Apparatus, systems and methods for improving visual outcomes for pseudophakic patients
A system and method of characterizing through-focus visual performance of an IOL using metrics based on an area under the modulation transfer function for different spatial frequencies at different defocus positions of the IOL. Also disclosed is a system and method of characterizing through-focus visual performance of an IOL using a metric based on an area under a cross-correlation coefficient for an image of a target acquired by the IOL at different defocus positions of the IOL.
1. An optical system configured to predict clinical visual performance of an intraocular lens (IOL), the system comprising:
an IOL optical quality measurement device configured to acquire a plurality of images of a target including objects with different spatial frequencies and obtain modulation transfer function (MTF) and/or phase transfer function (PTF) at different spatial frequencies for different defocus positions of the IOL in a vision range from the acquired plurality of images, the measurement device comprising:
a processor configured to execute programmable instructions stored in a non-transitory computer storage medium to calculate a metric based on at least one preclinical metric selected from:
an area under the MTF (MTFa) obtained by integrating preclinical through focus MTF measurements obtained for different spatial frequencies between 0 cycles per mm and 200 cycles per mm for each of the different defocus positions;
a cross correlation coefficient (X-cor) corresponding to a convolution of a reference image and the plurality of images acquired by the IOL optical quality measurement device at each of the different defocus positions;
a weighted MTF (wMTF) obtained by integrating a product of a threshold contrast sensitivity (CS th ) and through focus MTF measurements obtained for different spatial frequencies between 0 cycles per mm and 200 cycles per mm for each of the different defocus positions; or
a weighted OTF (wOTF) obtained by integrating a product of a threshold contrast sensitivity (CS th ), through focus MTF measurements, and cosine of the PTF obtained for different spatial frequencies between 0 cycles per mm and 200 cycles per mm for each of the different defocus positions; and
obtain a correlation between the calculated metric and clinical data that predicts visual acuity (VA) at different defocus positions of the intraocular lens (IOL).
2. The system of claim 1 , wherein the measurement device comprises:
a reference image illuminated by a light source; and
an imaging system including a pupil.
3. The system of claim 2 , wherein the light source is a white light source.
4. The system of claim 2 , wherein the pupil has a size between 1 mm and 6 mm.
5. The system of claim 1 , wherein the objects have spatial frequencies between about 0 cycles per mm (cpmm) and 200 cpmm.
6. The system of claim 1 , wherein the target is selected from the group consisting of an optotype, a slit, a 1951 USAF picture chart; and a subset of bars from a 1951 USAF picture chart.
7. The system of claim 1 , wherein the measurement device is a computing device including the processor, the computing device configured to simulate the plurality of images using models for the target and the IOL.
8. The system of claim 1 , wherein the metric is based on at least two preclinical metrics selected from:
the area under the MIT (MTFa) for each of the different defocus positions;
the cross correlation coefficient (X-cor) for the acquired plurality of images at each of the different defocus positions;
the weighted MIT (wMTF) for each of the different defocus positions; or
the weighted OTF (wOTF) for each of the different defocus positions.
9. The system of claim 1 , wherein the different defocus positions are between 0 D and −3.0 D.
10. The system of claim 1 , wherein the processor is configured to calculate the area under the MTF (MTFa) according to
∑
f
=
1
50
d
50
MTF
(
fd
)
,
wherein f denotes a spatial frequency in cycles per mm, and d denotes sampling size for preclinical measurement of MTF at each spatial frequency f.
11. The system of claim 1 , wherein the processor is configured to calculate the weighted MTF (wMTF) according to
∑
f
=
1
150
d
50
MTF
(
fd
)
CS
th
(
fd
)
,
wherein f denotes a spatial frequency in cycles per mm, and d denotes sampling size for preclinical measurement of MTF at each spatial frequency f.
12. The system of claim 1 , wherein the processor is configured to calculate the weighted OTF (wOTF) according to
∑
f
=
1
150
d
50
MTF
(
fd
)
CS
th
(
fd
)
cos
(
PTF
(
fd
)
)
,
wherein f denotes a spatial frequency in cycles per mm, and d denotes sampling size for preclinical measurement of MTF at each spatial frequency f.