cancel button was pressed ~R
C\ Print "Execution cancelled." EKf! j3 End _l{_n2D- End If
O2N~&<^ ~__rI-/_ 'Assign accommodation and pupil diameter & use defaults if field left empty Gc2:^FVlh If dlg.TextBox1 = "" Then B(,j*,f A = 0 'Default accommodation
( =t41-l Else Z^6qxZJ7 A = CDbl(dlg.TextBox1) :@K~>^+U End If VJOB+CKE uh&Qdy!I If dlg.TextBox2 = "" Then Q1[EiM3 pupilDiam = 4 'Default pupil diameter IZOO>-g'f Else buA/G-<e pupilDiam = CDbl(dlg.TextBox2) iPdR;O' End If mG.H=iw 3B?7h/f Print " " m t}3/d Print "Accommodation = " & A & " Diopters" qTI_'q Print "Pupil Diameter = " & pupilDiam & " mm" ((T6z$:hA )| 0(#R ' Calculate new parameters with accommodation !<= ^&\A taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness aqKrf(Rv O[W/=j[ Rant = 12.0 - 0.4*A 'Radius of anterior lens O1Nya\^g<I CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens lc\%7-%:5 KhZ\q|5 Rpost = -5.224557 + 0.2*A 'Radius of posterior lens r;SOAucX CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens '.IR|~ Y *s$:"g- tlens = 3.767 + 0.04*A 'Lens thickness UqNUP+K u$ff %`E nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction 2aJ_[3p/h] {"mb)zr 'Adjust parameters to account for accommodation |G(I,EPag !a^'Jbb '************************************************************************* 'DTq<`~? 'Aqueous thickness (Position of Lens) yt#~n_ '************************************************************************* "HtaJVp// eID = FindFullName( "Geometry.Arizona Eye.Lens" ) To =JE}jzo GetCustomElement eID, entity g96]>]A<{ M+-1/vR *@ parID = FindFullName( "Geometry.Arizona Eye" ) $Qcr8~+a g]jCR*] ' Delete any shift(s) in z 1)J'
pDa count = 0 R/jHH{T3 While GetOperationCount(eID)>count u+qj_Ej GetOperation eID, count, op X.[8L^ldh If op.Type="ShiftZ" Then Tzr'3m_ DeleteOperation eID,count 2 sK\.yS count=count-1 cS RmC End If n7pjj count=count+1
J7p?9 Wend GU7f27p @o>3
Bv. 'Set new shift in ][B>`gC- op.Type = "ShiftZ" a\tv,Lx op.val1 = taq _[,7DA.qc op.parent = parID ="P&!lu AddOperation eID, op $Go)Zs-bL? Print "Set aqueous humor thickness = " & taq-0.55 z?
Ck9 ~'0W(~Q8 '************************************************************************* 4q*mEV 'Radius and conic constant of anterior lens 4%5 + '************************************************************************* @6%o0p9zz eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) :I8HRkp GetConic eID, entity, curv, conic 8K2=WYN #A=ER[[ SetConic eID, entity, 1/Rant, CCant K(rWM>Jv Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant lS/l
iI'Y $fG~;`T '************************************************************************* =DwY-Ex 'Radius and conic constant of posterior lens tf6 Zz[ '************************************************************************* NE+
;<mW eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) A$-\Er+f GetConic eID, entity, curv, conic s^HI%mdf Y7<(_p7 SetConic eID, entity, 1/Rpost, CCpost G<Y}QhFU Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost xM**n3SZ` y\ax?(z '************************************************************************* sF~!qag4q' 'Lens thickness (Position of posterior lens surface) JzmX~|=Xi '************************************************************************* U &RZx&W }s:~E2?In parID = FindFullName( "Geometry.Arizona Eye.Lens" ) Zx)gLDd m.Ki4NUm ' Delete any z-shift(s) $y,tR.5.)[ count = 0 F[*/D/y( While GetOperationCount(eID)>count naVbcY GetOperation eID, count, op 70.Tm#qh If op.Type="ShiftZ" Then o8fY!C) DeleteOperation eID,count ,AwX7gx22 count=count-1 T+41, End If .qs5xGg#9 count=count+1 z
m+3aF Wend Lm*PHG +!$]a^3l 'Set new z-shift 5=/j op.Type = "ShiftZ" <aQ5chf7 op.val1 = tlens 1t} op.parent = parID 6UM1>xq9A AddOperation eID, op ei(S&u< Print "Set lens thickness = " & tlens q_Z6s5O xc,Wm/[ '************************************************************************* SLda>I(p7& 'Lens index of refraction 2b&Fu\2Dmv '************************************************************************* R)6"P?h._4 eID = FindMaterial( "Lens" ) VM<$!Aaz GetModelMaterial eID, mat xB5QM #w\ 1u~a*lO} mat.Nd = nlens iH8V] % SetModelMaterial eID, mat v(p<88.!m Print "Set lens index of refraction = " & nlens ~W-5-Nl{s 3EH7HW '************************************************************************* ;*cCaB0u 'Pupil diameter !Y10UmMu '************************************************************************* 2^y*O eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) D+y?KihE GK1oS 'Adjust pupil diameter (trimming volume inner hole) V/BU(`~i v {)8QF] SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" )j. .)o -Eoq#ULvR ' Adjust pupil location to just in front of the lens WWT1_&0 parID = FindFullName( "Geometry.Arizona Eye" ) !o\e/HGc! eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) gv,1 CK count = 0 sQn@:Gk While GetOperationCount(eID)>count MqRJ:x GetOperation eID, count, op >65\ If op.Type="ShiftZ" Then OO\$'%
y` DeleteOperation eID,count %e(DPX count=count-1 4+MaV<!tU^ End If O]KQ]zN count=count+1 ]I\9S{? Wend cp6I]#X op.Type = "ShiftZ" 38GZ_z}r op.val1 = taq-0.01 B_*Ayk
op.parent = parID L;v.X'f AddOperation eID, op &r2\P6J pA6A*~QE Print "Set pupil diameter = " & pupilDiam 51;[R8'w D#gC-, 'Update AZ Eye subassembly Description A_crK`3 eID = FindFullName( "Geometry.Arizona Eye" ) KxDp+]N]
GetEntity eID, entity /7x1Z*Hg entity.Description = "Accommodation = " & A & "D" AF>t{rw=/ SetEntity eID, entity /@U bN\ e xkPu-[W Update 4hzdc]
a Print "DONE!" QOY{j EI496bsRHm End Sub hD{
`j i&{%}==7 如果屈光度是4,光瞳直径是4,则会输出如下数据: [Y.=bfV! qG +PqK; Accommodation = 4 Diopters TX;)}\ Pupil Diameter = 4 mm z\$( @:{A Set aqueous humor thickness = 2.81 )iFXa<5h Set anterior lens radius = 10.4 and conic constant = -2.375869 $W%-Mm Set posterior lens radius = -4.424557 and conic constant = -3.081019 <h~=d("j Set lens thickness = 3.927 zbgGK7 Set lens index of refraction = 1.42672 C[5dhFZ Set pupil diameter = 4 ~K"nm {. DONE! |