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简介 3 \9][S-B *%f3rvt7@) 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。 .hnF]_QQ k%a?SU<f 模型 %[+/>e/m ^"/Dih\_ 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。 1uj05aZh} mc56L[ Table 1. AZ眼睛模型的定义 n%8#?GC` 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. )muv;Rf`e5 =1&}t%<X 光源 9M19UP& |7Yvq%E 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。 \6jF{ zVn* !c *@=fq|6l 2 图1. 光源和提示信息使用 zZw@c? 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。 Hm<M@M$aG 7j{Te)" 在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 6;[1Jz]?i Ny[s+2? 图2. 字母F光源的设定方法光 mKMGdN~ cEtZ}2,j 图3. 字母F在视网膜上位置点列图 8:BQHYeJK 视网膜的散射 nEuct4BcL} F F(^:N 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 gx&\Kw6HM .2{ 6h L_`Xbk y 图4. 视网膜朗伯散射设定 -y9Pn>~V 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 +,:nm_kQU FK?mS>G6 Rb yF#[} 图5. 视网膜重点采样规格设定 Udg&
eEF 脚本 KX$qM g1j CD$u=E
] 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: '&1 QJniM"8v 图6. 用户对话框的创建与编辑 Pi^ECSzQu[ 图7. 用户对话框编辑器 [Ja(ArO3|[ 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。 m.|qVN 余下的脚本计算与屈光度有关的所有参数。 Bl:{p>-q O>kXysM v> 分析 fB@K'JQG P((S2"D<4 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 V%VrAi. GC,vQ\ 图7. 字母F在视网膜上颜色分析 y_;]=hEL 脚本代码 3m?@7 F 1
yxZ Option Explicit 'Remove this to enable non-dimensioned variables to be used. xop-f#U* ~t1O]aO( Dim entity As T_ENTITY
)@sJTAK Dim op As T_OPERATION w50.gr7 Dim mat As T_MODELMATERIAL 9
kTD}" %2 Dim A As Double Ki&WS<,0Z Dim pupilDiam As Double sj?`7kg Dim eID As Long !-
Cs? Dim parID As Long $l0eI Dim count As Integer 5( mCBH Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double mdmZ1:PBM Dim tlens As Double, nlens As Double rQ9?N^&!% Dim curv As Double, conic As Double Ncs4<"{$ Dim ok As Long OtrXYiKB
|*/uN~[ Sub Main ir( -$*J |>jqH @\P '用户输入对话框 VNJDl Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 L<{OBuR TextBox 220,21,40,21,.TextBox1 'default: 0 d&$.jk8 2 Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 `[g#Mxw OKButton 40,91,90,21 %B*<BgJ;4F CancelButton 190,91,90,21 EU&6Tg Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 ~_/<PIm TextBox 220,49,40,21,.TextBox2 'default: 4 vfk7J5y End Dialog cQUH %7m Dim dlg As UserDialog E.WNykF- $;KQY7 ok = Dialog (dlg) ?[NTw./'7A *_<SWTE If ok=0 Then 'cancel button was pressed YFC0KU Print "Execution cancelled." OXa5Jg}= End UeK,q>i End If 0k .# f<$K.i 'Assign accommodation and pupil diameter & use defaults if field left empty CBz(hCaI If dlg.TextBox1 = "" Then -E,{r[Sp A = 0 'Default accommodation TV[6+i*# Else JaB tX' A = CDbl(dlg.TextBox1) 2s]]!{Z# End If *h5ld P !`d832 If dlg.TextBox2 = "" Then H *z0xxa pupilDiam = 4 'Default pupil diameter hhh: rmEZl Else ;_Of`C+ pupilDiam = CDbl(dlg.TextBox2) )0 42?emn End If y:^>(l #; X,C/x) Print " " qQ?,|4)y Print "Accommodation = " & A & " Diopters" H*:r>Lm= Print "Pupil Diameter = " & pupilDiam & " mm" >uqS k8t Na@H ' Calculate new parameters with accommodation B[U.CAUn taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness cr=FMfhB $
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< Rant = 12.0 - 0.4*A 'Radius of anterior lens ^|:{,d#Y CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens =^%Pwkz 2Xq!'NrS Rpost = -5.224557 + 0.2*A 'Radius of posterior lens $' I$n CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens (<:rKp a_}BTkfHa tlens = 3.767 + 0.04*A 'Lens thickness GQ8Dj!8 EL)/5-=S nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction "YdDaj</ |
xErA 'Adjust parameters to account for accommodation Ry*I~<m +%cr?g '************************************************************************* "n2xn%t{ 'Aqueous thickness (Position of Lens) \Kzt*C-ZH '************************************************************************* ?T%K + eID = FindFullName( "Geometry.Arizona Eye.Lens" ) e>i8 =U`; GetCustomElement eID, entity hvv>UC/ 0z<]\a4 parID = FindFullName( "Geometry.Arizona Eye" ) +ouy]b0`t /{#_Um0. ' Delete any shift(s) in z q0KXuMK count = 0 rc{[\1 -N While GetOperationCount(eID)>count _-yF9g"I GetOperation eID, count, op X7B)jH%N If op.Type="ShiftZ" Then HDae_. DeleteOperation eID,count 77bZ count=count-1 /j5-
"<;. End If @x>$_:] count=count+1 Q17o5##x7 Wend 1 0Tg> H i!+3uHWu`) 'Set new shift in X-) ]lAP op.Type = "ShiftZ" D 5wR?O op.val1 = taq )V =K#MCK op.parent = parID C9;X6 AddOperation eID, op x)qHeS Print "Set aqueous humor thickness = " & taq-0.55 ) GT?Wd a.*j8T '************************************************************************* ;g)Fhdy! 'Radius and conic constant of anterior lens ug3lMN4UX '************************************************************************* ah$7
Oudj eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) -D^y)
GetConic eID, entity, curv, conic nJ0eZBgB] `/j|Rb|eow SetConic eID, entity, 1/Rant, CCant GWE0 UO} Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant v]Q_ Ru\Lr=9 '************************************************************************* ii]=C(e9 'Radius and conic constant of posterior lens 1?#p !;& '************************************************************************* rOf eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) )/i|"`)>_ GetConic eID, entity, curv, conic W%<]_u[-} tVh4v#@+ SetConic eID, entity, 1/Rpost, CCpost H?bsK~ Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost 98BBsjkd oX~$'/2v '************************************************************************* JhXN8Bq33 'Lens thickness (Position of posterior lens surface) yt#;3 '************************************************************************* 6XCX#4'i% lJ1xx }k{U parID = FindFullName( "Geometry.Arizona Eye.Lens" ) KGLhl;a 3 &Zx*: ' Delete any z-shift(s) v^I %Wm count = 0 *RE-K36m|u While GetOperationCount(eID)>count `}Zbfe~ GetOperation eID, count, op Cspm\F If op.Type="ShiftZ" Then )0V]G{QN DeleteOperation eID,count @X><lz count=count-1 Pisr&"A End If \#c+vfq count=count+1 +dpj? Wend ){|Lh( #$rT 4Nc; 'Set new z-shift *H<g9<Dn op.Type = "ShiftZ" JkDZl?x5 op.val1 = tlens HD^~4\% op.parent = parID !w\;Q8irN AddOperation eID, op f9=X7"dzP Print "Set lens thickness = " & tlens Im1qWe . pEeR '************************************************************************* .wn_e=lT 'Lens index of refraction >w;W&[ '************************************************************************* k3h53QTmC eID = FindMaterial( "Lens" ) 4$w-A-\t GetModelMaterial eID, mat BjJ gQ`X Jl9TMu!1] mat.Nd = nlens `%I{l SetModelMaterial eID, mat _ShJ3\,K Print "Set lens index of refraction = " & nlens zd]L9 _ Nmq5Tv '************************************************************************* r>@/XYK&\ 'Pupil diameter 6U3@-+lF '************************************************************************* uy\+#:44d eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) T0)y5 qf$|z`c 'Adjust pupil diameter (trimming volume inner hole) hRcJ):Wyb 9+|,aG s SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" m;1e xa q)i(wEdUZ ' Adjust pupil location to just in front of the lens YAG3PWmD parID = FindFullName( "Geometry.Arizona Eye" ) ^Exq=oV eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) zXPj7K* count = 0 .]l2)OlLQ While GetOperationCount(eID)>count 7B :aJfxM GetOperation eID, count, op nQVBHL> If op.Type="ShiftZ" Then
`.-C6! DeleteOperation eID,count LA0x6E+I count=count-1 N Uml" End If }#^F'%zf count=count+1 /aEQ3x Wend )q-!5^ak op.Type = "ShiftZ" IvSrJe[; op.val1 = taq-0.01 Y)RikF > op.parent = parID [=!MS?-G AddOperation eID, op |mA*[?ye@ yln.E vJjD Print "Set pupil diameter = " & pupilDiam |{"7/~*[ WR1,J0UU6 'Update AZ Eye subassembly Description Lj,%pz J eID = FindFullName( "Geometry.Arizona Eye" ) . r"?w GetEntity eID, entity KrzM]x entity.Description = "Accommodation = " & A & "D" oI/ThM`=q SetEntity eID, entity |th )Q j(2T,WM Update |sAg@kM Print "DONE!" ,' B=eY, [ RuY' End Sub v[GHqZ 2F{IDcJI\ 如果屈光度是4,光瞳直径是4,则会输出如下数据: r"{1H zb$U'D_-f Accommodation = 4 Diopters |XZf:}q5: Pupil Diameter = 4 mm "TI?
qoz Set aqueous humor thickness = 2.81 I78pul8! Set anterior lens radius = 10.4 and conic constant = -2.375869 ?Fv(4g Set posterior lens radius = -4.424557 and conic constant = -3.081019 -]%@,L^@ Set lens thickness = 3.927 C3gz)!3 Set lens index of refraction = 1.42672 u>#'Y+7 Set pupil diameter = 4 (#lS?+w) DONE! "(GeW286k
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