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简介 _7>$'V{ ;:Q 5?zM 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。 p_S8m|% hW[/{2<@ 模型 WbC|2! mMm_=cfv 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。 =8S*t5 Xk%92Pto Table 1. AZ眼睛模型的定义 So?SBh1C 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. $},Y)"mI @mBZu!, 光源 GFasGHAw ;rWgt!l 多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 <CIJg* mw%do&e {aP5Mem 图1. 光源和提示信息使用 b=v 除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处,并增加了pre-propagation distance= -8。尽管光线在光瞳处创建,规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射,而不是在光瞳处入射。 z><=F,W K.c6n,' 在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 22S4q`j o@j]yA.5) 图2. 字母F光源的设定方法光 ^l|{*oj2 @ qWgokf 图3. 字母F在视网膜上位置点列图 ocBfs^ aW 视网膜的散射 3a #2 } +@[T0cXp 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 nsFOtOdd 4hdxqI!y2 :4s{?IY)l 图4. 视网膜朗伯散射设定 {pMbkAQ@ 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 f.acH]p (&R/ns~
fH?e9E4l 图5. 视网膜重点采样规格设定 aP^,@RrL 脚本 Y`jvza% t%Hg8oya 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: 89T xd9X -b+VzVJZ 图6. 用户对话框的创建与编辑 ,K=\Y9l3 图7. 用户对话框编辑器 >aXyi3B 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 U 2am1} 余下的脚本计算与屈光度有关的所有参数。 *4#)or ?t++IEoP 分析 nN1\ PjZsMHW% 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 JVbR5"+. /NfuR$oMd 图7. 字母F在视网膜上颜色分析 h`n,:Y^++P 脚本代码 m`
^o<V& =W'a6)WE Option Explicit 'Remove this to enable non-dimensioned variables to be used. *TQXE:vZ[ 1'DD9d{qN Dim entity As T_ENTITY "L^]a$& Dim op As T_OPERATION 9TRS#iVL+* Dim mat As T_MODELMATERIAL l&l&eOE Dim A As Double NrH2U Jm Dim pupilDiam As Double yJ*`OU# Dim eID As Long d_s=5+Yj Dim parID As Long ApHs`0=( Dim count As Integer {`,dWjy{% Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double i]&C=X Dim tlens As Double, nlens As Double 5%,5Xe4p Dim curv As Double, conic As Double $SAq/VHI1] Dim ok As Long dbM~41C6 J'c]':U Sub Main AjBwj5K B1)gudP` '用户输入对话框 ?'ID7mL Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 "D#+:ix8G| TextBox 220,21,40,21,.TextBox1 'default: 0 {FRUB(68b Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 |Iei!jm OKButton 40,91,90,21 ~I[Z2&I CancelButton 190,91,90,21 q6DuLFatc* Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 278:5yC TextBox 220,49,40,21,.TextBox2 'default: 4 iAD'MB End Dialog D2N| A Dim dlg As UserDialog u^.7zL+ | 4/'~cYV ok = Dialog (dlg) ~q]@Jp @@~OA>^ If ok=0 Then 'cancel button was pressed N$>.V7H& Print "Execution cancelled." >g7}JI& End r}351S5( End If /+^7lQo\] eC`} oEz 'Assign accommodation and pupil diameter & use defaults if field left empty '}#=I 9=ss If dlg.TextBox1 = "" Then kaM=Fk=t A = 0 'Default accommodation %N5gQXg Else fz/Ee1T\ A = CDbl(dlg.TextBox1) C\"nlNKw End If iF]G$@rbU Do1 Ip&X If dlg.TextBox2 = "" Then a#3+PB# pupilDiam = 4 'Default pupil diameter <Y%km[Mh Else {"{kWbXZ pupilDiam = CDbl(dlg.TextBox2) "&h{+DHS End If '-9B`O,& "^M/iv( Print " " ]q!,onJ Print "Accommodation = " & A & " Diopters" xvo""R/g8 Print "Pupil Diameter = " & pupilDiam & " mm" \S#Mc 581Jp'cje ' Calculate new parameters with accommodation %L;z ~C taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness h8Wv t's &CP0T:h Rant = 12.0 - 0.4*A 'Radius of anterior lens o[=h=&@5p CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens K4w %XVaH FPAy.cljJ Rpost = -5.224557 + 0.2*A 'Radius of posterior lens I*h%e,yIO CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens %3p~5jhm1 >O0z+tj tlens = 3.767 + 0.04*A 'Lens thickness 2rxZN\gyL nsf.wHGZ"J nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction sKE7U>mz| Ml-GAkgG 'Adjust parameters to account for accommodation .`w[A _#f+@)vR '************************************************************************* X8(H#Ef[ 'Aqueous thickness (Position of Lens) cf\PG&S '************************************************************************* vP k\b 3E eID = FindFullName( "Geometry.Arizona Eye.Lens" ) YoC{ t&rY GetCustomElement eID, entity h\qQ%|X 6f=,$:S$ parID = FindFullName( "Geometry.Arizona Eye" ) .kbo]P R0yPmh,{ ' Delete any shift(s) in z ]IF
QD count = 0 ?HD
eiJkX While GetOperationCount(eID)>count TNi4H:\ GetOperation eID, count, op A=N &(k If op.Type="ShiftZ" Then 8]G DeleteOperation eID,count ~Qg:_ @@\ count=count-1 <H; z4 End If tccw0 count=count+1 W#|30RU.G Wend LgG7|\(- F+!w[}0 'Set new shift in L>trLD1pt op.Type = "ShiftZ" R=7,F6. op.val1 = taq adCTo op.parent = parID *8I+D>x AddOperation eID, op B|fh 4FNy Print "Set aqueous humor thickness = " & taq-0.55 )Z/L &XvSAw+D@ '************************************************************************* AiF'*!1 'Radius and conic constant of anterior lens N~=,RPjq '************************************************************************* jH5VrN*Q eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) N}|<P[LW GetConic eID, entity, curv, conic /JcfAY \`kH2` SetConic eID, entity, 1/Rant, CCant pxGDzU Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant -(oFO'Lbg t[r<&1[& '************************************************************************* "Y1]6
Zu 'Radius and conic constant of posterior lens k vuSE '************************************************************************* ^i"~6QYE eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) :m&cm%W]ts GetConic eID, entity, curv, conic xr*%:TwCta SlaHhq3 SetConic eID, entity, 1/Rpost, CCpost ~10 >mg Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost (GCe D- W{El^')F '************************************************************************* ;q"Yz-3 'Lens thickness (Position of posterior lens surface) Y5/SbQYf1 '************************************************************************* %&Fsk]T%: hx.ln6=4 parID = FindFullName( "Geometry.Arizona Eye.Lens" ) Yl$R$u) xs}3=&c( ' Delete any z-shift(s) |_h$}~; count = 0 @$*LU:[ While GetOperationCount(eID)>count q,Nhfo( GetOperation eID, count, op u4KP;_,m If op.Type="ShiftZ" Then &^7^7:Y=? DeleteOperation eID,count 4Ou5Vp&y count=count-1 S-
N
[ End If \jpm
count=count+1 2{Johqf Wend K*/X{3 J; W2`/z)[*> 'Set new z-shift \/8oua_) op.Type = "ShiftZ" Sb|9U8h op.val1 = tlens au;ZAXM| op.parent = parID o,q47W=7$ AddOperation eID, op vVyX[ZZ Print "Set lens thickness = " & tlens xb (Cd @ L=dcO{r '************************************************************************* ll^#I/ 'Lens index of refraction c $fYK '************************************************************************* xX:N- eID = FindMaterial( "Lens" ) HZl//Uq GetModelMaterial eID, mat 2mt
S\bAF }o d5kK; mat.Nd = nlens FhFP M)[ SetModelMaterial eID, mat ,7/F?!G!J Print "Set lens index of refraction = " & nlens #*tWhXU Vb++K0CK '************************************************************************* F8pP(Wl 'Pupil diameter U3tA"X.K '************************************************************************* 1"fbQ^4` eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) U{Xx)l/o GE!fh1[[u 'Adjust pupil diameter (trimming volume inner hole) "Nh}_jO 7Ap==J{a SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" Q13>z%Rge >"|"Gy ( ' Adjust pupil location to just in front of the lens *>,#'C2 parID = FindFullName( "Geometry.Arizona Eye" ) Z[GeU>?P eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) HxnWM\ p count = 0 .Gcs/PN While GetOperationCount(eID)>count 9NEL[J| GetOperation eID, count, op &57s//PrX If op.Type="ShiftZ" Then k.6gX<T DeleteOperation eID,count +\s&v! count=count-1 2S@aG%-) End If &fRZaq'2R count=count+1 1=Y pNXX Wend TD^w|U. op.Type = "ShiftZ" p->b Vt op.val1 = taq-0.01 ;hZ^zL op.parent = parID N6<G`k, AddOperation eID, op *V[6ta' @3Nvf}He Print "Set pupil diameter = " & pupilDiam ~ \o
hH O!ngQrI 'Update AZ Eye subassembly Description 5~H}%W,P eID = FindFullName( "Geometry.Arizona Eye" ) iji2gWV}h GetEntity eID, entity |HfN<4NL entity.Description = "Accommodation = " & A & "D" I%'6IpR"d SetEntity eID, entity h7
c }pOJ M&I Update i"GCm` Print "DONE!" #Nv)SCc c0.? d] End Sub %Q. |qyq U%4s@{7 如果屈光度是4,光瞳直径是4,则会输出如下数据: XM:Y(#?l 3v,Bg4[i Accommodation = 4 Diopters ?>T ( Pupil Diameter = 4 mm m-AW}1:\f Set aqueous humor thickness = 2.81 ){FXonVP Set anterior lens radius = 10.4 and conic constant = -2.375869 @lu`oyM Set posterior lens radius = -4.424557 and conic constant = -3.081019 LG:Mksd8=4 Set lens thickness = 3.927 MzpDvnI9 Set lens index of refraction = 1.42672 ,cwjieM Set pupil diameter = 4 th]pqhl> DONE! F&)(G\
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