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简介 y-UutI& T5mdC 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。 P;&rh U^[ dx=\Pq 模型 QN %w\JXS 2gn*B$a 模型的定义如表1种所示,由半径、圆锥常数、折射率、阿贝数、到下一面的距离等一系列表面组成。一些参数由屈光度(A)来决定。 Nhh2P4gH _1z|QC Table 1. AZ眼睛模型的定义 \z}/=Qgc 在FRED中使用0屈光度来创建的,光瞳加在了透镜的前面。材料是创建一个新的材料并选择类型“Model Material”,输入的参数是nd和vd. moQ><>/ O|#N$a&_N 光源 pRsYA7Ti o<`)cb } 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。 l2DhFt$!= U] 2fV|Hn DRldRm/ 图1. 光源和提示信息使用 RB5fn+FiZ 除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处,并增加了pre-propagation distance= -8。尽管光线在光瞳处创建,规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射,而不是在光瞳处入射。 N-x~\B! `={s*^Ta 在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 ?[4!2T,Ca B,sv! p+q5 图2. 字母F光源的设定方法光 +ahr-v^R< Mr}]P(4h 图3. 字母F在视网膜上位置点列图 `aFy2x`3 视网膜的散射 Da)rzr|}>3 b P>!&s_ 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 4X2XSK4 s5 2c`+ qp(F}@ 图4. 视网膜朗伯散射设定 O*3x'I*a 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 qyP|`Pm4 xO2S|DH{ h&7]Bp 图5. 视网膜重点采样规格设定 b\zRwp 脚本 (fgX!G[W @`:n +r5u 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: KKm0@Y =d/\8\4 图6. 用户对话框的创建与编辑 !HA[:-JCz 图7. 用户对话框编辑器 VjU;[ 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 <!.'"*2 余下的脚本计算与屈光度有关的所有参数。 k^q}F%UV Jtj_Rl
! 分析 [/#c9RA Cc:4n1|]> 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 ;!4Bw"Gg lAsDdxB` 图7. 字母F在视网膜上颜色分析 ,jWMJ0X/N= 脚本代码 9Vx2VjK2' QDlEby m Option Explicit 'Remove this to enable non-dimensioned variables to be used. :sRV]!Iw G| pZ Dim entity As T_ENTITY LOyL:~$ Dim op As T_OPERATION SWr?>dl Dim mat As T_MODELMATERIAL DG8LoWZ Dim A As Double uX{n#i,~L Dim pupilDiam As Double u49zc9 Dim eID As Long Wvl>i HB Dim parID As Long .BGM1ph}~ Dim count As Integer ./@!k[ Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double -k{n"9a9? Dim tlens As Double, nlens As Double 66<3zadJZU Dim curv As Double, conic As Double JGPLVw Dim ok As Long Gx?p,Fj nAn/V u Sub Main #LlHsY530N ~\tI9L?|A '用户输入对话框 *loPwV8 Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 0bxB@(NO TextBox 220,21,40,21,.TextBox1 'default: 0 ODK$G
[- Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 OKfJ OKButton 40,91,90,21 Ec| Gom? CancelButton 190,91,90,21 u-Pa:wm0- Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 orn9;|8q TextBox 220,49,40,21,.TextBox2 'default: 4 wZVY h End Dialog _[-+%RP Dim dlg As UserDialog ]gYnw;W$ v8"plx=3 ok = Dialog (dlg) 5uMh#dm^ X3#/|> If ok=0 Then 'cancel button was pressed FR9<$ Print "Execution cancelled." F)/}Q[o8 End gK/mm\K@ End If ZSq7>} jC1mui|Y^ 'Assign accommodation and pupil diameter & use defaults if field left empty /_E8'qlx If dlg.TextBox1 = "" Then ghm5g/ A = 0 'Default accommodation !=@Lyt)_b Else *,hS- A = CDbl(dlg.TextBox1) Ed9ynJ~)X End If b:/ ; 0Vv6B2< If dlg.TextBox2 = "" Then yfeX=h pupilDiam = 4 'Default pupil diameter kH1hsDe|&y Else mD-qJ6AM pupilDiam = CDbl(dlg.TextBox2) 6V\YYrUz End If R0y={\*B5k `m?%{ \ Print " " IbC(/i#%` Print "Accommodation = " & A & " Diopters" Ed ,`1+ Print "Pupil Diameter = " & pupilDiam & " mm" :G9+-z{Y& SCE5|3j ' Calculate new parameters with accommodation L+Yn}"gIs taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness !s#25}9zX5 Ar4E $\W Rant = 12.0 - 0.4*A 'Radius of anterior lens ;4tVFqR CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens +9G
GC #k8bZ?*: Rpost = -5.224557 + 0.2*A 'Radius of posterior lens 0ZPwEP CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens C
J S pkpD1c^ tlens = 3.767 + 0.04*A 'Lens thickness $u_0"sUV b'Qia'a% nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction B
PTQm4TN C%d\DuJ5'~ 'Adjust parameters to account for accommodation [hA%VF.9 s42M[BW] '************************************************************************* duB{1 'Aqueous thickness (Position of Lens) ^]w!ow41 '************************************************************************* J]/TxUE eID = FindFullName( "Geometry.Arizona Eye.Lens" ) ES!$JWK| GetCustomElement eID, entity c^vPd]Ed F,Q\_H##x4 parID = FindFullName( "Geometry.Arizona Eye" ) $Z6g/bD`E py.lGywb_ ' Delete any shift(s) in z *LpEH,J count = 0 !!Z#'Wq While GetOperationCount(eID)>count l
T~RH0L GetOperation eID, count, op :b)IDcW&j: If op.Type="ShiftZ" Then !spp*Q)#\ DeleteOperation eID,count %0C<_drW count=count-1 $2qZds[ End If P:h;" count=count+1 m7wD#?lm Wend tFt56/4 1S9(Zn[2, 'Set new shift in t-Rfy`I3 op.Type = "ShiftZ" (n+2z"/ op.val1 = taq bh|M]*Pq op.parent = parID "MHm9D?5 AddOperation eID, op >nV~5f+ Print "Set aqueous humor thickness = " & taq-0.55 lo*OmAF !E!i`yF '************************************************************************* d4KTwn5g 'Radius and conic constant of anterior lens tJ[yx_mf '************************************************************************* e5G)83[= eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) i^Vb42 %y GetConic eID, entity, curv, conic [P.M>"c\ 0fwmQ'lW( SetConic eID, entity, 1/Rant, CCant twElLOE Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant bA}9He1 )3# gpM '************************************************************************* Z-|.j^n 'Radius and conic constant of posterior lens sC
>_ulkoa '************************************************************************* ?q a eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) D\|$!i} GetConic eID, entity, curv, conic nMXk1`|/)x pgbm2mT9 SetConic eID, entity, 1/Rpost, CCpost +v.uP [H Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost |/<,71Ae 0/K?'&$yvb '************************************************************************* {$D[l
hj 'Lens thickness (Position of posterior lens surface) ' i5 VU4?K '************************************************************************* {hQ0=rv< j6v|D>I parID = FindFullName( "Geometry.Arizona Eye.Lens" ) 8*7t1$ R<.<wQ4I ' Delete any z-shift(s) J1OZG6|e count = 0
m,}0p While GetOperationCount(eID)>count ZoX24C' GetOperation eID, count, op <T]%Gg8 If op.Type="ShiftZ" Then sd4eJ DeleteOperation eID,count kQ~2mU count=count-1 ?;84 M@ End If 1o"/5T:S[ count=count+1 *D`]7I~} Wend u=_"*:} c%1k'Q 'Set new z-shift mGx!{v~i& op.Type = "ShiftZ" HYVSi3[ op.val1 = tlens j"(o>bv7 op.parent = parID ;W%nBdE6| AddOperation eID, op ,b[}22 Print "Set lens thickness = " & tlens j("$qpv .*XELP=BT '************************************************************************* EWOS6Yg7 'Lens index of refraction @1+C* '************************************************************************* ;R[ xo! eID = FindMaterial( "Lens" ) 3#GZ6:rVJ GetModelMaterial eID, mat e7e6b-"_2 5)h#NkA\J mat.Nd = nlens m$N`Xj SetModelMaterial eID, mat WM y97*L< Print "Set lens index of refraction = " & nlens u.v
5!G [5[}2B_t '************************************************************************* G!]%xFwYa 'Pupil diameter Vb{5 -v
;a '************************************************************************* A8,9^cQ] eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) ++ O
L&n -CV_yySc 'Adjust pupil diameter (trimming volume inner hole) a=ye!CN^ [6 d~q]KH SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" 0|6]ps4Z7 E :gS*tsY ' Adjust pupil location to just in front of the lens RF3?q6j , parID = FindFullName( "Geometry.Arizona Eye" ) LV4\zd6 eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) 2_S%vA<L count = 0 R-7.q While GetOperationCount(eID)>count t "y[ GetOperation eID, count, op ~nit~; If op.Type="ShiftZ" Then L'i0|_ DeleteOperation eID,count j^4KczJl count=count-1 0cYd6u@ End If zzlqj){F
count=count+1 8aDSRfv* Wend eZ>KA+C[ op.Type = "ShiftZ" +IS+!K0?) op.val1 = taq-0.01 |W't-}yf op.parent = parID >L5fc". AddOperation eID, op ~bm
VpoI @ P:b\WCI Print "Set pupil diameter = " & pupilDiam bx!uHL= C\-Abqc 'Update AZ Eye subassembly Description C%c}lv8;^ eID = FindFullName( "Geometry.Arizona Eye" ) .&z/p3 1 GetEntity eID, entity M't~/&D# entity.Description = "Accommodation = " & A & "D" rbC4/ 9G\ SetEntity eID, entity 3k%fY ^pI&f{q Update F4P=Wz] Print "DONE!" 0^%\! Xxq @.rVg XE=! End Sub =J@M,mbHg 3HtLD5%Q 如果屈光度是4,光瞳直径是4,则会输出如下数据: wEQ7=Gyx |AosZeO_ Accommodation = 4 Diopters kzky{0yKk= Pupil Diameter = 4 mm Sf_q;Ws Set aqueous humor thickness = 2.81 w@K4u{| Set anterior lens radius = 10.4 and conic constant = -2.375869 I
JPpF` Set posterior lens radius = -4.424557 and conic constant = -3.081019 / 7i>0J] Set lens thickness = 3.927 <V> [H7 Set lens index of refraction = 1.42672 *.'9 eC0s Set pupil diameter = 4 UJ\[^/t DONE! C(=$0FIR ]'L#'"@ 8|-j]
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