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简介 9sfB+]}h .236d^l 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。 'b=eC
+ e5 模型 ^| FVc48{ /VhE<}OtH 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。 j(@g
*uI hxMX Table 1. AZ眼睛模型的定义 ^B&ahk 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. t[f9Z 1,%#O;ya 光源 @MlU!oR& (IoPU+1b 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。 7tf81*e bgzT3KZ lH,]ZA./ 图1. 光源和提示信息使用 3G%XG{dg 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。 $8X tI Fl#VKU3h 在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 )L(d$N=Bd }(g+: ]p- 图2. 字母F光源的设定方法光 9GtVI^] (8@hF#N1 图3. 字母F在视网膜上位置点列图 +>i<sk 视网膜的散射 ! 6p)t[s :~0^ib<v; 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。 "j.oR}s9?# mP5d!+[8 |4p<T!T 图4. 视网膜朗伯散射设定 oQ-|\?{;A 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。
#8Id:56 o7@4=m} 3"^)bGe 图5. 视网膜重点采样规格设定 q~g&hR}K 脚本 i k1L Gwrx)Mq 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: Mc$v~|i6 \\R*V'e! 图6. 用户对话框的创建与编辑 Wf`OyeRz 图7. 用户对话框编辑器 $5Y^fwIK 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 \HP,LH[P: 余下的脚本计算与屈光度有关的所有参数。 j$mt*z L !s[j1=y 分析 *09\\
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:VTs[5 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 vRb(eg >;' 1k' 图7. 字母F在视网膜上颜色分析 `~aLSpB65 脚本代码 Ti@P4:q
5rHnU<H@y Option Explicit 'Remove this to enable non-dimensioned variables to be used. XvzV
lKL J,^pt Ql Dim entity As T_ENTITY \")YKN=W Dim op As T_OPERATION e/HX,sf_g Dim mat As T_MODELMATERIAL /P8eI3R Dim A As Double [[66[;
Dim pupilDiam As Double !7NzW7j Dim eID As Long r/q1&*T Dim parID As Long 1O3<%T#LOZ Dim count As Integer "za*$DU Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double _"w!KNX>(~ Dim tlens As Double, nlens As Double ]-s`# Dim curv As Double, conic As Double C#?d=x Dim ok As Long _ KkVI7a h'YcNkM
2> Sub Main 9
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B '用户输入对话框 y1"^S Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 {R{%Z TextBox 220,21,40,21,.TextBox1 'default: 0 M4hN#0("4 Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 RoM*Qjw OKButton 40,91,90,21 jf)JPa_ CancelButton 190,91,90,21 7quwc'! Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 7jg(j~tQ TextBox 220,49,40,21,.TextBox2 'default: 4 p2NB~t7Z End Dialog Y)j,(9 Dim dlg As UserDialog 8s5ru) yYg&'3 ok = Dialog (dlg) ]MA)='~ TcKKI If ok=0 Then 'cancel button was pressed g`8
mh&u% Print "Execution cancelled." x]J-q5 End ohtn^o;C} End If 1yRd10 cV!/ 'Assign accommodation and pupil diameter & use defaults if field left empty owY_cDzrH If dlg.TextBox1 = "" Then LYq2A,wm$ A = 0 'Default accommodation "KTnX#<0 Else o(SJuZC/U A = CDbl(dlg.TextBox1) +U/ "F|M End If zUgkY`]:BJ l'{goy f If dlg.TextBox2 = "" Then 0_zSQn9c pupilDiam = 4 'Default pupil diameter ]aW.b_7<9 Else e"H+sM26- pupilDiam = CDbl(dlg.TextBox2) NCM{OAjS5U End If zt?w n*_ z` ?xS Print " " WT
{Cjn Print "Accommodation = " & A & " Diopters" S+xGHi) Print "Pupil Diameter = " & pupilDiam & " mm" I/-w65J] b!HFv;^N ' Calculate new parameters with accommodation Uus)2R7 taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness awW\$Q i\z0{;f|GX Rant = 12.0 - 0.4*A 'Radius of anterior lens n|,Vm@zV CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens :@ 8.t,| v%7JZ<I'A Rpost = -5.224557 + 0.2*A 'Radius of posterior lens 5'Ay@FJ: CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens &+{xR79+& S_ -mmzC( tlens = 3.767 + 0.04*A 'Lens thickness L#@$Mtc k 5r*?Os nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction jW$f(qAbm Oc+L^}elJ 'Adjust parameters to account for accommodation ,F9wc<V8 W2(=m!:U '************************************************************************* (V?`W7 'Aqueous thickness (Position of Lens) |w]i$`3'I '************************************************************************* C)^\?DH eID = FindFullName( "Geometry.Arizona Eye.Lens" ) '0M0F'R GetCustomElement eID, entity $`{q = p;Ok.cXVp parID = FindFullName( "Geometry.Arizona Eye" ) g#3x)97Z ^B=z_0 * ' Delete any shift(s) in z jtpN o~O count = 0 e/D\7Pf While GetOperationCount(eID)>count um;U;%?Q GetOperation eID, count, op P3FpU<OBwp If op.Type="ShiftZ" Then "Ksd9,J\b DeleteOperation eID,count 54_m{&hb count=count-1 |Qq'_4: End If W]7?;#Hpk count=count+1 TEyPlSGG Wend \/%Q PE8 (8F?yBu 'Set new shift in cJ{P,K op.Type = "ShiftZ" -*j; op.val1 = taq a2)*tbM9\ op.parent = parID m,fr?d/; AddOperation eID, op m,_oX1h Print "Set aqueous humor thickness = " & taq-0.55 .kDCcnm
X
KeK;+ '************************************************************************* gz:c_HJ 'Radius and conic constant of anterior lens )p](*Z^ '*************************************************************************
0d)n}fm eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) Y mSaIf GetConic eID, entity, curv, conic iU|C<A%Hh \s rOU| SetConic eID, entity, 1/Rant, CCant "d* Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant Ase 1 R=0 [vJosbU; '************************************************************************* }E_zW.{! 'Radius and conic constant of posterior lens ~z"->.u '************************************************************************* N.J:Qn`( eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) ~.SU$ GetConic eID, entity, curv, conic :9>nY
t/c^hTT SetConic eID, entity, 1/Rpost, CCpost Q'LU?>N)/ Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost ]z@]Fi33Y PSvRO%& '************************************************************************* L(YT6Vmm+t 'Lens thickness (Position of posterior lens surface) xk<0QYv
'************************************************************************* 'a9.JS[pj zy5bDL - parID = FindFullName( "Geometry.Arizona Eye.Lens" ) e=C,`&sz SxyFFt ' Delete any z-shift(s) N* QI>kzU count = 0 ;0WlvKF While GetOperationCount(eID)>count J#^M GetOperation eID, count, op BW1O1zIh\ If op.Type="ShiftZ" Then #-8/|_* DeleteOperation eID,count /;J;,G`? count=count-1 ![Y$[l End If wjs7K|PK count=count+1 ~'Hwszpb Wend cwM0Z6
=Ih_[$1dw 'Set new z-shift T~d';P op.Type = "ShiftZ" !h;VdCCi# op.val1 = tlens Iu]P^8 op.parent = parID $NSYQF%aO AddOperation eID, op L.(k8eX
Print "Set lens thickness = " & tlens qyC"}y- hy rJu{p '************************************************************************* q2Dg~et 'Lens index of refraction ZGBcy}U(k '************************************************************************* 2^:nlM{u eID = FindMaterial( "Lens" ) f+RDvgkKU GetModelMaterial eID, mat TlJF{ <E "5FeP; mat.Nd = nlens NH!!.Z" SetModelMaterial eID, mat fNumY|%3 Print "Set lens index of refraction = " & nlens }r[BME \qPrY.- '************************************************************************* $$w 1%#F= 'Pupil diameter >U].k8a) '************************************************************************* e78} eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) x3
<Lx^; j(hC't- 'Adjust pupil diameter (trimming volume inner hole) T/nRc_I+^B KA7nncg;, SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" w;O '6" ]cK@nq) ' Adjust pupil location to just in front of the lens -`JY] H parID = FindFullName( "Geometry.Arizona Eye" ) Smo'&x eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) -rBj-4|" count = 0 YrX{,YtiX While GetOperationCount(eID)>count 1{qg@xlj GetOperation eID, count, op iW)Ou?aS If op.Type="ShiftZ" Then ?UzHQr DeleteOperation eID,count "7d_$.Z count=count-1 ;F-kE4w End If ]v@,>!Wn count=count+1 >{[J+f{~| Wend NoT oLt\ op.Type = "ShiftZ" #N:o)I op.val1 = taq-0.01 ofV{SeD67 op.parent = parID C\Rd]P8\ AddOperation eID, op 60m1
>" Qoc-ZC"<6 Print "Set pupil diameter = " & pupilDiam }_S]!AWz :\Dm=Q\ 'Update AZ Eye subassembly Description uu:BN0 eID = FindFullName( "Geometry.Arizona Eye" ) <cS1}" GetEntity eID, entity ,k4
(b entity.Description = "Accommodation = " & A & "D" bk|>a=o3 SetEntity eID, entity ]`x~v4JU @W8RAS~ Update asb")NfIm Print "DONE!" mi+I)b= $t^`Pt*:u End Sub L=>N#QR7 Ag-*DH0 如果屈光度是4,光瞳直径是4,则会输出如下数据: H"sey +- &j$k58mX Accommodation = 4 Diopters q>?oV(sF Pupil Diameter = 4 mm U -(d~]$ Set aqueous humor thickness = 2.81 %NuS!v> Set anterior lens radius = 10.4 and conic constant = -2.375869 d] {^ Set posterior lens radius = -4.424557 and conic constant = -3.081019 3:r;(IaX Set lens thickness = 3.927 2X:n75() Set lens index of refraction = 1.42672 t_3XqjuA Set pupil diameter = 4 3s+D
x$Ud DONE! SExd-=G
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