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简介 shzG
Eb p6Gcts?, 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。 )qd={ 5*1#jiq 模型 x`L+7,&n 2LZS|fB9o 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。 uY]T:UVk ckWkZ
78\ Table 1. AZ眼睛模型的定义 sv`"\3N[ 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. WGMb8 /{$P ~1ps7[ 光源 o3\,gzJ AAo0M/U' 多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 }AJ L,Q7q (!-;T ~j]dct7 图1. 光源和提示信息使用 *{nunb>WO 除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处,并增加了pre-propagation distance= -8。尽管光线在光瞳处创建,规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射,而不是在光瞳处入射。 v#F-<?Vv ll2Vk*xs 在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 Man^<T%F 5us^B8Q 图2. 字母F光源的设定方法光 A_i zSzC1 70=(.[^+ 图3. 字母F在视网膜上位置点列图 fp tIc#4 视网膜的散射 qy&\Xgn;GA z{/LX
\ 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 q0g1EJar [Xq<EEb o?y"]RCM 图4. 视网膜朗伯散射设定 r,"7%1I 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 C]Q>*=r 69iM0X!'u 0$QIfT) 图5. 视网膜重点采样规格设定 fB7ljg 脚本 k:mlt: qCQu^S' iD 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: ;:?*t{r4# ki3 HcV 图6. 用户对话框的创建与编辑 4&]%e6,jH 图7. 用户对话框编辑器 >>j+LRf* 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。 nzWQQra|? 余下的脚本计算与屈光度有关的所有参数。 L^)qe^%3 s6/cL|Ex 分析 )vQNiik# 9cz )f\ 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 mYzcVhV ee^4KKsh\ 图7. 字母F在视网膜上颜色分析 _jo$)x+'x 脚本代码 %z2oDAjX PU"S;4m Option Explicit 'Remove this to enable non-dimensioned variables to be used. #w;;D7{@m *0\k
Z,#BJ Dim entity As T_ENTITY ,#
eO& Dim op As T_OPERATION ET3,9+Gj Dim mat As T_MODELMATERIAL 2^J/6R$ Dim A As Double d=F)y~&' Dim pupilDiam As Double GZS{&w! Dim eID As Long [WYJrk. Dim parID As Long wR(ttwxK3 Dim count As Integer <ZV7|'^ Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double f}%sO Dim tlens As Double, nlens As Double a}w&dE$!- Dim curv As Double, conic As Double F=:c5z Dim ok As Long pLPd[a ?`"<DH~:0B Sub Main &*jixqzvn y+= \z*9
'用户输入对话框 4L!e=>as"1 Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 -CwWs~! TextBox 220,21,40,21,.TextBox1 'default: 0 tpE3|5dZF Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 *5^ze+: OKButton 40,91,90,21 sI$:V7/! CancelButton 190,91,90,21 ^>eFm8`N Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 v >NTh TextBox 220,49,40,21,.TextBox2 'default: 4 IQ#So]9~Y End Dialog F;
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Dim dlg As UserDialog pIL`WE1' S`4e@Z$ ok = Dialog (dlg) u$\Tg3du2 x7Eeb!s0f, If ok=0 Then 'cancel button was pressed ^,>}%1\ Print "Execution cancelled." ,d5ia4\K End bnIf}ut-G End If 95VqaR, 2AmR(vVa" 'Assign accommodation and pupil diameter & use defaults if field left empty RBPYGu'6B If dlg.TextBox1 = "" Then u"eZa!# A = 0 'Default accommodation L-SdQTx_ Else E|\3f(aF A = CDbl(dlg.TextBox1) WGluZhRuT3 End If Xp.|.)Od H_v/}DEG If dlg.TextBox2 = "" Then rC=f#YjR pupilDiam = 4 'Default pupil diameter =y`-sU Hx Else :LG}yq^ pupilDiam = CDbl(dlg.TextBox2) Gl=@>Dc% End If m79m{!q$- l8eT{!4 Print " " ~rp.jd 0l Print "Accommodation = " & A & " Diopters" ">03~:oA Print "Pupil Diameter = " & pupilDiam & " mm" U. NeK{ aIY$5^x ' Calculate new parameters with accommodation `;R|V taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness u)wu=z8 !Mm+bWn=mB Rant = 12.0 - 0.4*A 'Radius of anterior lens tPQ2kEW CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens N.kuE=X Z8N@e<!*~8 Rpost = -5.224557 + 0.2*A 'Radius of posterior lens jp"XS CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens Ey
0>L r@\,VD6J tlens = 3.767 + 0.04*A 'Lens thickness hrUm}@d eYPt nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction x A@|I# `@W3sW/^ 'Adjust parameters to account for accommodation \>&@lA Q5T(;u6 '************************************************************************* H!Fr("6} 'Aqueous thickness (Position of Lens) EY=\C$3J: '************************************************************************* sqgD?:@J eID = FindFullName( "Geometry.Arizona Eye.Lens" ) 9CgXc5 GetCustomElement eID, entity =P@M&Yy' ayB=|*Q" parID = FindFullName( "Geometry.Arizona Eye" ) o;Hd W Ih9O Rp7 ' Delete any shift(s) in z .N'%hh count = 0 k
2
mkOb While GetOperationCount(eID)>count zzDNWPzsA GetOperation eID, count, op 11^ {WF If op.Type="ShiftZ" Then ljaAB+
DeleteOperation eID,count *rujdQf count=count-1 ^Y1AeJ$L End If
!;BZ# tF& count=count+1 &z{dr~ Wend 8,Q.t7v p0%6@_FT~ 'Set new shift in -;W\f<q] op.Type = "ShiftZ" oRtY?6^$ op.val1 = taq sYW1T @ op.parent = parID +?J_6Mo@X AddOperation eID, op t6! p\Y}} Print "Set aqueous humor thickness = " & taq-0.55 _ d(Ks9 }kgjLaQ^N '************************************************************************* `Lb _J 'Radius and conic constant of anterior lens =PeW$q+ '************************************************************************* ,_e/a eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) ~7)rKHau GetConic eID, entity, curv, conic f6(9wz$Trt dd
@COP? SetConic eID, entity, 1/Rant, CCant z[$9B#P Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant 8xeun~e"vS kOlI?wc '************************************************************************* ZipK;!9by 'Radius and conic constant of posterior lens 4`EvEv$i '************************************************************************* &})4?5 eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) O #uaGziFf GetConic eID, entity, curv, conic eX]9mQ]E hCOy\[2$ SetConic eID, entity, 1/Rpost, CCpost 80R=r Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost )KTWLr; 4IGQ,RTB '************************************************************************* ux/[d6To 'Lens thickness (Position of posterior lens surface) 9
up*g '************************************************************************* t"!8 8m13M5r parID = FindFullName( "Geometry.Arizona Eye.Lens" ) )=SYJ-ta< eL]w' }\ ' Delete any z-shift(s) rwV u?W count = 0 l,FG:"`Z@ While GetOperationCount(eID)>count L;(3u' GetOperation eID, count, op QBBJ1U If op.Type="ShiftZ" Then r)Mx.`d! DeleteOperation eID,count 5D02%U2N)G count=count-1 >>
8KL`l End If b$$L]$q2 count=count+1 j)lM:vXR Wend Y;I(6`,Y j{Qbzczy, 'Set new z-shift -$!Pf$l@ op.Type = "ShiftZ" %]= 'Uv^x op.val1 = tlens 3vvFF]D5k op.parent = parID +XaO?F[c AddOperation eID, op UdM5R
[ Print "Set lens thickness = " & tlens [7Kj$PB3 qT-nD} '************************************************************************* #D*J5k>2 'Lens index of refraction JwG5#CFu^ '************************************************************************* L^ jC&
dF eID = FindMaterial( "Lens" ) {u[K
^G GetModelMaterial eID, mat JXa%TpI:
E BX)cV mat.Nd = nlens `'k's]Y SetModelMaterial eID, mat iTBhLg, Print "Set lens index of refraction = " & nlens 4@V <Suw YaE['a '************************************************************************* <xh'@592 'Pupil diameter 0T{Y_IG '************************************************************************* Zv7$epDUz eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) kHIQ/\3?Q :92a34 'Adjust pupil diameter (trimming volume inner hole) '/"M02a d-S'y-V?d SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" H f mMf^c MH~qfH>K ' Adjust pupil location to just in front of the lens *]UEF_ parID = FindFullName( "Geometry.Arizona Eye" ) 1X:whS5S eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) <?va)
ou count = 0 p-03V"^& While GetOperationCount(eID)>count (j 8,n<o GetOperation eID, count, op v(nQd6;T If op.Type="ShiftZ" Then 7J_f/st DeleteOperation eID,count O=?X%m # count=count-1 l$_+WC*wp End If ^DCv-R+p count=count+1 co%_~xO Wend ZCF-*nm op.Type = "ShiftZ" Dp |FyP_w op.val1 = taq-0.01 25@j2K ( op.parent = parID {zN_l! AddOperation eID, op /WgW e 50hh0!1 Print "Set pupil diameter = " & pupilDiam />I8nS}T 5 9J$SE 'Update AZ Eye subassembly Description qN,FX#DP eID = FindFullName( "Geometry.Arizona Eye" ) %+W
>+xRb GetEntity eID, entity -/{}^QWB entity.Description = "Accommodation = " & A & "D" jHw2Q8s|R SetEntity eID, entity N'BctKL G(3la3\( Update B91PlM. Print "DONE!" `Q^Sm`R pPoC61F End Sub e;u8G/ ->9xw 如果屈光度是4,光瞳直径是4,则会输出如下数据: Qi]Z)v{^ 6
&Aa b56 Accommodation = 4 Diopters ?Pw\&q Pupil Diameter = 4 mm '
1]bjW*! Set aqueous humor thickness = 2.81 9F1stT0G% Set anterior lens radius = 10.4 and conic constant = -2.375869 oi4Wxcj Set posterior lens radius = -4.424557 and conic constant = -3.081019 O!+5As Set lens thickness = 3.927 ffd3QQ Set lens index of refraction = 1.42672 Yf`.Cq_: Set pupil diameter = 4 '*Mb
.s" DONE! G6bg ~V5Q:
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