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简介 B'/U#>/ /Qgb t 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。 r#- lM-\:Q! 模型 xvGYd,dlK (>`_N%_ 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。 lL}6IZ5sb ]4rmQAS7" Table 1. AZ眼睛模型的定义 s>9I#_4] 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. + V=<vT q NGR6i 光源 hB?#b`i^ lp*5;Ls'q 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。 Owp]>e DpHubqWz +Q&l}2 图1. 光源和提示信息使用 A-x^JC= 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。 Z<U,]iZB UG vIH m 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。 r*HSi.'21 ueg%yvO 图2. 字母F光源的设定方法光 =i~
= |K! &H_/`Z]Q 图3. 字母F在视网膜上位置点列图 o HK 视网膜的散射 y)r`<B <XL%* 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。 osc8;B/ I!zoo[/)% +;,{`*W+N 图4. 视网膜朗伯散射设定 74_?@Z( 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。 -=-^rQx9 <h(AJX7wsD `JIp$ 图5. 视网膜重点采样规格设定 Ehy(;n)\ 脚本 <n_?$ TJ h!B{7J 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: lU 9o"2 "t2T*'j{ 图6. 用户对话框的创建与编辑 8;M,l2pmR{ 图7. 用户对话框编辑器 M:O*_>KF 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。 N\|B06X 余下的脚本计算与屈光度有关的所有参数。 n3e,vP? R e"@r[pq-{u 分析
dX\OP> 5?3 v;B6 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 CW;zviH5 Q_T,=y 图7. 字母F在视网膜上颜色分析 <B%wq>4S 脚本代码 \]Y<d II^Rp],> Option Explicit 'Remove this to enable non-dimensioned variables to be used. uNewWtUb( 4#t'1tzu# Dim entity As T_ENTITY @Z0. }}Y Dim op As T_OPERATION Wv>`x?W Dim mat As T_MODELMATERIAL 2NFk#_9e~ Dim A As Double b$w66q8 Dim pupilDiam As Double 28JVW3&) Dim eID As Long *wAX&+); Dim parID As Long +sJ{9# 6 Dim count As Integer tE>FL Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double -raK Dim tlens As Double, nlens As Double oD%n} Dim curv As Double, conic As Double .0nT*LF Dim ok As Long fq1w <e %X\J%Fj Sub Main l[ko)%7V 8V(~u^!%_ '用户输入对话框 WLWfe- Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 '"Cqq{* TextBox 220,21,40,21,.TextBox1 'default: 0 uWGp>;m eO Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 yI=nu53BV OKButton 40,91,90,21 H F*~bL CancelButton 190,91,90,21 %B&O+~ Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 -/3h&g TextBox 220,49,40,21,.TextBox2 'default: 4 `B?+1Gv End Dialog H94_a e Dim dlg As UserDialog <S_0=U '>OEQU5- ok = Dialog (dlg) 4Zjd g` 7|Vpk&.> If ok=0 Then 'cancel button was pressed p;[.&oJ Print "Execution cancelled." 5i$P$ R End uUl ;}W End If ldG8hK *{JD=ua 'Assign accommodation and pupil diameter & use defaults if field left empty b`wT*& If dlg.TextBox1 = "" Then FpttH?^ A = 0 'Default accommodation n n[idw Else %to.'R A = CDbl(dlg.TextBox1) ;8F6a:\v End If >yyu:dk-; aorL ,l If dlg.TextBox2 = "" Then c5CxR#O pupilDiam = 4 'Default pupil diameter <q MX,h2 Else cLp9|y0r pupilDiam = CDbl(dlg.TextBox2) i(u zb< End If Vg(p_k45` Q#*qPgs Print " " ,0L< wa Print "Accommodation = " & A & " Diopters" .>`7d=KT Print "Pupil Diameter = " & pupilDiam & " mm" O[ans_8 uxrNkZia ' Calculate new parameters with accommodation s5b<KQ. taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness acpc[^' B_r:da CS: Rant = 12.0 - 0.4*A 'Radius of anterior lens ^[HX#JJ~ CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens wMH13i3 k \t6b1.M Rpost = -5.224557 + 0.2*A 'Radius of posterior lens Yv*i69" CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens gi
A(VUwI> Xp^>SSt:4 tlens = 3.767 + 0.04*A 'Lens thickness +'e3YF+' y9:o];/ nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction =c[mch%E m[5ed1+ 'Adjust parameters to account for accommodation lZ+1A0e Mf:x9# '************************************************************************* HV3D$~g F 'Aqueous thickness (Position of Lens) yErvgf '************************************************************************* D@mqfi(x eID = FindFullName( "Geometry.Arizona Eye.Lens" ) BW)t2kR& GetCustomElement eID, entity
(+\K [yAR%]i-7 parID = FindFullName( "Geometry.Arizona Eye" ) -}JRsQ+rgM i];@ e] ' Delete any shift(s) in z /3vj`#jD count = 0 j%0g*YI While GetOperationCount(eID)>count 9e1KH' GetOperation eID, count, op B415{ If op.Type="ShiftZ" Then 1n
ZE9;o DeleteOperation eID,count 6? (8KsaN count=count-1 `^E(P1oJ3 End If ]_)=xF19 count=count+1 ?@_,_gTQ Wend iQaF R@ qo;F]v*pkK 'Set new shift in E?f*Z{~, op.Type = "ShiftZ" A7:W0Gg op.val1 = taq !FnH; op.parent = parID 3412znM& AddOperation eID, op y+[wlo&WC Print "Set aqueous humor thickness = " & taq-0.55 d7QQ5FiB mCpoaGV_ '************************************************************************* Y6@A@VJ 'Radius and conic constant of anterior lens 8<ri"m, '************************************************************************* DU4Prjb' eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) E~!FEl; GetConic eID, entity, curv, conic 8>jd2'v{ My'6yQL SetConic eID, entity, 1/Rant, CCant kjW`k?'s Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant ZGOI8M]@ mk~Lkwl '************************************************************************* Ec]cCLB 'Radius and conic constant of posterior lens @{n2R3)k
B '************************************************************************* kR-5RaW eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) j&?NE1D>I GetConic eID, entity, curv, conic
*o[*,1Pw K`1\3J) SetConic eID, entity, 1/Rpost, CCpost ~F]- +| Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost ffyKAZ{]po (iiyptJ '************************************************************************* 71w$i
4 'Lens thickness (Position of posterior lens surface) %lPFq- '************************************************************************* vi>V6IC4v qx/GioPU parID = FindFullName( "Geometry.Arizona Eye.Lens" ) F3a"SKMW {ByT,92 ' Delete any z-shift(s) f-6E> count = 0 [OsW While GetOperationCount(eID)>count *Mqg_} 0Y GetOperation eID, count, op ODM<$Yo:d If op.Type="ShiftZ" Then DI!l.w5P_ DeleteOperation eID,count 'u.`!w '|L count=count-1 mvxg|< End If 'gE_xn7j count=count+1 { l LUZM Wend zUxF"g-W TO)wjF_ 'Set new z-shift !/$BXUrd op.Type = "ShiftZ" ^fb4g+Au op.val1 = tlens }qXi;u)) op.parent = parID PHD$E s AddOperation eID, op F:M3^I Print "Set lens thickness = " & tlens c Ew/F0 ~GS`@IU} '************************************************************************* VxfFk4 'Lens index of refraction ?(U>
)SvF '************************************************************************* @v2kAOw[ eID = FindMaterial( "Lens" ) eGLLh_V" GetModelMaterial eID, mat J(-#(kMyf G(4:yK0 mat.Nd = nlens Qo{^jDe,c* SetModelMaterial eID, mat h_d!G+-] Print "Set lens index of refraction = " & nlens 8F4#E
U \"PlM!0du '************************************************************************* DjL(-7'p 'Pupil diameter K#";! '************************************************************************* F{f "xM eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) ;nv4lxm |g4!Yd 'Adjust pupil diameter (trimming volume inner hole) >1mCjP K |Yr SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" +V7*vlx- JVTG3:zD ' Adjust pupil location to just in front of the lens ?^IM2}(p parID = FindFullName( "Geometry.Arizona Eye" ) NCSb`SC: eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) |vWx[=`o count = 0 I[<C)IG While GetOperationCount(eID)>count vC J GetOperation eID, count, op X'[SCs If op.Type="ShiftZ" Then [N#2uo DeleteOperation eID,count F K={% count=count-1 [>?B`1;@ End If FJ>| l#nO count=count+1 -\>Bphu,y Wend +\.gd L) op.Type = "ShiftZ" {u46m op.val1 = taq-0.01 rmR7^Ycv/ op.parent = parID bUz7!M$ AddOperation eID, op ~`mOs1 d U#,2et6 Print "Set pupil diameter = " & pupilDiam 0-4WLMx UO<%|{W+ 'Update AZ Eye subassembly Description }QG6KJh_% eID = FindFullName( "Geometry.Arizona Eye" ) }e9:2 GetEntity eID, entity O-bC+vB]M entity.Description = "Accommodation = " & A & "D" D,1S-< SetEntity eID, entity cD2}EqZ 9 Y@^MU->+ Update 3Xf}vdgdM$ Print "DONE!" MWsBZJRr vVZ@/D6w End Sub pt|u?T_+ c<-_Vh.:5 如果屈光度是4,光瞳直径是4,则会输出如下数据: 1c+[S]7rY UG48g} Accommodation = 4 Diopters A'6>"=ziP Pupil Diameter = 4 mm +&-/$\" Set aqueous humor thickness = 2.81 S1;#58 Set anterior lens radius = 10.4 and conic constant = -2.375869 OZLU>LU Set posterior lens radius = -4.424557 and conic constant = -3.081019 @y)-!MHN(8 Set lens thickness = 3.927 U{n
0Z Set lens index of refraction = 1.42672 #th^\pV Set pupil diameter = 4 |ay W _5} DONE! q}tLOVu1 nP4jOq*H :%)l*[ QQ:2987619807 =R?NOWrDY
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