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简介 b(McH*_8e
.4-I^W"1 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。 k1
+: oD?h 模型 K;_.WzWD= Q&Ox\*sMK 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。 9p5{,9 .3* 9AROvq|# Table 1. AZ眼睛模型的定义 >{]mN5 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. <r{ )*]#l YOHYXhc{S 光源 =2=n Kzd`|+?'`M 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。 -j 6U{l >@o}l:* I=3e@aTZ, 图1. 光源和提示信息使用 ii:h
E= 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。 ,3{z_Rax- (SlrV8; 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。 De*Z UN|< ?>p<!:E!r 图2. 字母F光源的设定方法光 tT;=l[7% Q`]El<$ 图3. 字母F在视网膜上位置点列图 G;%Pf9o26 视网膜的散射 Ur]~>-Z uUczD 8y 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。 $LF w*Gv#B9G 7gV"pa 图4. 视网膜朗伯散射设定 NgnHo\) 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。 ( |1 $zF+ \
l+RX* _r}oYs%1 图5. 视网膜重点采样规格设定 LyB$~wZx~@ 脚本 [k9aY$baT^ rwlV\BU 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: X]Emz" :fr 2K 图6. 用户对话框的创建与编辑 61Nj&1Ze 图7. 用户对话框编辑器 qG/a5i 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 %&yD^q_ 余下的脚本计算与屈光度有关的所有参数。 S4]xxc Lj$yGd K< 分析 sM?bUg0w ,0#5kc*X 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。
0O>8DX .Jz$)R 图7. 字母F在视网膜上颜色分析 PZF>ia} 脚本代码 )T:{(v7 d` 9Osjh G Option Explicit 'Remove this to enable non-dimensioned variables to be used. @$~ BU;kR ,$habq=; Dim entity As T_ENTITY ~4wbIE_rN Dim op As T_OPERATION 'A,&9E{%1 Dim mat As T_MODELMATERIAL sa`7_KB Dim A As Double :XMw="u= Dim pupilDiam As Double ?J+[|*'yK Dim eID As Long *0y+=,"QU Dim parID As Long vL13~q*F Dim count As Integer `
BH8v Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double AjaG.fa]k Dim tlens As Double, nlens As Double ML0o:8Bd\ Dim curv As Double, conic As Double !GMb~ Dim ok As Long ";j/k9DE 2C %{A Sub Main J[UL
f7: , {7wvXP '用户输入对话框 Um\Nd#=: Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 kRskeMr:Rd TextBox 220,21,40,21,.TextBox1 'default: 0 i6r%;ueLb Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 |Gjd OKButton 40,91,90,21 9c806>]U^ CancelButton 190,91,90,21 mqk~Pno|< Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 v|jBRKU99 TextBox 220,49,40,21,.TextBox2 'default: 4 #
3uXgZi End Dialog 7I`e5\ u Dim dlg As UserDialog /yIkHb^c q:-8W[_ ok = Dialog (dlg) &:8a[C2= ~,Q+E8 If ok=0 Then 'cancel button was pressed d> Y9g Print "Execution cancelled." [Y*p
I&f End A75IG4] End If i}RxTmG< UioLu90
P 'Assign accommodation and pupil diameter & use defaults if field left empty oj@B'j If dlg.TextBox1 = "" Then !yH&l6s A = 0 'Default accommodation E$f.&<>T Else c3!d4mC: A = CDbl(dlg.TextBox1) S'V0c%'QQV End If +"T?., R{@WlkG} If dlg.TextBox2 = "" Then -sGfpLy<6 pupilDiam = 4 'Default pupil diameter iO3@2J Else LKxyj@Eq pupilDiam = CDbl(dlg.TextBox2) `#2}[D End If vhZpYW8 &~G>pvZ Print " " 9pStArF?F0 Print "Accommodation = " & A & " Diopters" z)q9O_g9 Print "Pupil Diameter = " & pupilDiam & " mm" 8@Xq ,J &iL"=\# ' Calculate new parameters with accommodation qJVW :$1q taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness +D`IcR-x #
o)a`,f Rant = 12.0 - 0.4*A 'Radius of anterior lens
zfO0+fMH CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens \Q?r+VZ ?^2(|t9KU Rpost = -5.224557 + 0.2*A 'Radius of posterior lens z`xdRe{QP CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens [st4FaQ36 U9IN# ;W tlens = 3.767 + 0.04*A 'Lens thickness *xM4nUu<~ >Rjk d>K3 nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction jUZ84Gm{ 4iRcmsP 'Adjust parameters to account for accommodation &I:5<zK{ M2[;b+W9 '************************************************************************* lycY1 lK 'Aqueous thickness (Position of Lens) 5)2lZ(5.A# '************************************************************************* 3rTYe6q$U eID = FindFullName( "Geometry.Arizona Eye.Lens" ) nv*q
N\i' GetCustomElement eID, entity }9aYU;9D Q~#udEajI parID = FindFullName( "Geometry.Arizona Eye" ) &2Q4{i HzF ' Delete any shift(s) in z BE:HO^-.1 count = 0 #)tt}GX While GetOperationCount(eID)>count C\j|+s GetOperation eID, count, op 60*2k If op.Type="ShiftZ" Then n87B[R DeleteOperation eID,count 5<GC count=count-1 ^hq`dr|R= End If YbND2i count=count+1 g599Lc&
Wend e54wAypPOl 6OF&Q`*4 'Set new shift in sikG}p0mx< op.Type = "ShiftZ" EQ-r op.val1 = taq {l%Of op.parent = parID tz)aQ6p\X AddOperation eID, op {PnvQ?|Z Print "Set aqueous humor thickness = " & taq-0.55 vXAO#'4tm% H? Z5ex '************************************************************************* kKr7c4q 'Radius and conic constant of anterior lens E;*#fD~@ '************************************************************************* `6)GjZh^ eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) \ty{KAc& GetConic eID, entity, curv, conic uwXquOw 7$b!-I+a2 SetConic eID, entity, 1/Rant, CCant *R m>bLI Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant ']WS@MbJ y$Sn3_9 V '************************************************************************* casva; 'Radius and conic constant of posterior lens WolkW:(Cg '************************************************************************* $d3al%Uo eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) b
lP@Cn2 GetConic eID, entity, curv, conic y>_lxLhmO# SpU+y|\[0 SetConic eID, entity, 1/Rpost, CCpost &q^\*<B.^ Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost =J&vr I} m\(TS-" '************************************************************************* ;!q _+P 'Lens thickness (Position of posterior lens surface) =&;orP '************************************************************************* !}<d6&!py rU=qr&f"B parID = FindFullName( "Geometry.Arizona Eye.Lens" ) (/UW}$] h 'G;y!<a ' Delete any z-shift(s) ?&
qM C count = 0 % 4|* While GetOperationCount(eID)>count
$A]2Iw!& GetOperation eID, count, op @E
%:ALJ If op.Type="ShiftZ" Then h+<vWo}H DeleteOperation eID,count S.pL^Ru count=count-1 +!h~T5Ck End If 8[\F*H count=count+1 @E;'Ffo Wend %N$,1=0* r"sK@ 'Set new z-shift Q>Voa&tYn op.Type = "ShiftZ" 2fFZ70Yh op.val1 = tlens ]rGZ op.parent = parID :,Z'/e0& AddOperation eID, op 6<X.]"u+E~ Print "Set lens thickness = " & tlens .sI*\@w. z*n '************************************************************************* h_#x@p 'Lens index of refraction v EppkS U1 '************************************************************************* 3D32'KO_" eID = FindMaterial( "Lens" ) FcVQ_6 GetModelMaterial eID, mat ]^j:}#R kZ7\zbN> mat.Nd = nlens {w:*t)@j SetModelMaterial eID, mat J<hqF4z Print "Set lens index of refraction = " & nlens VBnD:w"z nb-]fa '************************************************************************* ^/@Z4(E 'Pupil diameter =h5&:?X '************************************************************************* e.-+zkQ8EI eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) WK$75G, z ntvKOIh 'Adjust pupil diameter (trimming volume inner hole) }
DQ<YF+ 2E5n07, SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" i!0w? /g9 v~E\u ' Adjust pupil location to just in front of the lens {zzc/!| parID = FindFullName( "Geometry.Arizona Eye" ) }_Y&kaM eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) TQ`s&8"P count = 0 <14,xYpE While GetOperationCount(eID)>count %!DdjC&5* GetOperation eID, count, op 5rp,xk! If op.Type="ShiftZ" Then -c%#Hd DeleteOperation eID,count cdd6*+E count=count-1 B|9[DNd End If *^[m?3"W count=count+1 oF'_x,0 Wend <MK4#I1I op.Type = "ShiftZ" zXX=WH op.val1 = taq-0.01 N"/J1
op.parent = parID Z4ekBdmCL AddOperation eID, op !s^[|2D_U [A jY~ Print "Set pupil diameter = " & pupilDiam YQ? "~[mL 2/o_,k 'Update AZ Eye subassembly Description `L~gERW# eID = FindFullName( "Geometry.Arizona Eye" ) 6&oaxAp<s GetEntity eID, entity .+3~
w entity.Description = "Accommodation = " & A & "D" 8O^< |