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简介 M<"H1>q@ $2+(|VG4F 人眼光学模型可用来设计眼科用设备,光学系统注定了要与人眼一起使用。本文演示了这样一个模型:Arizona眼睛模型,在Jim Schwiegerling教授的书中有详细描述:《Field Guide to Visual and Ophthalmic Optics》。AZ眼睛模型达到了基于平均临床数据所决定的轴上和轴外像差等级。FRED文件包含了此眼睛模型及几个用来分析它的光源,并包括一个基于想要的屈光度来调整模型的内嵌脚本。 bTN0 n +`H{ 模型 G'qGsKf\ 6}9`z8 模型的定义如表1种所示,由半径、圆锥常数、折射率、阿贝数、到下一面的距离等一系列表面组成。一些参数由屈光度(A)来决定。 1ZK~i voAen&>! Table 1. AZ眼睛模型的定义 3om4q2R 在FRED中使用0屈光度来创建的,光瞳加在了透镜的前面。材料是创建一个新的材料并选择类型“Model Material”,输入的参数是nd和vd. .8K ~ h o#ajBOJ 光源 AD/7k3: +rA:/!b)Y 多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 :VEy\ R>W =$t f-b#F2I 图1. 光源和提示信息使用 loPBHoE3@H 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。 r=o\!sh[ P:8P>#L 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。 ehCZhi~ Hg}@2n)/ 图2. 字母F光源的设定方法光 +GqV9x 8 7,![oY[ 图3. 字母F在视网膜上位置点列图 (#"iZv, 视网膜的散射 jJfV_#'N' M~/R1\'&j 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。 MH8 Selnv _x ;fTW0 b=-LQkcZhK 图4. 视网膜朗伯散射设定 qIIl,!&}A 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。 NtnKS@Ht =*Ad -P5M(Rt 图5. 视网膜重点采样规格设定 U;Ne"Jh 脚本 ^s=p'&6 R6KS&Ge_ 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>s2 `mfN3Q*[c 图6. 用户对话框的创建与编辑 9 yE
图7. 用户对话框编辑器 ~>(
N<:N 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。 ' Oe}Ja 余下的脚本计算与屈光度有关的所有参数。 !ufSO9eDx" ;.g <u 分析 4}\Dr
%US TT0~41&l 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 ~Uet)y< b&$sY!iU 图7. 字母F在视网膜上颜色分析 0f<$S$~h 脚本代码 , Q5Z<\
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Option Explicit 'Remove this to enable non-dimensioned variables to be used. HYkZMVH{ ]1XJQW@gF Dim entity As T_ENTITY =H\ig%%E@ Dim op As T_OPERATION ]_ON\v1 Dim mat As T_MODELMATERIAL CAPPOh Dim A As Double oNfNe^/T Dim pupilDiam As Double 07?| "c. Dim eID As Long 8+irul{H_ Dim parID As Long k^ZcgHHgb Dim count As Integer qL03iV#h*V Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double 3~%wA(|A Dim tlens As Double, nlens As Double =n}+p>\s Dim curv As Double, conic As Double d&'}~C`~k Dim ok As Long '*PJ-=G #(5hV7i Sub Main @%5$x]^ :&/b}b!)AX '用户输入对话框 %z_PEqRj Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 h xCt[G@ TextBox 220,21,40,21,.TextBox1 'default: 0 }Z~& XL= Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 _qPd)V6yb OKButton 40,91,90,21 d1`us G" CancelButton 190,91,90,21 *k]izWsV* Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 gUcG# TextBox 220,49,40,21,.TextBox2 'default: 4 0{Kb1Ut End Dialog Vf'r6Rf Dim dlg As UserDialog Y;L,}/[ yE \dv)(< ok = Dialog (dlg) @\=%M^bx XSu9C zx&I If ok=0 Then 'cancel button was pressed wd/"! A4( Print "Execution cancelled." l9%oKJ; End k3/V$*i,1b End If ]y3'6! ;LBq! 'Assign accommodation and pupil diameter & use defaults if field left empty Q+O3Wgjy If dlg.TextBox1 = "" Then Dm"@59x A = 0 'Default accommodation m 8Q[+_:$H Else vPV=K+1 A = CDbl(dlg.TextBox1) jG0o-x=X End If W* XG9 ;34 m!\N5 If dlg.TextBox2 = "" Then B^z3u=ll pupilDiam = 4 'Default pupil diameter (mOUbO8 Else Z?vbe}pUM pupilDiam = CDbl(dlg.TextBox2) FK$?8Jp End If s5s'$|h" g]=w_ Print " " \eD{bD Print "Accommodation = " & A & " Diopters" Y+k)d^6r Print "Pupil Diameter = " & pupilDiam & " mm" SLa\F 9K>$ ' Calculate new parameters with accommodation 5df~] -=0Y taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness xJvM
l`2; !;YmLJk;hN Rant = 12.0 - 0.4*A 'Radius of anterior lens *
7ki$f! CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens A&$oiLc f2sv$#' Rpost = -5.224557 + 0.2*A 'Radius of posterior lens l>i<J1 CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens {jOCz1J /A U&
X tlens = 3.767 + 0.04*A 'Lens thickness Y6|8;2E l%aiG+z%6} nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction Ol,Tw=? X0=#e54 'Adjust parameters to account for accommodation a!1\,. 24TQl<H{ '************************************************************************* m17H#!` 'Aqueous thickness (Position of Lens) F+Qp
mVU '************************************************************************* _?M71>3$. eID = FindFullName( "Geometry.Arizona Eye.Lens" ) g,5r)FU` GetCustomElement eID, entity F 8\nAX (z}q6Lfa parID = FindFullName( "Geometry.Arizona Eye" ) Y5}<7s\UDO 7*e7P[LQU ' Delete any shift(s) in z vwZrvjP2 count = 0 ;NrN#<j(! While GetOperationCount(eID)>count UIUCj8QJg GetOperation eID, count, op k{/2vV[`] If op.Type="ShiftZ" Then 'V reO52 DeleteOperation eID,count H0Q.; !^ count=count-1 Rw$>()}H8 End If \X5>HPB count=count+1 3Z* ' Wend k!gft'iU 7|A9 'Set new shift in SBBDlr^P op.Type = "ShiftZ" kKV`9&dZe op.val1 = taq Rh7unJ op.parent = parID VO|2 AddOperation eID, op -saisH6 Print "Set aqueous humor thickness = " & taq-0.55 ;%r#pv~ k%iZ.. '************************************************************************* 1C [j:Ly/ 'Radius and conic constant of anterior lens DwXzmp[qWH '************************************************************************* *5DOTWos eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) $7{| GetConic eID, entity, curv, conic 7l"N%e TI{W(2O * SetConic eID, entity, 1/Rant, CCant rrGsam\. Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant V9:h4] \;w+_<zE5{ '************************************************************************* .".xNHR# 'Radius and conic constant of posterior lens 'Ldlo+*|5 '************************************************************************* \de824 eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) Zy BN o] GetConic eID, entity, curv, conic 2QUZAV\ Y iyw"|+ SetConic eID, entity, 1/Rpost, CCpost Is~bA_-
; Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost p?OwcMT]M q' };.tv '************************************************************************* mOj6
4}_`" 'Lens thickness (Position of posterior lens surface) 8U8l
5r '************************************************************************* VXforI =W1`FbR parID = FindFullName( "Geometry.Arizona Eye.Lens" ) T<*i($
[ VmLV:"P}^ ' Delete any z-shift(s) Py$*c count = 0 2.=3:q!H<% While GetOperationCount(eID)>count @ \ip?= GetOperation eID, count, op =4z:Df If op.Type="ShiftZ" Then KsM2?aqwf_ DeleteOperation eID,count S$q:hXZ#e count=count-1 g:/l5~b End If .aWEXJ count=count+1 sidSY8j Wend ' bio:1 OczVOb bS 'Set new z-shift ^E&':6( op.Type = "ShiftZ" ShAI6j op.val1 = tlens eR.ucTji op.parent = parID MIPmsEdBi AddOperation eID, op Yr@)W~ Print "Set lens thickness = " & tlens >jjuWO3T k36%n
*4 '************************************************************************* /[YH
W] 'Lens index of refraction T)Byws '*************************************************************************
^|DI9G(Bs eID = FindMaterial( "Lens" ) tp2CMJc{L GetModelMaterial eID, mat {l=! V.PbAN mat.Nd = nlens "WOY`su> SetModelMaterial eID, mat CLI!( 8ZW Print "Set lens index of refraction = " & nlens o.DT`L8 vKppXm1 '************************************************************************* pX
]K- 'Pupil diameter s$e0;C!D '************************************************************************* U@v=q9'W eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) x0wy3+GZc gio'_X 'Adjust pupil diameter (trimming volume inner hole) cF_hU" :70cOt~Z SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" w~>V2u_- O#Ab1FQn ' Adjust pupil location to just in front of the lens jj8AV lN parID = FindFullName( "Geometry.Arizona Eye" ) ot P7;l eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) _@0>yMZ^ count = 0 T!eb=oy While GetOperationCount(eID)>count j;eR9jI$T GetOperation eID, count, op z8+3/jLN0B If op.Type="ShiftZ" Then qy6zHw DeleteOperation eID,count NZ`W`#{ count=count-1 u=
(
kii=/ End If HgY"nrogt$ count=count+1 )|f!}( p Wend @~Z:W<X op.Type = "ShiftZ" A<.`HCv2 op.val1 = taq-0.01 jvn:W{'Q op.parent = parID }~$zdgMT AddOperation eID, op uN V(r" ;1K[N0xE Print "Set pupil diameter = " & pupilDiam 2F+K( y8jk9Tv 'Update AZ Eye subassembly Description FQSepUl eID = FindFullName( "Geometry.Arizona Eye" ) Kr`Cr5v GetEntity eID, entity B@dA?w.x entity.Description = "Accommodation = " & A & "D" cMxTv4|wui SetEntity eID, entity *b9=&:pU( G&MI@Hq Update T:S+Pt~ Print "DONE!" U.UN=uv_ h_L-M}{OG End Sub +K2jYgy "Q;n-fqf 如果屈光度是4,光瞳直径是4,则会输出如下数据: xS]=WO* [#V?]P\uV Accommodation = 4 Diopters =rcqYPul0 Pupil Diameter = 4 mm ai[st+1 Set aqueous humor thickness = 2.81 4Y8/>uL Set anterior lens radius = 10.4 and conic constant = -2.375869 /,A:HM>B Set posterior lens radius = -4.424557 and conic constant = -3.081019 rWEJCFa Set lens thickness = 3.927 EX UjdJs" Set lens index of refraction = 1.42672 iqURlI);P Set pupil diameter = 4 ziCTvT DONE! jI!}}K)d
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