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简介 3z
-="_p lF~!F<^9 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。 bZu2.?{ Vsd4; 模型 -=)+)9~G Ted!*HKlB 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。 A\|:hzu+ &0SgEUZr Table 1. AZ眼睛模型的定义 ](>YjE0 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. %!]CP1S Vn?|\3KY 光源 lKV7IoJ&; o_cAelI[! 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。 B
!Z~j T AA[?a
p+16*f9,^ 图1. 光源和提示信息使用 i: 7cdhz 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。 ]s`cn}d =H?^G[ y 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。 Nzl`mx16 TmEh$M 图2. 字母F光源的设定方法光 tD> qHR D:PrFa 图3. 字母F在视网膜上位置点列图 Wx8n) 视网膜的散射 C5=m~ RSIhZYA 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 S y^et wN:vI(C PKYm{wO- 图4. 视网膜朗伯散射设定 ET\rd5Po 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 Ie4Xk !jRs5{n^Ol Xvxj-\ - 图5. 视网膜重点采样规格设定 ;Ngu(es6 脚本 ~>rnq7j
A{)p#K8 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: NUX$)c ]wEFm;N 图6. 用户对话框的创建与编辑 dl+:u}9M$ 图7. 用户对话框编辑器 Q'0:k{G
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。 -"}nm!j /5 余下的脚本计算与屈光度有关的所有参数。 %[BOe4[
y~Vl0f; 分析 M)CQ|P lLN5***47J 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 pI}6AAs}Z Z=^~]Mfa 图7. 字母F在视网膜上颜色分析 LNF|mS\+D 脚本代码 lD,;xuQ v[<;z(7Qk Option Explicit 'Remove this to enable non-dimensioned variables to be used. z W*Z ef:YYt{|q Dim entity As T_ENTITY \6vr)1~N> Dim op As T_OPERATION 8!qzG4F/ Dim mat As T_MODELMATERIAL 'v_k#% Dim A As Double BP8jReX^ Dim pupilDiam As Double dQ_yb+< Dim eID As Long 53l !$#o Dim parID As Long j "e]Ui Dim count As Integer q!<n\X3]u Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double 6dKJt Dim tlens As Double, nlens As Double -x+K#T0Z Dim curv As Double, conic As Double yXCJ? Dim ok As Long 0t -=*7w% R'h.lX Sub Main BZk0B? SFVqUg3"Z '用户输入对话框 :F
pt>g Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 $q0i=l&$& TextBox 220,21,40,21,.TextBox1 'default: 0 E6clVa Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 2I0Zr;\f OKButton 40,91,90,21 uw{K&Hxw CancelButton 190,91,90,21 r^;1Sm Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 Pk)H(, TextBox 220,49,40,21,.TextBox2 'default: 4 (gF{S*` End Dialog {3K`yDF Dim dlg As UserDialog sEcg;LFp +H
"j-:E@t ok = Dialog (dlg) zj7?2 #BhcW"@ If ok=0 Then 'cancel button was pressed !Er)|YP Print "Execution cancelled." #>O+!IH End C ,[q#D4 End If EsjZ;D,c( DB.)/(zWQ 'Assign accommodation and pupil diameter & use defaults if field left empty 2t:CK If dlg.TextBox1 = "" Then z{A~d A = 0 'Default accommodation ""x>-j4 Else IAb-O A = CDbl(dlg.TextBox1) _PGS"O?j End If 9bu1Ax1M f<*-; If dlg.TextBox2 = "" Then .Tc?PmN pupilDiam = 4 'Default pupil diameter !]=S A & Else }/M`G]wT# pupilDiam = CDbl(dlg.TextBox2) BH2JH>'X End If [Ee <SB{ rz.`$ Print " " 5@`dKFB5 Print "Accommodation = " & A & " Diopters" *m:'~\[u Print "Pupil Diameter = " & pupilDiam & " mm" h:{^&d
a N.q0D5 : ' Calculate new parameters with accommodation E\*M4n\! taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness A9ZK :i7 }W5~89" Rant = 12.0 - 0.4*A 'Radius of anterior lens .pPtBqp CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens iKA qM{( e+Sq&H!@ Rpost = -5.224557 + 0.2*A 'Radius of posterior lens $im6v CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens 3'6by!N,d UaM&/K9 tlens = 3.767 + 0.04*A 'Lens thickness |!uC [= |!*abc\`(` nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction R|R3Ob.e IZ9*
'0Z 'Adjust parameters to account for accommodation `l+9g"q lfyij[6q+ '************************************************************************* @zSj&4 'Aqueous thickness (Position of Lens) \_AoG8B '************************************************************************* KBwY _ eID = FindFullName( "Geometry.Arizona Eye.Lens" ) o5< w2( GetCustomElement eID, entity *DPKV$ DXx),?s> parID = FindFullName( "Geometry.Arizona Eye" ) Q6=>*}Cm6m *2r(!fJP=^ ' Delete any shift(s) in z smat6p[ count = 0 2 D!$x+| While GetOperationCount(eID)>count jP"yG# GetOperation eID, count, op /[>zFYaQ If op.Type="ShiftZ" Then 0l~z0pvT DeleteOperation eID,count PAs.T4Av^ count=count-1 XA-, End If (V#*}eGy count=count+1 %oiA'hz;* Wend Lr<?eWdCwJ JVh/<A 'Set new shift in c}D>.x|] op.Type = "ShiftZ" [_zoJ op.val1 = taq )/uCdSDIc op.parent = parID yr34&M(a AddOperation eID, op `lN
Z|U Print "Set aqueous humor thickness = " & taq-0.55 <*5` TE0J + wF5( '************************************************************************* i2n66d 'Radius and conic constant of anterior lens yrV]I(Xe '************************************************************************* 1eMaKT_= eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) zmh5x{US1 GetConic eID, entity, curv, conic A&=`?4> <(B: "wI SetConic eID, entity, 1/Rant, CCant KAm$^N5 Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant H263<^ <77v8=as5 '************************************************************************* lv\^@9r 'Radius and conic constant of posterior lens Oy~X@A '************************************************************************* lBfG#\rdW~ eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) b"&1l2\ A GetConic eID, entity, curv, conic uU#e54^ -0Q^k\X- SetConic eID, entity, 1/Rpost, CCpost {iq)[)n Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost z|sR
`]K zq4)Uab* '************************************************************************* gclw>((5 'Lens thickness (Position of posterior lens surface) =\)qUs\z '************************************************************************* WkK.ON^ e%.|PZ) parID = FindFullName( "Geometry.Arizona Eye.Lens" ) F+::UWKA i-31Cxb ' Delete any z-shift(s) :qO)^~x count = 0 1}b1RKKj< While GetOperationCount(eID)>count J7s\
GetOperation eID, count, op .DZ8kKY If op.Type="ShiftZ" Then iM{UB=C DeleteOperation eID,count K 6HH_T count=count-1 `#>JRQ= End If +B-;.]L
T count=count+1 7;H P_oAu Wend il>XV> #;9n_) 'Set new z-shift 1[H1l; op.Type = "ShiftZ" Y<9Lqc.i op.val1 = tlens b5d;_-~d op.parent = parID pPtw(5bH AddOperation eID, op }[8Nr+y Print "Set lens thickness = " & tlens 3(R]QO`%' lO5*n|Ic, '************************************************************************* %eLf6|1x 'Lens index of refraction h?`'%m?_b '************************************************************************* g)#.|d+ eID = FindMaterial( "Lens" ) 8i'EO6 GetModelMaterial eID, mat YztW1GvI PR*qyELu mat.Nd = nlens ;mLbgiqQ J SetModelMaterial eID, mat ZsepTtY Print "Set lens index of refraction = " & nlens +q@g R.B3
'************************************************************************* ?^W`7H F%0 'Pupil diameter \' ;zD-MX '************************************************************************* \)mV2r!% eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) xyc`p[n& S#l6=zI7^R 'Adjust pupil diameter (trimming volume inner hole) '*,P33h9<! TWAt)Q"J SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" r-k,4Yz ~q05xy8 ' Adjust pupil location to just in front of the lens VA0p1AD parID = FindFullName( "Geometry.Arizona Eye" ) @I,:(<6 eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) (L7@ez count = 0 Af{K#R8! While GetOperationCount(eID)>count mzh7E[S_,i GetOperation eID, count, op J|GEt@o3 If op.Type="ShiftZ" Then 8ECBi( DeleteOperation eID,count +_E96`P count=count-1 64h$sC0z/e End If v$i[dZSN[ count=count+1 5fVm392+ Wend "=ogO/_Q" op.Type = "ShiftZ" q&N1| f7 op.val1 = taq-0.01 h|S6LgB op.parent = parID FR9*WI
AddOperation eID, op H`028^CH$ G0VbW-`O Print "Set pupil diameter = " & pupilDiam Zn9ecN S&`iEwG 'Update AZ Eye subassembly Description 4x%R4tk eID = FindFullName( "Geometry.Arizona Eye" ) dl&402 GetEntity eID, entity js<}>wD7< entity.Description = "Accommodation = " & A & "D" TB SetEntity eID, entity YoEL|r| V]I+>Zn| 7 Update #3m7`}c Print "DONE!" `lA[-x~ ); <Le6 End Sub w`;>+_ E7 v<wR`7xG 如果屈光度是4,光瞳直径是4,则会输出如下数据: `tb@x ^ rAZsVnk? Accommodation = 4 Diopters Cvf^3~q Pupil Diameter = 4 mm G)'(%rl Set aqueous humor thickness = 2.81 \C(dWs Set anterior lens radius = 10.4 and conic constant = -2.375869 #(KE9h% Set posterior lens radius = -4.424557 and conic constant = -3.081019 :P1/kYg Set lens thickness = 3.927 Zc Y* TGx Set lens index of refraction = 1.42672 Hg}@2n)/ Set pupil diameter = 4 ?c!W*`yP DONE! 7,![oY[
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