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简介 #:E^($v *]>~lO1 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。 Q;k
D Jo %4x,^ K] 模型 7?]wAH89 "\O{!Hj8 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。 tpQ8
m( ^0(`:* Table 1. AZ眼睛模型的定义 ?OBB)hj 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. IN=l|Q$8f / xb37, 光源 :a*F>S! ow7*HN* 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。 50^CILKo7 7,3 g{8 hY/i)T{ 图1. 光源和提示信息使用 RPZ
- 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。 l'RuzBQr b8h6fB:2 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。 v
M $Tn &`}ACTY'P 图2. 字母F光源的设定方法光 =/kT| NC%)SG \ 图3. 字母F在视网膜上位置点列图 P,bis7X. 视网膜的散射 q)!G5j3 )AXa.y 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。 keS%w]87 e^h4cC\^ kj@m5`G 图4. 视网膜朗伯散射设定 +K61-Div 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。 %iD'2e: v;:. k,E0 Bw4PxJs- 图5. 视网膜重点采样规格设定 ,%]xT>kH 脚本 puK /;nns k-8$43 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: | (: PX [p96H)8YU 图6. 用户对话框的创建与编辑 /S`d?AV 图7. 用户对话框编辑器 +f\r?8s 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。 2KQpmNN 余下的脚本计算与屈光度有关的所有参数。 _j?/O)M
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FsSY 分析 G;;iGN F17nWvF 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 J-Wphc!m }tPI#[cfK 图7. 字母F在视网膜上颜色分析 W_ubgCB 脚本代码 $qk(yzY 8p.O rdp Option Explicit 'Remove this to enable non-dimensioned variables to be used. J}s)#va9R qW t 9Tr Dim entity As T_ENTITY uDG#L6 Dim op As T_OPERATION YojYb]y+j Dim mat As T_MODELMATERIAL QW6\~l 4 Dim A As Double A!p70km2 Dim pupilDiam As Double y0cB@pWp Dim eID As Long e]u3[ao Dim parID As Long P*6&0\af| Dim count As Integer \bumB<w(] Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double ~
H $q Dim tlens As Double, nlens As Double ]z5gC`E0 Dim curv As Double, conic As Double {9YNv<3 Dim ok As Long 5:~BGK&{Y 9 e0Oj3!B Sub Main y3pr(w9A i>L>3]SRr{ '用户输入对话框 F<N{ x^ Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 3NC-)S TextBox 220,21,40,21,.TextBox1 'default: 0 "ju0S & Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 yf7$m_$C' OKButton 40,91,90,21 ;c;PNihg CancelButton 190,91,90,21 U#1,]a\ Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 f
iu?mb=* TextBox 220,49,40,21,.TextBox2 'default: 4 $.-\2;U End Dialog psZ #^@>mJ Dim dlg As UserDialog
i;8tA! >$p|W~x ok = Dialog (dlg) Irnfr\l. h` ,! p If ok=0 Then 'cancel button was pressed :Vx5%4J Print "Execution cancelled." 7!-y72qx End RNn5,W End If [_?dp aTt -% Z?rn2 'Assign accommodation and pupil diameter & use defaults if field left empty '{xPdN If dlg.TextBox1 = "" Then nnPY8pdjSD A = 0 'Default accommodation Ff@Cs0R Else a'2^kds A = CDbl(dlg.TextBox1) sZ9VXnz24 End If QL_9a,R'r enJgk( If dlg.TextBox2 = "" Then x)Ls(Xh+g pupilDiam = 4 'Default pupil diameter {@w!kl~8 Else m'P,:S)= pupilDiam = CDbl(dlg.TextBox2) I,d5Y3mC End If
dr iw\ yxz"9PE/P Print " " ~i y]X:U Print "Accommodation = " & A & " Diopters" X,"(G}KUA Print "Pupil Diameter = " & pupilDiam & " mm" :gJ?3LwTf w
`0m[* ' Calculate new parameters with accommodation - r!sY+Z> taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness bI"_hvcFp EFNi# D8s Rant = 12.0 - 0.4*A 'Radius of anterior lens >l3iAy!sZ CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens nVt,= ?_ U ^yo~C3r~ Rpost = -5.224557 + 0.2*A 'Radius of posterior lens n6Qsug$z CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens lEe<!B$d" wjeuZNYf tlens = 3.767 + 0.04*A 'Lens thickness qu:nV"~_ OEFALt nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction p\ }Ep ?]]d
s] 'Adjust parameters to account for accommodation *P.Dbb8vn ?|;q=p`t- '************************************************************************* .!pr0/9B 'Aqueous thickness (Position of Lens) $|V@3`0 '************************************************************************* k ED1s's eID = FindFullName( "Geometry.Arizona Eye.Lens" ) shAoib?Kw: GetCustomElement eID, entity TppuEC> Dxlpo!
?# parID = FindFullName( "Geometry.Arizona Eye" ) ~DYv6-p% dRD t.U!T ' Delete any shift(s) in z lEWF~L5=: count = 0 E kvTl- While GetOperationCount(eID)>count +xc1cki_{ GetOperation eID, count, op 2`;&Uwt If op.Type="ShiftZ" Then i=^!?
i DeleteOperation eID,count Fb0r(vQ^ count=count-1 y9xvGr[l End If 0mMoDJRy count=count+1 4ru-qF Wend R#^.8g)t [ u.r]\[J 'Set new shift in qG<3H!Z!ky op.Type = "ShiftZ" 7B)m/%>3s op.val1 = taq 'C2X9/!, op.parent = parID <lo\7p$A AddOperation eID, op dz>2/' Print "Set aqueous humor thickness = " & taq-0.55 :[r/
Y NrK.DY4 '************************************************************************* EIrAq!CA 'Radius and conic constant of anterior lens D02(6| '************************************************************************* _* m<Z;Et eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) nUy. gAb GetConic eID, entity, curv, conic N7
FndB5% };Oyv7D+b SetConic eID, entity, 1/Rant, CCant js..k*j Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant =G,wR'M LN0pC}F '************************************************************************* 9>6DA^ 'Radius and conic constant of posterior lens u$38"&cmA '************************************************************************* )p^" J| eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) x=M%QFe GetConic eID, entity, curv, conic X;&Iu{&= tSVWO]< SetConic eID, entity, 1/Rpost, CCpost =f/CBYNw@V Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost 2t[P-on SIridZ*% '************************************************************************* QHDR*tB:{ 'Lens thickness (Position of posterior lens surface) !y\r.fm!A '************************************************************************* !7hjA=0
-k8<LR3 parID = FindFullName( "Geometry.Arizona Eye.Lens" ) 'w z6Zt [p+-]V ' Delete any z-shift(s) B%^W$7
q count = 0 %;eD.If} While GetOperationCount(eID)>count omMOA GetOperation eID, count, op 'CMbqLk# If op.Type="ShiftZ" Then , UsY0YC DeleteOperation eID,count 4=~+Bz count=count-1 dM=45$\q End If :;hz!6! count=count+1 F1)5"7f Wend AxtmG\o> lDSF 'Set new z-shift bEKh U\@=J op.Type = "ShiftZ" @xXVJWEU: op.val1 = tlens @9tzk [ op.parent = parID ![i)_XO AddOperation eID, op {sfA$ d0 Print "Set lens thickness = " & tlens *\(MG|S >t_h/:JZ) '************************************************************************* SF=TG84< 'Lens index of refraction GoLK
95"] '************************************************************************* FS)"MDs eID = FindMaterial( "Lens" ) I`f5)iF?0 GetModelMaterial eID, mat ]t0St~qUL) 3_ly"\I\ mat.Nd = nlens n_4 r'w SetModelMaterial eID, mat kV+%(Gl8 Print "Set lens index of refraction = " & nlens 1Q/=s,{u apOa E7| '************************************************************************* Vw|P;LLl` 'Pupil diameter rQxiG[0 '************************************************************************* 'u:-~nSX) eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) PjD9D. ^)(-7H 'Adjust pupil diameter (trimming volume inner hole) `*l aUn +CM>]Ze SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" ", p5}}/ 5a-x$Qb9 ' Adjust pupil location to just in front of the lens <2E|URo,# parID = FindFullName( "Geometry.Arizona Eye" ) FUarI5#fwF eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) B[I9<4} count = 0 )n]"~I^ While GetOperationCount(eID)>count >%ovL8F GetOperation eID, count, op Cz)&R^ If op.Type="ShiftZ" Then v\[+ DeleteOperation eID,count 1<Sg@ count=count-1 &7i&"TNptP End If Z5E; FGPb count=count+1 8t3m$<7 Wend |AH>EXhv op.Type = "ShiftZ" RG*Vdom op.val1 = taq-0.01 n)~*BpL3 op.parent = parID f S[-K?K AddOperation eID, op a'-u(Bw 9O- 2 Print "Set pupil diameter = " & pupilDiam m):*>o55 X$;&Mdo. 'Update AZ Eye subassembly Description ~o>Gm>5!HH eID = FindFullName( "Geometry.Arizona Eye" ) /)T~(o|i GetEntity eID, entity X Z . T%g entity.Description = "Accommodation = " & A & "D" lxm/*^
SetEntity eID, entity _1NK9dp: xbBqR_H_ Update mU]VFPr5 Print "DONE!" i!zFW-*5 pB4Uc<e End Sub {fnx=BaG jQ,Vs=*H 如果屈光度是4,光瞳直径是4,则会输出如下数据: |mP};&b <sw@P":F Accommodation = 4 Diopters <|3%}? Pupil Diameter = 4 mm \"1>NJn&k) Set aqueous humor thickness = 2.81 <n4` #d Set anterior lens radius = 10.4 and conic constant = -2.375869 x ZP*%yM Set posterior lens radius = -4.424557 and conic constant = -3.081019 l2LLM {B Set lens thickness = 3.927 r=&,2meo Set lens index of refraction = 1.42672 'w27Lt'V Set pupil diameter = 4 :{2~s DONE! IH;sVT$M
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