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简介 [)M%cyQ jyUjlYAAv` 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。 :D6
ON"6 _Xc8Yg }` 模型 p!7FpxZY 2g-j.TM 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。 KNvZm;Q6 Uw. `7b>B Table 1. AZ眼睛模型的定义 Nho>f 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. >}8j+t&T rdP[<Y9 光源 -`kW&I0 X::JV7hu 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。 wedbx00o t7Iv?5]N RQ'9m^ 图1. 光源和提示信息使用 v!6
c0a 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。 !Vn\u Bi 3<7 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。 qFCOUl N1}sHyVq7 图2. 字母F光源的设定方法光 KE5kOU; *=/ { HvJ 图3. 字母F在视网膜上位置点列图 -hGk?_Nqa/ 视网膜的散射 3tIVXtUCUk x;P_1J%Q 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。 /tx]5`#@7] kX7C3qdmt x:NY\._ 图4. 视网膜朗伯散射设定 r1`x=r
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。 A5I)^B<( QC
OM_$ y .Ni\\ 图5. 视网膜重点采样规格设定 X;
\+<LE 脚本 !&y8@MD15 45@ I *` 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: u"cV%(# # Yj 1w 图6. 用户对话框的创建与编辑 +ZaSM~ 图7. 用户对话框编辑器 y*jp79G 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。 T= y}y 余下的脚本计算与屈光度有关的所有参数。 Cx@);4arj ,F8 Yn5h 分析 )Pa'UGY 8sWJcmVo 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 r"3=44St FF`T\&u 图7. 字母F在视网膜上颜色分析 GbY7_N
脚本代码 shy-Gu& urs,34h Option Explicit 'Remove this to enable non-dimensioned variables to be used. wY{-BuXv F3[T.sf Dim entity As T_ENTITY TTX5EDCrC Dim op As T_OPERATION Q2w_X8 Dim mat As T_MODELMATERIAL KEo,m Dim A As Double 7UKh688 Dim pupilDiam As Double mUAi4N Dim eID As Long 7?!d^$B Dim parID As Long ?DS@e@lx Dim count As Integer "yy5F>0Wt Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double bivuqKA Dim tlens As Double, nlens As Double Drgv`z Dim curv As Double, conic As Double 'A=^Se`= Dim ok As Long ,GhS[VJjR UawyDs Sub Main 9IdA%RM~mH CAig]=2' '用户输入对话框 Fc)@,/R"v Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 HTv2# TextBox 220,21,40,21,.TextBox1 'default: 0 }z'8Bu Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 ~k-y &<UR OKButton 40,91,90,21 p}z<Fdu0 CancelButton 190,91,90,21 b4%??"&<Y Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 Ws3)gvpPA TextBox 220,49,40,21,.TextBox2 'default: 4 xf\ C|@i End Dialog }1L4"}L. Dim dlg As UserDialog cN-?l7 Jc&{`s^Nu ok = Dialog (dlg) &T?RZ2 ehGLk7@7& If ok=0 Then 'cancel button was pressed c)6m$5] Print "Execution cancelled." Gt8M&S-; End : %_LpZ End If RtkEGxw*^ '2A)}uR 'Assign accommodation and pupil diameter & use defaults if field left empty G/y5H;<9M If dlg.TextBox1 = "" Then P[G)sA_" A = 0 'Default accommodation "b~+;<}Q Else ^&9zw\x;z A = CDbl(dlg.TextBox1) #X+JHl End If n$A9_cHF7 T#T*Zw"+ If dlg.TextBox2 = "" Then Di,^% pupilDiam = 4 'Default pupil diameter GLH0 ] Else hIYNhZv pupilDiam = CDbl(dlg.TextBox2) y;m| End If H*?t^ @(EAq<5{ Print " " a Yg6H2Un Print "Accommodation = " & A & " Diopters" Si4!R+4w Print "Pupil Diameter = " & pupilDiam & " mm" 9R!atPz9 kP=eW_0D ' Calculate new parameters with accommodation T=
8 0, taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness X~bX5b[P ol\Utq, Rant = 12.0 - 0.4*A 'Radius of anterior lens W<h)HhyG CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens hk;5w{t}} @Myo'{3vF Rpost = -5.224557 + 0.2*A 'Radius of posterior lens JMCKcZ%N CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens '0;l]/i. Y1w9y tlens = 3.767 + 0.04*A 'Lens thickness rET\n(AJ aL\PGdgO nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction F>Ah0U0 ^x ]r`b 'Adjust parameters to account for accommodation i]c!~` w0 M>[ 4 '************************************************************************* ~Py`P'+ 'Aqueous thickness (Position of Lens) B6+khuG( '************************************************************************* GhAlx/K eID = FindFullName( "Geometry.Arizona Eye.Lens" ) ~f2z]JLr: GetCustomElement eID, entity V5@:#BIs ZuzEg *lb parID = FindFullName( "Geometry.Arizona Eye" ) RXMISt3+{y tH@Erh|% ' Delete any shift(s) in z DaQ?\uq count = 0 {S]}.7`l9( While GetOperationCount(eID)>count nAAs{ GetOperation eID, count, op )N{Pw$l_ If op.Type="ShiftZ" Then /s&9SYF DeleteOperation eID,count %@J.{@> count=count-1 6D;Sgc5" End If vQG5*pR*w count=count+1 Uk wP Wend 3)wN))VBX [C 7^r3w 'Set new shift in 94`7a<&ZNL op.Type = "ShiftZ" )bL'[h op.val1 = taq R{`(c/%8 op.parent = parID h%na>G AddOperation eID, op W\$`w Print "Set aqueous humor thickness = " & taq-0.55 FW;?s+Uyx T9|m7 '************************************************************************* VOsRAn/N 'Radius and conic constant of anterior lens Wx%H%FeK '************************************************************************* ;3coP{ eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) ah$b[\#C GetConic eID, entity, curv, conic .&iawz i$"F{|Z0 SetConic eID, entity, 1/Rant, CCant (62"8iD6 Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant |)DGkOtd Mmj;-u '************************************************************************* \[i1JG 'Radius and conic constant of posterior lens .[KrlfI '************************************************************************* 5X$ jl;6 eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) tmYz R%i GetConic eID, entity, curv, conic ;W
)Y
OT np^N8$i:n SetConic eID, entity, 1/Rpost, CCpost QD&`^(X1p Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost ~8Fk(E_ )gUR@V>e2 '************************************************************************* :A_@,Q 'Lens thickness (Position of posterior lens surface) =_*Zn(>t` '************************************************************************* ?3`UbN: Y=?3 js?O parID = FindFullName( "Geometry.Arizona Eye.Lens" ) Xf]d. : x_Y!5yg
E ' Delete any z-shift(s) :uS\3toj count = 0 CI0C1/:@ While GetOperationCount(eID)>count |$Sedzj' GetOperation eID, count, op Yx%Hs5}8 If op.Type="ShiftZ" Then V#$RR!X' DeleteOperation eID,count h
0Q5-EA count=count-1 '3tCH)s End If ibk6|pp count=count+1 7hcYD!DS Wend f|c{5$N! 9ULQrq$? 'Set new z-shift ,AFu C< op.Type = "ShiftZ" g}{aZ$sta op.val1 = tlens :J@gmY:C op.parent = parID R4cM%l_#W AddOperation eID, op c
( C%Hld Print "Set lens thickness = " & tlens =z69e%. n0 {i&[I~+ '************************************************************************* 6,"Q=9k4[ 'Lens index of refraction :Yh+>c}N '************************************************************************* L|xbR#v eID = FindMaterial( "Lens" ) g-bK|6?yz GetModelMaterial eID, mat I3I/bofz ;bib/ mat.Nd = nlens 7(8;to6( SetModelMaterial eID, mat 5c0 ZRV# Print "Set lens index of refraction = " & nlens Om\vMd@! cp7=epho '************************************************************************* Ya"a`ozq 'Pupil diameter zu{P#~21 '************************************************************************* J=I:CD% eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) >*_$]E ,m:.-iy? 'Adjust pupil diameter (trimming volume inner hole) AjMh,@ IfAZn_ SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" ,T$U'&; BM
.~ 5\ ' Adjust pupil location to just in front of the lens Id .nu/ parID = FindFullName( "Geometry.Arizona Eye" ) WiR(;m<g eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) NP3y+s count = 0 v MH While GetOperationCount(eID)>count b9HtR -iR; GetOperation eID, count, op %_W)~Pv{+ If op.Type="ShiftZ" Then f+,qNvBY/ DeleteOperation eID,count _op}1 count=count-1 )_S(UVI5 End If Fj3a.' count=count+1 )U:m:cr< Wend l4YJ c op.Type = "ShiftZ" !ons]^km op.val1 = taq-0.01 k2tF} op.parent = parID 7WS p($ AddOperation eID, op 6}Ci>_i4# jcf7n`L Print "Set pupil diameter = " & pupilDiam ?X<eV1a R"t,xM 'Update AZ Eye subassembly Description 04P}-L, eID = FindFullName( "Geometry.Arizona Eye" ) e\zm7_+i{ GetEntity eID, entity CxW>~O: entity.Description = "Accommodation = " & A & "D" j-}O0~Jz SetEntity eID, entity plstZ,#j mL{6L? Update V5>B])yQ Print "DONE!" 0 ZKx<]! G}raA% End Sub
|TH\`U SRDp* 如果屈光度是4,光瞳直径是4,则会输出如下数据: 4p;`C _8UU'1d Accommodation = 4 Diopters vr6w^&[c^ Pupil Diameter = 4 mm \V~eVf;~ Set aqueous humor thickness = 2.81 >@_^fw) Set anterior lens radius = 10.4 and conic constant = -2.375869 *P=VFP Set posterior lens radius = -4.424557 and conic constant = -3.081019 2eY_%Y0 Set lens thickness = 3.927 jLm ;ty2; Set lens index of refraction = 1.42672 <<5(0#y# Set pupil diameter = 4 N5
6g+,w%) DONE! iz PDd{[
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