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简介 }s)Z:6;(,q VqbiZOZ@ 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。 S;t~"87v* >^ Y9p~ 模型 >)N#n` qnA:[H;F 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。 ;m5M:Z" iF%q6R Table 1. AZ眼睛模型的定义 ]!A;-m 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. ^M80 F 7 hCDI;'ls 光源 VLO>{"{' 8odVdivh 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。 nuC K7X \;?\@vo< <pE G8_{} 图1. 光源和提示信息使用 G`
8j ^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。 t]` 2f3UO 0)/214^& 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。 )F~_KD)7jJ gRFC n6Q 图2. 字母F光源的设定方法光 Ym6ec|9; H 0h 图3. 字母F在视网膜上位置点列图 hD,-!R 视网膜的散射 $?s^HKF~ [qXpi'q[ 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 ?UxY4m%R; T9$U./69-L 9F-k:hD | 图4. 视网膜朗伯散射设定 h49Q2` 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。 $e_ps~{7$ \8$`:3,@ )s8r(.W 图5. 视网膜重点采样规格设定 H|!s. 脚本 [yyV`& vr vzV 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: yjr@v!o a(7ryl~c= 图6. 用户对话框的创建与编辑 NV gLq@F 图7. 用户对话框编辑器 };j&)M 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 Z\L@5.*ydE 余下的脚本计算与屈光度有关的所有参数。 Lg?'1dg `u}x:f ! 分析 k|_2aQ02 Om^/tp\ 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 7X|r';"?i
j{^(TE 图7. 字母F在视网膜上颜色分析 d"78:+ 脚本代码 HDEG/k/~m 9,W-KM Option Explicit 'Remove this to enable non-dimensioned variables to be used. K$.zO4 md`ToU Dim entity As T_ENTITY :qbG%_PJ Dim op As T_OPERATION yRYWx` G Dim mat As T_MODELMATERIAL X2`>@GR/> Dim A As Double P&GZe/6Y Dim pupilDiam As Double -b$OHFL Dim eID As Long caP Dim parID As Long |FFC8R%@]u Dim count As Integer d.AjH9 jg Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double (*ng$zZ$ Dim tlens As Double, nlens As Double E1C_d' Dim curv As Double, conic As Double LC{hoq\ Dim ok As Long sV<4^n7 Fjzk;o Sub Main @r ?`:&m0 /)1-^ju '用户输入对话框 5avO48;Vc Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 4I*Mc%dD TextBox 220,21,40,21,.TextBox1 'default: 0 Lm|X5RVq Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 qJA.+q.e$e OKButton 40,91,90,21 sJoi fl
7 CancelButton 190,91,90,21 !cb#fl Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 50&F#v%YB TextBox 220,49,40,21,.TextBox2 'default: 4 ~N9-an End Dialog 6\;1<Sw* Dim dlg As UserDialog YZl%JX ^rwSbM$ ok = Dialog (dlg) _w;+Jh dLf8w>i`T If ok=0 Then 'cancel button was pressed fO^6q1a Print "Execution cancelled." Bx-,"Z \ End Aa>gN End If MPbPq3an 'I]"=O, 'Assign accommodation and pupil diameter & use defaults if field left empty 3.X0!M;x If dlg.TextBox1 = "" Then =on!&M A = 0 'Default accommodation Td*Oljj._U Else sK0VT"7K A = CDbl(dlg.TextBox1) ?MM3LA! < End If Fz&ilB Qiw4'xQm If dlg.TextBox2 = "" Then v4_OUA>z, pupilDiam = 4 'Default pupil diameter yrAzD= Else "5:f{GfO#v pupilDiam = CDbl(dlg.TextBox2) k{jw%a<Sc End If 4QAIQQS V1)P=?%(US Print " " /dt!J
`: Print "Accommodation = " & A & " Diopters" VtiqAh}4 Print "Pupil Diameter = " & pupilDiam & " mm" %J7mZB9 b0Ov+ )7# ' Calculate new parameters with accommodation !`[I>:Ex taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness ]A$^ l, Lzx$"R- Rant = 12.0 - 0.4*A 'Radius of anterior lens I<./(X[H:# CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens +esNwz_ 5w)^~#' Rpost = -5.224557 + 0.2*A 'Radius of posterior lens ~e77w\Q0 CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens Nu/Qa:H_{ 07Q[L'}y@ tlens = 3.767 + 0.04*A 'Lens thickness N5s|a5 IXvz&4VD nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction gkML .u ef}E.Bl 'Adjust parameters to account for accommodation 5A$az03y$\ ?lDcaI>+n '************************************************************************* *rcuhw"^b# 'Aqueous thickness (Position of Lens) 8@yc}~8 * '************************************************************************* >xV<nLf/ eID = FindFullName( "Geometry.Arizona Eye.Lens" ) /~l/_Jct@G GetCustomElement eID, entity 8o7]XZE=) e=o{Zo?H= parID = FindFullName( "Geometry.Arizona Eye" ) >'-w%H/ >Ug?O~- ' Delete any shift(s) in z j%Z{.>mJ count = 0 _8b]o~[Z+ While GetOperationCount(eID)>count XDdcq ]*| GetOperation eID, count, op s i"` If op.Type="ShiftZ" Then 'CX.qxF1;p DeleteOperation eID,count (Ef2
w[' count=count-1 w$lfR, End If Uk*;C count=count+1 m/hi~.D9 Wend 8jjk?PUD8 KtUGI.X 'Set new shift in j&[.2PW\ op.Type = "ShiftZ" q"+ q op.val1 = taq HM@}!6/s op.parent = parID 1%hM8:)i_ AddOperation eID, op ra%R:xX Print "Set aqueous humor thickness = " & taq-0.55 co^P7+j ?$J7%I@ '************************************************************************* !*?(Q6 'Radius and conic constant of anterior lens d@6:|auO '************************************************************************* 2&gVZ z eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 9U7Mu;4 GetConic eID, entity, curv, conic 85%Pq:E &=z1$ih>2\ SetConic eID, entity, 1/Rant, CCant _7=pw5[ Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant yxC Ml. fsrg2:kQ '************************************************************************* loeLj4"" 'Radius and conic constant of posterior lens t ?9;cS4 '************************************************************************* BK(pJNBh eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) A&|Wvb= GetConic eID, entity, curv, conic hnsa)@ =nvAOvP{? SetConic eID, entity, 1/Rpost, CCpost @cu}3> Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost tB ,. !$p2z_n$@. '************************************************************************* of+phMev 'Lens thickness (Position of posterior lens surface) u+z .J4w '************************************************************************* kJurUDo XWUvP parID = FindFullName( "Geometry.Arizona Eye.Lens" ) v?YdLR cXb
@H# ' Delete any z-shift(s) }_a+X count = 0 hy$MV3LP While GetOperationCount(eID)>count c#{Ywh GetOperation eID, count, op {+C %D' If op.Type="ShiftZ" Then `R=a@DQ DeleteOperation eID,count 23}BW_m count=count-1 28T\@zi End If YQ 8j count=count+1 ~T>jBYI0 Wend nr<WO~Xw~ W(uP`M%][0 'Set new z-shift VY+(,\)U op.Type = "ShiftZ" x{NNx:T1 op.val1 = tlens ><;l:RGK| op.parent = parID A*7Io4e! AddOperation eID, op W{fULl Print "Set lens thickness = " & tlens ).0V%}> ="3a%\ '************************************************************************* v Q-ixh 'Lens index of refraction %_B:EMPd '************************************************************************* _`bS[%CJ eID = FindMaterial( "Lens" ) {B FT GetModelMaterial eID, mat JqI6k6~Q^ IF&g.R mat.Nd = nlens Sni&?tcY SetModelMaterial eID, mat >]Mq)V9 Print "Set lens index of refraction = " & nlens ; g Z%U [;(]Jy '************************************************************************* T&9`?QD 'Pupil diameter ps"/}u l '************************************************************************* O"
%Hprx eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) 8_xnWMOe {PN:bb 'Adjust pupil diameter (trimming volume inner hole) Dk)@>l:gI, 5Y(r\Dd SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" !Oeq
G )8pcf`h{ ' Adjust pupil location to just in front of the lens b%Wd<N2 parID = FindFullName( "Geometry.Arizona Eye" ) JQ*D eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) tO?21?AD D count = 0 reJ"r<2
While GetOperationCount(eID)>count 7<h.KZPc GetOperation eID, count, op kx|me~I
If op.Type="ShiftZ" Then yB-.sGu DeleteOperation eID,count 84iJ[Fq{ count=count-1 [X;>*- End If X3P&"}a count=count+1 R<Z^L~) Wend |if'_x1V op.Type = "ShiftZ" jmkRP"ZnA op.val1 = taq-0.01 3H1Pp*PH op.parent = parID y7CWBTH0> AddOperation eID, op 8ou e-:/a CXBzX:T?# Print "Set pupil diameter = " & pupilDiam OZG0AX+=# e &d3SQ% 'Update AZ Eye subassembly Description Kn']n91m eID = FindFullName( "Geometry.Arizona Eye" ) pp(H
PKs=} GetEntity eID, entity 2*+3RrJ entity.Description = "Accommodation = " & A & "D" 6H0W`S0a SetEntity eID, entity Gu2_dT 7nm}fT
z7 Update O4T'o. Print "DONE!" mRCHrw?WG d{W}p~UbH End Sub [u[ U_g* GOGt?iw*< 如果屈光度是4,光瞳直径是4,则会输出如下数据: L*P_vCC W3^.5I Accommodation = 4 Diopters _Aa[?2 O Pupil Diameter = 4 mm ,NDh@VYe Set aqueous humor thickness = 2.81 |Z
d]=tue Set anterior lens radius = 10.4 and conic constant = -2.375869 G OpjRA@ Set posterior lens radius = -4.424557 and conic constant = -3.081019 fVYiwE=F Set lens thickness = 3.927 d5Qd' Set lens index of refraction = 1.42672 T0r<O_ubOA Set pupil diameter = 4 kg:l:C)Tq DONE! UIn^_}jF`
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