Transcript PPT - Wildsoet Lab

Diurnal Fluctuations of Ocular
Dimensions and Aberrations:
Implication for Eye Growth Regulation
Yibin Tian & Christine F Wildsoet
School of Optometry
University of California at Berkeley
The eye is not static
Recent findings:
Aberrational changes on the scale of seconds, days,
weeks and months in humans (Cheng et al, 2004;
Hofer et al, 2001).
Diurnal axial length and choroid thickness changes
in chicks, rabbits, and monkeys (Nickla et al, 1998;
Nickla et al, 2002).
Diurnal dimensional change in human eyes (Stone
et al, 2004).
Why aberrations?
1. Image quality is important for normal eye
growth (Animal studies, Wallman et al, 2005;
Wildsoet, 1997).
Ocular aberrations degrade retinal image, and
myopes have more aberrations (Marcos et al,
2001; Collins et al, 1995).
So, aberrations MIGHT play some role in eye
growth.
2. Understanding ocular aberrations can improve
optical and surgical corrections for myopia.
Questions
How do aberrations change with age in growing
eyes?
Are there diurnal patterns in aberration change?
If there is, then are there connections between
diurnal ocular dimensional changes and
aberration changes?
Methods
• Subjects: 8 Ciliary nerve sectioned (CNX) and 8 normal
chicks raised in constant temperature, 12/12 light cycle.
• The lengths of anterior chamber, crystalline lens and
vitreous chamber, retina and choroid were measured with
A-scan ultrasonography 4 times a day (9AM, 12PM, 3PM
& 7:00PM) on days 11, 14, 18, 21, 32.
• The aberrations of the same eyes were measured the next
day (days 12, 15, 19, 22, 33) with aberrometer around the
same time points.
Methods (CNX)
In chicks CNX cuts off innervation to both lenticular and
corneal accommodation (Glasser et al, 1995).
Methods: aberration representation
K
W (r , )  
n

cnf Z nf (r , )
n 0 f   n
( n | f |  even )
RMS 
f 2
(
c
 n)
n, f
RMS CM  (c31 ) 2  (c31 ) 2
Methods: aberration representation
Spherical equivalent refractive error (SERE) and
astigmatism can be derived from Zernike coefficients.
Equivalent defocus power
for higher order aberrations
(Thibos et al, 2001)
4 3RMS
EDP 
2
r
Analyses were done on 2mm pupil diameter.
Spherical equivalent refractive error
CNX vs. Norm
(Red vs. Blue)
1.356D;
p=0.0009.
Age(Norm)
Not significant
Diurnal(Norm)
0.755D;
p<0.0001.
Astigmatism
CNX vs. Norm
(Red vs. Blue)
Not Significant.
Age(Norm)
-1.077D;
P<0.0001.
Diurnal(Norm)
Not Significant.
Spherical Aberration
CNX vs. Norm
(Red vs. Blue)
0.21D;
p=0.0402.
Age(Norm)
0.33D;
P=0.005.
Diurnal(Norm)
0.09D;
P=0.064.
Higher order aberrations
CNX vs. Norm
(Red vs. Blue)
Not significant.
Age(Norm)
-1.337D;
P<0.0001.
Diurnal(Norm)
-0.319D;
P=0.019.
Vitreous chamber depth
CNX vs. Norm
(Red vs. Blue)
0.028mm;
p=0.0133.
Age(Norm)
0.044mm;
p <0.0001.
Diurnal(Norm)
0.019mm;
p<0.0033.
Choroid thickness
CNX vs. Norm
(Red vs. Blue)
0.028mm;
p=0.0133.
Age(Norm)
0.044mm;
p <0.0001.
Diurnal(Norm)
-0.019mm;
p<0.0033.
Summary of results
•Astigmatism and HOA significantly decreased from
day 12 to day 33 on the same pupil size; decrease in
SERE was not significant; spherical aberration
remained positive in CNS eyes, while shifted from
negative to positive in normal eyes;
•ACD, LT and VCD significantly increased with age;
•SERE was significantly more hyperopic in the evening
than in the morning; there were also significant diurnal
variations in HOA;
•Significant diurnal changes in ACD, LT,VCD and OAL,
all of which were longer in the evening than in the
morning; while CT was shorter in the evening.
What’s going on?
• Refraction is about 0.8D more hyperopic in the
evening, while VCD and OAL are both longer???
Elongation of ACD can’t account for it.
0.01mm increase in ACD only contributes about 0.04D
(Let Pcornea = 100D; Plens = 50D);
0.05mm increase in VCD can lead to refraction change of
–0.9D;
Flattening of lens and/or cornea???
0.05mm RC cornea flattening contributes 1.4D.
Aberration Emmetropization
1
0.8
0.8
Relative coma
1
0.6
0.4
0.2
0
Relative trefoil
(b)
- - Geometric growth
--- Measured data
D12
D15
D19
D22
0.6
0.4
0.2
0
D33
0.8
0.6
0.4
- - Geometric growth
--- Measured data
D15
D19
(d)
0.8
D12
D15
(c)
1
0
D12
Age (day)
1
0.2
- - Geometric growth
--- Measured data
Age (day)
Relative HOA
Relative astigmatism
(a)
D19
Age (day)
D22
D33
D22
D33
0.6
0.4
0.2
0
- - Geometric growth
--- Measured data
D12
D15
D19
Age (day)
D22
D33
Possible role of diurnal fluctuation
Microfluctuations can provide accommodation cues (Kotulak et
al, 1986)
It has been shown that DoF of young chick eyes are smaller than
1D (Schimid et al, 1997)
B1(t)
B0
I
B2(t)
B0
S0
B3(t)
S
B0
L(I)
T1
T2
Time
Acknowledgements
• NEI grant NEI R01 EY12392-06 (to CFW)
• Thanks to Wildsoet lab members, especially
Kandy Guan for taking ultrasonogarphy
readings in pilot study.
Thank you!