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简介 89l{h8R [8rl{~9E 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。 ;0Mg\~T~' &BkdC,o 模型 `dm}|$X| ky{-NrK 模型的定义如表1种所示,由半径、圆锥常数、折射率、阿贝数、到下一面的距离等一系列表面组成。一些参数由屈光度(A)来决定。 #RVN7-x DS>qth Table 1. AZ眼睛模型的定义 4qmaL+Q 在FRED中使用0屈光度来创建的,光瞳加在了透镜的前面。材料是创建一个新的材料并选择类型“Model Material”,输入的参数是nd和vd. ;`}b
.S=n !/6KQdF 光源 '/Ag3R RtScv 多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 /]hE?cmj p'YNj3&u f}?q 图1. 光源和提示信息使用 JTfG^Nv>K 除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处,并增加了pre-propagation distance= -8。尽管光线在光瞳处创建,规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射,而不是在光瞳处入射。 XZ1WY( p<AzpkU,A 在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 YfUUbV I+FQ2\J*H 图2. 字母F光源的设定方法光 &dvL` a!*K)x,"< 图3. 字母F在视网膜上位置点列图 Q0-}!5`E1$ 视网膜的散射 V0a)9\x(\ $ZfoJR]% 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 7?EC
kuSv XdGA8%^cY Wz-7oP%;I 图4. 视网膜朗伯散射设定 D$PR<>=y 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。 )Qixde>]p =3<@{^Eg Kk<MS$Ov 图5. 视网膜重点采样规格设定 5Q.z#]Lg 脚本 5$Aiez~tBq _)F0oC { 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: xH/Pw?^ F]7$Y 图6. 用户对话框的创建与编辑 fk 图7. 用户对话框编辑器 = *~Q5F 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 X/-u$c 余下的脚本计算与屈光度有关的所有参数。 BuIly&qbm< LSN%k5G7. 分析 HE>sZ; !>gu#Q{\- 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 _
ZC[h~9H eE-c40Bae 图7. 字母F在视网膜上颜色分析 4.}J'3 . 脚本代码 v|K<3@J s^Wh!:>r/ Option Explicit 'Remove this to enable non-dimensioned variables to be used. @N,I}_ 9- #Hy fjj Dim entity As T_ENTITY _/%,ZoZ2 Dim op As T_OPERATION 'q9='TOk Dim mat As T_MODELMATERIAL ECF \/12 Dim A As Double >Vvjs Dim pupilDiam As Double ^lCQHz Dim eID As Long %?~`'vYoi Dim parID As Long 1X$hwkof Dim count As Integer #I|jFn9 Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double ] f~mR_E Dim tlens As Double, nlens As Double ZJeTx.Gi6 Dim curv As Double, conic As Double b+qdl`Vd Dim ok As Long sU}.2k 6fr@y=s2: Sub Main 8!q$8]M soi.`xE '用户输入对话框 ("$ ,FRTQ: Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 b&~s}IX TextBox 220,21,40,21,.TextBox1 'default: 0 f}U@e0Lsb Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 1=.+!Tg OKButton 40,91,90,21 A/+bwCDP CancelButton 190,91,90,21 >:yU bo) Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 69>N xr~k TextBox 220,49,40,21,.TextBox2 'default: 4 =fZMute End Dialog uY'77,G_J Dim dlg As UserDialog 39zwPoN> :4,
OA ok = Dialog (dlg) /"*eMe!= [J71aH If ok=0 Then 'cancel button was pressed @p}"B9h*^ Print "Execution cancelled." Z}*{4V`R End %Yi^{ZrM End If x!@P|c1nKC L&s|<<L 'Assign accommodation and pupil diameter & use defaults if field left empty 16N+ If dlg.TextBox1 = "" Then zjVQ \L A = 0 'Default accommodation K@UQ O Else CYCG5)<9 A = CDbl(dlg.TextBox1)
mtQlm5l End If C0bOPn }co*%F{1 If dlg.TextBox2 = "" Then Zg#VZg1
2 pupilDiam = 4 'Default pupil diameter 3.^Tm+ C Else ?U;KwS]% pupilDiam = CDbl(dlg.TextBox2) (T]< End If |`50Tf\J JO `KNI Print " " cii]-%J}c Print "Accommodation = " & A & " Diopters" rIg5Wcd Print "Pupil Diameter = " & pupilDiam & " mm" 8A 3pYW- UZ"jQJQ ' Calculate new parameters with accommodation Q5:8$
C}+ taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness t@(`24 _,m|gr,S Rant = 12.0 - 0.4*A 'Radius of anterior lens [`eqma CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens c>(`X@KL ^bjaa Rpost = -5.224557 + 0.2*A 'Radius of posterior lens @\|W#,~ CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens ,GH;jw)P |dxcEjcY_ tlens = 3.767 + 0.04*A 'Lens thickness WLe9m02r D@cv{
_M/ nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction ]$VYzE2e \~#$$Q-qtU 'Adjust parameters to account for accommodation foOwJ }JU :{ }]$+|)\ '************************************************************************* [4_JK 'Aqueous thickness (Position of Lens) 7oK7f=*Q '************************************************************************* ;GgW&*| eID = FindFullName( "Geometry.Arizona Eye.Lens" ) wCwJ#-z.= GetCustomElement eID, entity @@O=a m<DiYxK parID = FindFullName( "Geometry.Arizona Eye" ) L`M.Htm8 *yx&4)Or ' Delete any shift(s) in z ~baVS-v count = 0 M,ObzgW While GetOperationCount(eID)>count {4@+
2)l GetOperation eID, count, op O"<W<l7Q If op.Type="ShiftZ" Then 4%3R}-'mh DeleteOperation eID,count
>Mzk;TM count=count-1 opKk#40 End If EPZ^I) count=count+1 qXH\e| Wend @4'bI) x'.OLXx> 'Set new shift in *r&q;ER op.Type = "ShiftZ" ygvX}q op.val1 = taq Wx i|(} op.parent = parID nS53mLU) AddOperation eID, op #ZPU.NNT? Print "Set aqueous humor thickness = " & taq-0.55 =ca<..yh[d Gxtb@`f '************************************************************************* hSO(s 'Radius and conic constant of anterior lens
UA{tmIC\ '************************************************************************* qJQ!e eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) g@va@*|~d GetConic eID, entity, curv, conic x1$:u6YD22 \1AtBc& SetConic eID, entity, 1/Rant, CCant B4<W%lm Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant cNX0.7Ls vu&%e\gM '************************************************************************* Q
UQ"2oC 'Radius and conic constant of posterior lens Ls<.&3X2 '************************************************************************* ZwV`} 2{ eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) *6-f vqCv GetConic eID, entity, curv, conic ),<E-Ub }|k_sx: SetConic eID, entity, 1/Rpost, CCpost 0{8^)apII Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost [BH^SvE y}fF<qih'> '************************************************************************* j=%^CRum 'Lens thickness (Position of posterior lens surface) #q06K2 '************************************************************************* c\n&Z'vK 6(Qr!< parID = FindFullName( "Geometry.Arizona Eye.Lens" ) ?HP54G<{xz "71,vUW ' Delete any z-shift(s) #SHmAB count = 0 rcC}4mNe While GetOperationCount(eID)>count O:=%{/6&D GetOperation eID, count, op N(%%bHi#V If op.Type="ShiftZ" Then ,+u.FQv~ DeleteOperation eID,count Y1?"Ut count=count-1 6N%fJ End If (6aSDx
Sc count=count+1 Y7vTseq Wend &
*^FBJEa. sG/mmZHYzr 'Set new z-shift +@'{ op.Type = "ShiftZ" U5 `h op.val1 = tlens ]%{.zl! op.parent = parID RG'Ft]l92N AddOperation eID, op RGeM. Print "Set lens thickness = " & tlens X#qmwcF 4@K9% '************************************************************************* 9 >t 'Lens index of refraction "Ih>>|r '************************************************************************* K+0&~XU eID = FindMaterial( "Lens" ) h6*&1r GetModelMaterial eID, mat hmA$gR_ 5/v,| mat.Nd = nlens -xJ_5 SetModelMaterial eID, mat B? Vr9H 7n Print "Set lens index of refraction = " & nlens *h<=
(Y% 0{ZYYB&"~J '************************************************************************* s`j QX\{ 'Pupil diameter P87!+pB( '************************************************************************* fn%Gu s~ eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) A@8Ot-t:\2 %idn7STJ} 'Adjust pupil diameter (trimming volume inner hole) CQf<En|1 n{>Ge,enP0 SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" m;=wQYFr{I Xq3n7d. ' Adjust pupil location to just in front of the lens Ywj=6 +; parID = FindFullName( "Geometry.Arizona Eye" ) b`NXe7A eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) hX-([o count = 0 DCJmk6p%0 While GetOperationCount(eID)>count z (N3oBW GetOperation eID, count, op E8TJ*ZU If op.Type="ShiftZ" Then +`EF0sux DeleteOperation eID,count !]%M count=count-1 IETdL{`~ End If o/EN3J count=count+1 L<kIzB ! Wend Kn9O=?Xh; op.Type = "ShiftZ" zW`Zmt\T2 op.val1 = taq-0.01 W\(u1>lj op.parent = parID 49)A.Bh&! AddOperation eID, op f8ap+][ \JJ>y Print "Set pupil diameter = " & pupilDiam b-/zt Z@u =j)y.x( 'Update AZ Eye subassembly Description T6X%.tR>` eID = FindFullName( "Geometry.Arizona Eye" ) j3Ng] @N GetEntity eID, entity CaX0Jlk* entity.Description = "Accommodation = " & A & "D" %5N;SRtv SetEntity eID, entity Rw]4/ Cd4a7<- Update
z*Y4t?+ Print "DONE!" .g CC$ nI1DLVt End Sub CYr2~0<g y-UutI& 如果屈光度是4,光瞳直径是4,则会输出如下数据: |{#=#3X I91pX<NBf Accommodation = 4 Diopters &*G+-cF Pupil Diameter = 4 mm dx=\Pq Set aqueous humor thickness = 2.81 89I[Dg;"u Set anterior lens radius = 10.4 and conic constant = -2.375869 2gn*B$a Set posterior lens radius = -4.424557 and conic constant = -3.081019 vYh_<Rp5 Set lens thickness = 3.927 O1/U3/2/d Set lens index of refraction = 1.42672 \z}/=Qgc Set pupil diameter = 4 moQ><>/ DONE! O|#N$a&_N
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