38yoonlab_disp by peirongw

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									Wavefront-Guided Contact Lenses: Challenges in Moving from the Laboratory to the Dispensary
Geunyoung Yoon, Ph.D.
Assistant Professor

Department of Ophthalmology Center for Visual Science Department of Biomedical Engineering University of Rochester

Customized Vision Correction Laboratory
http://www.cvs.rochester.edu/yoonlab/ Email: yoon@cvs.rochester.edu Carl Chancy

Luis Carvalho, PhD Lana Nagy

Kamran Ahmad

Ramkumar Sabesan Seth Pantanelli

Futoshi Taketani, MD, PhD

Collaborators:

David Williams, Scott MacRae, Krystel Huxlin, Jay Wang; U. of Rochester Martin Banks; UC Berkeley Perry Rosenthal; Boston Foundation for Sight Ian Cox, Ravikumar Sumasundaram, Mohinder Merchea; Bausch & Lomb

Impact of the wave aberration on retinal image quality
-2.5 -2 -1.5 -1 -0.5
-2.5

0
-2

-1

No correction
0.5 1 1.5 2 2.5
0.5

3
1

1

Conventional correction

-2.5

-2

-1.5

-1

-0.5

0

+ Higher order aberrations correction
0.5 1 1.5 2 2.5 3

Abnormal eyes have much greater amounts of higher-order aberrations compared to normals
Magnitude of Zernike coefficient (µm)
6 mm pupil

2.0 1.5 1.0 0.5
Trefoil

Coma Spherical aberration

Zernike mode

Higher order aberrations have been successfully corrected using adaptive optics and wavefront-guided refractive surgery.
Adaptive Optics Customized refractive surgery

Distorted wavefront

Plane wavefront

Deformable mirror

Customized optics (phase plates) can also correct the higher order aberration.
Low contrast (10%) visual acuity Correcting 2nd order only
0.2

Correcting 2nd + higher order
20/32

Normal eyes
1
20/25 0.8 20/20 20/16

Keratoconus
20/200 20/125 20/80 20/50 20/32 20/20

Visual acuity (logMAR)

0.1 0

0.6 0.4 0.2

-0.1 -0.2 -0.3 -0.4

20/12.5

0

1.2 line improvement
GY JP MM IC Mean

20/10

-0.2 -0.4

3.2 line improvement
Mild KC Advanced KC Mean

20/12.5 20/8

Is it feasible to correct the higher order aberration with customized soft contact lenses?
With conventional contact lens

Blurred image

With customized contact lens

Sharp image

Higher order aberrations can be generated by customized contact lens.

Design

Measurement
3

Wavefront height (µm)

-3

CCL for normal eye for a 6 mm pupil

Manufacturing higher order RMS error = 0.25 µm

Correcting the higher order aberration with customized soft contact lenses
Normal eye for a 6 mm pupil
8 120 6 100

+3

With conventional lens

HO rms = 0.69 µm

Wavefront height (µm)

4 2 0

80

60

0

-2 40 -4

With customized lens

20

HO rms = 0.49 µm
20 40 60 80 100 120

-6 -8

-3

Correcting the higher order aberration with customized soft contact lenses
Keratoconic eyes
8 120
120 120 8 6 100 4 2 0 -2 40 -4 20 -6 -8 20

6 mm pupil
8 6 4 2 0 -2

6 100
100

4

8 6

With conventional lens
HO rms =

80

80

120 2
0

80

60

60

60

100 -2
40
40

Wavefront height (µm)

4
-4 -6 -8

-4 20
20

80
20 40

-6

2 0

3.07 µm

60

80

100

120

-8 20

60 8
120 6

3.74 µm

40

60

80

100

120

1.74 µm

40

60

80

100

120

8 120 6 100 4 2 0 -2 40 -4

8 6 4 2 0 -2 -4

120

-2 -4 -6 -8

100

100

40

4 2 0 -2

With customized lens
HO rms =

80

80

80

60

60

20

60

40

40 -4

20

20

-6 -8 20

20
40 60 80

40
100

60
120

20

-6 -8 20

80
40

100
60 80

120
100 120

-6 -8

20

40

1.05 µm

60

80

100

120

1.07 µm

0.52 µm

Improving visual performance with customized contact lenses in keratoconus
6 mm pupil
High contrast letter (100%) High contrastletter (100%)

Visual acuity (logMAR) Visual acuity (logMAR)

0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0

2.1 lines improved

Conventional lens
Series1 Customized Series2 lens

SC

1

Subjects

Subject

MX

2

MB

3

Improving visual performance with customized contact lenses in keratoconus
6 mm pupil
Low contrast (20%) Low contrast letter (20%)

Visual acuity(logMAR) Visual acuity (logMAR)

0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0

2.1 lines improved

Conventional lens Customized lens
Series1 Series2

SC

1

Subjects

Subject

MX

2

MB

3

Challenges to make customized contact lenses correct the higher order aberration better

- Manufacturing error - Decentration and rotation of lens - Image quality degradation immediately after blinks - Tear film uniformity on lens surface - Temporal changes of the aberration - …..

Manufacturing error
Design Measurement Manufacturing error

Normal eye

HO rms = 0.25 µm

Abnormal eye

HO rms = 0.58 µm

Dynamic movements of soft contact lens after blinks

Horizontal and vertical decentration of soft contact lens after blinks
Advanced keratoconus
600

blink

Lens decentration (µm)

Horizontal decentration

400 200 0 -200 -400 -600 0 5 10

Vertical decentration
15 20 25 30

Time (sec)

Rotation of soft contact lens after blinks
Advanced keratoconus
4

Lens rotation (degree)

3 2 1 0 -1 -2 -3 -4 0 5 10 15 20 25 30

Time (sec)

Partial vs Full Customization

Partially vs Fully customized contact lenses: averaged HO aberration in a normal population
0.4

6 mm pupil (n=159 normal eyes) Spherical aberration

Zernike coefficient (µm)

0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 5 7 9 11 13

15

17

19

21

Zernike mode

Partially vs Fully customized contact lenses: Averaged magnitude of HO aberration in a normal population
Magnitude of Zernike coefficient (µm)
0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 5 7 9 11 13 15 17 19 21

6 mm pupil (n=159 normal eyes)

Coma Spherical aberration

Zernike mode

Partially vs Fully customized contact lenses
- Aspherical lens
correcting averaged spherical aberration

- Customized aspherical lens
Correcting individual spherical aberration

- Customized coma lens
Correcting individual coma

- Customized aspherical + coma lens
Correcting individual spherical aberration and coma

- Fully customized lens
Correcting most higher order aberrations

Retinal image quality metric: volume MTF (vMTF) under white light condition
Modulation transfer
1 1

vMTFconventional

vMTFHO correction

0 60

0 60

Spatial frequency (cycles/deg)

Visual benefit =

vMTFHO correction vMTFconventional

Theoretical performance of partially customized contact lenses based on white light volume MTF
Without rotation
2.4 2.2 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0 200 400 600 800 1000
Fully customized SA & coma customized SA customized Aspherical Coma customized

6 mm pupil (n=159 normal eyes)

Visual Benefit

x

Magnitude of lens decentration (µm)

Theoretical performance of partially customized contact lenses based on white light volume MTF
With 5 degree rotation
2.4 2.2 2

6 mm pupil (n=159 normal eyes)

Visual Benefit

1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0 200 400

x

Fully customized SA + coma SA customized Aspherical Coma customized

600

800

1000

Magnitude of lens decentration (µm)

Conclusion
Customized soft contact lens has successfully reduced the ocular higher order aberrations by a factor of 3 in keratoconus. This reduction in the higher order aberration improved both high and low contrast visual acuity by 2.1 lines on average. Contact lens movements are the most critical factor that decreases visual benefit. Partially customized contact lenses are less sensitive to the lens movements. However, achievable visual benefit is smaller than fully customized contact lens in the presence of typical amounts of lens movements.

Acknowledgements
Research supported by grants from NIH/NEI (R01-EY014999)
Customized contact lens research

NYSTAR CEIS (5-23576) Research to Prevent Blindness Finger Lake Eye & Tissue Bank Bausch & Lomb


								
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