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简介 E "}@SaB- xE
w\'tH 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。 uBa<5YDF kI)}7e 模型 cl2_"O P|bow+4 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。 (=Cb)/s0 h7!O
K Table 1. AZ眼睛模型的定义 *k}m?;esb 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. &<]f- ZQ_6I}i") 光源 1.F&gP)9 <3x%-m+p4 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。 /oHCV0!0
14B',]` 2CO/K_Q 图1. 光源和提示信息使用 8YQuq.(>a 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。 gCb+hQq\ >bh+!5Y0 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。 3-
Kgz ,Gt!nm_ 图2. 字母F光源的设定方法光 P3&s<mh lx%c&~.DiB 图3. 字母F在视网膜上位置点列图 E]OexRJ^i 视网膜的散射 Z^&G9I# "/aZ*mkjfJ 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。 Swhz\/u9 &-yRa45? $v;WmYTJ 图4. 视网膜朗伯散射设定 rUb{iU;~m 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 wf\"&xwh? |q*yuK/ N>H@vt~ 图5. 视网膜重点采样规格设定 )[Tm[o?Y. 脚本 pux IJ x.+T65X~4 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: F}_b7|^ .dlsiBh 图6. 用户对话框的创建与编辑 ;
j!dbT~5 图7. 用户对话框编辑器 ^5sA*%T4 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 =0g!Q 余下的脚本计算与屈光度有关的所有参数。 =
j1Jl^[ 'Cc~|gOgD 分析 /mex{+p>tO v76Gwu$d 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 Jl~ *@0( BPO5=]W 7 图7. 字母F在视网膜上颜色分析 b)d;eS 脚本代码 /+Z*)q+SbT PILpWhjL$9 Option Explicit 'Remove this to enable non-dimensioned variables to be used. .4+Rac iW` tr Dim entity As T_ENTITY <YaT r9%w Dim op As T_OPERATION ?\V#^q- Dim mat As T_MODELMATERIAL W8d-4')| Dim A As Double o$No@~%v Dim pupilDiam As Double DDeU: Dim eID As Long aK_5@8+ZD Dim parID As Long E-z5mX.2 Dim count As Integer G}nJ3 Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double XY"b 90 Dim tlens As Double, nlens As Double gNCS*a Dim curv As Double, conic As Double =
lo.LFV Dim ok As Long xuioU sA2-3V<t8 Sub Main Ob$``31{s 4aXIRu%#7 '用户输入对话框 ,2FK$:M\ Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 b>-DX TextBox 220,21,40,21,.TextBox1 'default: 0 6<lo0PQ"Z Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 EvT$|#FY OKButton 40,91,90,21 QOWGQl%! CancelButton 190,91,90,21 bZ`v1d
(r Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 ?NMk|+ TextBox 220,49,40,21,.TextBox2 'default: 4 TLwxP" End Dialog ,L<JG Dim dlg As UserDialog $k~TVm
Yex 8['R D`O ok = Dialog (dlg) :&BPKqKp @v)Z>xv If ok=0 Then 'cancel button was pressed -XBZ1q Print "Execution cancelled." ]C \+b< End M$K%e End If n>'(d*[e& 6W
i
n!4 'Assign accommodation and pupil diameter & use defaults if field left empty P $`1} If dlg.TextBox1 = "" Then hr
vTFJ A = 0 'Default accommodation &_L@hsm Else 0Ui.nz j A = CDbl(dlg.TextBox1) o}AXp@cqi End If Y%
iqSY B!RfPk1B<* If dlg.TextBox2 = "" Then X$kLBG[o_ pupilDiam = 4 'Default pupil diameter "| '~y}v_ Else Wdd}y`lS pupilDiam = CDbl(dlg.TextBox2) rL5=8l End If Zl>SeTjB- I5"wa:Z Print " " /M2in]oH Print "Accommodation = " & A & " Diopters" m212
gc0u Print "Pupil Diameter = " & pupilDiam & " mm" Y'/6T]a :C5w5
Vnj ' Calculate new parameters with accommodation Gk:fw#R taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness j7!u;K^c 'w:ugb9] Rant = 12.0 - 0.4*A 'Radius of anterior lens +<E#_)}`D6 CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens /?81Ypt
u$?! Rpost = -5.224557 + 0.2*A 'Radius of posterior lens S#ryEgc] CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens MHwfJ{"zo J^8j|%h%e tlens = 3.767 + 0.04*A 'Lens thickness 'o&d!
<K)]kf nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction o)I)I/v 9a_P 9s3w 'Adjust parameters to account for accommodation ;lmg0dtJ *~8F.cx '************************************************************************* 8u*<GbKGI 'Aqueous thickness (Position of Lens) q^[t</_N '************************************************************************* ~<k>07 eID = FindFullName( "Geometry.Arizona Eye.Lens" ) i[z 2'tx4 GetCustomElement eID, entity @!iS`u 9d1km~ parID = FindFullName( "Geometry.Arizona Eye" ) wH"9N+82M -'c
qepC{T ' Delete any shift(s) in z 7~2_'YX>: count = 0 7nPg2K& While GetOperationCount(eID)>count !w7/G GetOperation eID, count, op DVd8Ix <
If op.Type="ShiftZ" Then 7#JnQ|
] DeleteOperation eID,count _4oAk @A count=count-1 5 =;cN9M@ End If ltOS()[X count=count+1 ]O;*Y{:Y Wend /J^dzvH }wo:1v8J 'Set new shift in e\~nqKCb op.Type = "ShiftZ" &/m^}x/_W op.val1 = taq 7bYwh8 op.parent = parID TJYhgna AddOperation eID, op :G6CWE Print "Set aqueous humor thickness = " & taq-0.55
~;?mD/0k q=^;lWs4 '************************************************************************* yoGG[l2k>s 'Radius and conic constant of anterior lens XR]bd '************************************************************************* a)lCp eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) *& w/*h$! GetConic eID, entity, curv, conic .+(ED ,|O6<u9 SetConic eID, entity, 1/Rant, CCant pcv\|)&} Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant N?c~AEk9U Dlz0*eHD '************************************************************************* <LZ#A@]71 'Radius and conic constant of posterior lens WS6Qp`c)e '************************************************************************* ,fiV xn Q eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) )
YB'W_ GetConic eID, entity, curv, conic .Ao
_cx G5|nt#> SetConic eID, entity, 1/Rpost, CCpost #-b}QhxH Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost aAP86MHO LRw-I.z '************************************************************************* 7*K2zu3 'Lens thickness (Position of posterior lens surface) 3u t<o- '************************************************************************* `_.:O,^n^ +P+h$gQ parID = FindFullName( "Geometry.Arizona Eye.Lens" ) c0l?+:0M !r6Yq,3 ' Delete any z-shift(s) ^[R/W VNk count = 0 9s!R_R&W. While GetOperationCount(eID)>count
n gJ{az GetOperation eID, count, op [OPF3W3z If op.Type="ShiftZ" Then Y_C6*T% DeleteOperation eID,count fHwS12SB count=count-1 jZ"j_=o@ End If yXIJeo" count=count+1 PB*G#2W Wend )x?)v#k ,c`Wmp^AY 'Set new z-shift X]2x0 op.Type = "ShiftZ" :_F 8O op.val1 = tlens DTsD<o op.parent = parID #N|JC d_ AddOperation eID, op NBBR>3nt Print "Set lens thickness = " & tlens mBB"e"o :)4c_51 ` '************************************************************************* -glGOTk 'Lens index of refraction SY:ISzB} '************************************************************************* u^Ktz
DmL eID = FindMaterial( "Lens" ) r?
}|W2^% GetModelMaterial eID, mat ?I+$KjE+ M+j*5wNy mat.Nd = nlens
$tc1te SetModelMaterial eID, mat *c%{b3T_ Print "Set lens index of refraction = " & nlens ~e)"!r 92C; a5s '************************************************************************* RFSwX*! 'Pupil diameter f;OB"p '************************************************************************* Ek_<2!%X eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) o9C#5%9 &sYxe:H 'Adjust pupil diameter (trimming volume inner hole) cf^ i!X0 QUZ+#*:s SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" IAN={";p G^.tAO5:f ' Adjust pupil location to just in front of the lens Jk7 Am-.0 parID = FindFullName( "Geometry.Arizona Eye" ) (u='&ka eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) 0%q H=do6 count = 0 'n\P S,[1R While GetOperationCount(eID)>count r1}1lJ>7H GetOperation eID, count, op 9%"\s2T If op.Type="ShiftZ" Then C(8!("tU DeleteOperation eID,count ( *K)D$y count=count-1 f87XE";:A End If N_Zd.VnY count=count+1 IGlyx'\_ Wend W:9l"' op.Type = "ShiftZ" )iK:BL*Nw op.val1 = taq-0.01 !"-.D4*r op.parent = parID &h!O<'*2 AddOperation eID, op .!i`YT*jF Z#^|h0 Print "Set pupil diameter = " & pupilDiam I36%oA G$QN_h,} 'Update AZ Eye subassembly Description WB<MU:.Vc eID = FindFullName( "Geometry.Arizona Eye" ) PyK!Cyq GetEntity eID, entity \j BA4?(S entity.Description = "Accommodation = " & A & "D" ~_F;>N~ SetEntity eID, entity H5
:,hrZY ,w9|?%S Update ^SsnCn-e Print "DONE!" {{>,c}O / vifw
FPe End Sub kUT^o N^PkSf[)h5 如果屈光度是4,光瞳直径是4,则会输出如下数据: 6X?:mn'%QF o`7 Z<HF Accommodation = 4 Diopters 5ug|crX Pupil Diameter = 4 mm Iu5 9W> Set aqueous humor thickness = 2.81 o~L(;A]yN Set anterior lens radius = 10.4 and conic constant = -2.375869 F#RN m5 Set posterior lens radius = -4.424557 and conic constant = -3.081019 ?$uF(>LD
Set lens thickness = 3.927 . &`YlK Set lens index of refraction = 1.42672 [u^ fy<jdp Set pupil diameter = 4 JRZp'Ln DONE! Dv`"3
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