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简介 DVlJ*A ]5'
d&f 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。 DIaYo4 z[C3 模型 a^t?vv Tde0 ~j} 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。 "0CjP+1k ?<U{{C Table 1. AZ眼睛模型的定义 ujr(K=E 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. hIYTe FY'ty@|_s 光源 t
P"\J(x w8Vw1wW 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。 Wh(
|+rJ?Z 3GH(wSv9\ rY0u|8.5Q 图1. 光源和提示信息使用 kL>d"w 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。 2-'Opu CSTI?A"P 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。 9zBMlc$X wW 2d\Zd& 图2. 字母F光源的设定方法光 t*G/] g&Vcg` 图3. 字母F在视网膜上位置点列图 _:g&,2bc 视网膜的散射 k|YWOy@D~ &QNY,Pj 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 VZy4_v=
d$W HYK!}& 图4. 视网膜朗伯散射设定 &fOdlQ? 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。 EH*o"N`!r .8WXC
=1p8i 图5. 视网膜重点采样规格设定 8RW&r 脚本 Q`%R[# L<V3KS2y 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: IA&L] k]A8% z 图6. 用户对话框的创建与编辑 O#a6+W"U 图7. 用户对话框编辑器 D${={x 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。 d[D&J 余下的脚本计算与屈光度有关的所有参数。 N8r*dadDd k S#
CEU7 分析 SOZPZUUEJ !v.9"!' N 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 S=`+Ryc BYrZEVM9 图7. 字母F在视网膜上颜色分析 X-LA}YH=tS 脚本代码 `d]IX^; +|iYg/2 Option Explicit 'Remove this to enable non-dimensioned variables to be used. @f+8%I3D 4mjgt<` Dim entity As T_ENTITY wC_l@7t Dim op As T_OPERATION nl aM Dim mat As T_MODELMATERIAL H9)m^* Dim A As Double M:KbD| Dim pupilDiam As Double b2,mCfLsv Dim eID As Long $2^`Uca Dim parID As Long (>4aibA'P Dim count As Integer 2&PPz}Sw Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double 51C2u)HE Dim tlens As Double, nlens As Double <h).fX Dim curv As Double, conic As Double 3.d"rl Dim ok As Long \c v?^AI 6lwta`2 Sub Main D4Al3fe =]`lN-rYw '用户输入对话框 }v9\F-0>Q Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 w%AcG~`j!B TextBox 220,21,40,21,.TextBox1 'default: 0 T<3BT Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 $
,SF@BhO OKButton 40,91,90,21 | Xi% CancelButton 190,91,90,21 FWue;pw3 Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 %J:SO_6 TextBox 220,49,40,21,.TextBox2 'default: 4 ,;?S\V End Dialog Ji1Pz)fq Dim dlg As UserDialog -oeL{9; *-W#G}O0 ok = Dialog (dlg) T{qTj6I G+xt5n.% If ok=0 Then 'cancel button was pressed {t"+
3zy' Print "Execution cancelled." A[IL
H_w End R[z`:1lo End If <!-sZ_qq ]<(]u#g_d 'Assign accommodation and pupil diameter & use defaults if field left empty ?Xdak|?i If dlg.TextBox1 = "" Then BqDKT A = 0 'Default accommodation 9a\nszwa Else Xs&TJ8a A = CDbl(dlg.TextBox1) MV_Srz End If :j|IP)-f ES~^M840f If dlg.TextBox2 = "" Then NK|? y pupilDiam = 4 'Default pupil diameter nJ4@I7Sk; Else ?
J}r pupilDiam = CDbl(dlg.TextBox2) CQel3Jtt. End If 8[r9HC J
PyOG_h Print " " ,B4VT 96* Print "Accommodation = " & A & " Diopters" }X
GEX:1K Print "Pupil Diameter = " & pupilDiam & " mm" oH0X<' M8H5K ' Calculate new parameters with accommodation JN^&S taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness j!7`] <YA&Dr3OD Rant = 12.0 - 0.4*A 'Radius of anterior lens ,+`61J3W CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens .@
xF6UZ G?f\>QSZ Rpost = -5.224557 + 0.2*A 'Radius of posterior lens 1/p*tZP8i CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens gtUUsQ%y . J=.`wZQkS tlens = 3.767 + 0.04*A 'Lens thickness Rqwzh@} UAR5^ nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction ^[%%r3"$C eC5 $#,HiC 'Adjust parameters to account for accommodation 6wco&7 zF5uN:-s '************************************************************************* 7t,t` 'Aqueous thickness (Position of Lens) 1c JF/"v '************************************************************************* I^o!n5VM eID = FindFullName( "Geometry.Arizona Eye.Lens" ) ikE<=:pe GetCustomElement eID, entity Fnk_\d6Ma n| GaV parID = FindFullName( "Geometry.Arizona Eye" ) Ax !+P\\2~ S+TOSjfis ' Delete any shift(s) in z 4f(Kt,0 count = 0 Vh}SCUof' While GetOperationCount(eID)>count eZ"1gYqy GetOperation eID, count, op FU=w(< R; If op.Type="ShiftZ" Then >0p$(>N] DeleteOperation eID,count qfcYE= count=count-1 GUsl PnG End If }|%eCVB count=count+1 4v[~r1!V Wend [ sd;`xk {'16:dTJ 'Set new shift in }I`a`0/ op.Type = "ShiftZ" [r/k% < op.val1 = taq 5NJ4 op.parent = parID oD}uOC}FS{ AddOperation eID, op vkLC-Mzm< Print "Set aqueous humor thickness = " & taq-0.55 gm9mg*aM r>GZ58i '************************************************************************* xkOpa,=FI 'Radius and conic constant of anterior lens OFje+S '************************************************************************* =@F&o4) r eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) e.c3nKXZ q GetConic eID, entity, curv, conic Zo>]rKeV pLv$\MiZ SetConic eID, entity, 1/Rant, CCant p&VU0[LIC0 Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant Gycm,Cy QRLt9L '************************************************************************* 9'hv%A:\3 'Radius and conic constant of posterior lens |lv|!]qAma '************************************************************************* *.)tG eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) !%dN<%Ah GetConic eID, entity, curv, conic yoAfc
]({~,8s SetConic eID, entity, 1/Rpost, CCpost RmZ]"
` Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost ah~YeJp ax
41N25 '************************************************************************* \c^45<G2qA 'Lens thickness (Position of posterior lens surface) V`@>MOw^d '************************************************************************* gk`zA I@\OaUGr+ parID = FindFullName( "Geometry.Arizona Eye.Lens" ) %/updw#{B Le%ZV%, ' Delete any z-shift(s) pKi& [ count = 0 y!]CJigpZ While GetOperationCount(eID)>count ,]b~t0|B GetOperation eID, count, op 3P;>XGCxZ If op.Type="ShiftZ" Then sUPz/Z.h DeleteOperation eID,count Fv<`AU count=count-1 :T9<der, End If vOg#Dqn- count=count+1 _ 84ut Wend a'\o7_
^eoLAL 'Set new z-shift KF4PJi;* op.Type = "ShiftZ" |r bWYl.b op.val1 = tlens |^@dFOz op.parent = parID 0?>dCu\ AddOperation eID, op `O'`eY1f Print "Set lens thickness = " & tlens P (S>=,Y& NzNA>[$[ '************************************************************************* %w7]@V Z 'Lens index of refraction @gG<le6 '************************************************************************* "*})3['n eID = FindMaterial( "Lens" ) I"KN"v^ GetModelMaterial eID, mat \}]!)}G K(q-?n`< mat.Nd = nlens )aX,% yK SetModelMaterial eID, mat j!3 Gz Print "Set lens index of refraction = " & nlens 1IVuSp`{FU |<O9Sb_ '************************************************************************* 2YDM9`5xs\ 'Pupil diameter a5w:u5 '************************************************************************* uw2hMt (N eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) ;D$)P7k6 zhf.NCSt( 'Adjust pupil diameter (trimming volume inner hole) <vwkjCA` 1T[et- SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" QD%L0;j ]7e =fM9V; ' Adjust pupil location to just in front of the lens uIZWO.OdU parID = FindFullName( "Geometry.Arizona Eye" ) q/n,,! eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) \_B[{e7z count = 0 K#"O
a
h While GetOperationCount(eID)>count 5<w g8y GetOperation eID, count, op L5,NP5RC If op.Type="ShiftZ" Then nR`ov1RH DeleteOperation eID,count '}$Dgp6e count=count-1 QV\eMuNy End If aE2.L;Tk? count=count+1 NQ6sGL Wend NC38fiH_N op.Type = "ShiftZ" >;[*!<pfK5 op.val1 = taq-0.01 {D=@n4JO op.parent = parID I(XOE$3 AddOperation eID, op AF%@VLf L`24?Y{ Print "Set pupil diameter = " & pupilDiam ^#sU*trr o]opdw 'Update AZ Eye subassembly Description pxa( eID = FindFullName( "Geometry.Arizona Eye" ) s;A@*Y;v GetEntity eID, entity KRA/MQ^7~U entity.Description = "Accommodation = " & A & "D" k5T,990 SetEntity eID, entity MNV%
=G Gn&4V}F Update hodgDrmO/ Print "DONE!" X*\J_ }+sT4'Ah> End Sub )vSRHE S;-
LIv 如果屈光度是4,光瞳直径是4,则会输出如下数据: L+i(TM= 9th,VnD0 Accommodation = 4 Diopters pfI"36]F Pupil Diameter = 4 mm aca=yDs2 Set aqueous humor thickness = 2.81 3p'I5,} Set anterior lens radius = 10.4 and conic constant = -2.375869 GI1 Set posterior lens radius = -4.424557 and conic constant = -3.081019 1.6:# Set lens thickness = 3.927 {yExQbN Set lens index of refraction = 1.42672 hzvd t Set pupil diameter = 4 <Sr DONE! f=9|b
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