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简介 gbM#jhQ EAp6IhW{ 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。 RekTWIspT/ nk9Kq\2f: 模型 S#dkJu]]# g
nJe!E 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。 J6/Mm7R J:Uf}!D Table 1. AZ眼睛模型的定义 'F^nW_ryW 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. S',i S/v+7oT 光源 7$x~}*u q}*"0r 多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 Fy5xIRyI\F (-DA% t=J\zyX! 图1. 光源和提示信息使用 fg"@qE-; 除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处,并增加了pre-propagation distance= -8。尽管光线在光瞳处创建,规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射,而不是在光瞳处入射。 ZvEcExA- z|[#6X6tT 在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 S3]Cz$ TDXLxoC? 图2. 字母F光源的设定方法光 _;",7bT80 Rq~\Yf+Pm 图3. 字母F在视网膜上位置点列图 =cE:,z;g 视网膜的散射 8WK%g0gm FCTz>N^p 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。 gBz$RfyF bs$x%CR @@K@;Jox 图4. 视网膜朗伯散射设定 _,(]T&j #2 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。 ^l;nBD#nJ K[Bq,nPo Yf
>SV # 图5. 视网膜重点采样规格设定 cMOvM0f 脚本 3>qUYxG8 R?!xO-^t 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: 5"xZ'M~= &n+3^JNl 图6. 用户对话框的创建与编辑 FDM&rQ 图7. 用户对话框编辑器 B8-v!4b0` 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。 zvB!= 余下的脚本计算与屈光度有关的所有参数。 J8I_tF6 zq-"jpZG 分析 qG3 [5lti t]LCe\# 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 x"h0Fe?J r1&b#r>
图7. 字母F在视网膜上颜色分析 0:UK)t)3I 脚本代码 D(xgadr wOQ-sp0q0 Option Explicit 'Remove this to enable non-dimensioned variables to be used. HVaWv ]. R>H*MvN Dim entity As T_ENTITY QxCZ<| Dim op As T_OPERATION D ODo
! Dim mat As T_MODELMATERIAL 0.S].Y[ Dim A As Double |1J=wp)# Dim pupilDiam As Double d
(]t} Dim eID As Long .kh%66: Dim parID As Long e:}8|e~T Dim count As Integer E15"AO Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double JmdXh/X Dim tlens As Double, nlens As Double c7T9kV8hS Dim curv As Double, conic As Double (UmoG Dim ok As Long %:^,7
.H@ bf2R15|t5` Sub Main g/,fjM_ >ijFQ667>j '用户输入对话框 M"[s5=:Lo Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 OQ"%(w>Hb TextBox 220,21,40,21,.TextBox1 'default: 0 :Z(?Ct&8 Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 d!/@+i OKButton 40,91,90,21 mN3}wJ}J CancelButton 190,91,90,21 x bF*4;^SI Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 [o8a(oC TextBox 220,49,40,21,.TextBox2 'default: 4 jq(3y|6, End Dialog OD<0,r0f, Dim dlg As UserDialog HH+R47%* 2%\Nq:;T ok = Dialog (dlg) ZxkX\gl91 @!6eRp>Z If ok=0 Then 'cancel button was pressed {H s""/sb Print "Execution cancelled." k7P~*ll$ End 6W$ #`N> End If <$Q\vCR )3v0ex@Jl 'Assign accommodation and pupil diameter & use defaults if field left empty @
fm\
H If dlg.TextBox1 = "" Then B[7|]"L@ A = 0 'Default accommodation j{N;2#.u Else P;0tI; A = CDbl(dlg.TextBox1) t ]{qizfOB End If ~LGkc
t hKjvD.6]% If dlg.TextBox2 = "" Then B'6^E#9 pupilDiam = 4 'Default pupil diameter b1{~j]"$L Else J'^s5hxn+0 pupilDiam = CDbl(dlg.TextBox2) dj4 g End If _i~n!v ,pir,Eozg Print " " HRi~TZ?\ Print "Accommodation = " & A & " Diopters" xG0IA 7 Print "Pupil Diameter = " & pupilDiam & " mm" {n%-^9b1{& FW&P`Iu ' Calculate new parameters with accommodation nMc3.fM taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness {OP-9P=p <K:?<F Rant = 12.0 - 0.4*A 'Radius of anterior lens [bkMl+:/HG CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens )xCpQ=nS 3 2Q/4 Rpost = -5.224557 + 0.2*A 'Radius of posterior lens oQ~Q?o]Ri CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens k\_>/)g G;615p1 tlens = 3.767 + 0.04*A 'Lens thickness 6"WR}S0o `
_()R`= nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction VBR@f<2L 'GQ1;9A57 'Adjust parameters to account for accommodation ]+)z}lr8 C |s|>46E '************************************************************************* h*)spwF- 'Aqueous thickness (Position of Lens) kac@yQD '************************************************************************* !;lA+O-t eID = FindFullName( "Geometry.Arizona Eye.Lens" ) $/,qw
GetCustomElement eID, entity 0:Js{$ZL4 ,^O**k9F parID = FindFullName( "Geometry.Arizona Eye" ) 7;KmJ}$ is{I5IR\/ ' Delete any shift(s) in z x(3E#7>1 count = 0 x*5'
6 While GetOperationCount(eID)>count u(02{V GetOperation eID, count, op xXH%7%W'f If op.Type="ShiftZ" Then NI=t)[\F DeleteOperation eID,count hd9fD[5 count=count-1 wM (!9Ws3 End If -Qo`UL.} count=count+1 UY
j Wend zm2&\8J .{HU1/! 'Set new shift in ] =b?^' op.Type = "ShiftZ" ~b5aT;ObR op.val1 = taq wQb")3dw op.parent = parID eJE?H] AddOperation eID, op !l~tBJr*sB Print "Set aqueous humor thickness = " & taq-0.55 GB\.msls ?nrd$, '************************************************************************* gd.P%KC!g 'Radius and conic constant of anterior lens R`G%eG)+ '************************************************************************* n?&G>`u* eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 8^p/?R^bu GetConic eID, entity, curv, conic N4!YaQQ;} C2AP SetConic eID, entity, 1/Rant, CCant 9%oLv25{) Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant 8~:qn@Z|E Ts:dnGR5 '************************************************************************* rj$u_y3S* 'Radius and conic constant of posterior lens :::"C"Ge '************************************************************************* c;w
cgU eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) C5i]n? )S GetConic eID, entity, curv, conic {~16j" #93;V'b] SetConic eID, entity, 1/Rpost, CCpost W6&".2 Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost HYLU]9aH8 ;W?e@ Lgxk '************************************************************************* en!cu_]t 'Lens thickness (Position of posterior lens surface) zdyS"H} '************************************************************************* HCb7`(@ =/.[&DG parID = FindFullName( "Geometry.Arizona Eye.Lens" ) T'\lntN #$K\:V+ 4 ' Delete any z-shift(s) 6aCAz2/ count = 0 ; z :}OD While GetOperationCount(eID)>count -:pLlN-f GetOperation eID, count, op q{@>2AlK If op.Type="ShiftZ" Then -DX|[70 DeleteOperation eID,count [rU8% count=count-1 `zC_?+ End If |g> K$m^ count=count+1 |6`yE]3-( Wend :2 ?dl:l `"I^nD^t>Y 'Set new z-shift 2aW&d=!ZV op.Type = "ShiftZ" Eo)Q> AM op.val1 = tlens [>;U1Wt op.parent = parID ;*wZgl AddOperation eID, op Wxb/|?, Print "Set lens thickness = " & tlens ED[PP2[/ kxWf1hIz0 '************************************************************************* 76}
N/C 'Lens index of refraction s4;SA '************************************************************************* z^{VqC*o+ eID = FindMaterial( "Lens" ) 6T"[M GetModelMaterial eID, mat AmRppbj/wO >\^:xxTf mat.Nd = nlens z]=A3!H/Y SetModelMaterial eID, mat ^=pn!lK;^ Print "Set lens index of refraction = " & nlens ~7 C` a$ GasIOPzK '************************************************************************* @4T+0&OI10 'Pupil diameter 4tCyd5u a8 '************************************************************************* o{
\cCZ" eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) e {N8|l IBQmm(+v 'Adjust pupil diameter (trimming volume inner hole) o9<jj> R; N02N
w(pi SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" dW,$yH_ t{Q9Kv ' Adjust pupil location to just in front of the lens ;?yd;GOt) parID = FindFullName( "Geometry.Arizona Eye" ) My:wA;# eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) fE|([` ! count = 0 G7M:LcX While GetOperationCount(eID)>count qdL;Ii<Y0 GetOperation eID, count, op $a(wM1S4 If op.Type="ShiftZ" Then ^B1Q";#
B^ DeleteOperation eID,count Q^DKKp count=count-1 K
{!eHTU End If (VWTYG7 count=count+1 :?U1^!$$1 Wend o\g",O4- op.Type = "ShiftZ" $0AN5 |`g\ op.val1 = taq-0.01 9%$4Ux*q op.parent = parID y%cg AddOperation eID, op 9H" u\t|? Fj7cI + Print "Set pupil diameter = " & pupilDiam SH<Nt[8C 0KHA5dt 'Update AZ Eye subassembly Description BQ)zm eID = FindFullName( "Geometry.Arizona Eye" ) lmp0Ye| GetEntity eID, entity Xi6XV3G entity.Description = "Accommodation = " & A & "D" &xj?MgdNL SetEntity eID, entity IyL2{5 [L{q Update ]}w~fjq Print "DONE!" R3jhq3F\Y DdN{=}A End Sub \6T&gX E/Q[J.$o 如果屈光度是4,光瞳直径是4,则会输出如下数据: [_^K}\/+ /U`"Xx Accommodation = 4 Diopters SYw>P1 Pupil Diameter = 4 mm |/Ggsfmby Set aqueous humor thickness = 2.81 D+ 9xI Set anterior lens radius = 10.4 and conic constant = -2.375869 V[(zRGa{ Set posterior lens radius = -4.424557 and conic constant = -3.081019 bvUjH5.7 Set lens thickness = 3.927 ,l_"%xYx Set lens index of refraction = 1.42672 ~Ub'5M Set pupil diameter = 4 ,*+F*:o(m DONE! {<v?Z_!68 GASDkVoij ol^OvG:TQ QQ:2987619807 ^{DXin 1O`
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