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简介 }#Iqq9[ A{T>Aac 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。 p6)6Gcx *"6A>:rQs 模型 5LU7}v~/
fD8GAav 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。 $?VYHkX U2~|AkL Table 1. AZ眼睛模型的定义 hewc5vrL 在FRED中使用0屈光度来创建的,光瞳加在了透镜的前面。材料是创建一个新的材料并选择类型“Model Material”,输入的参数是nd和vd. "GJ.`Hj vBM<M3 光源 PpNG`_O 1|>bG#| 多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 +JXn /rK/l YhooD,[. 图1. 光源和提示信息使用 !|9k&o 除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处,并增加了pre-propagation distance= -8。尽管光线在光瞳处创建,规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射,而不是在光瞳处入射。 f'`y-]"V5) -rHqU| 在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 {!wd5C@ )|5mW 图2. 字母F光源的设定方法光 I?%#`Rvu /5
OQ0{8p 图3. 字母F在视网膜上位置点列图 i1]}Q$ 视网膜的散射 bX5/xf$q AXnKhYlu 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 - ku8n%u I).eQ8: Ywcgt| 图4. 视网膜朗伯散射设定 Z *v`kl 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 |Vu`-L'Jz iuM ,aF C8}=fa3u 图5. 视网膜重点采样规格设定 /7Q9(} 脚本 oJ#;X R rg]z 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: Eq8:[o J%!vhQ 图6. 用户对话框的创建与编辑 89P7iSV#* 图7. 用户对话框编辑器 5a2;@}%V 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 ygK,t*T20 余下的脚本计算与屈光度有关的所有参数。 xf|C{XV@H %/!f^PIwX 分析 A,7* 52U !2/o]_K@+ 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 lACS^( BgB0 图7. 字母F在视网膜上颜色分析 w7\
\m9 脚本代码 9PaV*S(\TR 3J3wKw!` Option Explicit 'Remove this to enable non-dimensioned variables to be used. _U,Hi?b"$} Q]dKyMSSA Dim entity As T_ENTITY y"K[#&,0 Dim op As T_OPERATION li#ep?5h^ Dim mat As T_MODELMATERIAL y`7b3*P Dim A As Double G1I<B Dim pupilDiam As Double SWT)M1O2 Dim eID As Long '?3(& Dim parID As Long Zl.,pcL Dim count As Integer S]4!uv^y Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double wawJZ+V Dim tlens As Double, nlens As Double gXY]NWI Dim curv As Double, conic As Double kp6 &e Dim ok As Long Ksk[sf?J& f/m0,EERk Sub Main '=Acg"aT 7dR]$~+*e '用户输入对话框 X'xnJtk Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 e YiqT Wn: TextBox 220,21,40,21,.TextBox1 'default: 0 ~{{7y]3M- Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 Ldy(<cN OKButton 40,91,90,21 c;n\HYk CancelButton 190,91,90,21 _d>{Hz2 Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 ^t`0ul]c TextBox 220,49,40,21,.TextBox2 'default: 4 X3~@U7DU End Dialog /7ykmW Dim dlg As UserDialog L_M(Lj 9j0o)] ok = Dialog (dlg) crgVedx~} V~$?]Z %_ If ok=0 Then 'cancel button was pressed /#?!9c Print "Execution cancelled." fd&>p End u!t<2`:h End If L9!\\U wb39s^n 'Assign accommodation and pupil diameter & use defaults if field left empty xE*.,:,& If dlg.TextBox1 = "" Then EbJc%%c A = 0 'Default accommodation xgvwH?< Else Q+O./1x*, A = CDbl(dlg.TextBox1) z0&Y_Up+5 End If Ve xxdg x((Rm_' If dlg.TextBox2 = "" Then *0_Q0SeE,o pupilDiam = 4 'Default pupil diameter LYyud Else 4MCj*ok< pupilDiam = CDbl(dlg.TextBox2) iAt&927 End If CbOCL~ " ~*e@^Nv)v Print " " _KZTY`/* Print "Accommodation = " & A & " Diopters" WM
]eb, 8q Print "Pupil Diameter = " & pupilDiam & " mm" !1
Y[e^ YU\k D ' Calculate new parameters with accommodation Sf2xI' taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness v]}\Ns/ _s}`ohKvD Rant = 12.0 - 0.4*A 'Radius of anterior lens q RRvZhf CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens :*YnH& x
}]"jj2x Rpost = -5.224557 + 0.2*A 'Radius of posterior lens |3`8$- CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens VL|Z+3L @E>I<j,D tlens = 3.767 + 0.04*A 'Lens thickness Mt@Ma ]! !.499H3 nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction MHA_b^7? 2AEVBkF;M 'Adjust parameters to account for accommodation FB
%-$ F?qg?1vB| '************************************************************************* _ne
r 'Aqueous thickness (Position of Lens) DHZ`y[&}|N '************************************************************************* ZVrZkd` eID = FindFullName( "Geometry.Arizona Eye.Lens" ) |OuIQhoE GetCustomElement eID, entity lAkg47i /<Z3x
_c parID = FindFullName( "Geometry.Arizona Eye" ) e`Co =' sD|}?7 ' Delete any shift(s) in z cM]ZYi count = 0 e$&n)>% While GetOperationCount(eID)>count )4>7X)j> GetOperation eID, count, op {]$ )dz5 If op.Type="ShiftZ" Then #5iy^?N"w DeleteOperation eID,count Kq(JHB+ count=count-1 B&<P >AZ End If DcE4r>8B count=count+1 JEF ;Q Wend $#(j2sL1 k *>"@ 'Set new shift in D
,[yx=' op.Type = "ShiftZ" 9_ZGb"(Lj op.val1 = taq D0>Pc9 op.parent = parID }'K-1: AddOperation eID, op -aV(6i*n Print "Set aqueous humor thickness = " & taq-0.55 #w:nj1{_ "=V!-+*@G@ '************************************************************************* >*Ej2ex 'Radius and conic constant of anterior lens Eu%E2A|`I '************************************************************************* UD9JE S, eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) v8n^~=SH GetConic eID, entity, curv, conic N|3#pHm@ l=x(
SetConic eID, entity, 1/Rant, CCant M+b?qw Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant /Z[HU{4 X#zp,7j? '************************************************************************* T6."j_ 'Radius and conic constant of posterior lens cIcu=U '************************************************************************* ^;tB,7:*V eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) WdB\n/BWB GetConic eID, entity, curv, conic i1'G_bo4F7 oxdX2"WwU SetConic eID, entity, 1/Rpost, CCpost Nr).*]g@~ Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost LF#[$
so{i d8U<V<H< '************************************************************************* h4+*ssnYV 'Lens thickness (Position of posterior lens surface) 5=%KK3 '************************************************************************* {'z$5<| 7|GSs= parID = FindFullName( "Geometry.Arizona Eye.Lens" ) p#_5w X{<taD2~ ' Delete any z-shift(s) hljKBx~ count = 0 7_jlNr7uk While GetOperationCount(eID)>count :,g]Om^ GetOperation eID, count, op 29m$S7[ If op.Type="ShiftZ" Then Eggu-i(rD DeleteOperation eID,count f1;@a>X
count=count-1 "_&c[VptWi End If @#$(Cs*{] count=count+1 e8#83|h Wend M{)&SNI*C s|`wi}"x 'Set new z-shift 7upWM~H^ op.Type = "ShiftZ" W/}_ y8q op.val1 = tlens +\)Y,@cw op.parent = parID gNc;P[ AddOperation eID, op Nh}u]<B Print "Set lens thickness = " & tlens |lZp5MOc L]u^$=rI '************************************************************************* &Yc'X+'4 'Lens index of refraction =p"ma83 '************************************************************************* _zi| GD eID = FindMaterial( "Lens" ) &U7h9o H GetModelMaterial eID, mat sriDta?Cz j>uu3ADd2 mat.Nd = nlens ek]nLN SetModelMaterial eID, mat V|[NL4 Print "Set lens index of refraction = " & nlens s@{~8cHgU _[-W*,xJ) '************************************************************************* xSNGf@1b 'Pupil diameter K=nDC. '************************************************************************* 2eA.04F eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) pnyu&@e 'W>y v 'Adjust pupil diameter (trimming volume inner hole) S^|U" oveK;\7/m SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" SbzJeaZv RA;/ ?l ' Adjust pupil location to just in front of the lens [t$ r)vX parID = FindFullName( "Geometry.Arizona Eye" ) .Eb]}8/}E eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) R/*"N'nH-% count = 0 ';My"/
Z- While GetOperationCount(eID)>count j"aY\cLr t GetOperation eID, count, op BV
}CmU&DA If op.Type="ShiftZ" Then E_DQ.!U!o DeleteOperation eID,count c:&8B/ count=count-1 &q9=0So4\ End If } .Z` count=count+1 t|hc`| Wend 5E1`qof op.Type = "ShiftZ" *Uj;a. op.val1 = taq-0.01 :#35mBe}k op.parent = parID %KkC1.yu< AddOperation eID, op G2?#MO `j9\]50Z> Print "Set pupil diameter = " & pupilDiam }!R*Q`m R!
On 'Update AZ Eye subassembly Description Y:L[Iz95o eID = FindFullName( "Geometry.Arizona Eye" ) _cj=}!I GetEntity eID, entity _ DT,iF*6 entity.Description = "Accommodation = " & A & "D" DR:DXJc SetEntity eID, entity G5K?Q+n
.{*l, Update (GC5r#AnS Print "DONE!" ,(zV~-:9 2f@Cy+W'[ End Sub 8ih_S2Cd Ui" {0% 如果屈光度是4,光瞳直径是4,则会输出如下数据: N6\rjYx+7 h6^|f%\w*i Accommodation = 4 Diopters 9H/R@i[E Pupil Diameter = 4 mm |iX>hJSl Set aqueous humor thickness = 2.81 dcD#!v\0 Set anterior lens radius = 10.4 and conic constant = -2.375869 D4|Ajeo;1 Set posterior lens radius = -4.424557 and conic constant = -3.081019 ]+3M\ ib Set lens thickness = 3.927 7aKI=;60. Set lens index of refraction = 1.42672 ge.>#1f} Set pupil diameter = 4 \k`9s
q DONE! 6$=>ck P
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