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简介 ]VN1Y) TYxi&;w 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。 U|+`Eth8( pL.~z 模型 7pH[_]1" q~\[P4m 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。 LKud' "+&@iL Table 1. AZ眼睛模型的定义 p:!FB8 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. Ys5Iqj=mp |z)7XK 光源 _2})URU<S T !pHT'J 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。 kgX"I ?>d :r_/mzR# [}l
1`> 图1. 光源和提示信息使用 taSYR$VJ 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。 *u34~v16, k~1{|HxrE 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。 y$|OE%S U,`F2yD/! 图2. 字母F光源的设定方法光 xAf?E%_pi S.fb[gI] 图3. 字母F在视网膜上位置点列图 |y]8gL^ 视网膜的散射 rIj B{X{Z Js,.$t 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。 ][T>052v ; JHf0 pmDFmES 图4. 视网膜朗伯散射设定 ^ s/f.#' 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。 ]!N|3"Ls 3_Re>i 2CPh'7|l 图5. 视网膜重点采样规格设定 \//{\d 脚本 )9rJ]D^B 4V5h1/JPm 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: \z=!It]f. mLeK7?GL 图6. 用户对话框的创建与编辑 y-:d`>b>\ 图7. 用户对话框编辑器 rge/qUr/^ 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。 w5Yt mnP 余下的脚本计算与屈光度有关的所有参数。 i"y @Aj!7 eq36mIo 分析 !*-|s}e LZ~}*}jy 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 ?w "zW6U , *Z!Bd8 图7. 字母F在视网膜上颜色分析 nA#dXckoc 脚本代码 @w[HXb EYKV}` Option Explicit 'Remove this to enable non-dimensioned variables to be used. y)+lU HS
1zA Dim entity As T_ENTITY >VvA&p71b Dim op As T_OPERATION \w@ "`!% Dim mat As T_MODELMATERIAL @avG*Mr^ Dim A As Double IaR D"oCH Dim pupilDiam As Double BP0*`TY Dim eID As Long ~fF;GtP Dim parID As Long _2S(
* Dim count As Integer ]hi5nA Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double +Rd;>s*.Y Dim tlens As Double, nlens As Double 4#wZ#} Dim curv As Double, conic As Double zM|Y
X< Dim ok As Long ,9~2#[|lq +T]D\];D Sub Main Vqxxm&^P ~myY-nEY '用户输入对话框 5'[b:YC Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 p6W|4_a? TextBox 220,21,40,21,.TextBox1 'default: 0 XlU`jv+ Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 &X
OFc.u OKButton 40,91,90,21 /~;om\7r CancelButton 190,91,90,21 59M\uVWR Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 !"QvV6Lq\ TextBox 220,49,40,21,.TextBox2 'default: 4 tx||<8 End Dialog UrEfFtH' Dim dlg As UserDialog y^hCO:`l3 p;9"0rj,z ok = Dialog (dlg) '/QS
sZR +I r If ok=0 Then 'cancel button was pressed K0]42K Print "Execution cancelled." me&'BQ End C{U"Nsu+1 End If J'Y;j^ O
p,_d^ 'Assign accommodation and pupil diameter & use defaults if field left empty <e@+w6Kp'7 If dlg.TextBox1 = "" Then ^s?=$&8f![ A = 0 'Default accommodation .V`N^H:l Else XMw*4j2E A = CDbl(dlg.TextBox1) *32hIiCm End If g.T:72" Vo8gLX]a If dlg.TextBox2 = "" Then \*5${[ pupilDiam = 4 'Default pupil diameter E8]kd Else ;dZuO[4\ pupilDiam = CDbl(dlg.TextBox2) 0;2"X[e End If ![j?/376 oA]rwaUX Print " " .l$:0a Print "Accommodation = " & A & " Diopters" b,uudtlH Print "Pupil Diameter = " & pupilDiam & " mm" jPa"|9A |!E: [UH ' Calculate new parameters with accommodation _mc-CZ taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness u@pimRVo QSSA) Rant = 12.0 - 0.4*A 'Radius of anterior lens 6w)a.^yx7 CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens q1?}G5a? &ws^Dm]R Rpost = -5.224557 + 0.2*A 'Radius of posterior lens 25{-GaB CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens G_/DzJBF m< Y I} tlens = 3.767 + 0.04*A 'Lens thickness Yh2[
nF_ T1#r>3c\ nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction ]-"G:r xTg=oq 'Adjust parameters to account for accommodation y$[:Kh, chA7R'+LA '************************************************************************* =bJ7!& 'Aqueous thickness (Position of Lens)
liU8OXBl '************************************************************************* ble[@VW| eID = FindFullName( "Geometry.Arizona Eye.Lens" ) #.j}: GetCustomElement eID, entity h yK&)y?~ fs\A(]`$ parID = FindFullName( "Geometry.Arizona Eye" ) 1s/548wu _9:r4|S ' Delete any shift(s) in z h5<eU;Rw+ count = 0 RG_.0'5=hc While GetOperationCount(eID)>count xtO#reL"q? GetOperation eID, count, op Fj4>)!^kM If op.Type="ShiftZ" Then qs Wy
<yL+ DeleteOperation eID,count LY;FjbyU count=count-1 ->L> `<7( End If e2qSU[ count=count+1 +h08uo5c Wend a'Yi^;2+\ Q>(a JF 'Set new shift in y#zO1Nig` op.Type = "ShiftZ" 7!Qu+R op.val1 = taq i936+[ op.parent = parID T/]f5/ AddOperation eID, op 5Mz:$5Tm Print "Set aqueous humor thickness = " & taq-0.55 Q$(Fma 4a s@IgaF { '************************************************************************* _;M3=MTM9 'Radius and conic constant of anterior lens %+^Qs\j '************************************************************************* T>68 ,; p eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) l"-Z#[ GetConic eID, entity, curv, conic lhC hk7l 2Gh&h( SetConic eID, entity, 1/Rant, CCant -}3nIk<N Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant pO92cGJ8 \@[,UZ '************************************************************************* l];/,J^ 'Radius and conic constant of posterior lens dTjDVq&Hz '************************************************************************* +pRNrg?k eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) _iL?kf GetConic eID, entity, curv, conic pX+4B=* h4#'@% SetConic eID, entity, 1/Rpost, CCpost #%EHcgF Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost ,Qs%bq{t ,x$^^ '************************************************************************* T'{9!By,P 'Lens thickness (Position of posterior lens surface) =f!clhO '************************************************************************* )k;;O7Ck q=}1ud}1 parID = FindFullName( "Geometry.Arizona Eye.Lens" ) l dqU#{ Q':hmulT! ' Delete any z-shift(s) 6$[7hlE count = 0 tzthc*-< While GetOperationCount(eID)>count rr,w/[ GetOperation eID, count, op vA}_x7}n( If op.Type="ShiftZ" Then ~Up{zRD"B DeleteOperation eID,count VD<z]@ count=count-1 T+^c=[W End If bf|ePGW? count=count+1 NBHpM}1xtU Wend v2_` iwE hJsP;y:@Lm 'Set new z-shift ^=5x1<a9$ op.Type = "ShiftZ" T7%!JBg@ op.val1 = tlens LT"H-fTgs op.parent = parID ^GyZycch AddOperation eID, op $xWUzg1<U Print "Set lens thickness = " & tlens z_N";Rn 2?SbkU/3|P '************************************************************************* Z"RgqNf 'Lens index of refraction fjOq@thD '************************************************************************* =J4|"z: eID = FindMaterial( "Lens" ) le]~Cy0 GetModelMaterial eID, mat SiUu**zC [}]yJ+) mat.Nd = nlens 1)MDnODJ SetModelMaterial eID, mat ZP5 !O[Ut Print "Set lens index of refraction = " & nlens uZZRFioX| 9v[V"m`M '************************************************************************* =MMd& 'Pupil diameter g4eW< '************************************************************************* x-e6[_F eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) vaGF(hfTA kw@^4n+M 'Adjust pupil diameter (trimming volume inner hole) U3N9O.VC &iVdqr1, SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" c(e>Rmh I{jvUYrKH ' Adjust pupil location to just in front of the lens 50j8+xJPV parID = FindFullName( "Geometry.Arizona Eye" ) "X8jpg eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) {eV8h}KIl count = 0 s<)lC;#e While GetOperationCount(eID)>count q+y\pdhdO GetOperation eID, count, op 9&5<ZC-D If op.Type="ShiftZ" Then f+Sb>$ DeleteOperation eID,count }&t>j[ count=count-1 UhpJG O End If ?UZt30|1 count=count+1 \1Xk[% Wend !~Uj 'w op.Type = "ShiftZ" BUJ\[/ op.val1 = taq-0.01 8v4 o+wP op.parent = parID b.@a,:" AddOperation eID, op :t]HY2 R2gV(L(!! Print "Set pupil diameter = " & pupilDiam 8&)v%TX 8s@N NjV 'Update AZ Eye subassembly Description N);w~)MYh eID = FindFullName( "Geometry.Arizona Eye" ) $Sgf jm GetEntity eID, entity o^\Pt<~W entity.Description = "Accommodation = " & A & "D" 6JDHwV SetEntity eID, entity /,I cs ba);f[> Update K"H\gmV_g Print "DONE!" 6t6Z&0$h~ /.Ak'Vmi End Sub *[3xc*5F/A &$F<]]& 如果屈光度是4,光瞳直径是4,则会输出如下数据: }OL"38P N8b\OTk2 Accommodation = 4 Diopters xi=ApwNj Pupil Diameter = 4 mm kg[%Q]] Set aqueous humor thickness = 2.81 `za,sRFR Set anterior lens radius = 10.4 and conic constant = -2.375869 CwA_jOp Set posterior lens radius = -4.424557 and conic constant = -3.081019 2gPqB*H Set lens thickness = 3.927 [|DKBJ Set lens index of refraction = 1.42672 $(aq;DR Set pupil diameter = 4 //U1mDFT DONE! aa`(2%(: U]iI8c bf"'xn9 QQ:2987619807 )U?_&LY)[M
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